[a-f] -> [abcdef], so that we don't assume the C locale.

[bison.git] / doc / bison.texinfo

diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index 03d3cc907dcce223ce69a7ef2ad26e7cb2f71d8f..ef803899683d708014fae3c9f5bc53b46e3d8677 100644 (file)
--- a/doc/bison.texinfo
+++ b/doc/bison.texinfo
@@ -36,30 +36,31 @@
 
 @copying
 
 
 @copying
 

-This manual is for GNU Bison (version @value{VERSION}, @value{UPDATED}),
-the GNU parser generator.
+This manual is for @acronym{GNU} Bison (version @value{VERSION},
+@value{UPDATED}), the @acronym{GNU} parser generator.

 
 Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1995, 1998,
 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document
 
 Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1995, 1998,
 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document

-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with no
-Invariant Sections, with the Front-Cover texts being ``A GNU Manual,''
-and with the Back-Cover Texts as in (a) below.  A copy of the
-license is included in the section entitled ``GNU Free Documentation
-License.''
-
-(a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
-this GNU Manual, like GNU software.  Copies published by the Free
-Software Foundation raise funds for GNU development.''
+under the terms of the @acronym{GNU} Free Documentation License,
+Version 1.1 or any later version published by the Free Software
+Foundation; with no Invariant Sections, with the Front-Cover texts
+being ``A @acronym{GNU} Manual,'' and with the Back-Cover Texts as in
+(a) below.  A copy of the license is included in the section entitled
+``@acronym{GNU} Free Documentation License.''
+
+(a) The @acronym{FSF}'s Back-Cover Text is: ``You have freedom to copy
+and modify this @acronym{GNU} Manual, like @acronym{GNU} software.
+Copies published by the Free Software Foundation raise funds for
+@acronym{GNU} development.''

 @end quotation
 @end copying
 
 @dircategory GNU programming tools
 @direntry
 @end quotation
 @end copying
 
 @dircategory GNU programming tools
 @direntry

-* bison: (bison).      GNU parser generator (yacc replacement).
+* bison: (bison).       @acronym{GNU} parser generator (Yacc replacement).

 @end direntry
 
 @ifset shorttitlepage-enabled
 @end direntry
 
 @ifset shorttitlepage-enabled


@@ -67,7 +68,7 @@ Software Foundation raise funds for GNU development.''
 @end ifset
 @titlepage
 @title Bison
 @end ifset
 @titlepage
 @title Bison

-@subtitle The YACC-compatible Parser Generator
+@subtitle The Yacc-compatible Parser Generator

 @subtitle @value{UPDATED}, Bison Version @value{VERSION}
 
 @author by Charles Donnelly and Richard Stallman
 @subtitle @value{UPDATED}, Bison Version @value{VERSION}
 
 @author by Charles Donnelly and Richard Stallman


@@ -80,7 +81,7 @@ Published by the Free Software Foundation @*
 59 Temple Place, Suite 330 @*
 Boston, MA  02111-1307  USA @*
 Printed copies are available from the Free Software Foundation.@*
 59 Temple Place, Suite 330 @*
 Boston, MA  02111-1307  USA @*
 Printed copies are available from the Free Software Foundation.@*

-ISBN 1-882114-44-2
+@acronym{ISBN} 1-882114-44-2

 @sp 2
 Cover art by Etienne Suvasa.
 @end titlepage
 @sp 2
 Cover art by Etienne Suvasa.
 @end titlepage


@@ -96,7 +97,7 @@ Cover art by Etienne Suvasa.
 @menu
 * Introduction::
 * Conditions::
 @menu
 * Introduction::
 * Conditions::

-* Copying::           The GNU General Public License says
+* Copying::           The @acronym{GNU} General Public License says

                         how you can copy and share Bison
 
 Tutorial sections:
                         how you can copy and share Bison
 
 Tutorial sections:


@@ -114,6 +115,7 @@ Reference sections:
 * Invocation::        How to run Bison (to produce the parser source file).
 * Table of Symbols::  All the keywords of the Bison language are explained.
 * Glossary::          Basic concepts are explained.
 * Invocation::        How to run Bison (to produce the parser source file).
 * Table of Symbols::  All the keywords of the Bison language are explained.
 * Glossary::          Basic concepts are explained.

+* FAQ::               Frequently Asked Questions

 * Copying This Manual::  License for copying this manual.
 * Index::             Cross-references to the text.
 
 * Copying This Manual::  License for copying this manual.
 * Index::             Cross-references to the text.
 


@@ -206,6 +208,7 @@ Bison Declarations
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.
 * Type Decl::         Declaring the choice of type for a nonterminal symbol.
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.
 * Type Decl::         Declaring the choice of type for a nonterminal symbol.

+* Destructor Decl::   Declaring how symbols are freed.

 * Expect Decl::       Suppressing warnings about shift/reduce conflicts.
 * Start Decl::        Specifying the start symbol.
 * Pure Decl::         Requesting a reentrant parser.
 * Expect Decl::       Suppressing warnings about shift/reduce conflicts.
 * Start Decl::        Specifying the start symbol.
 * Pure Decl::         Requesting a reentrant parser.


@@ -264,9 +267,12 @@ Understanding or Debugging Your Parser
 Invoking Bison
 
 * Bison Options::     All the options described in detail,
 Invoking Bison
 
 * Bison Options::     All the options described in detail,

-                       in alphabetical order by short options.
+                        in alphabetical order by short options.

 * Option Cross Key::  Alphabetical list of long options.
 * Option Cross Key::  Alphabetical list of long options.

-* VMS Invocation::    Bison command syntax on VMS.
+
+Frequently Asked Questions
+
+* Parser Stack Overflow::      Breaking the Stack Limits

 
 Copying This Manual
 
 
 Copying This Manual
 


@@ -280,7 +286,7 @@ Copying This Manual
 @cindex introduction
 
 @dfn{Bison} is a general-purpose parser generator that converts a
 @cindex introduction
 
 @dfn{Bison} is a general-purpose parser generator that converts a

-grammar description for an LALR(1) context-free grammar into a C
+grammar description for an @acronym{LALR}(1) context-free grammar into a C

 program to parse that grammar.  Once you are proficient with Bison,
 you may use it to develop a wide range of language parsers, from those
 used in simple desk calculators to complex programming languages.
 program to parse that grammar.  Once you are proficient with Bison,
 you may use it to develop a wide range of language parsers, from those
 used in simple desk calculators to complex programming languages.


@@ -305,11 +311,12 @@ This edition corresponds to version @value{VERSION} of Bison.
 @unnumbered Conditions for Using Bison
 
 As of Bison version 1.24, we have changed the distribution terms for
 @unnumbered Conditions for Using Bison
 
 As of Bison version 1.24, we have changed the distribution terms for

-@code{yyparse} to permit using Bison's output in nonfree programs.
-Formerly, Bison parsers could be used only in programs that were free
-software.
+@code{yyparse} to permit using Bison's output in nonfree programs when
+Bison is generating C code for @acronym{LALR}(1) parsers.  Formerly, these
+parsers could be used only in programs that were free software.

 
 

-The other GNU programming tools, such as the GNU C compiler, have never
+The other @acronym{GNU} programming tools, such as the @acronym{GNU} C
+compiler, have never

 had such a requirement.  They could always be used for nonfree
 software.  The reason Bison was different was not due to a special
 policy decision; it resulted from applying the usual General Public
 had such a requirement.  They could always be used for nonfree
 software.  The reason Bison was different was not due to a special
 policy decision; it resulted from applying the usual General Public


@@ -319,7 +326,8 @@ The output of the Bison utility---the Bison parser file---contains a
 verbatim copy of a sizable piece of Bison, which is the code for the
 @code{yyparse} function.  (The actions from your grammar are inserted
 into this function at one point, but the rest of the function is not
 verbatim copy of a sizable piece of Bison, which is the code for the
 @code{yyparse} function.  (The actions from your grammar are inserted
 into this function at one point, but the rest of the function is not

-changed.)  When we applied the GPL terms to the code for @code{yyparse},
+changed.)  When we applied the @acronym{GPL} terms to the code for
+@code{yyparse},

 the effect was to restrict the use of Bison output to free software.
 
 We didn't change the terms because of sympathy for people who want to
 the effect was to restrict the use of Bison output to free software.
 
 We didn't change the terms because of sympathy for people who want to


@@ -327,7 +335,15 @@ make software proprietary.  @strong{Software should be free.}  But we
 concluded that limiting Bison's use to free software was doing little to
 encourage people to make other software free.  So we decided to make the
 practical conditions for using Bison match the practical conditions for
 concluded that limiting Bison's use to free software was doing little to
 encourage people to make other software free.  So we decided to make the
 practical conditions for using Bison match the practical conditions for

-using the other GNU tools.
+using the other @acronym{GNU} tools.
+
+This exception applies only when Bison is generating C code for a
+@acronym{LALR}(1) parser; otherwise, the @acronym{GPL} terms operate
+as usual.  You can
+tell whether the exception applies to your @samp{.c} output file by
+inspecting it to see whether it says ``As a special exception, when
+this file is copied by Bison into a Bison output file, you may use
+that output file without restriction.''

 
 @include gpl.texi
 
 
 @include gpl.texi
 


@@ -369,65 +385,68 @@ can be made of a minus sign and another expression''.  Another would be,
 recursive, but there must be at least one rule which leads out of the
 recursion.
 
 recursive, but there must be at least one rule which leads out of the
 recursion.
 

-@cindex BNF
+@cindex @acronym{BNF}

 @cindex Backus-Naur form
 The most common formal system for presenting such rules for humans to read
 @cindex Backus-Naur form
 The most common formal system for presenting such rules for humans to read

-is @dfn{Backus-Naur Form} or ``BNF'', which was developed in order to
-specify the language Algol 60.  Any grammar expressed in BNF is a
-context-free grammar.  The input to Bison is essentially machine-readable
-BNF.
+is @dfn{Backus-Naur Form} or ``@acronym{BNF}'', which was developed in
+order to specify the language Algol 60.  Any grammar expressed in
+@acronym{BNF} is a context-free grammar.  The input to Bison is
+essentially machine-readable @acronym{BNF}.

 
 

-@cindex LALR(1) grammars
-@cindex LR(1) grammars
+@cindex @acronym{LALR}(1) grammars
+@cindex @acronym{LR}(1) grammars

 There are various important subclasses of context-free grammar.  Although it
 can handle almost all context-free grammars, Bison is optimized for what
 There are various important subclasses of context-free grammar.  Although it
 can handle almost all context-free grammars, Bison is optimized for what

-are called LALR(1) grammars.
+are called @acronym{LALR}(1) grammars.

 In brief, in these grammars, it must be possible to
 tell how to parse any portion of an input string with just a single
 token of look-ahead.  Strictly speaking, that is a description of an
 In brief, in these grammars, it must be possible to
 tell how to parse any portion of an input string with just a single
 token of look-ahead.  Strictly speaking, that is a description of an

-LR(1) grammar, and LALR(1) involves additional restrictions that are
+@acronym{LR}(1) grammar, and @acronym{LALR}(1) involves additional
+restrictions that are

 hard to explain simply; but it is rare in actual practice to find an
 hard to explain simply; but it is rare in actual practice to find an

-LR(1) grammar that fails to be LALR(1).  @xref{Mystery Conflicts, ,
-Mysterious Reduce/Reduce Conflicts}, for more information on this.
+@acronym{LR}(1) grammar that fails to be @acronym{LALR}(1).
+@xref{Mystery Conflicts, ,Mysterious Reduce/Reduce Conflicts}, for
+more information on this.

 
 

-@cindex GLR parsing
-@cindex generalized LR (GLR) parsing
+@cindex @acronym{GLR} parsing
+@cindex generalized @acronym{LR} (@acronym{GLR}) parsing

 @cindex ambiguous grammars
 @cindex non-deterministic parsing
 @cindex ambiguous grammars
 @cindex non-deterministic parsing

-Parsers for LALR(1) grammars are @dfn{deterministic}, meaning roughly that
-the next grammar rule to apply at any point in the input is uniquely
-determined by the preceding input and a fixed, finite portion (called
-a @dfn{look-ahead}) of the remaining input.
-A context-free grammar can be @dfn{ambiguous}, meaning that
-there are multiple ways to apply the grammar rules to get the some inputs.
-Even unambiguous grammars can be @dfn{non-deterministic}, meaning that no
-fixed look-ahead always suffices to determine the next grammar rule to apply.
-With the proper declarations, Bison is also able to parse these more general
-context-free grammars, using a technique known as GLR parsing (for
-Generalized LR).  Bison's GLR parsers are able to handle any context-free
-grammar for which the number of possible parses of any given string
-is finite.
+
+Parsers for @acronym{LALR}(1) grammars are @dfn{deterministic}, meaning
+roughly that the next grammar rule to apply at any point in the input is
+uniquely determined by the preceding input and a fixed, finite portion
+(called a @dfn{look-ahead}) of the remaining input.  A context-free
+grammar can be @dfn{ambiguous}, meaning that there are multiple ways to
+apply the grammar rules to get the some inputs.  Even unambiguous
+grammars can be @dfn{non-deterministic}, meaning that no fixed
+look-ahead always suffices to determine the next grammar rule to apply.
+With the proper declarations, Bison is also able to parse these more
+general context-free grammars, using a technique known as @acronym{GLR}
+parsing (for Generalized @acronym{LR}).  Bison's @acronym{GLR} parsers
+are able to handle any context-free grammar for which the number of
+possible parses of any given string is finite.

 
 @cindex symbols (abstract)
 @cindex token
 @cindex syntactic grouping
 @cindex grouping, syntactic
 
 @cindex symbols (abstract)
 @cindex token
 @cindex syntactic grouping
 @cindex grouping, syntactic

-In the formal grammatical rules for a language, each kind of syntactic unit
-or grouping is named by a @dfn{symbol}.  Those which are built by grouping
-smaller constructs according to grammatical rules are called
+In the formal grammatical rules for a language, each kind of syntactic
+unit or grouping is named by a @dfn{symbol}.  Those which are built by
+grouping smaller constructs according to grammatical rules are called

 @dfn{nonterminal symbols}; those which can't be subdivided are called
 @dfn{terminal symbols} or @dfn{token types}.  We call a piece of input
 corresponding to a single terminal symbol a @dfn{token}, and a piece
 corresponding to a single nonterminal symbol a @dfn{grouping}.
 
 We can use the C language as an example of what symbols, terminal and
 @dfn{nonterminal symbols}; those which can't be subdivided are called
 @dfn{terminal symbols} or @dfn{token types}.  We call a piece of input
 corresponding to a single terminal symbol a @dfn{token}, and a piece
 corresponding to a single nonterminal symbol a @dfn{grouping}.
 
 We can use the C language as an example of what symbols, terminal and

-nonterminal, mean.  The tokens of C are identifiers, constants (numeric and
-string), and the various keywords, arithmetic operators and punctuation
-marks.  So the terminal symbols of a grammar for C include `identifier',
-`number', `string', plus one symbol for each keyword, operator or
-punctuation mark: `if', `return', `const', `static', `int', `char',
-`plus-sign', `open-brace', `close-brace', `comma' and many more.  (These
-tokens can be subdivided into characters, but that is a matter of
+nonterminal, mean.  The tokens of C are identifiers, constants (numeric
+and string), and the various keywords, arithmetic operators and
+punctuation marks.  So the terminal symbols of a grammar for C include
+`identifier', `number', `string', plus one symbol for each keyword,
+operator or punctuation mark: `if', `return', `const', `static', `int',
+`char', `plus-sign', `open-brace', `close-brace', `comma' and many more.
+(These tokens can be subdivided into characters, but that is a matter of

 lexicography, not grammar.)
 
 Here is a simple C function subdivided into tokens:
 lexicography, not grammar.)
 
 Here is a simple C function subdivided into tokens:


@@ -506,7 +525,7 @@ for Bison, you must write a file expressing the grammar in Bison syntax:
 a @dfn{Bison grammar} file.  @xref{Grammar File, ,Bison Grammar Files}.
 
 A nonterminal symbol in the formal grammar is represented in Bison input
 a @dfn{Bison grammar} file.  @xref{Grammar File, ,Bison Grammar Files}.
 
 A nonterminal symbol in the formal grammar is represented in Bison input

-as an identifier, like an identifier in C.  By convention, it should be
+as an identifier, like an identifier in C@.  By convention, it should be

 in lower case, such as @code{expr}, @code{stmt} or @code{declaration}.
 
 The Bison representation for a terminal symbol is also called a @dfn{token
 in lower case, such as @code{expr}, @code{stmt} or @code{declaration}.
 
 The Bison representation for a terminal symbol is also called a @dfn{token


@@ -555,7 +574,8 @@ grammatical.
 But the precise value is very important for what the input means once it is
 parsed.  A compiler is useless if it fails to distinguish between 4, 1 and
 3989 as constants in the program!  Therefore, each token in a Bison grammar
 But the precise value is very important for what the input means once it is
 parsed.  A compiler is useless if it fails to distinguish between 4, 1 and
 3989 as constants in the program!  Therefore, each token in a Bison grammar

-has both a token type and a @dfn{semantic value}.  @xref{Semantics, ,Defining Language Semantics},
+has both a token type and a @dfn{semantic value}.  @xref{Semantics,
+,Defining Language Semantics},

 for details.
 
 The token type is a terminal symbol defined in the grammar, such as
 for details.
 
 The token type is a terminal symbol defined in the grammar, such as


@@ -614,33 +634,35 @@ The action says how to produce the semantic value of the sum expression
 from the values of the two subexpressions.
 
 @node GLR Parsers
 from the values of the two subexpressions.
 
 @node GLR Parsers

-@section Writing GLR Parsers
-@cindex GLR parsing
-@cindex generalized LR (GLR) parsing
+@section Writing @acronym{GLR} Parsers
+@cindex @acronym{GLR} parsing
+@cindex generalized @acronym{LR} (@acronym{GLR}) parsing

 @findex %glr-parser
 @cindex conflicts
 @cindex shift/reduce conflicts
 
 @findex %glr-parser
 @cindex conflicts
 @cindex shift/reduce conflicts
 

-In some grammars, there will be cases where Bison's standard LALR(1)
-parsing algorithm cannot decide whether to apply a certain grammar rule
-at a given point.  That is, it may not be able to decide (on the basis
-of the input read so far) which of two possible reductions (applications
-of a grammar rule) applies, or whether to apply a reduction or read more
-of the input and apply a reduction later in the input.  These are known
-respectively as @dfn{reduce/reduce} conflicts (@pxref{Reduce/Reduce}),
-and @dfn{shift/reduce} conflicts (@pxref{Shift/Reduce}).
-
-To use a grammar that is not easily modified to be LALR(1), a more
-general parsing algorithm is sometimes necessary.  If you include
+In some grammars, there will be cases where Bison's standard
+@acronym{LALR}(1) parsing algorithm cannot decide whether to apply a
+certain grammar rule at a given point.  That is, it may not be able to
+decide (on the basis of the input read so far) which of two possible
+reductions (applications of a grammar rule) applies, or whether to apply
+a reduction or read more of the input and apply a reduction later in the
+input.  These are known respectively as @dfn{reduce/reduce} conflicts
+(@pxref{Reduce/Reduce}), and @dfn{shift/reduce} conflicts
+(@pxref{Shift/Reduce}).
+
+To use a grammar that is not easily modified to be @acronym{LALR}(1), a
+more general parsing algorithm is sometimes necessary.  If you include

 @code{%glr-parser} among the Bison declarations in your file
 @code{%glr-parser} among the Bison declarations in your file

-(@pxref{Grammar Outline}), the result will be a Generalized LR (GLR)
-parser.  These parsers handle Bison grammars that contain no unresolved
-conflicts (i.e., after applying precedence declarations) identically to
-LALR(1) parsers.  However, when faced with unresolved shift/reduce and
-reduce/reduce conflicts, GLR parsers use the simple expedient of doing
-both, effectively cloning the parser to follow both possibilities.  Each
-of the resulting parsers can again split, so that at any given time,
-there can be any number of possible parses being explored.  The parsers
+(@pxref{Grammar Outline}), the result will be a Generalized @acronym{LR}
+(@acronym{GLR}) parser.  These parsers handle Bison grammars that
+contain no unresolved conflicts (i.e., after applying precedence
+declarations) identically to @acronym{LALR}(1) parsers.  However, when
+faced with unresolved shift/reduce and reduce/reduce conflicts,
+@acronym{GLR} parsers use the simple expedient of doing both,
+effectively cloning the parser to follow both possibilities.  Each of
+the resulting parsers can again split, so that at any given time, there
+can be any number of possible parses being explored.  The parsers

 proceed in lockstep; that is, all of them consume (shift) a given input
 symbol before any of them proceed to the next.  Each of the cloned
 parsers eventually meets one of two possible fates: either it runs into
 proceed in lockstep; that is, all of them consume (shift) a given input
 symbol before any of them proceed to the next.  Each of the cloned
 parsers eventually meets one of two possible fates: either it runs into


@@ -659,7 +681,7 @@ involved, or by performing both actions, and then calling a designated
 user-defined function on the resulting values to produce an arbitrary
 merged result.
 
 user-defined function on the resulting values to produce an arbitrary
 merged result.
 

-Let's consider an example, vastly simplified from C++.
+Let's consider an example, vastly simplified from a C++ grammar.

 
 @example
 %@{
 
 @example
 %@{


@@ -683,20 +705,20 @@ stmt : expr ';'  %dprec 1
      | decl      %dprec 2
      ;
 
      | decl      %dprec 2
      ;
 

-expr : ID              @{ printf ("%s ", $$); @}
+expr : ID               @{ printf ("%s ", $$); @}

      | TYPENAME '(' expr ')'
      | TYPENAME '(' expr ')'

-                       @{ printf ("%s <cast> ", $1); @}
-     | expr '+' expr   @{ printf ("+ "); @}
-     | expr '=' expr   @{ printf ("= "); @}
+                        @{ printf ("%s <cast> ", $1); @}
+     | expr '+' expr    @{ printf ("+ "); @}
+     | expr '=' expr    @{ printf ("= "); @}

      ;
 
 decl : TYPENAME declarator ';'
      ;
 
 decl : TYPENAME declarator ';'

-                       @{ printf ("%s <declare> ", $1); @}
+                        @{ printf ("%s <declare> ", $1); @}

      | TYPENAME declarator '=' expr ';'
      | TYPENAME declarator '=' expr ';'

-                       @{ printf ("%s <init-declare> ", $1); @}
+                        @{ printf ("%s <init-declare> ", $1); @}

      ;
 
      ;
 

-declarator : ID                @{ printf ("\"%s\" ", $1); @}
+declarator : ID         @{ printf ("\"%s\" ", $1); @}

      | '(' declarator ')'
      ;
 @end example
      | '(' declarator ')'
      ;
 @end example


@@ -711,7 +733,8 @@ T (x) = y+z;
 
 @noindent
 parses as either an @code{expr} or a @code{stmt}
 
 @noindent
 parses as either an @code{expr} or a @code{stmt}

-(assuming that @samp{T} is recognized as a TYPENAME and @samp{x} as an ID).
+(assuming that @samp{T} is recognized as a @code{TYPENAME} and
+@samp{x} as an @code{ID}).

 Bison detects this as a reduce/reduce conflict between the rules
 @code{expr : ID} and @code{declarator : ID}, which it cannot resolve at the
 time it encounters @code{x} in the example above.  The two @code{%dprec}
 Bison detects this as a reduce/reduce conflict between the rules
 @code{expr : ID} and @code{declarator : ID}, which it cannot resolve at the
 time it encounters @code{x} in the example above.  The two @code{%dprec}


@@ -786,6 +809,32 @@ as both an @code{expr} and a @code{decl}, and print
 "x" y z + T <init-declare> x T <cast> y z + = <OR>
 @end example
 
 "x" y z + T <init-declare> x T <cast> y z + = <OR>
 @end example
 

+@sp 1
+
+@cindex @code{incline}
+@cindex @acronym{GLR} parsers and @code{inline}
+Note that the @acronym{GLR} parsers require an ISO C89 compiler.  In
+addition, they use the @code{inline} keyword, which is not C89, but a
+common extension.  It is up to the user of these parsers to handle
+portability issues.  For instance, if using Autoconf and the Autoconf
+macro @code{AC_C_INLINE}, a mere
+
+@example
+%@{
+#include <config.h>
+%@}
+@end example
+
+@noindent
+will suffice.  Otherwise, we suggest
+
+@example
+%@{
+#if ! defined __GNUC__ && ! defined inline
+# define inline
+#endif
+%@}
+@end example

 
 @node Locations Overview
 @section Locations
 
 @node Locations Overview
 @section Locations


@@ -794,25 +843,25 @@ as both an @code{expr} and a @code{decl}, and print
 @cindex position, textual
 
 Many applications, like interpreters or compilers, have to produce verbose
 @cindex position, textual
 
 Many applications, like interpreters or compilers, have to produce verbose

-and useful error messages. To achieve this, one must be able to keep track of
+and useful error messages.  To achieve this, one must be able to keep track of

 the @dfn{textual position}, or @dfn{location}, of each syntactic construct.
 Bison provides a mechanism for handling these locations.
 
 the @dfn{textual position}, or @dfn{location}, of each syntactic construct.
 Bison provides a mechanism for handling these locations.
 

-Each token has a semantic value. In a similar fashion, each token has an
+Each token has a semantic value.  In a similar fashion, each token has an

 associated location, but the type of locations is the same for all tokens and
 associated location, but the type of locations is the same for all tokens and

-groupings. Moreover, the output parser is equipped with a default data
+groupings.  Moreover, the output parser is equipped with a default data

 structure for storing locations (@pxref{Locations}, for more details).
 
 Like semantic values, locations can be reached in actions using a dedicated
 structure for storing locations (@pxref{Locations}, for more details).
 
 Like semantic values, locations can be reached in actions using a dedicated

-set of constructs. In the example above, the location of the whole grouping
+set of constructs.  In the example above, the location of the whole grouping

 is @code{@@$}, while the locations of the subexpressions are @code{@@1} and
 @code{@@3}.
 
 When a rule is matched, a default action is used to compute the semantic value
 is @code{@@$}, while the locations of the subexpressions are @code{@@1} and
 @code{@@3}.
 
 When a rule is matched, a default action is used to compute the semantic value

-of its left hand side (@pxref{Actions}). In the same way, another default
-action is used for locations. However, the action for locations is general
+of its left hand side (@pxref{Actions}).  In the same way, another default
+action is used for locations.  However, the action for locations is general

 enough for most cases, meaning there is usually no need to describe for each
 enough for most cases, meaning there is usually no need to describe for each

-rule how @code{@@$} should be formed. When building a new location for a given
+rule how @code{@@$} should be formed.  When building a new location for a given

 grouping, the default behavior of the output parser is to take the beginning
 of the first symbol, and the end of the last symbol.
 
 grouping, the default behavior of the output parser is to take the beginning
 of the first symbol, and the end of the last symbol.
 


@@ -864,7 +913,7 @@ this manual.
 
 In some cases the Bison parser file includes system headers, and in
 those cases your code should respect the identifiers reserved by those
 
 In some cases the Bison parser file includes system headers, and in
 those cases your code should respect the identifiers reserved by those

-headers.  On some non-@sc{gnu} hosts, @code{<alloca.h>},
+headers.  On some non-@acronym{GNU} hosts, @code{<alloca.h>},

 @code{<stddef.h>}, and @code{<stdlib.h>} are included as needed to
 declare memory allocators and related types.  Other system headers may
 be included if you define @code{YYDEBUG} to a nonzero value
 @code{<stddef.h>}, and @code{<stdlib.h>} are included as needed to
 declare memory allocators and related types.  Other system headers may
 be included if you define @code{YYDEBUG} to a nonzero value


@@ -940,7 +989,7 @@ general form of a Bison grammar file is as follows:
 The @samp{%%}, @samp{%@{} and @samp{%@}} are punctuation that appears
 in every Bison grammar file to separate the sections.
 
 The @samp{%%}, @samp{%@{} and @samp{%@}} are punctuation that appears
 in every Bison grammar file to separate the sections.
 

-The prologue may define types and variables used in the actions. You can
+The prologue may define types and variables used in the actions.  You can

 also use preprocessor commands to define macros used there, and use
 @code{#include} to include header files that do any of these things.
 
 also use preprocessor commands to define macros used there, and use
 @code{#include} to include header files that do any of these things.
 


@@ -951,7 +1000,7 @@ semantic values of various symbols.
 The grammar rules define how to construct each nonterminal symbol from its
 parts.
 
 The grammar rules define how to construct each nonterminal symbol from its
 parts.
 

-The epilogue can contain any code you want to use. Often the definition of
+The epilogue can contain any code you want to use.  Often the definition of

 the lexical analyzer @code{yylex} goes here, plus subroutines called by the
 actions in the grammar rules.  In a simple program, all the rest of the
 program can go here.
 the lexical analyzer @code{yylex} goes here, plus subroutines called by the
 actions in the grammar rules.  In a simple program, all the rest of the
 program can go here.


@@ -1018,7 +1067,7 @@ Here are the C and Bison declarations for the reverse polish notation
 calculator.  As in C, comments are placed between @samp{/*@dots{}*/}.
 
 @example
 calculator.  As in C, comments are placed between @samp{/*@dots{}*/}.
 
 @example

-/* Reverse polish notation calculator. */
+/* Reverse polish notation calculator.  */

 
 %@{
 #define YYSTYPE double
 
 %@{
 #define YYSTYPE double


@@ -1027,7 +1076,7 @@ calculator.  As in C, comments are placed between @samp{/*@dots{}*/}.
 
 %token NUM
 
 
 %token NUM
 

-%% /* Grammar rules and actions follow */
+%% /* Grammar rules and actions follow.  */

 @end example
 
 The declarations section (@pxref{Prologue, , The prologue}) contains two
 @end example
 
 The declarations section (@pxref{Prologue, , The prologue}) contains two


@@ -1064,18 +1113,18 @@ input:    /* empty */
 ;
 
 line:     '\n'
 ;
 
 line:     '\n'

-        | exp '\n'  @{ printf ("\t%.10g\n", $1); @}
+        | exp '\n'      @{ printf ("\t%.10g\n", $1); @}

 ;
 
 ;
 

-exp:      NUM             @{ $$ = $1;         @}
-        | exp exp '+'     @{ $$ = $1 + $2;    @}
-        | exp exp '-'     @{ $$ = $1 - $2;    @}
-        | exp exp '*'     @{ $$ = $1 * $2;    @}
-        | exp exp '/'     @{ $$ = $1 / $2;    @}
-      /* Exponentiation */
-        | exp exp '^'     @{ $$ = pow ($1, $2); @}
-      /* Unary minus    */
-        | exp 'n'         @{ $$ = -$1;        @}
+exp:      NUM           @{ $$ = $1;           @}
+        | exp exp '+'   @{ $$ = $1 + $2;      @}
+        | exp exp '-'   @{ $$ = $1 - $2;      @}
+        | exp exp '*'   @{ $$ = $1 * $2;      @}
+        | exp exp '/'   @{ $$ = $1 / $2;      @}
+         /* Exponentiation */
+        | exp exp '^'   @{ $$ = pow ($1, $2); @}
+         /* Unary minus    */
+        | exp 'n'       @{ $$ = -$1;          @}

 ;
 %%
 @end example
 ;
 %%
 @end example


@@ -1136,7 +1185,7 @@ more times.
 
 The parser function @code{yyparse} continues to process input until a
 grammatical error is seen or the lexical analyzer says there are no more
 
 The parser function @code{yyparse} continues to process input until a
 grammatical error is seen or the lexical analyzer says there are no more

-input tokens; we will arrange for the latter to happen at end of file.
+input tokens; we will arrange for the latter to happen at end-of-input.

 
 @node Rpcalc Line
 @subsubsection Explanation of @code{line}
 
 @node Rpcalc Line
 @subsubsection Explanation of @code{line}


@@ -1203,7 +1252,7 @@ action, Bison by default copies the value of @code{$1} into @code{$$}.
 This is what happens in the first rule (the one that uses @code{NUM}).
 
 The formatting shown here is the recommended convention, but Bison does
 This is what happens in the first rule (the one that uses @code{NUM}).
 
 The formatting shown here is the recommended convention, but Bison does

-not require it.  You can add or change whitespace as much as you wish.
+not require it.  You can add or change white space as much as you wish.

 For example, this:
 
 @example
 For example, this:
 
 @example


@@ -1232,7 +1281,8 @@ or sequences of characters into tokens.  The Bison parser gets its
 tokens by calling the lexical analyzer.  @xref{Lexical, ,The Lexical
 Analyzer Function @code{yylex}}.
 
 tokens by calling the lexical analyzer.  @xref{Lexical, ,The Lexical
 Analyzer Function @code{yylex}}.
 

-Only a simple lexical analyzer is needed for the RPN calculator.  This
+Only a simple lexical analyzer is needed for the @acronym{RPN}
+calculator.  This

 lexical analyzer skips blanks and tabs, then reads in numbers as
 @code{double} and returns them as @code{NUM} tokens.  Any other character
 that isn't part of a number is a separate token.  Note that the token-code
 lexical analyzer skips blanks and tabs, then reads in numbers as
 @code{double} and returns them as @code{NUM} tokens.  Any other character
 that isn't part of a number is a separate token.  Note that the token-code


@@ -1254,18 +1304,17 @@ for it.  (The C data type of @code{yylval} is @code{YYSTYPE}, which was
 defined at the beginning of the grammar; @pxref{Rpcalc Decls,
 ,Declarations for @code{rpcalc}}.)
 
 defined at the beginning of the grammar; @pxref{Rpcalc Decls,
 ,Declarations for @code{rpcalc}}.)
 

-A token type code of zero is returned if the end-of-file is encountered.
-(Bison recognizes any nonpositive value as indicating the end of the
-input.)
+A token type code of zero is returned if the end-of-input is encountered.
+(Bison recognizes any nonpositive value as indicating end-of-input.)

 
 Here is the code for the lexical analyzer:
 
 @example
 @group
 
 Here is the code for the lexical analyzer:
 
 @example
 @group

-/* Lexical analyzer returns a double floating point
+/* The lexical analyzer returns a double floating point

    number on the stack and the token NUM, or the numeric code
    number on the stack and the token NUM, or the numeric code

-   of the character read if not a number.  Skips all blanks
-   and tabs, returns 0 for EOF. */
+   of the character read if not a number.  It skips all blanks
+   and tabs, and returns 0 for end-of-input.  */

 
 #include <ctype.h>
 @end group
 
 #include <ctype.h>
 @end group


@@ -1276,12 +1325,12 @@ yylex (void)
 @{
   int c;
 
 @{
   int c;
 

-  /* skip white space  */
+  /* Skip white space.  */

   while ((c = getchar ()) == ' ' || c == '\t')
     ;
 @end group
 @group
   while ((c = getchar ()) == ' ' || c == '\t')
     ;
 @end group
 @group

-  /* process numbers   */
+  /* Process numbers.  */

   if (c == '.' || isdigit (c))
     @{
       ungetc (c, stdin);
   if (c == '.' || isdigit (c))
     @{
       ungetc (c, stdin);


@@ -1290,10 +1339,10 @@ yylex (void)
     @}
 @end group
 @group
     @}
 @end group
 @group

-  /* return end-of-file  */
+  /* Return end-of-input.  */

   if (c == EOF)
     return 0;
   if (c == EOF)
     return 0;

-  /* return single chars */
+  /* Return a single char.  */

   return c;
 @}
 @end group
   return c;
 @}
 @end group


@@ -1324,7 +1373,7 @@ main (void)
 
 When @code{yyparse} detects a syntax error, it calls the error reporting
 function @code{yyerror} to print an error message (usually but not
 
 When @code{yyparse} detects a syntax error, it calls the error reporting
 function @code{yyerror} to print an error message (usually but not

-always @code{"parse error"}).  It is up to the programmer to supply
+always @code{"syntax error"}).  It is up to the programmer to supply

 @code{yyerror} (@pxref{Interface, ,Parser C-Language Interface}), so
 here is the definition we will use:
 
 @code{yyerror} (@pxref{Interface, ,Parser C-Language Interface}), so
 here is the definition we will use:
 


@@ -1333,7 +1382,7 @@ here is the definition we will use:
 #include <stdio.h>
 
 void
 #include <stdio.h>
 
 void

-yyerror (const char *s)  /* Called by yyparse on error */
+yyerror (const char *s)  /* Called by yyparse on error.  */

 @{
   printf ("%s\n", s);
 @}
 @{
   printf ("%s\n", s);
 @}


@@ -1370,8 +1419,8 @@ bison @var{file_name}.y
 
 @noindent
 In this example the file was called @file{rpcalc.y} (for ``Reverse Polish
 
 @noindent
 In this example the file was called @file{rpcalc.y} (for ``Reverse Polish

-CALCulator'').  Bison produces a file named @file{@var{file_name}.tab.c},
-removing the @samp{.y} from the original file name. The file output by
+@sc{calc}ulator'').  Bison produces a file named @file{@var{file_name}.tab.c},
+removing the @samp{.y} from the original file name.  The file output by

 Bison contains the source code for @code{yyparse}.  The additional
 functions in the input file (@code{yylex}, @code{yyerror} and @code{main})
 are copied verbatim to the output.
 Bison contains the source code for @code{yyparse}.  The additional
 functions in the input file (@code{yylex}, @code{yyerror} and @code{main})
 are copied verbatim to the output.


@@ -1392,7 +1441,7 @@ rpcalc.tab.c  rpcalc.y
 @group
 # @r{Compile the Bison parser.}
 # @r{@samp{-lm} tells compiler to search math library for @code{pow}.}
 @group
 # @r{Compile the Bison parser.}
 # @r{@samp{-lm} tells compiler to search math library for @code{pow}.}

-$ @kbd{cc rpcalc.tab.c -lm -o rpcalc}
+$ @kbd{cc -lm -o rpcalc rpcalc.tab.c}

 @end group
 
 @group
 @end group
 
 @group


@@ -1440,7 +1489,7 @@ parentheses nested to arbitrary depth.  Here is the Bison code for
 #include <math.h>
 %@}
 
 #include <math.h>
 %@}
 

-/* BISON Declarations */
+/* Bison Declarations */

 %token NUM
 %left '-' '+'
 %left '*' '/'
 %token NUM
 %left '-' '+'
 %left '*' '/'


@@ -1534,7 +1583,7 @@ line:     '\n'
 @end example
 
 This addition to the grammar allows for simple error recovery in the
 @end example
 
 This addition to the grammar allows for simple error recovery in the

-event of a parse error.  If an expression that cannot be evaluated is
+event of a syntax error.  If an expression that cannot be evaluated is

 read, the error will be recognized by the third rule for @code{line},
 and parsing will continue.  (The @code{yyerror} function is still called
 upon to print its message as well.)  The action executes the statement
 read, the error will be recognized by the third rule for @code{line},
 and parsing will continue.  (The @code{yyerror} function is still called
 upon to print its message as well.)  The action executes the statement


@@ -1561,7 +1610,7 @@ This example extends the infix notation calculator with location
 tracking.  This feature will be used to improve the error messages.  For
 the sake of clarity, this example is a simple integer calculator, since
 most of the work needed to use locations will be done in the lexical
 tracking.  This feature will be used to improve the error messages.  For
 the sake of clarity, this example is a simple integer calculator, since
 most of the work needed to use locations will be done in the lexical

-analyser.
+analyzer.

 
 @menu
 * Decls: Ltcalc Decls.  Bison and C declarations for ltcalc.
 
 @menu
 * Decls: Ltcalc Decls.  Bison and C declarations for ltcalc.


@@ -1669,7 +1718,7 @@ hand.
 @subsection The @code{ltcalc} Lexical Analyzer.
 
 Until now, we relied on Bison's defaults to enable location
 @subsection The @code{ltcalc} Lexical Analyzer.
 
 Until now, we relied on Bison's defaults to enable location

-tracking. The next step is to rewrite the lexical analyser, and make it
+tracking.  The next step is to rewrite the lexical analyzer, and make it

 able to feed the parser with the token locations, as it already does for
 semantic values.
 
 able to feed the parser with the token locations, as it already does for
 semantic values.
 


@@ -1682,18 +1731,22 @@ int
 yylex (void)
 @{
   int c;
 yylex (void)
 @{
   int c;

+@end group

 
 

-  /* skip white space */
+@group
+  /* Skip white space.  */

   while ((c = getchar ()) == ' ' || c == '\t')
     ++yylloc.last_column;
   while ((c = getchar ()) == ' ' || c == '\t')
     ++yylloc.last_column;

+@end group

 
 

-  /* step */
+@group
+  /* Step.  */

   yylloc.first_line = yylloc.last_line;
   yylloc.first_column = yylloc.last_column;
 @end group
 
 @group
   yylloc.first_line = yylloc.last_line;
   yylloc.first_column = yylloc.last_column;
 @end group
 
 @group

-  /* process numbers */
+  /* Process numbers.  */

   if (isdigit (c))
     @{
       yylval = c - '0';
   if (isdigit (c))
     @{
       yylval = c - '0';


@@ -1708,11 +1761,11 @@ yylex (void)
     @}
 @end group
 
     @}
 @end group
 

-  /* return end-of-file */
+  /* Return end-of-input.  */

   if (c == EOF)
     return 0;
 
   if (c == EOF)
     return 0;
 

-  /* return single chars and update location */
+  /* Return a single char, and update location.  */

   if (c == '\n')
     @{
       ++yylloc.last_line;
   if (c == '\n')
     @{
       ++yylloc.last_line;


@@ -1730,7 +1783,7 @@ In addition, it updates @code{yylloc}, the global variable (of type
 @code{YYLTYPE}) containing the token's location.
 
 Now, each time this function returns a token, the parser has its number
 @code{YYLTYPE}) containing the token's location.
 
 Now, each time this function returns a token, the parser has its number

-as well as its semantic value, and its location in the text. The last
+as well as its semantic value, and its location in the text.  The last

 needed change is to initialize @code{yylloc}, for example in the
 controlling function:
 
 needed change is to initialize @code{yylloc}, for example in the
 controlling function:
 


@@ -1808,27 +1861,30 @@ Note that multiple assignment and nested function calls are permitted.
 Here are the C and Bison declarations for the multi-function calculator.
 
 @smallexample
 Here are the C and Bison declarations for the multi-function calculator.
 
 @smallexample

+@group

 %@{
 %@{

-#include <math.h>  /* For math functions, cos(), sin(), etc. */
-#include "calc.h"  /* Contains definition of `symrec'        */
+#include <math.h>  /* For math functions, cos(), sin(), etc.  */
+#include "calc.h"  /* Contains definition of `symrec'         */

 %@}
 %@}

+@end group
+@group

 %union @{
 %union @{

-double     val;  /* For returning numbers.                   */
-symrec  *tptr;   /* For returning symbol-table pointers      */
+  double    val;   /* For returning numbers.                  */
+  symrec  *tptr;   /* For returning symbol-table pointers.    */

 @}
 @}

-
-%token <val>  NUM        /* Simple double precision number   */
-%token <tptr> VAR FNCT   /* Variable and Function            */
+@end group
+%token <val>  NUM        /* Simple double precision number.   */
+%token <tptr> VAR FNCT   /* Variable and Function.            */

 %type  <val>  exp
 
 %type  <val>  exp
 

+@group

 %right '='
 %left '-' '+'
 %left '*' '/'
 %left NEG     /* Negation--unary minus */
 %right '^'    /* Exponentiation        */
 %right '='
 %left '-' '+'
 %left '*' '/'
 %left NEG     /* Negation--unary minus */
 %right '^'    /* Exponentiation        */

-
+@end group

 /* Grammar follows */
 /* Grammar follows */

-

 %%
 @end smallexample
 
 %%
 @end smallexample
 


@@ -1862,16 +1918,21 @@ Most of them are copied directly from @code{calc}; three rules,
 those which mention @code{VAR} or @code{FNCT}, are new.
 
 @smallexample
 those which mention @code{VAR} or @code{FNCT}, are new.
 
 @smallexample

+@group

 input:   /* empty */
         | input line
 ;
 input:   /* empty */
         | input line
 ;

+@end group

 
 

+@group

 line:
           '\n'
         | exp '\n'   @{ printf ("\t%.10g\n", $1); @}
         | error '\n' @{ yyerrok;                  @}
 ;
 line:
           '\n'
         | exp '\n'   @{ printf ("\t%.10g\n", $1); @}
         | error '\n' @{ yyerrok;                  @}
 ;

+@end group

 
 

+@group

 exp:      NUM                @{ $$ = $1;                         @}
         | VAR                @{ $$ = $1->value.var;              @}
         | VAR '=' exp        @{ $$ = $3; $1->value.var = $3;     @}
 exp:      NUM                @{ $$ = $1;                         @}
         | VAR                @{ $$ = $1->value.var;              @}
         | VAR '=' exp        @{ $$ = $3; $1->value.var = $3;     @}


@@ -1884,6 +1945,7 @@ exp:      NUM                @{ $$ = $1;                         @}
         | exp '^' exp        @{ $$ = pow ($1, $3);               @}
         | '(' exp ')'        @{ $$ = $2;                         @}
 ;
         | exp '^' exp        @{ $$ = pow ($1, $3);               @}
         | '(' exp ')'        @{ $$ = $2;                         @}
 ;

+@end group

 /* End of grammar */
 %%
 @end smallexample
 /* End of grammar */
 %%
 @end smallexample


@@ -1903,9 +1965,11 @@ provides for either functions or variables to be placed in the table.
 
 @smallexample
 @group
 
 @smallexample
 @group

-/* Fonctions type.                                   */
+/* Function type.                                    */

 typedef double (*func_t) (double);
 typedef double (*func_t) (double);

+@end group

 
 

+@group

 /* Data type for links in the chain of symbols.      */
 struct symrec
 @{
 /* Data type for links in the chain of symbols.      */
 struct symrec
 @{


@@ -1936,9 +2000,9 @@ function that initializes the symbol table.  Here it is, and
 @code{init_table} as well:
 
 @smallexample
 @code{init_table} as well:
 
 @smallexample

-@group

 #include <stdio.h>
 
 #include <stdio.h>
 

+@group

 int
 main (void)
 @{
 int
 main (void)
 @{


@@ -1949,11 +2013,13 @@ main (void)
 
 @group
 void
 
 @group
 void

-yyerror (const char *s)  /* Called by yyparse on error */
+yyerror (const char *s)  /* Called by yyparse on error.  */

 @{
   printf ("%s\n", s);
 @}
 @{
   printf ("%s\n", s);
 @}

+@end group

 
 

+@group

 struct init
 @{
   char *fname;
 struct init
 @{
   char *fname;


@@ -1972,13 +2038,15 @@ struct init arith_fncts[] =
   "sqrt", sqrt,
   0, 0
 @};
   "sqrt", sqrt,
   0, 0
 @};

+@end group

 
 

+@group

 /* The symbol table: a chain of `struct symrec'.  */
 symrec *sym_table = (symrec *) 0;
 @end group
 
 @group
 /* The symbol table: a chain of `struct symrec'.  */
 symrec *sym_table = (symrec *) 0;
 @end group
 
 @group

-/* Put arithmetic functions in table. */
+/* Put arithmetic functions in table.  */

 void
 init_table (void)
 @{
 void
 init_table (void)
 @{


@@ -2012,7 +2080,7 @@ putsym (char *sym_name, int sym_type)
   ptr->name = (char *) malloc (strlen (sym_name) + 1);
   strcpy (ptr->name,sym_name);
   ptr->type = sym_type;
   ptr->name = (char *) malloc (strlen (sym_name) + 1);
   strcpy (ptr->name,sym_name);
   ptr->type = sym_type;

-  ptr->value.var = 0; /* set value to 0 even if fctn.  */
+  ptr->value.var = 0; /* Set value to 0 even if fctn.  */

   ptr->next = (struct symrec *)sym_table;
   sym_table = ptr;
   return ptr;
   ptr->next = (struct symrec *)sym_table;
   sym_table = ptr;
   return ptr;


@@ -2048,13 +2116,15 @@ operators in @code{yylex}.
 @smallexample
 @group
 #include <ctype.h>
 @smallexample
 @group
 #include <ctype.h>

+@end group

 
 

+@group

 int
 yylex (void)
 @{
   int c;
 
 int
 yylex (void)
 @{
   int c;
 

-  /* Ignore whitespace, get first nonwhite character.  */
+  /* Ignore white space, get first nonwhite character.  */

   while ((c = getchar ()) == ' ' || c == '\t');
 
   if (c == EOF)
   while ((c = getchar ()) == ' ' || c == '\t');
 
   if (c == EOF)


@@ -2096,7 +2166,7 @@ yylex (void)
           if (i == length)
             @{
               length *= 2;
           if (i == length)
             @{
               length *= 2;

-              symbuf = (char *)realloc (symbuf, length + 1);
+              symbuf = (char *) realloc (symbuf, length + 1);

             @}
           /* Add this character to the buffer.         */
           symbuf[i++] = c;
             @}
           /* Add this character to the buffer.         */
           symbuf[i++] = c;


@@ -2105,7 +2175,7 @@ yylex (void)
         @}
 @end group
 @group
         @}
 @end group
 @group

-      while (c != EOF && isalnum (c));
+      while (isalnum (c));

 
       ungetc (c, stdin);
       symbuf[i] = '\0';
 
       ungetc (c, stdin);
       symbuf[i] = '\0';


@@ -2125,7 +2195,7 @@ yylex (void)
 @end group
 @end smallexample
 
 @end group
 @end smallexample
 

-This program is both powerful and flexible. You may easily add new
+This program is both powerful and flexible.  You may easily add new

 functions, and it is a simple job to modify this code to install
 predefined variables such as @code{pi} or @code{e} as well.
 
 functions, and it is a simple job to modify this code to install
 predefined variables such as @code{pi} or @code{e} as well.
 


@@ -2188,6 +2258,8 @@ appropriate delimiters:
 @end example
 
 Comments enclosed in @samp{/* @dots{} */} may appear in any of the sections.
 @end example
 
 Comments enclosed in @samp{/* @dots{} */} may appear in any of the sections.

+As a @acronym{GNU} extension, @samp{//} introduces a comment that
+continues until end of line.

 
 @menu
 * Prologue::          Syntax and usage of the prologue.
 
 @menu
 * Prologue::          Syntax and usage of the prologue.


@@ -2230,8 +2302,8 @@ can be done with two @var{Prologue} blocks, one before and one after the
 @}
 
 %@{
 @}
 
 %@{

-static void yyprint(FILE *, int, YYSTYPE);
-#define YYPRINT(F, N, L) yyprint(F, N, L)
+static void print_token_value (FILE *, int, YYSTYPE);
+#define YYPRINT(F, N, L) print_token_value (F, N, L)

 %@}
 
 @dots{}
 %@}
 
 @dots{}


@@ -2310,7 +2382,7 @@ There are three ways of writing terminal symbols in the grammar:
 @itemize @bullet
 @item
 A @dfn{named token type} is written with an identifier, like an
 @itemize @bullet
 @item
 A @dfn{named token type} is written with an identifier, like an

-identifier in C.  By convention, it should be all upper case.  Each
+identifier in C@.  By convention, it should be all upper case.  Each

 such name must be defined with a Bison declaration such as
 @code{%token}.  @xref{Token Decl, ,Token Type Names}.
 
 such name must be defined with a Bison declaration such as
 @code{%token}.  @xref{Token Decl, ,Token Type Names}.
 


@@ -2334,9 +2406,11 @@ your program will confuse other readers.
 
 All the usual escape sequences used in character literals in C can be
 used in Bison as well, but you must not use the null character as a
 
 All the usual escape sequences used in character literals in C can be
 used in Bison as well, but you must not use the null character as a

-character literal because its numeric code, zero, is the code @code{yylex}
-returns for end-of-input (@pxref{Calling Convention, ,Calling Convention
-for @code{yylex}}).
+character literal because its numeric code, zero, signifies
+end-of-input (@pxref{Calling Convention, ,Calling Convention
+for @code{yylex}}).  Also, unlike standard C, trigraphs have no
+special meaning in Bison character literals, nor is backslash-newline
+allowed.

 
 @item
 @cindex string token
 
 @item
 @cindex string token


@@ -2354,7 +2428,7 @@ Declarations}).  If you don't do that, the lexical analyzer has to
 retrieve the token number for the literal string token from the
 @code{yytname} table (@pxref{Calling Convention}).
 
 retrieve the token number for the literal string token from the
 @code{yytname} table (@pxref{Calling Convention}).
 

-@strong{WARNING}: literal string tokens do not work in Yacc.
+@strong{Warning}: literal string tokens do not work in Yacc.

 
 By convention, a literal string token is used only to represent a token
 that consists of that particular string.  Thus, you should use the token
 
 By convention, a literal string token is used only to represent a token
 that consists of that particular string.  Thus, you should use the token


@@ -2363,21 +2437,25 @@ does not enforce this convention, but if you depart from it, people who
 read your program will be confused.
 
 All the escape sequences used in string literals in C can be used in
 read your program will be confused.
 
 All the escape sequences used in string literals in C can be used in

-Bison as well.  A literal string token must contain two or more
-characters; for a token containing just one character, use a character
-token (see above).
+Bison as well.  However, unlike Standard C, trigraphs have no special
+meaning in Bison string literals, nor is backslash-newline allowed.  A
+literal string token must contain two or more characters; for a token
+containing just one character, use a character token (see above).

 @end itemize
 
 How you choose to write a terminal symbol has no effect on its
 grammatical meaning.  That depends only on where it appears in rules and
 on when the parser function returns that symbol.
 
 @end itemize
 
 How you choose to write a terminal symbol has no effect on its
 grammatical meaning.  That depends only on where it appears in rules and
 on when the parser function returns that symbol.
 

-The value returned by @code{yylex} is always one of the terminal symbols
-(or 0 for end-of-input).  Whichever way you write the token type in the
-grammar rules, you write it the same way in the definition of @code{yylex}.
-The numeric code for a character token type is simply the numeric code of
-the character, so @code{yylex} can use the identical character constant to
-generate the requisite code.  Each named token type becomes a C macro in
+The value returned by @code{yylex} is always one of the terminal
+symbols, except that a zero or negative value signifies end-of-input.
+Whichever way you write the token type in the grammar rules, you write
+it the same way in the definition of @code{yylex}.  The numeric code
+for a character token type is simply the positive numeric code of the
+character, so @code{yylex} can use the identical value to generate the
+requisite code, though you may need to convert it to @code{unsigned
+char} to avoid sign-extension on hosts where @code{char} is signed.
+Each named token type becomes a C macro in

 the parser file, so @code{yylex} can use the name to stand for the code.
 (This is why periods don't make sense in terminal symbols.)
 @xref{Calling Convention, ,Calling Convention for @code{yylex}}.
 the parser file, so @code{yylex} can use the name to stand for the code.
 (This is why periods don't make sense in terminal symbols.)
 @xref{Calling Convention, ,Calling Convention for @code{yylex}}.


@@ -2388,18 +2466,26 @@ option when you run Bison, so that it will write these macro definitions
 into a separate header file @file{@var{name}.tab.h} which you can include
 in the other source files that need it.  @xref{Invocation, ,Invoking Bison}.
 
 into a separate header file @file{@var{name}.tab.h} which you can include
 in the other source files that need it.  @xref{Invocation, ,Invoking Bison}.
 

-The @code{yylex} function must use the same character set and encoding
-that was used by Bison.  For example, if you run Bison in an
-@sc{ascii} environment, but then compile and run the resulting program
+If you want to write a grammar that is portable to any Standard C
+host, you must use only non-null character tokens taken from the basic
+execution character set of Standard C@.  This set consists of the ten
+digits, the 52 lower- and upper-case English letters, and the
+characters in the following C-language string:
+
+@example
+"\a\b\t\n\v\f\r !\"#%&'()*+,-./:;<=>?[\\]^_@{|@}~"
+@end example
+
+The @code{yylex} function and Bison must use a consistent character
+set and encoding for character tokens.  For example, if you run Bison in an
+@acronym{ASCII} environment, but then compile and run the resulting program

 in an environment that uses an incompatible character set like
 in an environment that uses an incompatible character set like

-@sc{ebcdic}, the resulting program will probably not work because the
-tables generated by Bison will assume @sc{ascii} numeric values for
-character tokens.  Portable grammars should avoid non-@sc{ascii}
-character tokens, as implementations in practice often use different
-and incompatible extensions in this area.  However, it is standard
+@acronym{EBCDIC}, the resulting program may not work because the
+tables generated by Bison will assume @acronym{ASCII} numeric values for
+character tokens.  It is standard

 practice for software distributions to contain C source files that
 practice for software distributions to contain C source files that

-were generated by Bison in an @sc{ascii} environment, so installers on
-platforms that are incompatible with @sc{ascii} must rebuild those
+were generated by Bison in an @acronym{ASCII} environment, so installers on
+platforms that are incompatible with @acronym{ASCII} must rebuild those

 files before compiling them.
 
 The symbol @code{error} is a terminal symbol reserved for error recovery
 files before compiling them.
 
 The symbol @code{error} is a terminal symbol reserved for error recovery


@@ -2441,8 +2527,8 @@ exp:      exp '+' exp
 says that two groupings of type @code{exp}, with a @samp{+} token in between,
 can be combined into a larger grouping of type @code{exp}.
 
 says that two groupings of type @code{exp}, with a @samp{+} token in between,
 can be combined into a larger grouping of type @code{exp}.
 

-Whitespace in rules is significant only to separate symbols.  You can add
-extra whitespace as you wish.
+White space in rules is significant only to separate symbols.  You can add
+extra white space as you wish.

 
 Scattered among the components can be @var{actions} that determine
 the semantics of the rule.  An action looks like this:
 
 Scattered among the components can be @var{actions} that determine
 the semantics of the rule.  An action looks like this:


@@ -2605,7 +2691,7 @@ the numbers associated with @var{x} and @var{y}.
 
 In a simple program it may be sufficient to use the same data type for
 the semantic values of all language constructs.  This was true in the
 
 In a simple program it may be sufficient to use the same data type for
 the semantic values of all language constructs.  This was true in the

-RPN and infix calculator examples (@pxref{RPN Calc, ,Reverse Polish
+@acronym{RPN} and infix calculator examples (@pxref{RPN Calc, ,Reverse Polish

 Notation Calculator}).
 
 Bison's default is to use type @code{int} for all semantic values.  To
 Notation Calculator}).
 
 Bison's default is to use type @code{int} for all semantic values.  To


@@ -2656,7 +2742,13 @@ is to compute a semantic value for the grouping built by the rule from the
 semantic values associated with tokens or smaller groupings.
 
 An action consists of C statements surrounded by braces, much like a
 semantic values associated with tokens or smaller groupings.
 
 An action consists of C statements surrounded by braces, much like a

-compound statement in C.  It can be placed at any position in the rule;
+compound statement in C@.  An action can contain any sequence of C
+statements.  Bison does not look for trigraphs, though, so if your C
+code uses trigraphs you should ensure that they do not affect the
+nesting of braces or the boundaries of comments, strings, or character
+literals.
+
+An action can be placed at any position in the rule;

 it is executed at that position.  Most rules have just one action at the
 end of the rule, following all the components.  Actions in the middle of
 a rule are tricky and used only for special purposes (@pxref{Mid-Rule
 it is executed at that position.  Most rules have just one action at the
 end of the rule, following all the components.  Actions in the middle of
 a rule are tricky and used only for special purposes (@pxref{Mid-Rule


@@ -2703,11 +2795,11 @@ a-or-b: 'a'|'b'   @{ a_or_b_found = 1; @};
 
 @cindex default action
 If you don't specify an action for a rule, Bison supplies a default:
 
 @cindex default action
 If you don't specify an action for a rule, Bison supplies a default:

-@w{@code{$$ = $1}.}  Thus, the value of the first symbol in the rule becomes
-the value of the whole rule.  Of course, the default rule is valid only
-if the two data types match.  There is no meaningful default action for
-an empty rule; every empty rule must have an explicit action unless the
-rule's value does not matter.
+@w{@code{$$ = $1}.}  Thus, the value of the first symbol in the rule
+becomes the value of the whole rule.  Of course, the default action is
+valid only if the two data types match.  There is no meaningful default
+action for an empty rule; every empty rule must have an explicit action
+unless the rule's value does not matter.

 
 @code{$@var{n}} with @var{n} zero or negative is allowed for reference
 to tokens and groupings on the stack @emph{before} those that match the
 
 @code{$@var{n}} with @var{n} zero or negative is allowed for reference
 to tokens and groupings on the stack @emph{before} those that match the


@@ -2947,7 +3039,7 @@ actually does to implement mid-rule actions.
 @cindex position, textual
 
 Though grammar rules and semantic actions are enough to write a fully
 @cindex position, textual
 
 Though grammar rules and semantic actions are enough to write a fully

-functional parser, it can be useful to process some additionnal informations,
+functional parser, it can be useful to process some additional information,

 especially symbol locations.
 
 @c (terminal or not) ?
 especially symbol locations.
 
 @c (terminal or not) ?


@@ -2994,7 +3086,7 @@ Actions are not only useful for defining language semantics, but also for
 describing the behavior of the output parser with locations.
 
 The most obvious way for building locations of syntactic groupings is very
 describing the behavior of the output parser with locations.
 
 The most obvious way for building locations of syntactic groupings is very

-similar to the way semantic values are computed. In a given rule, several
+similar to the way semantic values are computed.  In a given rule, several

 constructs can be used to access the locations of the elements being matched.
 The location of the @var{n}th component of the right hand side is
 @code{@@@var{n}}, while the location of the left hand side grouping is
 constructs can be used to access the locations of the elements being matched.
 The location of the @var{n}th component of the right hand side is
 @code{@@@var{n}}, while the location of the left hand side grouping is


@@ -3025,11 +3117,11 @@ exp:    @dots{}
 @end example
 
 As for semantic values, there is a default action for locations that is
 @end example
 
 As for semantic values, there is a default action for locations that is

-run each time a rule is matched. It sets the beginning of @code{@@$} to the
+run each time a rule is matched.  It sets the beginning of @code{@@$} to the

 beginning of the first symbol, and the end of @code{@@$} to the end of the
 last symbol.
 
 beginning of the first symbol, and the end of @code{@@$} to the end of the
 last symbol.
 

-With this default action, the location tracking can be fully automatic. The
+With this default action, the location tracking can be fully automatic.  The

 example above simply rewrites this way:
 
 @example
 example above simply rewrites this way:
 
 @example


@@ -3054,21 +3146,21 @@ exp:    @dots{}
 @subsection Default Action for Locations
 @vindex YYLLOC_DEFAULT
 
 @subsection Default Action for Locations
 @vindex YYLLOC_DEFAULT
 

-Actually, actions are not the best place to compute locations. Since
+Actually, actions are not the best place to compute locations.  Since

 locations are much more general than semantic values, there is room in
 the output parser to redefine the default action to take for each
 locations are much more general than semantic values, there is room in
 the output parser to redefine the default action to take for each

-rule. The @code{YYLLOC_DEFAULT} macro is invoked each time a rule is
+rule.  The @code{YYLLOC_DEFAULT} macro is invoked each time a rule is

 matched, before the associated action is run.
 
 Most of the time, this macro is general enough to suppress location
 dedicated code from semantic actions.
 
 matched, before the associated action is run.
 
 Most of the time, this macro is general enough to suppress location
 dedicated code from semantic actions.
 

-The @code{YYLLOC_DEFAULT} macro takes three parameters. The first one is
-the location of the grouping (the result of the computation). The second one
+The @code{YYLLOC_DEFAULT} macro takes three parameters.  The first one is
+the location of the grouping (the result of the computation).  The second one

 is an array holding locations of all right hand side elements of the rule
 is an array holding locations of all right hand side elements of the rule

-being matched. The last one is the size of the right hand side rule.
+being matched.  The last one is the size of the right hand side rule.

 
 

-By default, it is defined this way for simple LALR(1) parsers:
+By default, it is defined this way for simple @acronym{LALR}(1) parsers:

 
 @example
 @group
 
 @example
 @group


@@ -3081,7 +3173,7 @@ By default, it is defined this way for simple LALR(1) parsers:
 @end example
 
 @noindent
 @end example
 
 @noindent

-and like this for GLR parsers:
+and like this for @acronym{GLR} parsers:

 
 @example
 @group
 
 @example
 @group


@@ -3097,7 +3189,7 @@ When defining @code{YYLLOC_DEFAULT}, you should consider that:
 
 @itemize @bullet
 @item
 
 @itemize @bullet
 @item

-All arguments are free of side-effects. However, only the first one (the
+All arguments are free of side-effects.  However, only the first one (the

 result) should be modified by @code{YYLLOC_DEFAULT}.
 
 @item
 result) should be modified by @code{YYLLOC_DEFAULT}.
 
 @item


@@ -3129,6 +3221,7 @@ Grammars}).
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.
 * Type Decl::         Declaring the choice of type for a nonterminal symbol.
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.
 * Type Decl::         Declaring the choice of type for a nonterminal symbol.

+* Destructor Decl::   Declaring how symbols are freed.

 * Expect Decl::       Suppressing warnings about shift/reduce conflicts.
 * Start Decl::        Specifying the start symbol.
 * Pure Decl::         Requesting a reentrant parser.
 * Expect Decl::       Suppressing warnings about shift/reduce conflicts.
 * Start Decl::        Specifying the start symbol.
 * Pure Decl::         Requesting a reentrant parser.


@@ -3319,6 +3412,71 @@ use the same @code{<@var{type}>} construction in a declaration for the
 terminal symbol.  All kinds of token declarations allow
 @code{<@var{type}>}.
 
 terminal symbol.  All kinds of token declarations allow
 @code{<@var{type}>}.
 

+@node Destructor Decl
+@subsection Freeing Discarded Symbols
+@cindex freeing discarded symbols
+@findex %destructor
+
+Some symbols can be discarded by the parser, typically during error
+recovery (@pxref{Error Recovery}).  Basically, during error recovery,
+embarrassing symbols already pushed on the stack, and embarrassing
+tokens coming from the rest of the file are thrown away until the parser
+falls on its feet.  If these symbols convey heap based information, this
+memory is lost.  While this behavior is tolerable for batch parsers,
+such as in compilers, it is unacceptable for parsers that can
+possibility ``never end'' such as shells, or implementations of
+communication protocols.
+
+The @code{%destructor} directive allows for the definition of code that
+is called when a symbol is thrown away.
+
+@deffn {Directive} %destructor @{ @var{code} @} @var{symbols}
+@findex %destructor
+Declare that the @var{code} must be invoked for each of the
+@var{symbols} that will be discarded by the parser.  The @var{code}
+should use @code{$$} to designate the semantic value associated to the
+@var{symbols}.  The additional parser parameters are also avaible
+(@pxref{Parser Function, , The Parser Function @code{yyparse}}).
+
+@strong{Warning:} as of Bison 1.875, this feature is still considered as
+experimental, as there was not enough users feedback.  In particular,
+the syntax might still change.
+@end deffn
+
+For instance:
+
+@smallexample
+%union
+@{
+  char *string;
+@}
+%token <string> STRING
+%type  <string> string
+%destructor @{ free ($$); @} STRING string
+@end smallexample
+
+@noindent
+guarantees that when a @code{STRING} or a @code{string} will be discarded,
+its associated memory will be freed.
+
+Note that in the future, Bison might also consider that right hand side
+members that are not mentioned in the action can be destroyed.  For
+instance, in:
+
+@smallexample
+comment: "/*" STRING "*/";
+@end smallexample
+
+@noindent
+the parser is entitled to destroy the semantic value of the
+@code{string}.  Of course, this will not apply to the default action;
+compare:
+
+@smallexample
+typeless: string;  // $$ = $1 does not apply; $1 is destroyed.
+typefull: string;  // $$ = $1 applies, $1 is not destroyed.
+@end smallexample
+

 @node Expect Decl
 @subsection Suppressing Conflict Warnings
 @cindex suppressing conflict warnings
 @node Expect Decl
 @subsection Suppressing Conflict Warnings
 @cindex suppressing conflict warnings


@@ -3397,8 +3555,8 @@ handler.  In systems with multiple threads of control, a non-reentrant
 program must be called only within interlocks.
 
 Normally, Bison generates a parser which is not reentrant.  This is
 program must be called only within interlocks.
 
 Normally, Bison generates a parser which is not reentrant.  This is

-suitable for most uses, and it permits compatibility with YACC.  (The
-standard YACC interfaces are inherently nonreentrant, because they use
+suitable for most uses, and it permits compatibility with Yacc.  (The
+standard Yacc interfaces are inherently nonreentrant, because they use

 statically allocated variables for communication with @code{yylex},
 including @code{yylval} and @code{yylloc}.)
 
 statically allocated variables for communication with @code{yylex},
 including @code{yylval} and @code{yylloc}.)
 


@@ -3431,53 +3589,60 @@ valid grammar.
 
 Here is a summary of the declarations used to define a grammar:
 
 
 Here is a summary of the declarations used to define a grammar:
 

-@table @code
-@item %union
+@deffn {Directive} %union

 Declare the collection of data types that semantic values may have
 (@pxref{Union Decl, ,The Collection of Value Types}).
 Declare the collection of data types that semantic values may have
 (@pxref{Union Decl, ,The Collection of Value Types}).

+@end deffn

 
 

-@item %token
+@deffn {Directive} %token

 Declare a terminal symbol (token type name) with no precedence
 or associativity specified (@pxref{Token Decl, ,Token Type Names}).
 Declare a terminal symbol (token type name) with no precedence
 or associativity specified (@pxref{Token Decl, ,Token Type Names}).

+@end deffn

 
 

-@item %right
+@deffn {Directive} %right

 Declare a terminal symbol (token type name) that is right-associative
 (@pxref{Precedence Decl, ,Operator Precedence}).
 Declare a terminal symbol (token type name) that is right-associative
 (@pxref{Precedence Decl, ,Operator Precedence}).

+@end deffn

 
 

-@item %left
+@deffn {Directive} %left

 Declare a terminal symbol (token type name) that is left-associative
 (@pxref{Precedence Decl, ,Operator Precedence}).
 Declare a terminal symbol (token type name) that is left-associative
 (@pxref{Precedence Decl, ,Operator Precedence}).

+@end deffn

 
 

-@item %nonassoc
+@deffn {Directive} %nonassoc

 Declare a terminal symbol (token type name) that is nonassociative
 (using it in a way that would be associative is a syntax error)
 Declare a terminal symbol (token type name) that is nonassociative
 (using it in a way that would be associative is a syntax error)

+@end deffn

 (@pxref{Precedence Decl, ,Operator Precedence}).
 
 (@pxref{Precedence Decl, ,Operator Precedence}).
 

-@item %type
+@deffn {Directive} %type

 Declare the type of semantic values for a nonterminal symbol
 (@pxref{Type Decl, ,Nonterminal Symbols}).
 Declare the type of semantic values for a nonterminal symbol
 (@pxref{Type Decl, ,Nonterminal Symbols}).

+@end deffn

 
 

-@item %start
+@deffn {Directive} %start

 Specify the grammar's start symbol (@pxref{Start Decl, ,The
 Start-Symbol}).
 Specify the grammar's start symbol (@pxref{Start Decl, ,The
 Start-Symbol}).

+@end deffn

 
 

-@item %expect
+@deffn {Directive} %expect

 Declare the expected number of shift-reduce conflicts
 (@pxref{Expect Decl, ,Suppressing Conflict Warnings}).
 Declare the expected number of shift-reduce conflicts
 (@pxref{Expect Decl, ,Suppressing Conflict Warnings}).

-@end table
+@end deffn
+

 
 @sp 1
 @noindent
 In order to change the behavior of @command{bison}, use the following
 directives:
 
 
 @sp 1
 @noindent
 In order to change the behavior of @command{bison}, use the following
 directives:
 

-@table @code
-@item %debug
+@deffn {Directive} %debug

 In the parser file, define the macro @code{YYDEBUG} to 1 if it is not
 already defined, so that the debugging facilities are compiled.
 In the parser file, define the macro @code{YYDEBUG} to 1 if it is not
 already defined, so that the debugging facilities are compiled.

+@end deffn

 @xref{Tracing, ,Tracing Your Parser}.
 
 @xref{Tracing, ,Tracing Your Parser}.
 

-@item %defines
+@deffn {Directive} %defines

 Write an extra output file containing macro definitions for the token
 type names defined in the grammar and the semantic value type
 @code{YYSTYPE}, as well as a few @code{extern} variable declarations.
 Write an extra output file containing macro definitions for the token
 type names defined in the grammar and the semantic value type
 @code{YYSTYPE}, as well as a few @code{extern} variable declarations.


@@ -3489,36 +3654,38 @@ This output file is essential if you wish to put the definition of
 @code{yylex} in a separate source file, because @code{yylex} needs to
 be able to refer to token type codes and the variable
 @code{yylval}.  @xref{Token Values, ,Semantic Values of Tokens}.
 @code{yylex} in a separate source file, because @code{yylex} needs to
 be able to refer to token type codes and the variable
 @code{yylval}.  @xref{Token Values, ,Semantic Values of Tokens}.

+@end deffn
+
+@deffn {Directive} %destructor
+Specifying how the parser should reclaim the memory associated to
+discarded symbols. @xref{Destructor Decl, , Freeing Discarded Symbols}.
+@end deffn

 
 

-@item %file-prefix="@var{prefix}"
+@deffn {Directive} %file-prefix="@var{prefix}"

 Specify a prefix to use for all Bison output file names.  The names are
 chosen as if the input file were named @file{@var{prefix}.y}.
 Specify a prefix to use for all Bison output file names.  The names are
 chosen as if the input file were named @file{@var{prefix}.y}.

+@end deffn

 
 

-@c @item %header-extension
-@c Specify the extension of the parser header file generated when
-@c @code{%define} or @samp{-d} are used.
-@c
-@c For example, a grammar file named @file{foo.ypp} and containing a
-@c @code{%header-extension .hh} directive will produce a header file
-@c named @file{foo.tab.hh}
-
-@item %locations
+@deffn {Directive} %locations

 Generate the code processing the locations (@pxref{Action Features,
 ,Special Features for Use in Actions}).  This mode is enabled as soon as
 the grammar uses the special @samp{@@@var{n}} tokens, but if your
 grammar does not use it, using @samp{%locations} allows for more
 Generate the code processing the locations (@pxref{Action Features,
 ,Special Features for Use in Actions}).  This mode is enabled as soon as
 the grammar uses the special @samp{@@@var{n}} tokens, but if your
 grammar does not use it, using @samp{%locations} allows for more

-accurate parse error messages.
+accurate syntax error messages.
+@end deffn

 
 

-@item %name-prefix="@var{prefix}"
+@deffn {Directive} %name-prefix="@var{prefix}"

 Rename the external symbols used in the parser so that they start with
 @var{prefix} instead of @samp{yy}.  The precise list of symbols renamed
 is @code{yyparse}, @code{yylex}, @code{yyerror}, @code{yynerrs},
 Rename the external symbols used in the parser so that they start with
 @var{prefix} instead of @samp{yy}.  The precise list of symbols renamed
 is @code{yyparse}, @code{yylex}, @code{yyerror}, @code{yynerrs},

-@code{yylval}, @code{yychar}, @code{yydebug}, and possible
-@code{yylloc}.  For example, if you use @samp{%name-prefix="c_"}, the
-names become @code{c_parse}, @code{c_lex}, and so on.  @xref{Multiple
-Parsers, ,Multiple Parsers in the Same Program}.
-
-@item %no-parser
+@code{yylval}, @code{yylloc}, @code{yychar}, @code{yydebug}, and
+possible @code{yylloc}.  For example, if you use
+@samp{%name-prefix="c_"}, the names become @code{c_parse}, @code{c_lex},
+and so on.  @xref{Multiple Parsers, ,Multiple Parsers in the Same
+Program}.
+@end deffn
+
+@deffn {Directive} %no-parser

 Do not include any C code in the parser file; generate tables only.  The
 parser file contains just @code{#define} directives and static variable
 declarations.
 Do not include any C code in the parser file; generate tables only.  The
 parser file contains just @code{#define} directives and static variable
 declarations.


@@ -3526,36 +3693,33 @@ declarations.
 This option also tells Bison to write the C code for the grammar actions
 into a file named @file{@var{filename}.act}, in the form of a
 brace-surrounded body fit for a @code{switch} statement.
 This option also tells Bison to write the C code for the grammar actions
 into a file named @file{@var{filename}.act}, in the form of a
 brace-surrounded body fit for a @code{switch} statement.

+@end deffn

 
 

-@item %no-lines
+@deffn {Directive} %no-lines

 Don't generate any @code{#line} preprocessor commands in the parser
 file.  Ordinarily Bison writes these commands in the parser file so that
 the C compiler and debuggers will associate errors and object code with
 your source file (the grammar file).  This directive causes them to
 associate errors with the parser file, treating it an independent source
 file in its own right.
 Don't generate any @code{#line} preprocessor commands in the parser
 file.  Ordinarily Bison writes these commands in the parser file so that
 the C compiler and debuggers will associate errors and object code with
 your source file (the grammar file).  This directive causes them to
 associate errors with the parser file, treating it an independent source
 file in its own right.

+@end deffn

 
 

-@item %output="@var{filename}"
+@deffn {Directive} %output="@var{filename}"

 Specify the @var{filename} for the parser file.
 Specify the @var{filename} for the parser file.

+@end deffn

 
 

-@item %pure-parser
+@deffn {Directive} %pure-parser

 Request a pure (reentrant) parser program (@pxref{Pure Decl, ,A Pure
 (Reentrant) Parser}).
 Request a pure (reentrant) parser program (@pxref{Pure Decl, ,A Pure
 (Reentrant) Parser}).

+@end deffn

 
 

-@c @item %source-extension
-@c Specify the extension of the parser output file.
-@c
-@c For example, a grammar file named @file{foo.yy} and containing a
-@c @code{%source-extension .cpp} directive will produce a parser file
-@c named @file{foo.tab.cpp}
-
-@item %token-table
+@deffn {Directive} %token-table

 Generate an array of token names in the parser file.  The name of the
 array is @code{yytname}; @code{yytname[@var{i}]} is the name of the
 Generate an array of token names in the parser file.  The name of the
 array is @code{yytname}; @code{yytname[@var{i}]} is the name of the

-token whose internal Bison token code number is @var{i}.  The first three
-elements of @code{yytname} are always @code{"$"}, @code{"error"}, and
-@code{"$illegal"}; after these come the symbols defined in the grammar
-file.
+token whose internal Bison token code number is @var{i}.  The first
+three elements of @code{yytname} are always @code{"$end"},
+@code{"error"}, and @code{"$undefined"}; after these come the symbols
+defined in the grammar file.

 
 For single-character literal tokens and literal string tokens, the name
 in the table includes the single-quote or double-quote characters: for
 
 For single-character literal tokens and literal string tokens, the name
 in the table includes the single-quote or double-quote characters: for


@@ -3581,21 +3745,19 @@ The number of grammar rules,
 @item YYNSTATES
 The number of parser states (@pxref{Parser States}).
 @end table
 @item YYNSTATES
 The number of parser states (@pxref{Parser States}).
 @end table

+@end deffn

 
 

-@item %verbose
+@deffn {Directive} %verbose

 Write an extra output file containing verbose descriptions of the
 parser states and what is done for each type of look-ahead token in
 Write an extra output file containing verbose descriptions of the
 parser states and what is done for each type of look-ahead token in

-that state. @xref{Understanding, , Understanding Your Parser}, for more
+that state.  @xref{Understanding, , Understanding Your Parser}, for more

 information.
 information.

+@end deffn

 
 

-
-
-@item %yacc
+@deffn {Directive} %yacc

 Pretend the option @option{--yacc} was given, i.e., imitate Yacc,
 including its naming conventions.  @xref{Bison Options}, for more.
 Pretend the option @option{--yacc} was given, i.e., imitate Yacc,
 including its naming conventions.  @xref{Bison Options}, for more.

-@end table
-
-
+@end deffn

 
 
 @node Multiple Parsers
 
 
 @node Multiple Parsers


@@ -3613,9 +3775,9 @@ instead of @samp{yy}.  You can use this to give each parser distinct
 names that do not conflict.
 
 The precise list of symbols renamed is @code{yyparse}, @code{yylex},
 names that do not conflict.
 
 The precise list of symbols renamed is @code{yyparse}, @code{yylex},

-@code{yyerror}, @code{yynerrs}, @code{yylval}, @code{yychar} and
-@code{yydebug}.  For example, if you use @samp{-p c}, the names become
-@code{cparse}, @code{clex}, and so on.
+@code{yyerror}, @code{yynerrs}, @code{yylval}, @code{yylloc},
+@code{yychar} and @code{yydebug}.  For example, if you use @samp{-p c},
+the names become @code{cparse}, @code{clex}, and so on.

 
 @strong{All the other variables and macros associated with Bison are not
 renamed.} These others are not global; there is no conflict if the same
 
 @strong{All the other variables and macros associated with Bison are not
 renamed.} These others are not global; there is no conflict if the same


@@ -3660,23 +3822,66 @@ encounters end-of-input or an unrecoverable syntax error.  You can also
 write an action which directs @code{yyparse} to return immediately
 without reading further.
 
 write an action which directs @code{yyparse} to return immediately
 without reading further.
 

+
+@deftypefun int yyparse (void)

 The value returned by @code{yyparse} is 0 if parsing was successful (return
 is due to end-of-input).
 
 The value is 1 if parsing failed (return is due to a syntax error).
 The value returned by @code{yyparse} is 0 if parsing was successful (return
 is due to end-of-input).
 
 The value is 1 if parsing failed (return is due to a syntax error).

+@end deftypefun

 
 In an action, you can cause immediate return from @code{yyparse} by using
 these macros:
 
 
 In an action, you can cause immediate return from @code{yyparse} by using
 these macros:
 

-@table @code
-@item YYACCEPT
+@defmac YYACCEPT

 @findex YYACCEPT
 Return immediately with value 0 (to report success).
 @findex YYACCEPT
 Return immediately with value 0 (to report success).

+@end defmac

 
 

-@item YYABORT
+@defmac YYABORT

 @findex YYABORT
 Return immediately with value 1 (to report failure).
 @findex YYABORT
 Return immediately with value 1 (to report failure).

-@end table
+@end defmac
+
+If you use a reentrant parser, you can optionally pass additional
+parameter information to it in a reentrant way.  To do so, use the
+declaration @code{%parse-param}:
+
+@deffn {Directive} %parse-param @{@var{argument-declaration}@}
+@findex %parse-param
+Declare that an argument declared by @code{argument-declaration} is an
+additional @code{yyparse} argument.  This argument is also passed to
+@code{yyerror}.  The @var{argument-declaration} is used when declaring
+functions or prototypes.  The last identifier in
+@var{argument-declaration} must be the argument name.
+@end deffn
+
+Here's an example.  Write this in the parser:
+
+@example
+%parse-param @{int *nastiness@}
+%parse-param @{int *randomness@}
+@end example
+
+@noindent
+Then call the parser like this:
+
+@example
+@{
+  int nastiness, randomness;
+  @dots{}  /* @r{Store proper data in @code{nastiness} and @code{randomness}.}  */
+  value = yyparse (&nastiness, &randomness);
+  @dots{}
+@}
+@end example
+
+@noindent
+In the grammar actions, use expressions like this to refer to the data:
+
+@example
+exp: @dots{}    @{ @dots{}; *randomness += 1; @dots{} @}
+@end example
+

 
 @node Lexical
 @section The Lexical Analyzer Function @code{yylex}
 
 @node Lexical
 @section The Lexical Analyzer Function @code{yylex}


@@ -3710,8 +3915,9 @@ that need it.  @xref{Invocation, ,Invoking Bison}.
 @node Calling Convention
 @subsection Calling Convention for @code{yylex}
 
 @node Calling Convention
 @subsection Calling Convention for @code{yylex}
 

-The value that @code{yylex} returns must be the numeric code for the type
-of token it has just found, or 0 for end-of-input.
+The value that @code{yylex} returns must be the positive numeric code
+for the type of token it has just found; a zero or negative value
+signifies end-of-input.

 
 When a token is referred to in the grammar rules by a name, that name
 in the parser file becomes a C macro whose definition is the proper
 
 When a token is referred to in the grammar rules by a name, that name
 in the parser file becomes a C macro whose definition is the proper


@@ -3720,8 +3926,9 @@ to indicate that type.  @xref{Symbols}.
 
 When a token is referred to in the grammar rules by a character literal,
 the numeric code for that character is also the code for the token type.
 
 When a token is referred to in the grammar rules by a character literal,
 the numeric code for that character is also the code for the token type.

-So @code{yylex} can simply return that character code.  The null character
-must not be used this way, because its code is zero and that is what
+So @code{yylex} can simply return that character code, possibly converted
+to @code{unsigned char} to avoid sign-extension.  The null character
+must not be used this way, because its code is zero and that

 signifies end-of-input.
 
 Here is an example showing these things:
 signifies end-of-input.
 
 Here is an example showing these things:


@@ -3731,13 +3938,13 @@ int
 yylex (void)
 @{
   @dots{}
 yylex (void)
 @{
   @dots{}

-  if (c == EOF)     /* Detect end of file. */
+  if (c == EOF)    /* Detect end-of-input.  */

     return 0;
   @dots{}
   if (c == '+' || c == '-')
     return 0;
   @dots{}
   if (c == '+' || c == '-')

-    return c;      /* Assume token type for `+' is '+'. */
+    return c;      /* Assume token type for `+' is '+'.  */

   @dots{}
   @dots{}

-  return INT;      /* Return the type of the token. */
+  return INT;      /* Return the type of the token.  */

   @dots{}
 @}
 @end example
   @dots{}
 @}
 @end example


@@ -3772,8 +3979,8 @@ for (i = 0; i < YYNTOKENS; i++)
   @{
     if (yytname[i] != 0
         && yytname[i][0] == '"'
   @{
     if (yytname[i] != 0
         && yytname[i][0] == '"'

-        && strncmp (yytname[i] + 1, token_buffer,
-                    strlen (token_buffer))
+        && ! strncmp (yytname[i] + 1, token_buffer,
+                      strlen (token_buffer))

         && yytname[i][strlen (token_buffer) + 1] == '"'
         && yytname[i][strlen (token_buffer) + 2] == 0)
       break;
         && yytname[i][strlen (token_buffer) + 1] == '"'
         && yytname[i][strlen (token_buffer) + 2] == 0)
       break;


@@ -3797,8 +4004,8 @@ Thus, if the type is @code{int} (the default), you might write this in
 @example
 @group
   @dots{}
 @example
 @group
   @dots{}

-  yylval = value;  /* Put value onto Bison stack. */
-  return INT;      /* Return the type of the token. */
+  yylval = value;  /* Put value onto Bison stack.  */
+  return INT;      /* Return the type of the token.  */

   @dots{}
 @end group
 @end example
   @dots{}
 @end group
 @end example


@@ -3825,8 +4032,8 @@ then the code in @code{yylex} might look like this:
 @example
 @group
   @dots{}
 @example
 @group
   @dots{}

-  yylval.intval = value; /* Put value onto Bison stack. */
-  return INT;          /* Return the type of the token. */
+  yylval.intval = value; /* Put value onto Bison stack.  */
+  return INT;            /* Return the type of the token.  */

   @dots{}
 @end group
 @end example
   @dots{}
 @end group
 @end example


@@ -3879,85 +4086,47 @@ textual positions, then the type @code{YYLTYPE} will not be defined.  In
 this case, omit the second argument; @code{yylex} will be called with
 only one argument.
 
 this case, omit the second argument; @code{yylex} will be called with
 only one argument.
 

-@vindex YYPARSE_PARAM
-If you use a reentrant parser, you can optionally pass additional
-parameter information to it in a reentrant way.  To do so, define the
-macro @code{YYPARSE_PARAM} as a variable name.  This modifies the
-@code{yyparse} function to accept one argument, of type @code{void *},
-with that name.

 
 

-When you call @code{yyparse}, pass the address of an object, casting the
-address to @code{void *}.  The grammar actions can refer to the contents
-of the object by casting the pointer value back to its proper type and
-then dereferencing it.  Here's an example.  Write this in the parser:
+If you wish to pass the additional parameter data to @code{yylex}, use
+@code{%lex-param} just like @code{%parse-param} (@pxref{Parser
+Function}).

 
 

-@example
-%@{
-struct parser_control
-@{
-  int nastiness;
-  int randomness;
-@};
+@deffn {Directive} lex-param @{@var{argument-declaration}@}
+@findex %lex-param
+Declare that @code{argument-declaration} is an additional @code{yylex}
+argument declaration.
+@end deffn

 
 

-#define YYPARSE_PARAM parm
-%@}
-@end example
-
-@noindent
-Then call the parser like this:
+For instance:

 
 @example
 
 @example

-struct parser_control
-@{
-  int nastiness;
-  int randomness;
-@};
-
-@dots{}
-
-@{
-  struct parser_control foo;
-  @dots{}  /* @r{Store proper data in @code{foo}.}  */
-  value = yyparse ((void *) &foo);
-  @dots{}
-@}
+%parse-param @{int *nastiness@}
+%lex-param   @{int *nastiness@}
+%parse-param @{int *randomness@}

 @end example
 
 @noindent
 @end example
 
 @noindent

-In the grammar actions, use expressions like this to refer to the data:
+results in the following signature:

 
 @example
 
 @example

-((struct parser_control *) parm)->randomness
+int yylex   (int *nastiness);
+int yyparse (int *nastiness, int *randomness);

 @end example
 
 @end example
 

-@vindex YYLEX_PARAM
-If you wish to pass the additional parameter data to @code{yylex},
-define the macro @code{YYLEX_PARAM} just like @code{YYPARSE_PARAM}, as
-shown here:
+If @code{%pure-parser} is added:

 
 @example
 
 @example

-%@{
-struct parser_control
-@{
-  int nastiness;
-  int randomness;
-@};
-
-#define YYPARSE_PARAM parm
-#define YYLEX_PARAM parm
-%@}
+int yylex   (YYSTYPE *lvalp, int *nastiness);
+int yyparse (int *nastiness, int *randomness);

 @end example
 
 @end example
 

-You should then define @code{yylex} to accept one additional
-argument---the value of @code{parm}.  (This makes either two or three
-arguments in total, depending on whether an argument of type
-@code{YYLTYPE} is passed.)  You can declare the argument as a pointer to
-the proper object type, or you can declare it as @code{void *} and
-access the contents as shown above.
+@noindent
+and finally, if both @code{%pure-parser} and @code{%locations} are used:

 
 

-You can use @samp{%pure-parser} to request a reentrant parser without
-also using @code{YYPARSE_PARAM}.  Then you should call @code{yyparse}
-with no arguments, as usual.
+@example
+int yylex   (YYSTYPE *lvalp, YYLTYPE *llocp, int *nastiness);
+int yyparse (int *nastiness, int *randomness);
+@end example

 
 @node Error Reporting
 @section The Error Reporting Function @code{yyerror}
 
 @node Error Reporting
 @section The Error Reporting Function @code{yyerror}


@@ -3966,7 +4135,7 @@ with no arguments, as usual.
 @cindex parse error
 @cindex syntax error
 
 @cindex parse error
 @cindex syntax error
 

-The Bison parser detects a @dfn{parse error} or @dfn{syntax error}
+The Bison parser detects a @dfn{syntax error} or @dfn{parse error}

 whenever it reads a token which cannot satisfy any syntax rule.  An
 action in the grammar can also explicitly proclaim an error, using the
 macro @code{YYERROR} (@pxref{Action Features, ,Special Features for Use
 whenever it reads a token which cannot satisfy any syntax rule.  An
 action in the grammar can also explicitly proclaim an error, using the
 macro @code{YYERROR} (@pxref{Action Features, ,Special Features for Use


@@ -3975,16 +4144,14 @@ in Actions}).
 The Bison parser expects to report the error by calling an error
 reporting function named @code{yyerror}, which you must supply.  It is
 called by @code{yyparse} whenever a syntax error is found, and it
 The Bison parser expects to report the error by calling an error
 reporting function named @code{yyerror}, which you must supply.  It is
 called by @code{yyparse} whenever a syntax error is found, and it

-receives one argument.  For a parse error, the string is normally
-@w{@code{"parse error"}}.
+receives one argument.  For a syntax error, the string is normally
+@w{@code{"syntax error"}}.

 
 

-@findex YYERROR_VERBOSE
-If you define the macro @code{YYERROR_VERBOSE} in the Bison declarations
-section (@pxref{Bison Declarations, ,The Bison Declarations Section}),
-then Bison provides a more verbose and specific error message string
-instead of just plain @w{@code{"parse error"}}.  It doesn't matter what
-definition you use for @code{YYERROR_VERBOSE}, just whether you define
-it.
+@findex %error-verbose
+If you invoke the directive @code{%error-verbose} in the Bison
+declarations section (@pxref{Bison Declarations, ,The Bison Declarations
+Section}), then Bison provides a more verbose and specific error message
+string instead of just plain @w{@code{"syntax error"}}.

 
 The parser can detect one other kind of error: stack overflow.  This
 happens when the input contains constructions that are very deeply
 
 The parser can detect one other kind of error: stack overflow.  This
 happens when the input contains constructions that are very deeply


@@ -3999,7 +4166,7 @@ The following definition suffices in simple programs:
 @example
 @group
 void
 @example
 @group
 void

-yyerror (char *s)
+yyerror (const char *s)

 @{
 @end group
 @group
 @{
 @end group
 @group


@@ -4013,6 +4180,57 @@ error recovery if you have written suitable error recovery grammar rules
 (@pxref{Error Recovery}).  If recovery is impossible, @code{yyparse} will
 immediately return 1.
 
 (@pxref{Error Recovery}).  If recovery is impossible, @code{yyparse} will
 immediately return 1.
 

+Obviously, in location tracking pure parsers, @code{yyerror} should have
+an access to the current location.  This is indeed the case for the GLR
+parsers, but not for the Yacc parser, for historical reasons.  I.e., if
+@samp{%locations %pure-parser} is passed then the prototypes for
+@code{yyerror} are:
+
+@example
+void yyerror (const char *msg);                 /* Yacc parsers.  */
+void yyerror (YYLTYPE *locp, const char *msg);  /* GLR parsers.   */
+@end example
+
+If @samp{%parse-param @{int *nastiness@}} is used, then:
+
+@example
+void yyerror (int *randomness, const char *msg);  /* Yacc parsers.  */
+void yyerror (int *randomness, const char *msg);  /* GLR parsers.   */
+@end example
+
+Finally, GLR and Yacc parsers share the same @code{yyerror} calling
+convention for absolutely pure parsers, i.e., when the calling
+convention of @code{yylex} @emph{and} the calling convention of
+@code{%pure-parser} are pure.  I.e.:
+
+@example
+/* Location tracking.  */
+%locations
+/* Pure yylex.  */
+%pure-parser
+%lex-param   @{int *nastiness@}
+/* Pure yyparse.  */
+%parse-param @{int *nastiness@}
+%parse-param @{int *randomness@}
+@end example
+
+@noindent
+results in the following signatures for all the parser kinds:
+
+@example
+int yylex (YYSTYPE *lvalp, YYLTYPE *llocp, int *nastiness);
+int yyparse (int *nastiness, int *randomness);
+void yyerror (YYLTYPE *locp,
+              int *nastiness, int *randomness,
+              const char *msg);
+@end example
+
+@noindent
+Please, note that the prototypes are only indications of how the code
+produced by Bison will use @code{yyerror}; you still have freedom on the
+exit value, and even on making @code{yyerror} a variadic function.  It
+is precisely to enable this that the message is always passed last.
+

 @vindex yynerrs
 The variable @code{yynerrs} contains the number of syntax errors
 encountered so far.  Normally this variable is global; but if you
 @vindex yynerrs
 The variable @code{yynerrs} contains the number of syntax errors
 encountered so far.  Normally this variable is global; but if you


@@ -4027,38 +4245,43 @@ then it is a local variable which only the actions can access.
 Here is a table of Bison constructs, variables and macros that
 are useful in actions.
 
 Here is a table of Bison constructs, variables and macros that
 are useful in actions.
 

-@table @samp
-@item $$
+@deffn {Variable} $$

 Acts like a variable that contains the semantic value for the
 grouping made by the current rule.  @xref{Actions}.
 Acts like a variable that contains the semantic value for the
 grouping made by the current rule.  @xref{Actions}.

+@end deffn

 
 

-@item $@var{n}
+@deffn {Variable} $@var{n}

 Acts like a variable that contains the semantic value for the
 @var{n}th component of the current rule.  @xref{Actions}.
 Acts like a variable that contains the semantic value for the
 @var{n}th component of the current rule.  @xref{Actions}.

+@end deffn

 
 

-@item $<@var{typealt}>$
+@deffn {Variable} $<@var{typealt}>$

 Like @code{$$} but specifies alternative @var{typealt} in the union
 specified by the @code{%union} declaration.  @xref{Action Types, ,Data
 Types of Values in Actions}.
 Like @code{$$} but specifies alternative @var{typealt} in the union
 specified by the @code{%union} declaration.  @xref{Action Types, ,Data
 Types of Values in Actions}.

+@end deffn

 
 

-@item $<@var{typealt}>@var{n}
+@deffn {Variable} $<@var{typealt}>@var{n}

 Like @code{$@var{n}} but specifies alternative @var{typealt} in the
 union specified by the @code{%union} declaration.
 @xref{Action Types, ,Data Types of Values in Actions}.
 Like @code{$@var{n}} but specifies alternative @var{typealt} in the
 union specified by the @code{%union} declaration.
 @xref{Action Types, ,Data Types of Values in Actions}.

+@end deffn

 
 

-@item YYABORT;
+@deffn {Macro} YYABORT;

 Return immediately from @code{yyparse}, indicating failure.
 @xref{Parser Function, ,The Parser Function @code{yyparse}}.
 Return immediately from @code{yyparse}, indicating failure.
 @xref{Parser Function, ,The Parser Function @code{yyparse}}.

+@end deffn

 
 

-@item YYACCEPT;
+@deffn {Macro} YYACCEPT;

 Return immediately from @code{yyparse}, indicating success.
 @xref{Parser Function, ,The Parser Function @code{yyparse}}.
 Return immediately from @code{yyparse}, indicating success.
 @xref{Parser Function, ,The Parser Function @code{yyparse}}.

+@end deffn

 
 

-@item YYBACKUP (@var{token}, @var{value});
+@deffn {Macro} YYBACKUP (@var{token}, @var{value});

 @findex YYBACKUP
 Unshift a token.  This macro is allowed only for rules that reduce
 a single value, and only when there is no look-ahead token.
 @findex YYBACKUP
 Unshift a token.  This macro is allowed only for rules that reduce
 a single value, and only when there is no look-ahead token.

-It is also disallowed in GLR parsers.
+It is also disallowed in @acronym{GLR} parsers.

 It installs a look-ahead token with token type @var{token} and
 semantic value @var{value}; then it discards the value that was
 going to be reduced by this rule.
 It installs a look-ahead token with token type @var{token} and
 semantic value @var{value}; then it discards the value that was
 going to be reduced by this rule.


@@ -4069,40 +4292,47 @@ a message @samp{cannot back up} and performs ordinary error
 recovery.
 
 In either case, the rest of the action is not executed.
 recovery.
 
 In either case, the rest of the action is not executed.

+@end deffn

 
 

-@item YYEMPTY
+@deffn {Macro} YYEMPTY

 @vindex YYEMPTY
 Value stored in @code{yychar} when there is no look-ahead token.
 @vindex YYEMPTY
 Value stored in @code{yychar} when there is no look-ahead token.

+@end deffn

 
 

-@item YYERROR;
+@deffn {Macro} YYERROR;

 @findex YYERROR
 Cause an immediate syntax error.  This statement initiates error
 recovery just as if the parser itself had detected an error; however, it
 does not call @code{yyerror}, and does not print any message.  If you
 want to print an error message, call @code{yyerror} explicitly before
 the @samp{YYERROR;} statement.  @xref{Error Recovery}.
 @findex YYERROR
 Cause an immediate syntax error.  This statement initiates error
 recovery just as if the parser itself had detected an error; however, it
 does not call @code{yyerror}, and does not print any message.  If you
 want to print an error message, call @code{yyerror} explicitly before
 the @samp{YYERROR;} statement.  @xref{Error Recovery}.

+@end deffn

 
 

-@item YYRECOVERING
+@deffn {Macro} YYRECOVERING

 This macro stands for an expression that has the value 1 when the parser
 is recovering from a syntax error, and 0 the rest of the time.
 @xref{Error Recovery}.
 This macro stands for an expression that has the value 1 when the parser
 is recovering from a syntax error, and 0 the rest of the time.
 @xref{Error Recovery}.

+@end deffn

 
 

-@item yychar
+@deffn {Variable} yychar

 Variable containing the current look-ahead token.  (In a pure parser,
 this is actually a local variable within @code{yyparse}.)  When there is
 no look-ahead token, the value @code{YYEMPTY} is stored in the variable.
 @xref{Look-Ahead, ,Look-Ahead Tokens}.
 Variable containing the current look-ahead token.  (In a pure parser,
 this is actually a local variable within @code{yyparse}.)  When there is
 no look-ahead token, the value @code{YYEMPTY} is stored in the variable.
 @xref{Look-Ahead, ,Look-Ahead Tokens}.

+@end deffn

 
 

-@item yyclearin;
+@deffn {Macro} yyclearin;

 Discard the current look-ahead token.  This is useful primarily in
 error rules.  @xref{Error Recovery}.
 Discard the current look-ahead token.  This is useful primarily in
 error rules.  @xref{Error Recovery}.

+@end deffn

 
 

-@item yyerrok;
+@deffn {Macro} yyerrok;

 Resume generating error messages immediately for subsequent syntax
 errors.  This is useful primarily in error rules.
 @xref{Error Recovery}.
 Resume generating error messages immediately for subsequent syntax
 errors.  This is useful primarily in error rules.
 @xref{Error Recovery}.

+@end deffn

 
 

-@item @@$
+@deffn {Value} @@$

 @findex @@$
 Acts like a structure variable containing information on the textual position
 of the grouping made by the current rule.  @xref{Locations, ,
 @findex @@$
 Acts like a structure variable containing information on the textual position
 of the grouping made by the current rule.  @xref{Locations, ,


@@ -4126,14 +4356,15 @@ Tracking Locations}.
 @c those members.
 
 @c The use of this feature makes the parser noticeably slower.
 @c those members.
 
 @c The use of this feature makes the parser noticeably slower.

+@end deffn

 
 

-@item @@@var{n}
+@deffn {Value} @@@var{n}

 @findex @@@var{n}
 Acts like a structure variable containing information on the textual position
 of the @var{n}th component of the current rule.  @xref{Locations, ,
 Tracking Locations}.
 @findex @@@var{n}
 Acts like a structure variable containing information on the textual position
 of the @var{n}th component of the current rule.  @xref{Locations, ,
 Tracking Locations}.

+@end deffn

 
 

-@end table

 
 @node Algorithm
 @chapter The Bison Parser Algorithm
 
 @node Algorithm
 @chapter The Bison Parser Algorithm


@@ -4727,12 +4958,13 @@ name_list:
 It would seem that this grammar can be parsed with only a single token
 of look-ahead: when a @code{param_spec} is being read, an @code{ID} is
 a @code{name} if a comma or colon follows, or a @code{type} if another
 It would seem that this grammar can be parsed with only a single token
 of look-ahead: when a @code{param_spec} is being read, an @code{ID} is
 a @code{name} if a comma or colon follows, or a @code{type} if another

-@code{ID} follows.  In other words, this grammar is LR(1).
+@code{ID} follows.  In other words, this grammar is @acronym{LR}(1).

 
 

-@cindex LR(1)
-@cindex LALR(1)
+@cindex @acronym{LR}(1)
+@cindex @acronym{LALR}(1)

 However, Bison, like most parser generators, cannot actually handle all
 However, Bison, like most parser generators, cannot actually handle all

-LR(1) grammars.  In this grammar, two contexts, that after an @code{ID}
+@acronym{LR}(1) grammars.  In this grammar, two contexts, that after
+an @code{ID}

 at the beginning of a @code{param_spec} and likewise at the beginning of
 a @code{return_spec}, are similar enough that Bison assumes they are the
 same.  They appear similar because the same set of rules would be
 at the beginning of a @code{param_spec} and likewise at the beginning of
 a @code{return_spec}, are similar enough that Bison assumes they are the
 same.  They appear similar because the same set of rules would be


@@ -4741,11 +4973,12 @@ a @code{type}.  Bison is unable to determine at that stage of processing
 that the rules would require different look-ahead tokens in the two
 contexts, so it makes a single parser state for them both.  Combining
 the two contexts causes a conflict later.  In parser terminology, this
 that the rules would require different look-ahead tokens in the two
 contexts, so it makes a single parser state for them both.  Combining
 the two contexts causes a conflict later.  In parser terminology, this

-occurrence means that the grammar is not LALR(1).
+occurrence means that the grammar is not @acronym{LALR}(1).

 
 In general, it is better to fix deficiencies than to document them.  But
 this particular deficiency is intrinsically hard to fix; parser
 
 In general, it is better to fix deficiencies than to document them.  But
 this particular deficiency is intrinsically hard to fix; parser

-generators that can handle LR(1) grammars are hard to write and tend to
+generators that can handle @acronym{LR}(1) grammars are hard to write
+and tend to

 produce parsers that are very large.  In practice, Bison is more useful
 as it is now.
 
 produce parsers that are very large.  In practice, Bison is more useful
 as it is now.
 


@@ -4795,9 +5028,9 @@ return_spec:
 @end example
 
 @node Generalized LR Parsing
 @end example
 
 @node Generalized LR Parsing

-@section Generalized LR (GLR) Parsing
-@cindex GLR parsing
-@cindex generalized LR (GLR) parsing
+@section Generalized @acronym{LR} (@acronym{GLR}) Parsing
+@cindex @acronym{GLR} parsing
+@cindex generalized @acronym{LR} (@acronym{GLR}) parsing

 @cindex ambiguous grammars
 @cindex non-deterministic parsing
 
 @cindex ambiguous grammars
 @cindex non-deterministic parsing
 


@@ -4817,16 +5050,18 @@ summarize the input seen so far loses necessary information.
 
 When you use the @samp{%glr-parser} declaration in your grammar file,
 Bison generates a parser that uses a different algorithm, called
 
 When you use the @samp{%glr-parser} declaration in your grammar file,
 Bison generates a parser that uses a different algorithm, called

-Generalized LR (or GLR).  A Bison GLR parser uses the same basic
+Generalized @acronym{LR} (or @acronym{GLR}).  A Bison @acronym{GLR}
+parser uses the same basic

 algorithm for parsing as an ordinary Bison parser, but behaves
 differently in cases where there is a shift-reduce conflict that has not
 been resolved by precedence rules (@pxref{Precedence}) or a
 algorithm for parsing as an ordinary Bison parser, but behaves
 differently in cases where there is a shift-reduce conflict that has not
 been resolved by precedence rules (@pxref{Precedence}) or a

-reduce-reduce conflict.  When a GLR parser encounters such a situation, it
+reduce-reduce conflict.  When a @acronym{GLR} parser encounters such a
+situation, it

 effectively @emph{splits} into a several parsers, one for each possible
 shift or reduction.  These parsers then proceed as usual, consuming
 tokens in lock-step.  Some of the stacks may encounter other conflicts
 and split further, with the result that instead of a sequence of states,
 effectively @emph{splits} into a several parsers, one for each possible
 shift or reduction.  These parsers then proceed as usual, consuming
 tokens in lock-step.  Some of the stacks may encounter other conflicts
 and split further, with the result that instead of a sequence of states,

-a Bison GLR parsing stack is what is in effect a tree of states.
+a Bison @acronym{GLR} parsing stack is what is in effect a tree of states.

 
 In effect, each stack represents a guess as to what the proper parse
 is.  Additional input may indicate that a guess was wrong, in which case
 
 In effect, each stack represents a guess as to what the proper parse
 is.  Additional input may indicate that a guess was wrong, in which case


@@ -4842,7 +5077,7 @@ grammar symbol that produces the same segment of the input token
 stream.
 
 Whenever the parser makes a transition from having multiple
 stream.
 
 Whenever the parser makes a transition from having multiple

-states to having one, it reverts to the normal LALR(1) parsing
+states to having one, it reverts to the normal @acronym{LALR}(1) parsing

 algorithm, after resolving and executing the saved-up actions.
 At this transition, some of the states on the stack will have semantic
 values that are sets (actually multisets) of possible actions.  The
 algorithm, after resolving and executing the saved-up actions.
 At this transition, some of the states on the stack will have semantic
 values that are sets (actually multisets) of possible actions.  The


@@ -4854,9 +5089,10 @@ rules by the @samp{%merge} declaration,
 Bison resolves and evaluates both and then calls the merge function on
 the result.  Otherwise, it reports an ambiguity.
 
 Bison resolves and evaluates both and then calls the merge function on
 the result.  Otherwise, it reports an ambiguity.
 

-It is possible to use a data structure for the GLR parsing tree that
-permits the processing of any LALR(1) grammar in linear time (in the
-size of the input), any unambiguous (not necessarily LALR(1)) grammar in
+It is possible to use a data structure for the @acronym{GLR} parsing tree that
+permits the processing of any @acronym{LALR}(1) grammar in linear time (in the
+size of the input), any unambiguous (not necessarily
+@acronym{LALR}(1)) grammar in

 quadratic worst-case time, and any general (possibly ambiguous)
 context-free grammar in cubic worst-case time.  However, Bison currently
 uses a simpler data structure that requires time proportional to the
 quadratic worst-case time, and any general (possibly ambiguous)
 context-free grammar in cubic worst-case time.  However, Bison currently
 uses a simpler data structure that requires time proportional to the


@@ -4866,7 +5102,7 @@ grammars can require exponential time and space to process.  Such badly
 behaving examples, however, are not generally of practical interest.
 Usually, non-determinism in a grammar is local---the parser is ``in
 doubt'' only for a few tokens at a time.  Therefore, the current data
 behaving examples, however, are not generally of practical interest.
 Usually, non-determinism in a grammar is local---the parser is ``in
 doubt'' only for a few tokens at a time.  Therefore, the current data

-structure should generally be adequate.  On LALR(1) portions of a
+structure should generally be adequate.  On @acronym{LALR}(1) portions of a

 grammar, in particular, it is only slightly slower than with the default
 Bison parser.
 
 grammar, in particular, it is only slightly slower than with the default
 Bison parser.
 


@@ -4881,6 +5117,10 @@ not reduced.  When this happens, the parser function @code{yyparse}
 returns a nonzero value, pausing only to call @code{yyerror} to report
 the overflow.
 
 returns a nonzero value, pausing only to call @code{yyerror} to report
 the overflow.
 

+Because Bison parsers have growing stacks, hitting the upper limit
+usually results from using a right recursion instead of a left
+recursion, @xref{Recursion, ,Recursive Rules}.
+

 @vindex YYMAXDEPTH
 By defining the macro @code{YYMAXDEPTH}, you can control how deep the
 parser stack can become before a stack overflow occurs.  Define the
 @vindex YYMAXDEPTH
 By defining the macro @code{YYMAXDEPTH}, you can control how deep the
 parser stack can become before a stack overflow occurs.  Define the


@@ -4904,12 +5144,20 @@ You can control how much stack is allocated initially by defining the
 macro @code{YYINITDEPTH}.  This value too must be a compile-time
 constant integer.  The default is 200.
 
 macro @code{YYINITDEPTH}.  This value too must be a compile-time
 constant integer.  The default is 200.
 

+@c FIXME: C++ output.
+Because of semantical differences between C and C++, the
+@acronym{LALR}(1) parsers
+in C produced by Bison by compiled as C++ cannot grow.  In this precise
+case (compiling a C parser as C++) you are suggested to grow
+@code{YYINITDEPTH}.  In the near future, a C++ output output will be
+provided which addresses this issue.
+

 @node Error Recovery
 @chapter Error Recovery
 @cindex error recovery
 @cindex recovery from errors
 
 @node Error Recovery
 @chapter Error Recovery
 @cindex error recovery
 @cindex recovery from errors
 

-It is not usually acceptable to have a program terminate on a parse
+It is not usually acceptable to have a program terminate on a syntax

 error.  For example, a compiler should recover sufficiently to parse the
 rest of the input file and check it for errors; a calculator should accept
 another expression.
 error.  For example, a compiler should recover sufficiently to parse the
 rest of the input file and check it for errors; a calculator should accept
 another expression.


@@ -4951,22 +5199,24 @@ will be tokens to read before the next newline.  So the rule is not
 applicable in the ordinary way.
 
 But Bison can force the situation to fit the rule, by discarding part of
 applicable in the ordinary way.
 
 But Bison can force the situation to fit the rule, by discarding part of

-the semantic context and part of the input.  First it discards states and
-objects from the stack until it gets back to a state in which the
+the semantic context and part of the input.  First it discards states
+and objects from the stack until it gets back to a state in which the

 @code{error} token is acceptable.  (This means that the subexpressions
 @code{error} token is acceptable.  (This means that the subexpressions

-already parsed are discarded, back to the last complete @code{stmnts}.)  At
-this point the @code{error} token can be shifted.  Then, if the old
+already parsed are discarded, back to the last complete @code{stmnts}.)
+At this point the @code{error} token can be shifted.  Then, if the old

 look-ahead token is not acceptable to be shifted next, the parser reads
 tokens and discards them until it finds a token which is acceptable.  In
 look-ahead token is not acceptable to be shifted next, the parser reads
 tokens and discards them until it finds a token which is acceptable.  In

-this example, Bison reads and discards input until the next newline
-so that the fourth rule can apply.
+this example, Bison reads and discards input until the next newline so
+that the fourth rule can apply.  Note that discarded symbols are
+possible sources of memory leaks, see @ref{Destructor Decl, , Freeing
+Discarded Symbols}, for a means to reclaim this memory.

 
 The choice of error rules in the grammar is a choice of strategies for
 error recovery.  A simple and useful strategy is simply to skip the rest of
 the current input line or current statement if an error is detected:
 
 @example
 
 The choice of error rules in the grammar is a choice of strategies for
 error recovery.  A simple and useful strategy is simply to skip the rest of
 the current input line or current statement if an error is detected:
 
 @example

-stmnt: error ';'  /* on error, skip until ';' is read */
+stmnt: error ';'  /* On error, skip until ';' is read.  */

 @end example
 
 It is also useful to recover to the matching close-delimiter of an
 @end example
 
 It is also useful to recover to the matching close-delimiter of an


@@ -5010,7 +5260,7 @@ this is unacceptable, then the macro @code{yyclearin} may be used to clear
 this token.  Write the statement @samp{yyclearin;} in the error rule's
 action.
 
 this token.  Write the statement @samp{yyclearin;} in the error rule's
 action.
 

-For example, suppose that on a parse error, an error handling routine is
+For example, suppose that on a syntax error, an error handling routine is

 called that advances the input stream to some point where parsing should
 once again commence.  The next symbol returned by the lexical scanner is
 probably correct.  The previous look-ahead token ought to be discarded
 called that advances the input stream to some point where parsing should
 once again commence.  The next symbol returned by the lexical scanner is
 probably correct.  The previous look-ahead token ought to be discarded


@@ -5055,7 +5305,7 @@ This looks like a function call statement, but if @code{foo} is a typedef
 name, then this is actually a declaration of @code{x}.  How can a Bison
 parser for C decide how to parse this input?
 
 name, then this is actually a declaration of @code{x}.  How can a Bison
 parser for C decide how to parse this input?
 

-The method used in GNU C is to have two different token types,
+The method used in @acronym{GNU} C is to have two different token types,

 @code{IDENTIFIER} and @code{TYPENAME}.  When @code{yylex} finds an
 identifier, it looks up the current declaration of the identifier in order
 to decide which token type to return: @code{TYPENAME} if the identifier is
 @code{IDENTIFIER} and @code{TYPENAME}.  When @code{yylex} finds an
 identifier, it looks up the current declaration of the identifier in order
 to decide which token type to return: @code{TYPENAME} if the identifier is


@@ -5248,7 +5498,7 @@ As documented elsewhere (@pxref{Algorithm, ,The Bison Parser Algorithm})
 Bison parsers are @dfn{shift/reduce automata}.  In some cases (much more
 frequent than one would hope), looking at this automaton is required to
 tune or simply fix a parser.  Bison provides two different
 Bison parsers are @dfn{shift/reduce automata}.  In some cases (much more
 frequent than one would hope), looking at this automaton is required to
 tune or simply fix a parser.  Bison provides two different

-representation of it, either textually or graphically (as a @sc{vcg}
+representation of it, either textually or graphically (as a @acronym{VCG}

 file).
 
 The textual file is generated when the options @option{--report} or
 file).
 
 The textual file is generated when the options @option{--report} or


@@ -5276,12 +5526,19 @@ useless: STR;
 %%
 @end example
 
 %%
 @end example
 

-@command{bison} reports that @samp{calc.y contains 1 useless nonterminal
-and 1 useless rule} and that @samp{calc.y contains 7 shift/reduce
-conflicts}.  When given @option{--report=state}, in addition to
-@file{calc.tab.c}, it creates a file @file{calc.output} with contents
-detailed below.  The order of the output and the exact presentation
-might vary, but the interpretation is the same.
+@command{bison} reports:
+
+@example
+calc.y: warning: 1 useless nonterminal and 1 useless rule
+calc.y:11.1-7: warning: useless nonterminal: useless
+calc.y:11.8-12: warning: useless rule: useless: STR
+calc.y contains 7 shift/reduce conflicts.
+@end example
+
+When given @option{--report=state}, in addition to @file{calc.tab.c}, it
+creates a file @file{calc.output} with contents detailed below.  The
+order of the output and the exact presentation might vary, but the
+interpretation is the same.

 
 The first section includes details on conflicts that were solved thanks
 to precedence and/or associativity:
 
 The first section includes details on conflicts that were solved thanks
 to precedence and/or associativity:


@@ -5334,7 +5591,7 @@ The next section reproduces the exact grammar that Bison used:
 Grammar
 
   Number, Line, Rule
 Grammar
 
   Number, Line, Rule

-    0   5 $axiom -> exp $
+    0   5 $accept -> exp $end

     1   5 exp -> exp '+' exp
     2   6 exp -> exp '-' exp
     3   7 exp -> exp '*' exp
     1   5 exp -> exp '+' exp
     2   6 exp -> exp '-' exp
     3   7 exp -> exp '*' exp


@@ -5348,7 +5605,7 @@ and reports the uses of the symbols:
 @example
 Terminals, with rules where they appear
 
 @example
 Terminals, with rules where they appear
 

-$ (0) 0
+$end (0) 0

 '*' (42) 3
 '+' (43) 1
 '-' (45) 2
 '*' (42) 3
 '+' (43) 1
 '-' (45) 2


@@ -5358,7 +5615,7 @@ NUM (258) 5
 
 Nonterminals, with rules where they appear
 
 
 Nonterminals, with rules where they appear
 

-$axiom (8)
+$accept (8)

     on left: 0
 exp (9)
     on left: 1 2 3 4 5, on right: 0 1 2 3 4
     on left: 0
 exp (9)
     on left: 1 2 3 4 5, on right: 0 1 2 3 4


@@ -5376,11 +5633,11 @@ that the input cursor.
 @example
 state 0
 
 @example
 state 0
 

-    $axiom  ->  . exp $   (rule 0)
+    $accept  ->  . exp $   (rule 0)

 
 

-    NUM        shift, and go to state 1
+    NUM         shift, and go to state 1

 
 

-    exp        go to state 2
+    exp         go to state 2

 @end example
 
 This reads as follows: ``state 0 corresponds to being at the very
 @end example
 
 This reads as follows: ``state 0 corresponds to being at the very


@@ -5390,7 +5647,7 @@ after having reduced a rule that produced an @code{exp}, the control
 flow jumps to state 2.  If there is no such transition on a nonterminal
 symbol, and the lookahead is a @code{NUM}, then this token is shifted on
 the parse stack, and the control flow jumps to state 1.  Any other
 flow jumps to state 2.  If there is no such transition on a nonterminal
 symbol, and the lookahead is a @code{NUM}, then this token is shifted on
 the parse stack, and the control flow jumps to state 1.  Any other

-lookahead triggers a parse error.''
+lookahead triggers a syntax error.''

 
 @cindex core, item set
 @cindex item set core
 
 @cindex core, item set
 @cindex item set core


@@ -5407,7 +5664,7 @@ be derived:
 @example
 state 0
 
 @example
 state 0
 

-    $axiom  ->  . exp $   (rule 0)
+    $accept  ->  . exp $   (rule 0)

     exp  ->  . exp '+' exp   (rule 1)
     exp  ->  . exp '-' exp   (rule 2)
     exp  ->  . exp '*' exp   (rule 3)
     exp  ->  . exp '+' exp   (rule 1)
     exp  ->  . exp '-' exp   (rule 2)
     exp  ->  . exp '*' exp   (rule 3)


@@ -5427,7 +5684,7 @@ state 1
 
     exp  ->  NUM .   (rule 5)
 
 
     exp  ->  NUM .   (rule 5)
 

-    $default   reduce using rule 5 (exp)
+    $default    reduce using rule 5 (exp)

 @end example
 
 @noindent
 @end example
 
 @noindent


@@ -5439,17 +5696,17 @@ jump to state 2 (@samp{exp: go to state 2}).
 @example
 state 2
 
 @example
 state 2
 

-    $axiom  ->  exp . $   (rule 0)
+    $accept  ->  exp . $   (rule 0)

     exp  ->  exp . '+' exp   (rule 1)
     exp  ->  exp . '-' exp   (rule 2)
     exp  ->  exp . '*' exp   (rule 3)
     exp  ->  exp . '/' exp   (rule 4)
 
     exp  ->  exp . '+' exp   (rule 1)
     exp  ->  exp . '-' exp   (rule 2)
     exp  ->  exp . '*' exp   (rule 3)
     exp  ->  exp . '/' exp   (rule 4)
 

-    $          shift, and go to state 3
-    '+'        shift, and go to state 4
-    '-'        shift, and go to state 5
-    '*'        shift, and go to state 6
-    '/'        shift, and go to state 7
+    $           shift, and go to state 3
+    '+'         shift, and go to state 4
+    '-'         shift, and go to state 5
+    '*'         shift, and go to state 6
+    '/'         shift, and go to state 7

 @end example
 
 @noindent
 @end example
 
 @noindent


@@ -5458,7 +5715,7 @@ because of the item @samp{exp -> exp . '+' exp}, if the lookahead if
 @samp{+}, it will be shifted on the parse stack, and the automaton
 control will jump to state 4, corresponding to the item @samp{exp -> exp
 '+' . exp}.  Since there is no default action, any other token than
 @samp{+}, it will be shifted on the parse stack, and the automaton
 control will jump to state 4, corresponding to the item @samp{exp -> exp
 '+' . exp}.  Since there is no default action, any other token than

-those listed above will trigger a parse error.
+those listed above will trigger a syntax error.

 
 The state 3 is named the @dfn{final state}, or the @dfn{accepting
 state}:
 
 The state 3 is named the @dfn{final state}, or the @dfn{accepting
 state}:


@@ -5466,9 +5723,9 @@ state}:
 @example
 state 3
 
 @example
 state 3
 

-    $axiom  ->  exp $ .   (rule 0)
+    $accept  ->  exp $ .   (rule 0)

 
 

-    $default   accept
+    $default    accept

 @end example
 
 @noindent
 @end example
 
 @noindent


@@ -5483,33 +5740,33 @@ state 4
 
     exp  ->  exp '+' . exp   (rule 1)
 
 
     exp  ->  exp '+' . exp   (rule 1)
 

-    NUM        shift, and go to state 1
+    NUM         shift, and go to state 1

 
 

-    exp        go to state 8
+    exp         go to state 8

 
 state 5
 
     exp  ->  exp '-' . exp   (rule 2)
 
 
 state 5
 
     exp  ->  exp '-' . exp   (rule 2)
 

-    NUM        shift, and go to state 1
+    NUM         shift, and go to state 1

 
 

-    exp        go to state 9
+    exp         go to state 9

 
 state 6
 
     exp  ->  exp '*' . exp   (rule 3)
 
 
 state 6
 
     exp  ->  exp '*' . exp   (rule 3)
 

-    NUM        shift, and go to state 1
+    NUM         shift, and go to state 1

 
 

-    exp        go to state 10
+    exp         go to state 10

 
 state 7
 
     exp  ->  exp '/' . exp   (rule 4)
 
 
 state 7
 
     exp  ->  exp '/' . exp   (rule 4)
 

-    NUM        shift, and go to state 1
+    NUM         shift, and go to state 1

 
 

-    exp        go to state 11
+    exp         go to state 11

 @end example
 
 As was announced in beginning of the report, @samp{State 8 contains 1
 @end example
 
 As was announced in beginning of the report, @samp{State 8 contains 1


@@ -5524,11 +5781,11 @@ state 8
     exp  ->  exp . '*' exp   (rule 3)
     exp  ->  exp . '/' exp   (rule 4)
 
     exp  ->  exp . '*' exp   (rule 3)
     exp  ->  exp . '/' exp   (rule 4)
 

-    '*'        shift, and go to state 6
-    '/'        shift, and go to state 7
+    '*'         shift, and go to state 6
+    '/'         shift, and go to state 7

 
 

-    '/'        [reduce using rule 1 (exp)]
-    $default   reduce using rule 1 (exp)
+    '/'         [reduce using rule 1 (exp)]
+    $default    reduce using rule 1 (exp)

 @end example
 
 Indeed, there are two actions associated to the lookahead @samp{/}:
 @end example
 
 Indeed, there are two actions associated to the lookahead @samp{/}:


@@ -5540,7 +5797,7 @@ sentence @samp{NUM + NUM / NUM} can be parsed as @samp{NUM + (NUM /
 NUM)}, which corresponds to shifting @samp{/}, or as @samp{(NUM + NUM) /
 NUM}, which corresponds to reducing rule 1.
 
 NUM)}, which corresponds to shifting @samp{/}, or as @samp{(NUM + NUM) /
 NUM}, which corresponds to reducing rule 1.
 

-Because in LALR(1) parsing a single decision can be made, Bison
+Because in @acronym{LALR}(1) parsing a single decision can be made, Bison

 arbitrarily chose to disable the reduction, see @ref{Shift/Reduce, ,
 Shift/Reduce Conflicts}.  Discarded actions are reported in between
 square brackets.
 arbitrarily chose to disable the reduction, see @ref{Shift/Reduce, ,
 Shift/Reduce Conflicts}.  Discarded actions are reported in between
 square brackets.


@@ -5585,11 +5842,11 @@ state 9
     exp  ->  exp . '*' exp   (rule 3)
     exp  ->  exp . '/' exp   (rule 4)
 
     exp  ->  exp . '*' exp   (rule 3)
     exp  ->  exp . '/' exp   (rule 4)
 

-    '*'        shift, and go to state 6
-    '/'        shift, and go to state 7
+    '*'         shift, and go to state 6
+    '/'         shift, and go to state 7

 
 

-    '/'        [reduce using rule 2 (exp)]
-    $default   reduce using rule 2 (exp)
+    '/'         [reduce using rule 2 (exp)]
+    $default    reduce using rule 2 (exp)

 
 state 10
 
 
 state 10
 


@@ -5599,10 +5856,10 @@ state 10
     exp  ->  exp '*' exp .   (rule 3)
     exp  ->  exp . '/' exp   (rule 4)
 
     exp  ->  exp '*' exp .   (rule 3)
     exp  ->  exp . '/' exp   (rule 4)
 

-    '/'        shift, and go to state 7
+    '/'         shift, and go to state 7

 
 

-    '/'        [reduce using rule 3 (exp)]
-    $default   reduce using rule 3 (exp)
+    '/'         [reduce using rule 3 (exp)]
+    $default    reduce using rule 3 (exp)

 
 state 11
 
 
 state 11
 


@@ -5612,16 +5869,16 @@ state 11
     exp  ->  exp . '/' exp   (rule 4)
     exp  ->  exp '/' exp .   (rule 4)
 
     exp  ->  exp . '/' exp   (rule 4)
     exp  ->  exp '/' exp .   (rule 4)
 

-    '+'        shift, and go to state 4
-    '-'        shift, and go to state 5
-    '*'        shift, and go to state 6
-    '/'        shift, and go to state 7
+    '+'         shift, and go to state 4
+    '-'         shift, and go to state 5
+    '*'         shift, and go to state 6
+    '/'         shift, and go to state 7

 
 

-    '+'        [reduce using rule 4 (exp)]
-    '-'        [reduce using rule 4 (exp)]
-    '*'        [reduce using rule 4 (exp)]
-    '/'        [reduce using rule 4 (exp)]
-    $default   reduce using rule 4 (exp)
+    '+'         [reduce using rule 4 (exp)]
+    '-'         [reduce using rule 4 (exp)]
+    '*'         [reduce using rule 4 (exp)]
+    '/'         [reduce using rule 4 (exp)]
+    $default    reduce using rule 4 (exp)

 @end example
 
 @noindent
 @end example
 
 @noindent


@@ -5645,21 +5902,22 @@ There are several means to enable compilation of trace facilities:
 @item the macro @code{YYDEBUG}
 @findex YYDEBUG
 Define the macro @code{YYDEBUG} to a nonzero value when you compile the
 @item the macro @code{YYDEBUG}
 @findex YYDEBUG
 Define the macro @code{YYDEBUG} to a nonzero value when you compile the

-parser.  This is compliant with POSIX Yacc.  You could use
+parser.  This is compliant with @acronym{POSIX} Yacc.  You could use

 @samp{-DYYDEBUG=1} as a compiler option or you could put @samp{#define
 YYDEBUG 1} in the prologue of the grammar file (@pxref{Prologue, , The
 Prologue}).
 
 @item the option @option{-t}, @option{--debug}
 Use the @samp{-t} option when you run Bison (@pxref{Invocation,
 @samp{-DYYDEBUG=1} as a compiler option or you could put @samp{#define
 YYDEBUG 1} in the prologue of the grammar file (@pxref{Prologue, , The
 Prologue}).
 
 @item the option @option{-t}, @option{--debug}
 Use the @samp{-t} option when you run Bison (@pxref{Invocation,

-,Invoking Bison}).  This is POSIX compliant too.
+,Invoking Bison}).  This is @acronym{POSIX} compliant too.

 
 @item the directive @samp{%debug}
 @findex %debug
 Add the @code{%debug} directive (@pxref{Decl Summary, ,Bison
 Declaration Summary}).  This is a Bison extension, which will prove
 useful when Bison will output parsers for languages that don't use a
 
 @item the directive @samp{%debug}
 @findex %debug
 Add the @code{%debug} directive (@pxref{Decl Summary, ,Bison
 Declaration Summary}).  This is a Bison extension, which will prove
 useful when Bison will output parsers for languages that don't use a

-preprocessor.  Useless POSIX and Yacc portability matter to you, this is
+preprocessor.  Unless @acronym{POSIX} and Yacc portability matter to
+you, this is

 the preferred solution.
 @end table
 
 the preferred solution.
 @end table
 


@@ -5723,15 +5981,15 @@ Here is an example of @code{YYPRINT} suitable for the multi-function
 calculator (@pxref{Mfcalc Decl, ,Declarations for @code{mfcalc}}):
 
 @smallexample
 calculator (@pxref{Mfcalc Decl, ,Declarations for @code{mfcalc}}):
 
 @smallexample

-#define YYPRINT(file, type, value)   yyprint (file, type, value)
+#define YYPRINT(file, type, value) print_token_value (file, type, value)

 
 static void
 
 static void

-yyprint (FILE *file, int type, YYSTYPE value)
+print_token_value (FILE *file, int type, YYSTYPE value)

 @{
   if (type == VAR)
 @{
   if (type == VAR)

-    fprintf (file, " %s", value.tptr->name);
+    fprintf (file, "%s", value.tptr->name);

   else if (type == NUM)
   else if (type == NUM)

-    fprintf (file, " %d", value.val);
+    fprintf (file, "%d", value.val);

 @}
 @end smallexample
 
 @}
 @end smallexample
 


@@ -5753,10 +6011,11 @@ Here @var{infile} is the grammar file name, which usually ends in
 @samp{.y}.  The parser file's name is made by replacing the @samp{.y}
 with @samp{.tab.c}.  Thus, the @samp{bison foo.y} filename yields
 @file{foo.tab.c}, and the @samp{bison hack/foo.y} filename yields
 @samp{.y}.  The parser file's name is made by replacing the @samp{.y}
 with @samp{.tab.c}.  Thus, the @samp{bison foo.y} filename yields
 @file{foo.tab.c}, and the @samp{bison hack/foo.y} filename yields

-@file{hack/foo.tab.c}. It's is also possible, in case you are writing
+@file{hack/foo.tab.c}.  It's also possible, in case you are writing

 C++ code instead of C in your grammar file, to name it @file{foo.ypp}
 C++ code instead of C in your grammar file, to name it @file{foo.ypp}

-or @file{foo.y++}. Then, the output files will take an extention like
-the given one as input (repectively @file{foo.tab.cpp} and @file{foo.tab.c++}).
+or @file{foo.y++}.  Then, the output files will take an extension like
+the given one as input (respectively @file{foo.tab.cpp} and
+@file{foo.tab.c++}).

 This feature takes effect with all options that manipulate filenames like
 @samp{-o} or @samp{-d}.
 
 This feature takes effect with all options that manipulate filenames like
 @samp{-o} or @samp{-d}.
 


@@ -5766,20 +6025,18 @@ For example :
 bison -d @var{infile.yxx}
 @end example
 @noindent
 bison -d @var{infile.yxx}
 @end example
 @noindent

-will produce @file{infile.tab.cxx} and @file{infile.tab.hxx}. and
+will produce @file{infile.tab.cxx} and @file{infile.tab.hxx}, and

 
 @example
 
 @example

-bison -d @var{infile.y} -o @var{output.c++}
+bison -d -o @var{output.c++} @var{infile.y}

 @end example
 @noindent
 will produce @file{output.c++} and @file{outfile.h++}.
 
 @end example
 @noindent
 will produce @file{output.c++} and @file{outfile.h++}.
 

-

 @menu
 * Bison Options::     All the options described in detail,
 @menu
 * Bison Options::     All the options described in detail,

-                       in alphabetical order by short options.
+                        in alphabetical order by short options.

 * Option Cross Key::  Alphabetical list of long options.
 * Option Cross Key::  Alphabetical list of long options.

-* VMS Invocation::    Bison command syntax on VMS.

 @end menu
 
 @node Bison Options
 @end menu
 
 @node Bison Options


@@ -5879,7 +6136,7 @@ Same as above, but save in the file @var{defines-file}.
 @item -b @var{file-prefix}
 @itemx --file-prefix=@var{prefix}
 Pretend that @code{%verbose} was specified, i.e, specify prefix to use
 @item -b @var{file-prefix}
 @itemx --file-prefix=@var{prefix}
 Pretend that @code{%verbose} was specified, i.e, specify prefix to use

-for all Bison output file names. @xref{Decl Summary}.
+for all Bison output file names.  @xref{Decl Summary}.

 
 @item -r @var{things}
 @itemx --report=@var{things}
 
 @item -r @var{things}
 @itemx --report=@var{things}


@@ -5889,7 +6146,7 @@ separated list of @var{things} among:
 @table @code
 @item state
 Description of the grammar, conflicts (resolved and unresolved), and
 @table @code
 @item state
 Description of the grammar, conflicts (resolved and unresolved), and

-LALR automaton.
+@acronym{LALR} automaton.

 
 @item lookahead
 Implies @code{state} and augments the description of the automaton with
 
 @item lookahead
 Implies @code{state} and augments the description of the automaton with


@@ -5906,7 +6163,7 @@ For instance, on the following grammar
 @itemx --verbose
 Pretend that @code{%verbose} was specified, i.e, write an extra output
 file containing verbose descriptions of the grammar and
 @itemx --verbose
 Pretend that @code{%verbose} was specified, i.e, write an extra output
 file containing verbose descriptions of the grammar and

-parser. @xref{Decl Summary}.
+parser.  @xref{Decl Summary}.

 
 @item -o @var{filename}
 @itemx --output=@var{filename}
 
 @item -o @var{filename}
 @itemx --output=@var{filename}


@@ -5916,13 +6173,14 @@ The other output files' names are constructed from @var{filename} as
 described under the @samp{-v} and @samp{-d} options.
 
 @item -g
 described under the @samp{-v} and @samp{-d} options.
 
 @item -g

-Output a VCG definition of the LALR(1) grammar automaton computed by
-Bison. If the grammar file is @file{foo.y}, the VCG output file will
+Output a @acronym{VCG} definition of the @acronym{LALR}(1) grammar
+automaton computed by Bison.  If the grammar file is @file{foo.y}, the
+@acronym{VCG} output file will

 be @file{foo.vcg}.
 
 @item --graph=@var{graph-file}
 be @file{foo.vcg}.
 
 @item --graph=@var{graph-file}

-The behaviour of @var{--graph} is the same than @samp{-g}. The only
-difference is that it has an optionnal argument which is the name of
+The behavior of @var{--graph} is the same than @samp{-g}.  The only
+difference is that it has an optional argument which is the name of

 the output graph filename.
 @end table
 
 the output graph filename.
 @end table
 


@@ -5970,311 +6228,401 @@ the corresponding short option.
 @end example
 @end ifinfo
 
 @end example
 @end ifinfo
 

-@node VMS Invocation
-@section Invoking Bison under VMS
-@cindex invoking Bison under VMS
-@cindex VMS
+@c ================================================= Invoking Bison

 
 

-The command line syntax for Bison on VMS is a variant of the usual
-Bison command syntax---adapted to fit VMS conventions.
+@node FAQ
+@chapter Frequently Asked Questions
+@cindex frequently asked questions
+@cindex questions

 
 

-To find the VMS equivalent for any Bison option, start with the long
-option, and substitute a @samp{/} for the leading @samp{--}, and
-substitute a @samp{_} for each @samp{-} in the name of the long option.
-For example, the following invocation under VMS:
+Several questions about Bison come up occasionally.  Here some of them
+are addressed.

 
 

-@example
-bison /debug/name_prefix=bar foo.y
-@end example
+@menu
+* Parser Stack Overflow::      Breaking the Stack Limits
+@end menu

 
 

-@noindent
-is equivalent to the following command under POSIX.
+@node Parser Stack Overflow
+@section Parser Stack Overflow

 
 

-@example
-bison --debug --name-prefix=bar foo.y
-@end example
+@display
+My parser returns with error with a @samp{parser stack overflow}
+message.  What can I do?
+@end display
+
+This question is already addressed elsewhere, @xref{Recursion,
+,Recursive Rules}.

 
 

-The VMS file system does not permit filenames such as
-@file{foo.tab.c}.  In the above example, the output file
-would instead be named @file{foo_tab.c}.
+@c ================================================= Table of Symbols

 
 @node Table of Symbols
 @appendix Bison Symbols
 @cindex Bison symbols, table of
 @cindex symbols in Bison, table of
 
 
 @node Table of Symbols
 @appendix Bison Symbols
 @cindex Bison symbols, table of
 @cindex symbols in Bison, table of
 

-@table @code
-@item @@$
+@deffn {Variable} @@$

 In an action, the location of the left-hand side of the rule.
 In an action, the location of the left-hand side of the rule.

-  @xref{Locations, , Locations Overview}.
+@xref{Locations, , Locations Overview}.
+@end deffn

 
 

-@item @@@var{n}
+@deffn {Variable} @@@var{n}

 In an action, the location of the @var{n}-th symbol of the right-hand
 side of the rule.  @xref{Locations, , Locations Overview}.
 In an action, the location of the @var{n}-th symbol of the right-hand
 side of the rule.  @xref{Locations, , Locations Overview}.

+@end deffn

 
 

-@item $$
+@deffn {Variable} $$

 In an action, the semantic value of the left-hand side of the rule.
 @xref{Actions}.
 In an action, the semantic value of the left-hand side of the rule.
 @xref{Actions}.

+@end deffn

 
 

-@item $@var{n}
+@deffn {Variable} $@var{n}

 In an action, the semantic value of the @var{n}-th symbol of the
 right-hand side of the rule.  @xref{Actions}.
 In an action, the semantic value of the @var{n}-th symbol of the
 right-hand side of the rule.  @xref{Actions}.

-
-@item error
+@end deffn
+
+@deffn {Symbol} $accept
+The predefined nonterminal whose only rule is @samp{$accept: @var{start}
+$end}, where @var{start} is the start symbol.  @xref{Start Decl, , The
+Start-Symbol}.  It cannot be used in the grammar.
+@end deffn
+
+@deffn {Symbol} $end
+The predefined token marking the end of the token stream.  It cannot be
+used in the grammar.
+@end deffn
+
+@deffn {Symbol} $undefined
+The predefined token onto which all undefined values returned by
+@code{yylex} are mapped.  It cannot be used in the grammar, rather, use
+@code{error}.
+@end deffn
+
+@deffn {Symbol} error

 A token name reserved for error recovery.  This token may be used in
 grammar rules so as to allow the Bison parser to recognize an error in
 the grammar without halting the process.  In effect, a sentence
 A token name reserved for error recovery.  This token may be used in
 grammar rules so as to allow the Bison parser to recognize an error in
 the grammar without halting the process.  In effect, a sentence

-containing an error may be recognized as valid.  On a parse error, the
+containing an error may be recognized as valid.  On a syntax error, the

 token @code{error} becomes the current look-ahead token.  Actions
 corresponding to @code{error} are then executed, and the look-ahead
 token is reset to the token that originally caused the violation.
 @xref{Error Recovery}.
 token @code{error} becomes the current look-ahead token.  Actions
 corresponding to @code{error} are then executed, and the look-ahead
 token is reset to the token that originally caused the violation.
 @xref{Error Recovery}.

+@end deffn

 
 

-@item YYABORT
+@deffn {Macro} YYABORT

 Macro to pretend that an unrecoverable syntax error has occurred, by
 making @code{yyparse} return 1 immediately.  The error reporting
 function @code{yyerror} is not called.  @xref{Parser Function, ,The
 Parser Function @code{yyparse}}.
 Macro to pretend that an unrecoverable syntax error has occurred, by
 making @code{yyparse} return 1 immediately.  The error reporting
 function @code{yyerror} is not called.  @xref{Parser Function, ,The
 Parser Function @code{yyparse}}.

+@end deffn

 
 

-@item YYACCEPT
+@deffn {Macro} YYACCEPT

 Macro to pretend that a complete utterance of the language has been
 read, by making @code{yyparse} return 0 immediately.
 @xref{Parser Function, ,The Parser Function @code{yyparse}}.
 Macro to pretend that a complete utterance of the language has been
 read, by making @code{yyparse} return 0 immediately.
 @xref{Parser Function, ,The Parser Function @code{yyparse}}.

+@end deffn

 
 

-@item YYBACKUP
+@deffn {Macro} YYBACKUP

 Macro to discard a value from the parser stack and fake a look-ahead
 token.  @xref{Action Features, ,Special Features for Use in Actions}.
 Macro to discard a value from the parser stack and fake a look-ahead
 token.  @xref{Action Features, ,Special Features for Use in Actions}.

+@end deffn

 
 

-@item YYDEBUG
-Macro to define to equip the parser with tracing code. @xref{Tracing,
+@deffn {Macro} YYDEBUG
+Macro to define to equip the parser with tracing code.  @xref{Tracing,

 ,Tracing Your Parser}.
 ,Tracing Your Parser}.

+@end deffn

 
 

-@item YYERROR
+@deffn {Macro} YYERROR

 Macro to pretend that a syntax error has just been detected: call
 @code{yyerror} and then perform normal error recovery if possible
 (@pxref{Error Recovery}), or (if recovery is impossible) make
 @code{yyparse} return 1.  @xref{Error Recovery}.
 Macro to pretend that a syntax error has just been detected: call
 @code{yyerror} and then perform normal error recovery if possible
 (@pxref{Error Recovery}), or (if recovery is impossible) make
 @code{yyparse} return 1.  @xref{Error Recovery}.

+@end deffn

 
 

-@item YYERROR_VERBOSE
-Macro that you define with @code{#define} in the Bison declarations
-section to request verbose, specific error message strings when
-@code{yyerror} is called.
+@deffn {Macro} YYERROR_VERBOSE
+An obsolete macro that you define with @code{#define} in the Bison
+declarations section to request verbose, specific error message strings
+when @code{yyerror} is called.  It doesn't matter what definition you
+use for @code{YYERROR_VERBOSE}, just whether you define it.  Using
+@code{%error-verbose} is preferred.
+@end deffn

 
 

-@item YYINITDEPTH
+@deffn {Macro} YYINITDEPTH

 Macro for specifying the initial size of the parser stack.
 @xref{Stack Overflow}.
 Macro for specifying the initial size of the parser stack.
 @xref{Stack Overflow}.

+@end deffn

 
 

-@item YYLEX_PARAM
-Macro for specifying an extra argument (or list of extra arguments) for
-@code{yyparse} to pass to @code{yylex}.  @xref{Pure Calling,, Calling
-Conventions for Pure Parsers}.
+@deffn {Macro} YYLEX_PARAM
+An obsolete macro for specifying an extra argument (or list of extra
+arguments) for @code{yyparse} to pass to @code{yylex}.  he use of this
+macro is deprecated, and is supported only for Yacc like parsers.
+@xref{Pure Calling,, Calling Conventions for Pure Parsers}.
+@end deffn

 
 

-@item YYLTYPE
+@deffn {Macro} YYLTYPE

 Macro for the data type of @code{yylloc}; a structure with four
 members.  @xref{Location Type, , Data Types of Locations}.
 Macro for the data type of @code{yylloc}; a structure with four
 members.  @xref{Location Type, , Data Types of Locations}.

+@end deffn

 
 

-@item yyltype
+@deffn {Type} yyltype

 Default value for YYLTYPE.
 Default value for YYLTYPE.

+@end deffn

 
 

-@item YYMAXDEPTH
-Macro for specifying the maximum size of the parser stack.
-@xref{Stack Overflow}.
+@deffn {Macro} YYMAXDEPTH
+Macro for specifying the maximum size of the parser stack.  @xref{Stack
+Overflow}.
+@end deffn

 
 

-@item YYPARSE_PARAM
-Macro for specifying the name of a parameter that @code{yyparse} should
-accept.  @xref{Pure Calling,, Calling Conventions for Pure Parsers}.
+@deffn {Macro} YYPARSE_PARAM
+An obsolete macro for specifying the name of a parameter that
+@code{yyparse} should accept.  The use of this macro is deprecated, and
+is supported only for Yacc like parsers.  @xref{Pure Calling,, Calling
+Conventions for Pure Parsers}.
+@end deffn

 
 

-@item YYRECOVERING
+@deffn {Macro} YYRECOVERING

 Macro whose value indicates whether the parser is recovering from a
 syntax error.  @xref{Action Features, ,Special Features for Use in Actions}.
 Macro whose value indicates whether the parser is recovering from a
 syntax error.  @xref{Action Features, ,Special Features for Use in Actions}.

+@end deffn

 
 

-@item YYSTACK_USE_ALLOCA
-Macro used to control the use of @code{alloca}. If defined to @samp{0},
+@deffn {Macro} YYSTACK_USE_ALLOCA
+Macro used to control the use of @code{alloca}.  If defined to @samp{0},

 the parser will not use @code{alloca} but @code{malloc} when trying to
 the parser will not use @code{alloca} but @code{malloc} when trying to

-grow its internal stacks. Do @emph{not} define @code{YYSTACK_USE_ALLOCA}
+grow its internal stacks.  Do @emph{not} define @code{YYSTACK_USE_ALLOCA}

 to anything else.
 to anything else.

+@end deffn

 
 

-@item YYSTYPE
+@deffn {Macro} YYSTYPE

 Macro for the data type of semantic values; @code{int} by default.
 @xref{Value Type, ,Data Types of Semantic Values}.
 Macro for the data type of semantic values; @code{int} by default.
 @xref{Value Type, ,Data Types of Semantic Values}.

+@end deffn

 
 

-@item yychar
+@deffn {Variable} yychar

 External integer variable that contains the integer value of the current
 look-ahead token.  (In a pure parser, it is a local variable within
 @code{yyparse}.)  Error-recovery rule actions may examine this variable.
 @xref{Action Features, ,Special Features for Use in Actions}.
 External integer variable that contains the integer value of the current
 look-ahead token.  (In a pure parser, it is a local variable within
 @code{yyparse}.)  Error-recovery rule actions may examine this variable.
 @xref{Action Features, ,Special Features for Use in Actions}.

+@end deffn

 
 

-@item yyclearin
+@deffn {Variable} yyclearin

 Macro used in error-recovery rule actions.  It clears the previous
 look-ahead token.  @xref{Error Recovery}.
 Macro used in error-recovery rule actions.  It clears the previous
 look-ahead token.  @xref{Error Recovery}.

+@end deffn

 
 

-@item yydebug
+@deffn {Variable} yydebug

 External integer variable set to zero by default.  If @code{yydebug}
 is given a nonzero value, the parser will output information on input
 symbols and parser action.  @xref{Tracing, ,Tracing Your Parser}.
 External integer variable set to zero by default.  If @code{yydebug}
 is given a nonzero value, the parser will output information on input
 symbols and parser action.  @xref{Tracing, ,Tracing Your Parser}.

+@end deffn

 
 

-@item yyerrok
+@deffn {Macro} yyerrok

 Macro to cause parser to recover immediately to its normal mode
 Macro to cause parser to recover immediately to its normal mode

-after a parse error.  @xref{Error Recovery}.
+after a syntax error.  @xref{Error Recovery}.
+@end deffn

 
 

-@item yyerror
+@deffn {Function} yyerror

 User-supplied function to be called by @code{yyparse} on error.  The
 function receives one argument, a pointer to a character string
 containing an error message.  @xref{Error Reporting, ,The Error
 Reporting Function @code{yyerror}}.
 User-supplied function to be called by @code{yyparse} on error.  The
 function receives one argument, a pointer to a character string
 containing an error message.  @xref{Error Reporting, ,The Error
 Reporting Function @code{yyerror}}.

+@end deffn

 
 

-@item yylex
+@deffn {Function} yylex

 User-supplied lexical analyzer function, called with no arguments to get
 the next token.  @xref{Lexical, ,The Lexical Analyzer Function
 @code{yylex}}.
 User-supplied lexical analyzer function, called with no arguments to get
 the next token.  @xref{Lexical, ,The Lexical Analyzer Function
 @code{yylex}}.

+@end deffn

 
 

-@item yylval
+@deffn {Variable} yylval

 External variable in which @code{yylex} should place the semantic
 value associated with a token.  (In a pure parser, it is a local
 variable within @code{yyparse}, and its address is passed to
 @code{yylex}.)  @xref{Token Values, ,Semantic Values of Tokens}.
 External variable in which @code{yylex} should place the semantic
 value associated with a token.  (In a pure parser, it is a local
 variable within @code{yyparse}, and its address is passed to
 @code{yylex}.)  @xref{Token Values, ,Semantic Values of Tokens}.

+@end deffn

 
 

-@item yylloc
+@deffn {Variable} yylloc

 External variable in which @code{yylex} should place the line and column
 numbers associated with a token.  (In a pure parser, it is a local
 variable within @code{yyparse}, and its address is passed to
 @code{yylex}.)  You can ignore this variable if you don't use the
 @samp{@@} feature in the grammar actions.  @xref{Token Positions,
 ,Textual Positions of Tokens}.
 External variable in which @code{yylex} should place the line and column
 numbers associated with a token.  (In a pure parser, it is a local
 variable within @code{yyparse}, and its address is passed to
 @code{yylex}.)  You can ignore this variable if you don't use the
 @samp{@@} feature in the grammar actions.  @xref{Token Positions,
 ,Textual Positions of Tokens}.

+@end deffn

 
 

-@item yynerrs
-Global variable which Bison increments each time there is a parse error.
+@deffn {Variable} yynerrs
+Global variable which Bison increments each time there is a syntax error.

 (In a pure parser, it is a local variable within @code{yyparse}.)
 @xref{Error Reporting, ,The Error Reporting Function @code{yyerror}}.
 (In a pure parser, it is a local variable within @code{yyparse}.)
 @xref{Error Reporting, ,The Error Reporting Function @code{yyerror}}.

+@end deffn

 
 

-@item yyparse
+@deffn {Function} yyparse

 The parser function produced by Bison; call this function to start
 parsing.  @xref{Parser Function, ,The Parser Function @code{yyparse}}.
 The parser function produced by Bison; call this function to start
 parsing.  @xref{Parser Function, ,The Parser Function @code{yyparse}}.

+@end deffn

 
 

-@item %debug
+@deffn {Directive} %debug

 Equip the parser for debugging.  @xref{Decl Summary}.
 Equip the parser for debugging.  @xref{Decl Summary}.

+@end deffn

 
 

-@item %defines
+@deffn {Directive} %defines

 Bison declaration to create a header file meant for the scanner.
 @xref{Decl Summary}.
 Bison declaration to create a header file meant for the scanner.
 @xref{Decl Summary}.

+@end deffn
+
+@deffn {Directive} %destructor
+Specifying how the parser should reclaim the memory associated to
+discarded symbols. @xref{Destructor Decl, , Freeing Discarded Symbols}.
+@end deffn

 
 

-@item %dprec
+@deffn {Directive} %dprec

 Bison declaration to assign a precedence to a rule that is used at parse
 Bison declaration to assign a precedence to a rule that is used at parse

-time to resolve reduce/reduce conflicts.  @xref{GLR Parsers}.
+time to resolve reduce/reduce conflicts.  @xref{GLR Parsers, ,Writing
+@acronym{GLR} Parsers}.
+@end deffn

 
 

-@item %file-prefix="@var{prefix}"
-Bison declaration to set the prefix of the output files. @xref{Decl
-Summary}.
+@deffn {Directive} %error-verbose
+Bison declaration to request verbose, specific error message strings
+when @code{yyerror} is called.
+@end deffn

 
 

-@item %glr-parser
-Bison declaration to produce a GLR parser.  @xref{GLR Parsers}.
+@deffn {Directive} %file-prefix="@var{prefix}"
+Bison declaration to set the prefix of the output files.  @xref{Decl
+Summary}.
+@end deffn

 
 

-@c @item %source-extension
-@c Bison declaration to specify the generated parser output file extension.
-@c @xref{Decl Summary}.
-@c
-@c @item %header-extension
-@c Bison declaration to specify the generated parser header file extension
-@c if required. @xref{Decl Summary}.
+@deffn {Directive} %glr-parser
+Bison declaration to produce a @acronym{GLR} parser.  @xref{GLR
+Parsers, ,Writing @acronym{GLR} Parsers}.
+@end deffn

 
 

-@item %left
+@deffn {Directive} %left

 Bison declaration to assign left associativity to token(s).
 @xref{Precedence Decl, ,Operator Precedence}.
 Bison declaration to assign left associativity to token(s).
 @xref{Precedence Decl, ,Operator Precedence}.

+@end deffn

 
 

-@item %merge
+@deffn {Directive} %lex-param @{@var{argument-declaration}@}
+Bison declaration to specifying an additional parameter that
+@code{yylex} should accept.  @xref{Pure Calling,, Calling Conventions
+for Pure Parsers}.
+@end deffn
+
+@deffn {Directive} %merge

 Bison declaration to assign a merging function to a rule.  If there is a
 reduce/reduce conflict with a rule having the same merging function, the
 function is applied to the two semantic values to get a single result.
 Bison declaration to assign a merging function to a rule.  If there is a
 reduce/reduce conflict with a rule having the same merging function, the
 function is applied to the two semantic values to get a single result.

-@xref{GLR Parsers}.
+@xref{GLR Parsers, ,Writing @acronym{GLR} Parsers}.
+@end deffn

 
 

-@item %name-prefix="@var{prefix}"
-Bison declaration to rename the external symbols. @xref{Decl Summary}.
+@deffn {Directive} %name-prefix="@var{prefix}"
+Bison declaration to rename the external symbols.  @xref{Decl Summary}.
+@end deffn

 
 

-@item %no-lines
+@deffn {Directive} %no-lines

 Bison declaration to avoid generating @code{#line} directives in the
 parser file.  @xref{Decl Summary}.
 Bison declaration to avoid generating @code{#line} directives in the
 parser file.  @xref{Decl Summary}.

+@end deffn

 
 

-@item %nonassoc
+@deffn {Directive} %nonassoc

 Bison declaration to assign non-associativity to token(s).
 @xref{Precedence Decl, ,Operator Precedence}.
 Bison declaration to assign non-associativity to token(s).
 @xref{Precedence Decl, ,Operator Precedence}.

+@end deffn

 
 

-@item %output="@var{filename}"
-Bison declaration to set the name of the parser file. @xref{Decl
+@deffn {Directive} %output="@var{filename}"
+Bison declaration to set the name of the parser file.  @xref{Decl

 Summary}.
 Summary}.

+@end deffn
+
+@deffn {Directive} %parse-param @{@var{argument-declaration}@}
+Bison declaration to specifying an additional parameter that
+@code{yyparse} should accept.  @xref{Parser Function,, The Parser
+Function @code{yyparse}}.
+@end deffn

 
 

-@item %prec
+@deffn {Directive} %prec

 Bison declaration to assign a precedence to a specific rule.
 @xref{Contextual Precedence, ,Context-Dependent Precedence}.
 Bison declaration to assign a precedence to a specific rule.
 @xref{Contextual Precedence, ,Context-Dependent Precedence}.

+@end deffn

 
 

-@item %pure-parser
+@deffn {Directive} %pure-parser

 Bison declaration to request a pure (reentrant) parser.
 @xref{Pure Decl, ,A Pure (Reentrant) Parser}.
 Bison declaration to request a pure (reentrant) parser.
 @xref{Pure Decl, ,A Pure (Reentrant) Parser}.

+@end deffn

 
 

-@item %right
+@deffn {Directive} %right

 Bison declaration to assign right associativity to token(s).
 @xref{Precedence Decl, ,Operator Precedence}.
 Bison declaration to assign right associativity to token(s).
 @xref{Precedence Decl, ,Operator Precedence}.

+@end deffn

 
 

-@item %start
+@deffn {Directive} %start

 Bison declaration to specify the start symbol.  @xref{Start Decl, ,The
 Start-Symbol}.
 Bison declaration to specify the start symbol.  @xref{Start Decl, ,The
 Start-Symbol}.

+@end deffn

 
 

-@item %token
+@deffn {Directive} %token

 Bison declaration to declare token(s) without specifying precedence.
 @xref{Token Decl, ,Token Type Names}.
 Bison declaration to declare token(s) without specifying precedence.
 @xref{Token Decl, ,Token Type Names}.

+@end deffn

 
 

-@item %token-table
+@deffn {Directive} %token-table

 Bison declaration to include a token name table in the parser file.
 @xref{Decl Summary}.
 Bison declaration to include a token name table in the parser file.
 @xref{Decl Summary}.

+@end deffn

 
 

-@item %type
+@deffn {Directive} %type

 Bison declaration to declare nonterminals.  @xref{Type Decl,
 ,Nonterminal Symbols}.
 Bison declaration to declare nonterminals.  @xref{Type Decl,
 ,Nonterminal Symbols}.

+@end deffn

 
 

-@item %union
+@deffn {Directive} %union

 Bison declaration to specify several possible data types for semantic
 values.  @xref{Union Decl, ,The Collection of Value Types}.
 Bison declaration to specify several possible data types for semantic
 values.  @xref{Union Decl, ,The Collection of Value Types}.

-@end table
+@end deffn

 
 @sp 1
 
 These are the punctuation and delimiters used in Bison input:
 
 
 @sp 1
 
 These are the punctuation and delimiters used in Bison input:
 

-@table @samp
-@item %%
+@deffn {Delimiter} %%

 Delimiter used to separate the grammar rule section from the
 Bison declarations section or the epilogue.
 @xref{Grammar Layout, ,The Overall Layout of a Bison Grammar}.
 Delimiter used to separate the grammar rule section from the
 Bison declarations section or the epilogue.
 @xref{Grammar Layout, ,The Overall Layout of a Bison Grammar}.

+@end deffn

 
 

-@item %@{ %@}
+@c Don't insert spaces, or check the DVI output.
+@deffn {Delimiter} %@{@var{code}%@}

 All code listed between @samp{%@{} and @samp{%@}} is copied directly to
 the output file uninterpreted.  Such code forms the prologue of the input
 file.  @xref{Grammar Outline, ,Outline of a Bison
 Grammar}.
 All code listed between @samp{%@{} and @samp{%@}} is copied directly to
 the output file uninterpreted.  Such code forms the prologue of the input
 file.  @xref{Grammar Outline, ,Outline of a Bison
 Grammar}.

+@end deffn

 
 

-@item /*@dots{}*/
+@deffn {Construct} /*@dots{}*/

 Comment delimiters, as in C.
 Comment delimiters, as in C.

+@end deffn

 
 

-@item :
+@deffn {Delimiter} :

 Separates a rule's result from its components.  @xref{Rules, ,Syntax of
 Grammar Rules}.
 Separates a rule's result from its components.  @xref{Rules, ,Syntax of
 Grammar Rules}.

+@end deffn

 
 

-@item ;
+@deffn {Delimiter} ;

 Terminates a rule.  @xref{Rules, ,Syntax of Grammar Rules}.
 Terminates a rule.  @xref{Rules, ,Syntax of Grammar Rules}.

+@end deffn

 
 

-@item |
+@deffn {Delimiter} |

 Separates alternate rules for the same result nonterminal.
 @xref{Rules, ,Syntax of Grammar Rules}.
 Separates alternate rules for the same result nonterminal.
 @xref{Rules, ,Syntax of Grammar Rules}.

-@end table
+@end deffn

 
 @node Glossary
 @appendix Glossary
 @cindex glossary
 
 @table @asis
 
 @node Glossary
 @appendix Glossary
 @cindex glossary
 
 @table @asis

-@item Backus-Naur Form (BNF)
-Formal method of specifying context-free grammars.  BNF was first used
-in the @cite{ALGOL-60} report, 1963.  @xref{Language and Grammar,
-,Languages and Context-Free Grammars}.
+@item Backus-Naur Form (@acronym{BNF}; also called ``Backus Normal Form'')
+Formal method of specifying context-free grammars originally proposed
+by John Backus, and slightly improved by Peter Naur in his 1960-01-02
+committee document contributing to what became the Algol 60 report.
+@xref{Language and Grammar, ,Languages and Context-Free Grammars}.

 
 @item Context-free grammars
 Grammars specified as rules that can be applied regardless of context.
 
 @item Context-free grammars
 Grammars specified as rules that can be applied regardless of context.


@@ -6297,18 +6645,20 @@ each instant in time.  As input to the machine is processed, the
 machine moves from state to state as specified by the logic of the
 machine.  In the case of the parser, the input is the language being
 parsed, and the states correspond to various stages in the grammar
 machine moves from state to state as specified by the logic of the
 machine.  In the case of the parser, the input is the language being
 parsed, and the states correspond to various stages in the grammar

-rules.  @xref{Algorithm, ,The Bison Parser Algorithm }.
+rules.  @xref{Algorithm, ,The Bison Parser Algorithm}.

 
 

-@item Generalized LR (GLR)
+@item Generalized @acronym{LR} (@acronym{GLR})

 A parsing algorithm that can handle all context-free grammars, including those
 A parsing algorithm that can handle all context-free grammars, including those

-that are not LALR(1).  It resolves situations that Bison's usual LALR(1)
+that are not @acronym{LALR}(1).  It resolves situations that Bison's
+usual @acronym{LALR}(1)

 algorithm cannot by effectively splitting off multiple parsers, trying all
 possible parsers, and discarding those that fail in the light of additional
 algorithm cannot by effectively splitting off multiple parsers, trying all
 possible parsers, and discarding those that fail in the light of additional

-right context.  @xref{Generalized LR Parsing, ,Generalized LR Parsing}.
+right context.  @xref{Generalized LR Parsing, ,Generalized
+@acronym{LR} Parsing}.

 
 @item Grouping
 A language construct that is (in general) grammatically divisible;
 
 @item Grouping
 A language construct that is (in general) grammatically divisible;

-for example, `expression' or `declaration' in C.
+for example, `expression' or `declaration' in C@.

 @xref{Language and Grammar, ,Languages and Context-Free Grammars}.
 
 @item Infix operator
 @xref{Language and Grammar, ,Languages and Context-Free Grammars}.
 
 @item Infix operator


@@ -6335,7 +6685,7 @@ Rules}.
 
 @item Left-to-right parsing
 Parsing a sentence of a language by analyzing it token by token from
 
 @item Left-to-right parsing
 Parsing a sentence of a language by analyzing it token by token from

-left to right.  @xref{Algorithm, ,The Bison Parser Algorithm }.
+left to right.  @xref{Algorithm, ,The Bison Parser Algorithm}.

 
 @item Lexical analyzer (scanner)
 A function that reads an input stream and returns tokens one by one.
 
 @item Lexical analyzer (scanner)
 A function that reads an input stream and returns tokens one by one.


@@ -6352,12 +6702,12 @@ A token which consists of two or more fixed characters.  @xref{Symbols}.
 A token already read but not yet shifted.  @xref{Look-Ahead, ,Look-Ahead
 Tokens}.
 
 A token already read but not yet shifted.  @xref{Look-Ahead, ,Look-Ahead
 Tokens}.
 

-@item LALR(1)
+@item @acronym{LALR}(1)

 The class of context-free grammars that Bison (like most other parser
 The class of context-free grammars that Bison (like most other parser

-generators) can handle; a subset of LR(1).  @xref{Mystery Conflicts, ,
-Mysterious Reduce/Reduce Conflicts}.
+generators) can handle; a subset of @acronym{LR}(1).  @xref{Mystery
+Conflicts, ,Mysterious Reduce/Reduce Conflicts}.

 
 

-@item LR(1)
+@item @acronym{LR}(1)

 The class of context-free grammars in which at most one token of
 look-ahead is needed to disambiguate the parsing of any piece of input.
 
 The class of context-free grammars in which at most one token of
 look-ahead is needed to disambiguate the parsing of any piece of input.
 


@@ -6366,10 +6716,6 @@ A grammar symbol standing for a grammatical construct that can
 be expressed through rules in terms of smaller constructs; in other
 words, a construct that is not a token.  @xref{Symbols}.
 
 be expressed through rules in terms of smaller constructs; in other
 words, a construct that is not a token.  @xref{Symbols}.
 

-@item Parse error
-An error encountered during parsing of an input stream due to invalid
-syntax.  @xref{Error Recovery}.
-

 @item Parser
 A function that recognizes valid sentences of a language by analyzing
 the syntax structure of a set of tokens passed to it from a lexical
 @item Parser
 A function that recognizes valid sentences of a language by analyzing
 the syntax structure of a set of tokens passed to it from a lexical


@@ -6382,7 +6728,7 @@ performs some operation.
 @item Reduction
 Replacing a string of nonterminals and/or terminals with a single
 nonterminal, according to a grammar rule.  @xref{Algorithm, ,The Bison
 @item Reduction
 Replacing a string of nonterminals and/or terminals with a single
 nonterminal, according to a grammar rule.  @xref{Algorithm, ,The Bison

-Parser Algorithm }.
+Parser Algorithm}.

 
 @item Reentrant
 A reentrant subprogram is a subprogram which can be in invoked any
 
 @item Reentrant
 A reentrant subprogram is a subprogram which can be in invoked any


@@ -6405,7 +6751,7 @@ each statement.  @xref{Semantics, ,Defining Language Semantics}.
 @item Shift
 A parser is said to shift when it makes the choice of analyzing
 further input from the stream rather than reducing immediately some
 @item Shift
 A parser is said to shift when it makes the choice of analyzing
 further input from the stream rather than reducing immediately some

-already-recognized rule.  @xref{Algorithm, ,The Bison Parser Algorithm }.
+already-recognized rule.  @xref{Algorithm, ,The Bison Parser Algorithm}.

 
 @item Single-character literal
 A single character that is recognized and interpreted as is.
 
 @item Single-character literal
 A single character that is recognized and interpreted as is.


@@ -6422,6 +6768,10 @@ A data structure where symbol names and associated data are stored
 during parsing to allow for recognition and use of existing
 information in repeated uses of a symbol.  @xref{Multi-function Calc}.
 
 during parsing to allow for recognition and use of existing
 information in repeated uses of a symbol.  @xref{Multi-function Calc}.
 

+@item Syntax error
+An error encountered during parsing of an input stream due to invalid
+syntax.  @xref{Error Recovery}.
+

 @item Token
 A basic, grammatically indivisible unit of a language.  The symbol
 that describes a token in the grammar is a terminal symbol.
 @item Token
 A basic, grammatically indivisible unit of a language.  The symbol
 that describes a token in the grammar is a terminal symbol.