* doc/bison.texinfo (Introduction): Mention GLR and C++ as on the web

[bison.git] / doc / bison.texinfo

diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index 1d4097e32cdeb29e1de46252fd986c42d27efa94..3aac11e436fce244f03c087432bb43b34dcd224e 100644 (file)
--- a/doc/bison.texinfo
+++ b/doc/bison.texinfo
@@ -44,7 +44,7 @@ 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,
 @value{UPDATED}), the @acronym{GNU} parser generator.
 
 Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1995, 1998,

-1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.

 
 @quotation
 Permission is granted to copy, distribute and/or modify this document
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document


@@ -145,9 +145,10 @@ The Concepts of Bison
 
 Writing @acronym{GLR} Parsers
 
 
 Writing @acronym{GLR} Parsers
 

-* Simple GLR Parsers::          Using @acronym{GLR} parsers on unambiguous grammars
-* Merging GLR Parses::          Using @acronym{GLR} parsers to resolve ambiguities
-* Compiler Requirements::       @acronym{GLR} parsers require a modern C compiler
+* Simple GLR Parsers::      Using @acronym{GLR} parsers on unambiguous grammars.
+* Merging GLR Parses::      Using @acronym{GLR} parsers to resolve ambiguities.
+* GLR Semantic Actions::    Deferred semantic actions have special concerns.
+* Compiler Requirements::   @acronym{GLR} parsers require a modern C compiler.

 
 Examples
 
 
 Examples
 


@@ -225,6 +226,7 @@ Tracking Locations
 
 Bison Declarations
 
 
 Bison Declarations
 

+* Require Decl::      Requiring a Bison version.

 * Token Decl::        Declaring terminal symbols.
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.
 * Token Decl::        Declaring terminal symbols.
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.


@@ -267,7 +269,7 @@ The Bison Parser Algorithm
 * Reduce/Reduce::     When two rules are applicable in the same situation.
 * Mystery Conflicts::  Reduce/reduce conflicts that look unjustified.
 * Generalized LR Parsing::  Parsing arbitrary context-free grammars.
 * Reduce/Reduce::     When two rules are applicable in the same situation.
 * Mystery Conflicts::  Reduce/reduce conflicts that look unjustified.
 * Generalized LR Parsing::  Parsing arbitrary context-free grammars.

-* Stack Overflow::    What happens when stack gets full.  How to avoid it.
+* Memory Management:: What happens when memory is exhausted.  How to avoid it.

 
 Operator Precedence
 
 
 Operator Precedence
 


@@ -318,7 +320,7 @@ A Complete C++ Example
 
 Frequently Asked Questions
 
 
 Frequently Asked Questions
 

-* Parser Stack Overflow::      Breaking the Stack Limits
+* Memory Exhausted::           Breaking the Stack Limits

 * How Can I Reset the Parser:: @code{yyparse} Keeps some State
 * Strings are Destroyed::      @code{yylval} Loses Track of Strings
 * Implementing Gotos/Loops::   Control Flow in the Calculator
 * How Can I Reset the Parser:: @code{yyparse} Keeps some State
 * Strings are Destroyed::      @code{yylval} Loses Track of Strings
 * Implementing Gotos/Loops::   Control Flow in the Calculator


@@ -334,16 +336,16 @@ Copying This Manual
 @unnumbered Introduction
 @cindex introduction
 
 @unnumbered Introduction
 @cindex introduction
 

-@dfn{Bison} is a general-purpose parser generator that converts a
-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
+@dfn{Bison} is a general-purpose parser generator that converts a grammar
+description for an @acronym{LALR}(1) or @acronym{GLR} context-free grammar
+into a C or C++ program to parse that grammar.  Once you are proficient with
+Bison, you can use it to develop a wide range of language parsers, from those

 used in simple desk calculators to complex programming languages.
 
 Bison is upward compatible with Yacc: all properly-written Yacc grammars
 ought to work with Bison with no change.  Anyone familiar with Yacc
 should be able to use Bison with little trouble.  You need to be fluent in
 used in simple desk calculators to complex programming languages.
 
 Bison is upward compatible with Yacc: all properly-written Yacc grammars
 ought to work with Bison with no change.  Anyone familiar with Yacc
 should be able to use Bison with little trouble.  You need to be fluent in

-C programming in order to use Bison or to understand this manual.
+C or C++ programming in order to use Bison or to understand this manual.

 
 We begin with tutorial chapters that explain the basic concepts of using
 Bison and show three explained examples, each building on the last.  If you
 
 We begin with tutorial chapters that explain the basic concepts of using
 Bison and show three explained examples, each building on the last.  If you


@@ -460,7 +462,7 @@ more information on this.
 @cindex @acronym{GLR} parsing
 @cindex generalized @acronym{LR} (@acronym{GLR}) parsing
 @cindex ambiguous grammars
 @cindex @acronym{GLR} parsing
 @cindex generalized @acronym{LR} (@acronym{GLR}) parsing
 @cindex ambiguous grammars

-@cindex non-deterministic parsing
+@cindex nondeterministic parsing

 
 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
 
 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


@@ -468,7 +470,7 @@ 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 same inputs.  Even unambiguous
 (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 same inputs.  Even unambiguous

-grammars can be @dfn{non-deterministic}, meaning that no fixed
+grammars can be @dfn{nondeterministic}, 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}
 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}


@@ -732,9 +734,10 @@ user-defined function on the resulting values to produce an arbitrary
 merged result.
 
 @menu
 merged result.
 
 @menu

-* Simple GLR Parsers::          Using @acronym{GLR} parsers on unambiguous grammars
-* Merging GLR Parses::          Using @acronym{GLR} parsers to resolve ambiguities
-* Compiler Requirements::       @acronym{GLR} parsers require a modern C compiler
+* Simple GLR Parsers::      Using @acronym{GLR} parsers on unambiguous grammars.
+* Merging GLR Parses::      Using @acronym{GLR} parsers to resolve ambiguities.
+* GLR Semantic Actions::    Deferred semantic actions have special concerns.
+* Compiler Requirements::   @acronym{GLR} parsers require a modern C compiler.

 @end menu
 
 @node Simple GLR Parsers
 @end menu
 
 @node Simple GLR Parsers


@@ -909,29 +912,27 @@ parser recognizes all valid declarations, according to the
 limited syntax above, transparently.  In fact, the user does not even
 notice when the parser splits.
 
 limited syntax above, transparently.  In fact, the user does not even
 notice when the parser splits.
 

-So here we have a case where we can use the benefits of @acronym{GLR}, almost
-without disadvantages.  Even in simple cases like this, however, there
-are at least two potential problems to beware.
-First, always analyze the conflicts reported by
-Bison to make sure that @acronym{GLR} splitting is only done where it is
-intended.  A @acronym{GLR} parser splitting inadvertently may cause
-problems less obvious than an @acronym{LALR} parser statically choosing the
-wrong alternative in a conflict.
-Second, consider interactions with the lexer (@pxref{Semantic Tokens})
-with great care.  Since a split parser consumes tokens
-without performing any actions during the split, the lexer cannot
-obtain information via parser actions.  Some cases of
-lexer interactions can be eliminated by using @acronym{GLR} to
-shift the complications from the lexer to the parser.  You must check
-the remaining cases for correctness.
-
-In our example, it would be safe for the lexer to return tokens
-based on their current meanings in some symbol table, because no new
-symbols are defined in the middle of a type declaration.  Though it
-is possible for a parser to define the enumeration
-constants as they are parsed, before the type declaration is
-completed, it actually makes no difference since they cannot be used
-within the same enumerated type declaration.
+So here we have a case where we can use the benefits of @acronym{GLR},
+almost without disadvantages.  Even in simple cases like this, however,
+there are at least two potential problems to beware.  First, always
+analyze the conflicts reported by Bison to make sure that @acronym{GLR}
+splitting is only done where it is intended.  A @acronym{GLR} parser
+splitting inadvertently may cause problems less obvious than an
+@acronym{LALR} parser statically choosing the wrong alternative in a
+conflict.  Second, consider interactions with the lexer (@pxref{Semantic
+Tokens}) with great care.  Since a split parser consumes tokens without
+performing any actions during the split, the lexer cannot obtain
+information via parser actions.  Some cases of lexer interactions can be
+eliminated by using @acronym{GLR} to shift the complications from the
+lexer to the parser.  You must check the remaining cases for
+correctness.
+
+In our example, it would be safe for the lexer to return tokens based on
+their current meanings in some symbol table, because no new symbols are
+defined in the middle of a type declaration.  Though it is possible for
+a parser to define the enumeration constants as they are parsed, before
+the type declaration is completed, it actually makes no difference since
+they cannot be used within the same enumerated type declaration.

 
 @node Merging GLR Parses
 @subsection Using @acronym{GLR} to Resolve Ambiguities
 
 @node Merging GLR Parses
 @subsection Using @acronym{GLR} to Resolve Ambiguities


@@ -1095,6 +1096,55 @@ productions that participate in any particular merge have identical
 and the parser will report an error during any parse that results in
 the offending merge.
 
 and the parser will report an error during any parse that results in
 the offending merge.
 

+@node GLR Semantic Actions
+@subsection GLR Semantic Actions
+
+@cindex deferred semantic actions
+By definition, a deferred semantic action is not performed at the same time as
+the associated reduction.
+This raises caveats for several Bison features you might use in a semantic
+action in a @acronym{GLR} parser.
+
+@vindex yychar
+@cindex @acronym{GLR} parsers and @code{yychar}
+@vindex yylval
+@cindex @acronym{GLR} parsers and @code{yylval}
+@vindex yylloc
+@cindex @acronym{GLR} parsers and @code{yylloc}
+In any semantic action, you can examine @code{yychar} to determine the type of
+the look-ahead token present at the time of the associated reduction.
+After checking that @code{yychar} is not set to @code{YYEMPTY} or @code{YYEOF},
+you can then examine @code{yylval} and @code{yylloc} to determine the
+look-ahead token's semantic value and location, if any.
+In a nondeferred semantic action, you can also modify any of these variables to
+influence syntax analysis.
+@xref{Look-Ahead, ,Look-Ahead Tokens}.
+
+@findex yyclearin
+@cindex @acronym{GLR} parsers and @code{yyclearin}
+In a deferred semantic action, it's too late to influence syntax analysis.
+In this case, @code{yychar}, @code{yylval}, and @code{yylloc} are set to
+shallow copies of the values they had at the time of the associated reduction.
+For this reason alone, modifying them is dangerous.
+Moreover, the result of modifying them is undefined and subject to change with
+future versions of Bison.
+For example, if a semantic action might be deferred, you should never write it
+to invoke @code{yyclearin} (@pxref{Action Features}) or to attempt to free
+memory referenced by @code{yylval}.
+
+@findex YYERROR
+@cindex @acronym{GLR} parsers and @code{YYERROR}
+Another Bison feature requiring special consideration is @code{YYERROR}
+(@pxref{Action Features}), which you can invoke in a semantic action to
+initiate error recovery.
+During deterministic @acronym{GLR} operation, the effect of @code{YYERROR} is
+the same as its effect in an @acronym{LALR}(1) parser.
+In a deferred semantic action, its effect is undefined.
+@c The effect is probably a syntax error at the split point.
+
+Also, see @ref{Location Default Action, ,Default Action for Locations}, which
+describes a special usage of @code{YYLLOC_DEFAULT} in @acronym{GLR} parsers.
+

 @node Compiler Requirements
 @subsection Considerations when Compiling @acronym{GLR} Parsers
 @cindex @code{inline}
 @node Compiler Requirements
 @subsection Considerations when Compiling @acronym{GLR} Parsers
 @cindex @code{inline}


@@ -1197,11 +1247,13 @@ function @code{yyerror} and the parser function @code{yyparse} itself.
 This also includes numerous identifiers used for internal purposes.
 Therefore, you should avoid using C identifiers starting with @samp{yy}
 or @samp{YY} in the Bison grammar file except for the ones defined in
 This also includes numerous identifiers used for internal purposes.
 Therefore, you should avoid using C identifiers starting with @samp{yy}
 or @samp{YY} in the Bison grammar file except for the ones defined in

-this manual.
+this manual.  Also, you should avoid using the C identifiers
+@samp{malloc} and @samp{free} for anything other than their usual
+meanings.

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

 @code{<stddef.h>}, and @code{<stdlib.h>} are included as needed to
 declare memory allocators and related types.  @code{<libintl.h>} is
 included if message translation is in use
 @code{<stddef.h>}, and @code{<stdlib.h>} are included as needed to
 declare memory allocators and related types.  @code{<libintl.h>} is
 included if message translation is in use


@@ -1716,12 +1768,12 @@ With all the source in a single file, you use the following command to
 convert it into a parser file:
 
 @example
 convert it into a parser file:
 
 @example

-bison @var{file_name}.y
+bison @var{file}.y

 @end example
 
 @noindent
 In this example the file was called @file{rpcalc.y} (for ``Reverse Polish
 @end example
 
 @noindent
 In this example the file was called @file{rpcalc.y} (for ``Reverse Polish

-@sc{calc}ulator'').  Bison produces a file named @file{@var{file_name}.tab.c},
+@sc{calc}ulator'').  Bison produces a file named @file{@var{file}.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})
 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})


@@ -2123,7 +2175,7 @@ as @code{sin}, @code{cos}, etc.
 
 It is easy to add new operators to the infix calculator as long as they are
 only single-character literals.  The lexical analyzer @code{yylex} passes
 
 It is easy to add new operators to the infix calculator as long as they are
 only single-character literals.  The lexical analyzer @code{yylex} passes

-back all nonnumber characters as tokens, so new grammar rules suffice for
+back all nonnumeric characters as tokens, so new grammar rules suffice for

 adding a new operator.  But we want something more flexible: built-in
 functions whose syntax has this form:
 
 adding a new operator.  But we want something more flexible: built-in
 functions whose syntax has this form:
 


@@ -2408,7 +2460,7 @@ getsym (char const *sym_name)
 
 The function @code{yylex} must now recognize variables, numeric values, and
 the single-character arithmetic operators.  Strings of alphanumeric
 
 The function @code{yylex} must now recognize variables, numeric values, and
 the single-character arithmetic operators.  Strings of alphanumeric

-characters with a leading non-digit are recognized as either variables or
+characters with a leading letter are recognized as either variables or

 functions depending on what the symbol table says about them.
 
 The string is passed to @code{getsym} for look up in the symbol table.  If
 functions depending on what the symbol table says about them.
 
 The string is passed to @code{getsym} for look up in the symbol table.  If


@@ -2582,13 +2634,17 @@ continues until end of line.
 @cindex Prologue
 @cindex declarations
 
 @cindex Prologue
 @cindex declarations
 

-The @var{Prologue} section contains macro definitions and
-declarations of functions and variables that are used in the actions in the
-grammar rules.  These are copied to the beginning of the parser file so
-that they precede the definition of @code{yyparse}.  You can use
-@samp{#include} to get the declarations from a header file.  If you don't
-need any C declarations, you may omit the @samp{%@{} and @samp{%@}}
-delimiters that bracket this section.
+The @var{Prologue} section contains macro definitions and declarations
+of functions and variables that are used in the actions in the grammar
+rules.  These are copied to the beginning of the parser file so that
+they precede the definition of @code{yyparse}.  You can use
+@samp{#include} to get the declarations from a header file.  If you
+don't need any C declarations, you may omit the @samp{%@{} and
+@samp{%@}} delimiters that bracket this section.
+
+The @var{Prologue} section is terminated by the the first occurrence
+of @samp{%@}} that is outside a comment, a string literal, or a
+character constant.

 
 You may have more than one @var{Prologue} section, intermixed with the
 @var{Bison declarations}.  This allows you to have C and Bison
 
 You may have more than one @var{Prologue} section, intermixed with the
 @var{Bison declarations}.  This allows you to have C and Bison


@@ -2658,10 +2714,10 @@ even if you define them in the Epilogue.
 If the last section is empty, you may omit the @samp{%%} that separates it
 from the grammar rules.
 
 If the last section is empty, you may omit the @samp{%%} that separates it
 from the grammar rules.
 

-The Bison parser itself contains many macros and identifiers whose
-names start with @samp{yy} or @samp{YY}, so it is a
-good idea to avoid using any such names (except those documented in this
-manual) in the epilogue of the grammar file.
+The Bison parser itself contains many macros and identifiers whose names
+start with @samp{yy} or @samp{YY}, so it is a good idea to avoid using
+any such names (except those documented in this manual) in the epilogue
+of the grammar file.

 
 @node Symbols
 @section Symbols, Terminal and Nonterminal
 
 @node Symbols
 @section Symbols, Terminal and Nonterminal


@@ -2677,13 +2733,13 @@ A @dfn{terminal symbol} (also known as a @dfn{token type}) represents a
 class of syntactically equivalent tokens.  You use the symbol in grammar
 rules to mean that a token in that class is allowed.  The symbol is
 represented in the Bison parser by a numeric code, and the @code{yylex}
 class of syntactically equivalent tokens.  You use the symbol in grammar
 rules to mean that a token in that class is allowed.  The symbol is
 represented in the Bison parser by a numeric code, and the @code{yylex}

-function returns a token type code to indicate what kind of token has been
-read.  You don't need to know what the code value is; you can use the
-symbol to stand for it.
+function returns a token type code to indicate what kind of token has
+been read.  You don't need to know what the code value is; you can use
+the symbol to stand for it.

 
 

-A @dfn{nonterminal symbol} stands for a class of syntactically equivalent
-groupings.  The symbol name is used in writing grammar rules.  By convention,
-it should be all lower case.
+A @dfn{nonterminal symbol} stands for a class of syntactically
+equivalent groupings.  The symbol name is used in writing grammar rules.
+By convention, it should be all lower case.

 
 Symbol names can contain letters, digits (not at the beginning),
 underscores and periods.  Periods make sense only in nonterminals.
 
 Symbol names can contain letters, digits (not at the beginning),
 underscores and periods.  Periods make sense only in nonterminals.


@@ -2779,7 +2835,7 @@ 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}.
 
 If you want to write a grammar that is portable to any Standard C
 in the other source files that need it.  @xref{Invocation, ,Invoking Bison}.
 
 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
+host, you must use only nonnull 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:
 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:


@@ -2788,17 +2844,17 @@ characters in the following C-language string:
 "\a\b\t\n\v\f\r !\"#%&'()*+,-./:;<=>?[\\]^_@{|@}~"
 @end 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
-@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
-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 @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
+@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 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
 (@pxref{Error Recovery}); you shouldn't use it for any other purpose.
 
 The symbol @code{error} is a terminal symbol reserved for error recovery
 (@pxref{Error Recovery}); you shouldn't use it for any other purpose.


@@ -2850,6 +2906,22 @@ the semantics of the rule.  An action looks like this:
 @end example
 
 @noindent
 @end example
 
 @noindent

+@cindex braced code
+This is an example of @dfn{braced code}, that is, C code surrounded by
+braces, much like a compound statement in C@.  Braced code can contain
+any sequence of C tokens, so long as its braces are balanced.  Bison
+does not check the braced code for correctness directly; it merely
+copies the code to the output file, where the C compiler can check it.
+
+Within braced code, the balanced-brace count is not affected by braces
+within comments, string literals, or character constants, but it is
+affected by the C digraphs @samp{<%} and @samp{%>} that represent
+braces.  At the top level braced code must be terminated by @samp{@}}
+and not by a digraph.  Bison does not look for trigraphs, so if braced
+code uses trigraphs you should ensure that they do not affect the
+nesting of braces or the boundaries of comments, string literals, or
+character constants.
+

 Usually there is only one action and it follows the components.
 @xref{Actions}.
 
 Usually there is only one action and it follows the components.
 @xref{Actions}.
 


@@ -2905,10 +2977,10 @@ with no components.
 @section Recursive Rules
 @cindex recursive rule
 
 @section Recursive Rules
 @cindex recursive rule
 

-A rule is called @dfn{recursive} when its @var{result} nonterminal appears
-also on its right hand side.  Nearly all Bison grammars need to use
-recursion, because that is the only way to define a sequence of any number
-of a particular thing.  Consider this recursive definition of a
+A rule is called @dfn{recursive} when its @var{result} nonterminal
+appears also on its right hand side.  Nearly all Bison grammars need to
+use recursion, because that is the only way to define a sequence of any
+number of a particular thing.  Consider this recursive definition of a

 comma-separated sequence of one or more expressions:
 
 @example
 comma-separated sequence of one or more expressions:
 
 @example


@@ -3022,8 +3094,9 @@ This macro definition must go in the prologue of the grammar file
 
 In most programs, you will need different data types for different kinds
 of tokens and groupings.  For example, a numeric constant may need type
 
 In most programs, you will need different data types for different kinds
 of tokens and groupings.  For example, a numeric constant may need type

-@code{int} or @code{long int}, while a string constant needs type @code{char *},
-and an identifier might need a pointer to an entry in the symbol table.
+@code{int} or @code{long int}, while a string constant needs type
+@code{char *}, and an identifier might need a pointer to an entry in the
+symbol table.

 
 To use more than one data type for semantic values in one parser, Bison
 requires you to do two things:
 
 To use more than one data type for semantic values in one parser, Bison
 requires you to do two things:


@@ -3053,14 +3126,8 @@ each time an instance of that rule is recognized.  The task of most actions
 is to compute a semantic value for the grouping built by the rule from the
 semantic values associated with tokens or smaller groupings.
 
 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
-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;
+An action consists of braced code containing C statements, and 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


@@ -3138,6 +3205,12 @@ As long as @code{bar} is used only in the fashion shown here, @code{$0}
 always refers to the @code{expr} which precedes @code{bar} in the
 definition of @code{foo}.
 
 always refers to the @code{expr} which precedes @code{bar} in the
 definition of @code{foo}.
 

+@vindex yylval
+It is also possible to access the semantic value of the look-ahead token, if
+any, from a semantic action.
+This semantic value is stored in @code{yylval}.
+@xref{Action Features, ,Special Features for Use in Actions}.
+

 @node Action Types
 @subsection Data Types of Values in Actions
 @cindex action data types
 @node Action Types
 @subsection Data Types of Values in Actions
 @cindex action data types


@@ -3247,6 +3320,46 @@ earlier action is used to restore the prior list of variables.  This
 removes the temporary @code{let}-variable from the list so that it won't
 appear to exist while the rest of the program is parsed.
 
 removes the temporary @code{let}-variable from the list so that it won't
 appear to exist while the rest of the program is parsed.
 

+@findex %destructor
+@cindex discarded symbols, mid-rule actions
+@cindex error recovery, mid-rule actions
+In the above example, if the parser initiates error recovery (@pxref{Error
+Recovery}) while parsing the tokens in the embedded statement @code{stmt},
+it might discard the previous semantic context @code{$<context>5} without
+restoring it.
+Thus, @code{$<context>5} needs a destructor (@pxref{Destructor Decl, , Freeing
+Discarded Symbols}).
+However, Bison currently provides no means to declare a destructor for a
+mid-rule action's semantic value.
+
+One solution is to bury the mid-rule action inside a nonterminal symbol and to
+declare a destructor for that symbol:
+
+@example
+@group
+%type <context> let
+%destructor @{ pop_context ($$); @} let
+
+%%
+
+stmt:  let stmt
+               @{ $$ = $2;
+                 pop_context ($1); @}
+       ;
+
+let:   LET '(' var ')'
+               @{ $$ = push_context ();
+                 declare_variable ($3); @}
+       ;
+
+@end group
+@end example
+
+@noindent
+Note that the action is now at the end of its rule.
+Any mid-rule action can be converted to an end-of-rule action in this way, and
+this is what Bison actually does to implement mid-rule actions.
+

 Taking action before a rule is completely recognized often leads to
 conflicts since the parser must commit to a parse in order to execute the
 action.  For example, the following two rules, without mid-rule actions,
 Taking action before a rule is completely recognized often leads to
 conflicts since the parser must commit to a parse in order to execute the
 action.  For example, the following two rules, without mid-rule actions,


@@ -3340,10 +3453,7 @@ compound: subroutine
 
 @noindent
 Now Bison can execute the action in the rule for @code{subroutine} without
 
 @noindent
 Now Bison can execute the action in the rule for @code{subroutine} without

-deciding which rule for @code{compound} it will eventually use.  Note that
-the action is now at the end of its rule.  Any mid-rule action can be
-converted to an end-of-rule action in this way, and this is what Bison
-actually does to implement mid-rule actions.
+deciding which rule for @code{compound} it will eventually use.

 
 @node Locations
 @section Tracking Locations
 
 @node Locations
 @section Tracking Locations


@@ -3455,9 +3565,16 @@ exp:    @dots{}
 @end group
 @end example
 
 @end group
 @end example
 

+@vindex yylloc
+It is also possible to access the location of the look-ahead token, if any,
+from a semantic action.
+This location is stored in @code{yylloc}.
+@xref{Action Features, ,Special Features for Use in Actions}.
+

 @node Location Default Action
 @subsection Default Action for Locations
 @vindex YYLLOC_DEFAULT
 @node Location Default Action
 @subsection Default Action for Locations
 @vindex YYLLOC_DEFAULT

+@cindex @acronym{GLR} parsers and @code{YYLLOC_DEFAULT}

 
 Actually, actions are not the best place to compute locations.  Since
 locations are much more general than semantic values, there is room in
 
 Actually, actions are not the best place to compute locations.  Since
 locations are much more general than semantic values, there is room in


@@ -3465,6 +3582,9 @@ 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
 matched, before the associated action is run.  It is also invoked
 while processing a syntax error, to compute the error's location.
 rule.  The @code{YYLLOC_DEFAULT} macro is invoked each time a rule is
 matched, before the associated action is run.  It is also invoked
 while processing a syntax error, to compute the error's location.

+Before reporting an unresolvable syntactic ambiguity, a @acronym{GLR}
+parser invokes @code{YYLLOC_DEFAULT} recursively to compute the location
+of that ambiguity.

 
 Most of the time, this macro is general enough to suppress location
 dedicated code from semantic actions.
 
 Most of the time, this macro is general enough to suppress location
 dedicated code from semantic actions.


@@ -3473,9 +3593,11 @@ The @code{YYLLOC_DEFAULT} macro takes three parameters.  The first one is
 the location of the grouping (the result of the computation).  When a
 rule is matched, the second parameter identifies locations of
 all right hand side elements of the rule being matched, and the third
 the location of the grouping (the result of the computation).  When a
 rule is matched, the second parameter identifies locations of
 all right hand side elements of the rule being matched, and the third

-parameter is the size of the rule's right hand side.  When processing
-a syntax error, the second parameter identifies locations of
-the symbols that were discarded during error processing, and the third
+parameter is the size of the rule's right hand side.
+When a @acronym{GLR} parser reports an ambiguity, which of multiple candidate
+right hand sides it passes to @code{YYLLOC_DEFAULT} is undefined.
+When processing a syntax error, the second parameter identifies locations
+of the symbols that were discarded during error processing, and the third

 parameter is the number of discarded symbols.
 
 By default, @code{YYLLOC_DEFAULT} is defined this way:
 parameter is the number of discarded symbols.
 
 By default, @code{YYLLOC_DEFAULT} is defined this way:


@@ -3546,6 +3668,7 @@ it explicitly (@pxref{Language and Grammar, ,Languages and Context-Free
 Grammars}).
 
 @menu
 Grammars}).
 
 @menu

+* Require Decl::      Requiring a Bison version.

 * Token Decl::        Declaring terminal symbols.
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.
 * Token Decl::        Declaring terminal symbols.
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.


@@ -3558,6 +3681,20 @@ Grammars}).
 * Decl Summary::      Table of all Bison declarations.
 @end menu
 
 * Decl Summary::      Table of all Bison declarations.
 @end menu
 

+@node Require Decl
+@subsection Require a Version of Bison
+@cindex version requirement
+@cindex requiring a version of Bison
+@findex %require
+
+You may require the minimum version of Bison to process the grammar.  If
+the requirement is not met, @command{bison} exits with an error (exit
+status 63).
+
+@example
+%require "@var{version}"
+@end example
+

 @node Token Decl
 @subsection Token Type Names
 @cindex declaring token type names
 @node Token Decl
 @subsection Token Type Names
 @cindex declaring token type names


@@ -3691,10 +3828,10 @@ the one declared later has the higher precedence and is grouped first.
 @cindex value types, declaring
 @findex %union
 
 @cindex value types, declaring
 @findex %union
 

-The @code{%union} declaration specifies the entire collection of possible
-data types for semantic values.  The keyword @code{%union} is followed by a
-pair of braces containing the same thing that goes inside a @code{union} in
-C.
+The @code{%union} declaration specifies the entire collection of
+possible data types for semantic values.  The keyword @code{%union} is
+followed by braced code containing the same thing that goes inside a
+@code{union} in C@.

 
 For example:
 
 
 For example:
 


@@ -3725,10 +3862,15 @@ As an extension to @acronym{POSIX}, a tag is allowed after the
 @end group
 @end example
 
 @end group
 @end example
 

+@noindent

 specifies the union tag @code{value}, so the corresponding C type is
 @code{union value}.  If you do not specify a tag, it defaults to
 @code{YYSTYPE}.
 
 specifies the union tag @code{value}, so the corresponding C type is
 @code{union value}.  If you do not specify a tag, it defaults to
 @code{YYSTYPE}.
 

+As another extension to @acronym{POSIX}, you may specify multiple
+@code{%union} declarations; their contents are concatenated.  However,
+only the first @code{%union} declaration can specify a tag.
+

 Note that, unlike making a @code{union} declaration in C, you need not write
 a semicolon after the closing brace.
 
 Note that, unlike making a @code{union} declaration in C, you need not write
 a semicolon after the closing brace.
 


@@ -3770,7 +3912,7 @@ code.
 
 @deffn {Directive} %initial-action @{ @var{code} @}
 @findex %initial-action
 
 @deffn {Directive} %initial-action @{ @var{code} @}
 @findex %initial-action

-Declare that the @var{code} must be invoked before parsing each time
+Declare that the braced @var{code} must be invoked before parsing each time

 @code{yyparse} is called.  The @var{code} may use @code{$$} and
 @code{@@$} --- initial value and location of the look-ahead --- and the
 @code{%parse-param}.
 @code{yyparse} is called.  The @var{code} may use @code{$$} and
 @code{@@$} --- initial value and location of the look-ahead --- and the
 @code{%parse-param}.


@@ -3779,10 +3921,10 @@ Declare that the @var{code} must be invoked before parsing each time
 For instance, if your locations use a file name, you may use
 
 @example
 For instance, if your locations use a file name, you may use
 
 @example

-%parse-param @{ const char *filename @};
+%parse-param @{ char const *file_name @};

 %initial-action
 @{
 %initial-action
 @{

-  @@$.begin.filename = @@$.end.filename = filename;
+  @@$.initialize (file_name);

 @};
 @end example
 
 @};
 @end example
 


@@ -3792,29 +3934,29 @@ For instance, if your locations use a file name, you may use
 @cindex freeing discarded symbols
 @findex %destructor
 
 @cindex freeing discarded symbols
 @findex %destructor
 

-Some symbols can be discarded by the parser.  For instance, during error
-recovery (@pxref{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
-can be tolerable for batch parsers, such as in compilers, it is not for
-possibly ``never ending'' parsers such as shells, or implementations of
-communication protocols.
+During error recovery (@pxref{Error Recovery}), symbols already pushed
+on the stack and tokens coming from the rest of the file are discarded
+until the parser falls on its feet.  If the parser runs out of memory,
+or if it returns via @code{YYABORT} or @code{YYACCEPT}, all the
+symbols on the stack must be discarded.  Even if the parser succeeds, it
+must discard the start symbol.
+
+When discarded symbols convey heap based information, this memory is
+lost.  While this behavior can be tolerable for batch parsers, such as
+in traditional compilers, it is unacceptable for programs like shells or
+protocol implementations that may parse and execute indefinitely.

 
 

-The @code{%destructor} directive allows for the definition of code that
-is called when a symbol is thrown away.
+The @code{%destructor} directive defines code that is called when a
+symbol is automatically discarded.

 
 @deffn {Directive} %destructor @{ @var{code} @} @var{symbols}
 @findex %destructor
 
 @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{$$} to designate the semantic value associated to the
-@var{symbols}.  The additional parser parameters are also available
-(@pxref{Parser Function, , The Parser Function @code{yyparse}}).
-
-@strong{Warning:} as of Bison 1.875, this feature is still considered as
-experimental, as there was not enough user feedback.  In particular,
-the syntax might still change.
+Invoke the braced @var{code} whenever the parser discards one of the
+@var{symbols}.
+Within @var{code}, @code{$$} designates the semantic value associated
+with the discarded symbol.  The additional parser parameters are also
+available (@pxref{Parser Function, , The Parser Function
+@code{yyparse}}).

 @end deffn
 
 For instance:
 @end deffn
 
 For instance:


@@ -3830,27 +3972,9 @@ For instance:
 @end smallexample
 
 @noindent
 @end smallexample
 
 @noindent

-guarantees that when a @code{STRING} or a @code{string} will be discarded,
+guarantees that when a @code{STRING} or a @code{string} is discarded,

 its associated memory will be freed.
 
 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
-

 @sp 1
 
 @cindex discarded symbols
 @sp 1
 
 @cindex discarded symbols


@@ -3862,10 +3986,20 @@ stacked symbols popped during the first phase of error recovery,
 @item
 incoming terminals during the second phase of error recovery,
 @item
 @item
 incoming terminals during the second phase of error recovery,
 @item

-the current look-ahead when the parser aborts (either via an explicit
-call to @code{YYABORT}, or as a consequence of a failed error recovery).
+the current look-ahead and the entire stack (except the current
+right-hand side symbols) when the parser returns immediately, and
+@item
+the start symbol, when the parser succeeds.

 @end itemize
 
 @end itemize
 

+The parser can @dfn{return immediately} because of an explicit call to
+@code{YYABORT} or @code{YYACCEPT}, or failed error recovery, or memory
+exhaustion.
+
+Right-hand size symbols of a rule that explicitly triggers a syntax
+error via @code{YYERROR} are not discarded automatically.  As a rule
+of thumb, destructors are invoked only when user actions cannot manage
+the memory.

 
 @node Expect Decl
 @subsection Suppressing Conflict Warnings
 
 @node Expect Decl
 @subsection Suppressing Conflict Warnings


@@ -3889,19 +4023,18 @@ The declaration looks like this:
 %expect @var{n}
 @end example
 
 %expect @var{n}
 @end example
 

-Here @var{n} is a decimal integer.  The declaration says there should be
-no warning if there are @var{n} shift/reduce conflicts and no
-reduce/reduce conflicts.  The usual warning is
-given if there are either more or fewer conflicts, or if there are any
-reduce/reduce conflicts.
+Here @var{n} is a decimal integer.  The declaration says there should
+be @var{n} shift/reduce conflicts and no reduce/reduce conflicts.
+Bison reports an error if the number of shift/reduce conflicts differs
+from @var{n}, or if there are any reduce/reduce conflicts.

 
 

-For normal @acronym{LALR}(1) parsers, reduce/reduce conflicts are more serious,
-and should be eliminated entirely.  Bison will always report
-reduce/reduce conflicts for these parsers.  With @acronym{GLR} parsers, however,
-both shift/reduce and reduce/reduce are routine (otherwise, there
-would be no need to use @acronym{GLR} parsing).  Therefore, it is also possible
-to specify an expected number of reduce/reduce conflicts in @acronym{GLR}
-parsers, using the declaration:
+For normal @acronym{LALR}(1) parsers, reduce/reduce conflicts are more
+serious, and should be eliminated entirely.  Bison will always report
+reduce/reduce conflicts for these parsers.  With @acronym{GLR}
+parsers, however, both kinds of conflicts are routine; otherwise,
+there would be no need to use @acronym{GLR} parsing.  Therefore, it is
+also possible to specify an expected number of reduce/reduce conflicts
+in @acronym{GLR} parsers, using the declaration:

 
 @example
 %expect-rr @var{n}
 
 @example
 %expect-rr @var{n}


@@ -3922,12 +4055,12 @@ go back to the beginning.
 
 @item
 Add an @code{%expect} declaration, copying the number @var{n} from the
 
 @item
 Add an @code{%expect} declaration, copying the number @var{n} from the

-number which Bison printed.
+number which Bison printed.  With @acronym{GLR} parsers, add an
+@code{%expect-rr} declaration as well.

 @end itemize
 
 @end itemize
 

-Now Bison will stop annoying you if you do not change the number of
-conflicts, but it will warn you again if changes in the grammar result
-in more or fewer conflicts.
+Now Bison will warn you if you introduce an unexpected conflict, but
+will keep silent otherwise.

 
 @node Start Decl
 @subsection The Start-Symbol
 
 @node Start Decl
 @subsection The Start-Symbol


@@ -3953,8 +4086,8 @@ may override this restriction with the @code{%start} declaration as follows:
 A @dfn{reentrant} program is one which does not alter in the course of
 execution; in other words, it consists entirely of @dfn{pure} (read-only)
 code.  Reentrancy is important whenever asynchronous execution is possible;
 A @dfn{reentrant} program is one which does not alter in the course of
 execution; in other words, it consists entirely of @dfn{pure} (read-only)
 code.  Reentrancy is important whenever asynchronous execution is possible;

-for example, a non-reentrant program may not be safe to call from a signal
-handler.  In systems with multiple threads of control, a non-reentrant
+for example, a nonreentrant program may not be safe to call from a signal
+handler.  In systems with multiple threads of control, a nonreentrant

 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


@@ -4060,13 +4193,12 @@ is named @file{@var{name}.h}.
 
 Unless @code{YYSTYPE} is already defined as a macro, the output header
 declares @code{YYSTYPE}.  Therefore, if you are using a @code{%union}
 
 Unless @code{YYSTYPE} is already defined as a macro, the output header
 declares @code{YYSTYPE}.  Therefore, if you are using a @code{%union}

-(@pxref{Multiple Types, ,More Than One Value Type}) with components
-that require other definitions, or if you have defined a
-@code{YYSTYPE} macro (@pxref{Value Type, ,Data Types of Semantic
-Values}), you need to arrange for these definitions to be propagated to
-all modules, e.g., by putting them in a
-prerequisite header that is included both by your parser and by any
-other module that needs @code{YYSTYPE}.
+(@pxref{Multiple Types, ,More Than One Value Type}) with components that
+require other definitions, or if you have defined a @code{YYSTYPE} macro
+(@pxref{Value Type, ,Data Types of Semantic Values}), you need to
+arrange for these definitions to be propagated to all modules, e.g., by
+putting them in a prerequisite header that is included both by your
+parser and by any other module that needs @code{YYSTYPE}.

 
 Unless your parser is pure, the output header declares @code{yylval}
 as an external variable.  @xref{Pure Decl, ,A Pure (Reentrant)
 
 Unless your parser is pure, the output header declares @code{yylval}
 as an external variable.  @xref{Pure Decl, ,A Pure (Reentrant)


@@ -4077,15 +4209,15 @@ If you have also used locations, the output header declares
 @code{YYSTYPE} and @code{yylval}.  @xref{Locations, ,Tracking
 Locations}.
 
 @code{YYSTYPE} and @code{yylval}.  @xref{Locations, ,Tracking
 Locations}.
 

-This output file is normally essential if you wish to put the
-definition of @code{yylex} in a separate source file, because
-@code{yylex} typically needs to be able to refer to the
-above-mentioned declarations and to the token type codes.
-@xref{Token Values, ,Semantic Values of Tokens}.
+This output file is normally essential if you wish to put the definition
+of @code{yylex} in a separate source file, because @code{yylex}
+typically needs to be able to refer to the above-mentioned declarations
+and to the token type codes.  @xref{Token Values, ,Semantic Values of
+Tokens}.

 @end deffn
 
 @deffn {Directive} %destructor
 @end deffn
 
 @deffn {Directive} %destructor

-Specifying how the parser should reclaim the memory associated to
+Specify how the parser should reclaim the memory associated to

 discarded symbols.  @xref{Destructor Decl, , Freeing Discarded Symbols}.
 @end deffn
 
 discarded symbols.  @xref{Destructor Decl, , Freeing Discarded Symbols}.
 @end deffn
 


@@ -4127,7 +4259,7 @@ parser file contains just @code{#define} directives and static variable
 declarations.
 
 This option also tells Bison to write the C code for the grammar actions
 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
+into a file named @file{@var{file}.act}, in the form of a

 brace-surrounded body fit for a @code{switch} statement.
 @end deffn
 
 brace-surrounded body fit for a @code{switch} statement.
 @end deffn
 


@@ -4140,8 +4272,8 @@ associate errors with the parser file, treating it an independent source
 file in its own right.
 @end deffn
 
 file in its own right.
 @end deffn
 

-@deffn {Directive} %output="@var{filename}"
-Specify the @var{filename} for the parser file.
+@deffn {Directive} %output="@var{file}"
+Specify @var{file} for the parser file.

 @end deffn
 
 @deffn {Directive} %pure-parser
 @end deffn
 
 @deffn {Directive} %pure-parser


@@ -4149,6 +4281,11 @@ Request a pure (reentrant) parser program (@pxref{Pure Decl, ,A Pure
 (Reentrant) Parser}).
 @end deffn
 
 (Reentrant) Parser}).
 @end deffn
 

+@deffn {Directive} %require "@var{version}"
+Require version @var{version} or higher of Bison.  @xref{Require Decl, ,
+Require a Version of Bison}.
+@end deffn
+

 @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
 @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


@@ -4158,15 +4295,14 @@ three elements of @code{yytname} correspond to the predefined tokens
 @code{"error"}, and @code{"$undefined"}; after these come the symbols
 defined in the grammar file.
 
 @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
-example, @code{"'+'"} is a single-character literal and @code{"\"<=\""}
-is a literal string token.  All the characters of the literal string
-token appear verbatim in the string found in the table; even
-double-quote characters are not escaped.  For example, if the token
-consists of three characters @samp{*"*}, its string in @code{yytname}
-contains @samp{"*"*"}.  (In C, that would be written as
-@code{"\"*\"*\""}).
+The name in the table includes all the characters needed to represent
+the token in Bison.  For single-character literals and literal
+strings, this includes the surrounding quoting characters and any
+escape sequences.  For example, the Bison single-character literal
+@code{'+'} corresponds to a three-character name, represented in C as
+@code{"'+'"}; and the Bison two-character literal string @code{"\\/"}
+corresponds to a five-character name, represented in C as
+@code{"\"\\\\/\""}.

 
 When you specify @code{%token-table}, Bison also generates macro
 definitions for macros @code{YYNTOKENS}, @code{YYNNTS}, and
 
 When you specify @code{%token-table}, Bison also generates macro
 definitions for macros @code{YYNTOKENS}, @code{YYNNTS}, and


@@ -4266,7 +4402,11 @@ without reading further.
 The value returned by @code{yyparse} is 0 if parsing was successful (return
 is due to end-of-input).
 
 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 is 1 if parsing failed because of invalid input, i.e., input
+that contains a syntax error or that causes @code{YYABORT} to be
+invoked.
+
+The value is 2 if parsing failed due to memory exhaustion.

 @end deftypefun
 
 In an action, you can cause immediate return from @code{yyparse} by using
 @end deftypefun
 
 In an action, you can cause immediate return from @code{yyparse} by using


@@ -4288,8 +4428,8 @@ declaration @code{%parse-param}:
 
 @deffn {Directive} %parse-param @{@var{argument-declaration}@}
 @findex %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.
+Declare that an argument declared by the braced-code
+@var{argument-declaration} is an additional @code{yyparse} argument.

 The @var{argument-declaration} is used when declaring
 functions or prototypes.  The last identifier in
 @var{argument-declaration} must be the argument name.
 The @var{argument-declaration} is used when declaring
 functions or prototypes.  The last identifier in
 @var{argument-declaration} must be the argument name.


@@ -4407,11 +4547,13 @@ the grammar file has no effect on @code{yylex}.
 table.  The index of the token in the table is the token type's code.
 The name of a multicharacter token is recorded in @code{yytname} with a
 double-quote, the token's characters, and another double-quote.  The
 table.  The index of the token in the table is the token type's code.
 The name of a multicharacter token is recorded in @code{yytname} with a
 double-quote, the token's characters, and another double-quote.  The

-token's characters are not escaped in any way; they appear verbatim in
-the contents of the string in the table.
+token's characters are escaped as necessary to be suitable as input
+to Bison.

 
 

-Here's code for looking up a token in @code{yytname}, assuming that the
-characters of the token are stored in @code{token_buffer}.
+Here's code for looking up a multicharacter token in @code{yytname},
+assuming that the characters of the token are stored in
+@code{token_buffer}, and assuming that the token does not contain any
+characters like @samp{"} that require escaping.

 
 @smallexample
 for (i = 0; i < YYNTOKENS; i++)
 
 @smallexample
 for (i = 0; i < YYNTOKENS; i++)


@@ -4434,7 +4576,7 @@ The @code{yytname} table is generated only if you use the
 @subsection Semantic Values of Tokens
 
 @vindex yylval
 @subsection Semantic Values of Tokens
 
 @vindex yylval

-In an ordinary (non-reentrant) parser, the semantic value of the token must
+In an ordinary (nonreentrant) parser, the semantic value of the token must

 be stored into the global variable @code{yylval}.  When you are using
 just one data type for semantic values, @code{yylval} has that type.
 Thus, if the type is @code{int} (the default), you might write this in
 be stored into the global variable @code{yylval}.  When you are using
 just one data type for semantic values, @code{yylval} has that type.
 Thus, if the type is @code{int} (the default), you might write this in


@@ -4482,12 +4624,11 @@ then the code in @code{yylex} might look like this:
 
 @vindex yylloc
 If you are using the @samp{@@@var{n}}-feature (@pxref{Locations, ,
 
 @vindex yylloc
 If you are using the @samp{@@@var{n}}-feature (@pxref{Locations, ,

-Tracking Locations}) in actions to keep track of the
-textual locations of tokens and groupings, then you must provide this
-information in @code{yylex}.  The function @code{yyparse} expects to
-find the textual location of a token just parsed in the global variable
-@code{yylloc}.  So @code{yylex} must store the proper data in that
-variable.
+Tracking Locations}) in actions to keep track of the textual locations
+of tokens and groupings, then you must provide this information in
+@code{yylex}.  The function @code{yyparse} expects to find the textual
+location of a token just parsed in the global variable @code{yylloc}.
+So @code{yylex} must store the proper data in that variable.

 
 By default, the value of @code{yylloc} is a structure and you need only
 initialize the members that are going to be used by the actions.  The
 
 By default, the value of @code{yylloc} is a structure and you need only
 initialize the members that are going to be used by the actions.  The


@@ -4532,8 +4673,8 @@ Function}).
 
 @deffn {Directive} lex-param @{@var{argument-declaration}@}
 @findex %lex-param
 
 @deffn {Directive} lex-param @{@var{argument-declaration}@}
 @findex %lex-param

-Declare that @code{argument-declaration} is an additional @code{yylex}
-argument declaration.
+Declare that the braced-code @var{argument-declaration} is an
+additional @code{yylex} argument declaration.

 @end deffn
 
 For instance:
 @end deffn
 
 For instance:


@@ -4592,13 +4733,16 @@ 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"}}.
 
 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: memory exhaustion.  This
+can happen when the input contains constructions that are very deeply

 nested.  It isn't likely you will encounter this, since the Bison
 nested.  It isn't likely you will encounter this, since the Bison

-parser extends its stack automatically up to a very large limit.  But
-if overflow happens, @code{yyparse} calls @code{yyerror} in the usual
-fashion, except that the argument string is @w{@code{"parser stack
-overflow"}}.
+parser normally extends its stack automatically up to a very large limit.  But
+if memory is exhausted, @code{yyparse} calls @code{yyerror} in the usual
+fashion, except that the argument string is @w{@code{"memory exhausted"}}.
+
+In some cases diagnostics like @w{@code{"syntax error"}} are
+translated automatically from English to some other language before
+they are passed to @code{yyerror}.  @xref{Internationalization}.

 
 The following definition suffices in simple programs:
 
 
 The following definition suffices in simple programs:
 


@@ -4679,7 +4823,7 @@ preferable since it more accurately describes the return type for
 
 @vindex yynerrs
 The variable @code{yynerrs} contains the number of syntax errors
 
 @vindex yynerrs
 The variable @code{yynerrs} contains the number of syntax errors

-encountered so far.  Normally this variable is global; but if you
+reported so far.  Normally this variable is global; but if you

 request a pure parser (@pxref{Pure Decl, ,A Pure (Reentrant) Parser})
 then it is a local variable which only the actions can access.
 
 request a pure parser (@pxref{Pure Decl, ,A Pure (Reentrant) Parser})
 then it is a local variable which only the actions can access.
 


@@ -4745,6 +4889,12 @@ In either case, the rest of the action is not executed.
 Value stored in @code{yychar} when there is no look-ahead token.
 @end deffn
 
 Value stored in @code{yychar} when there is no look-ahead token.
 @end deffn
 

+@deffn {Macro} YYEOF
+@vindex YYEOF
+Value stored in @code{yychar} when the look-ahead is the end of the input
+stream.
+@end deffn
+

 @deffn {Macro} YYERROR;
 @findex YYERROR
 Cause an immediate syntax error.  This statement initiates error
 @deffn {Macro} YYERROR;
 @findex YYERROR
 Cause an immediate syntax error.  This statement initiates error


@@ -4761,15 +4911,20 @@ is recovering from a syntax error, and 0 the rest of the time.
 @end deffn
 
 @deffn {Variable} yychar
 @end deffn
 
 @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.
+Variable containing either the look-ahead token, or @code{YYEOF} when the
+look-ahead is the end of the input stream, or @code{YYEMPTY} when no look-ahead
+has been performed so the next token is not yet known.
+Do not modify @code{yychar} in a deferred semantic action (@pxref{GLR Semantic
+Actions}).

 @xref{Look-Ahead, ,Look-Ahead Tokens}.
 @end deffn
 
 @deffn {Macro} yyclearin;
 Discard the current look-ahead token.  This is useful primarily in
 @xref{Look-Ahead, ,Look-Ahead Tokens}.
 @end deffn
 
 @deffn {Macro} yyclearin;
 Discard the current look-ahead token.  This is useful primarily in

-error rules.  @xref{Error Recovery}.
+error rules.
+Do not invoke @code{yyclearin} in a deferred semantic action (@pxref{GLR
+Semantic Actions}).
+@xref{Error Recovery}.

 @end deffn
 
 @deffn {Macro} yyerrok;
 @end deffn
 
 @deffn {Macro} yyerrok;


@@ -4778,6 +4933,22 @@ errors.  This is useful primarily in error rules.
 @xref{Error Recovery}.
 @end deffn
 
 @xref{Error Recovery}.
 @end deffn
 

+@deffn {Variable} yylloc
+Variable containing the look-ahead token location when @code{yychar} is not set
+to @code{YYEMPTY} or @code{YYEOF}.
+Do not modify @code{yylloc} in a deferred semantic action (@pxref{GLR Semantic
+Actions}).
+@xref{Actions and Locations, ,Actions and Locations}.
+@end deffn
+
+@deffn {Variable} yylval
+Variable containing the look-ahead token semantic value when @code{yychar} is
+not set to @code{YYEMPTY} or @code{YYEOF}.
+Do not modify @code{yylval} in a deferred semantic action (@pxref{GLR Semantic
+Actions}).
+@xref{Actions, ,Actions}.
+@end deffn
+

 @deffn {Value} @@$
 @findex @@$
 Acts like a structure variable containing information on the textual location
 @deffn {Value} @@$
 @findex @@$
 Acts like a structure variable containing information on the textual location


@@ -4821,12 +4992,11 @@ Tracking Locations}.
 
 A Bison-generated parser can print diagnostics, including error and
 tracing messages.  By default, they appear in English.  However, Bison
 
 A Bison-generated parser can print diagnostics, including error and
 tracing messages.  By default, they appear in English.  However, Bison

-also supports outputting diagnostics in the user's native language.
-To make this work, the user should set the usual environment
-variables.  @xref{Users, , The User's View, gettext, GNU
-@code{gettext} utilities}.  For
-example, the shell command @samp{export LC_ALL=fr_CA.UTF-8} might set
-the user's locale to French Canadian using the @acronym{UTF}-8
+also supports outputting diagnostics in the user's native language.  To
+make this work, the user should set the usual environment variables.
+@xref{Users, , The User's View, gettext, GNU @code{gettext} utilities}.
+For example, the shell command @samp{export LC_ALL=fr_CA.UTF-8} might
+set the user's locale to French Canadian using the @acronym{UTF}-8

 encoding.  The exact set of available locales depends on the user's
 installation.
 
 encoding.  The exact set of available locales depends on the user's
 installation.
 


@@ -4961,7 +5131,7 @@ This kind of parser is known in the literature as a bottom-up parser.
 * Reduce/Reduce::     When two rules are applicable in the same situation.
 * Mystery Conflicts::  Reduce/reduce conflicts that look unjustified.
 * Generalized LR Parsing::  Parsing arbitrary context-free grammars.
 * Reduce/Reduce::     When two rules are applicable in the same situation.
 * Mystery Conflicts::  Reduce/reduce conflicts that look unjustified.
 * Generalized LR Parsing::  Parsing arbitrary context-free grammars.

-* Stack Overflow::    What happens when stack gets full.  How to avoid it.
+* Memory Management:: What happens when memory is exhausted.  How to avoid it.

 @end menu
 
 @node Look-Ahead
 @end menu
 
 @node Look-Ahead


@@ -5016,7 +5186,11 @@ doing so would produce on the stack the sequence of symbols @code{expr
 '!'}.  No rule allows that sequence.
 
 @vindex yychar
 '!'}.  No rule allows that sequence.
 
 @vindex yychar

-The current look-ahead token is stored in the variable @code{yychar}.
+@vindex yylval
+@vindex yylloc
+The look-ahead token is stored in the variable @code{yychar}.
+Its semantic value and location, if any, are stored in the variables
+@code{yylval} and @code{yylloc}.

 @xref{Action Features, ,Special Features for Use in Actions}.
 
 @node Shift/Reduce
 @xref{Action Features, ,Special Features for Use in Actions}.
 
 @node Shift/Reduce


@@ -5591,7 +5765,7 @@ pp.@: 615--649 @uref{http://doi.acm.org/10.1145/69622.357187}.
 @cindex @acronym{GLR} parsing
 @cindex generalized @acronym{LR} (@acronym{GLR}) parsing
 @cindex ambiguous grammars
 @cindex @acronym{GLR} parsing
 @cindex generalized @acronym{LR} (@acronym{GLR}) parsing
 @cindex ambiguous grammars

-@cindex non-deterministic parsing
+@cindex nondeterministic parsing

 
 Bison produces @emph{deterministic} parsers that choose uniquely
 when to reduce and which reduction to apply
 
 Bison produces @emph{deterministic} parsers that choose uniquely
 when to reduce and which reduction to apply


@@ -5656,10 +5830,10 @@ 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
 length of the input times the maximum number of stacks required for any
 context-free grammar in cubic worst-case time.  However, Bison currently
 uses a simpler data structure that requires time proportional to the
 length of the input times the maximum number of stacks required for any

-prefix of the input.  Thus, really ambiguous or non-deterministic
+prefix of the input.  Thus, really ambiguous or nondeterministic

 grammars can require exponential time and space to process.  Such badly
 behaving examples, however, are not generally of practical interest.
 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
+Usually, nondeterminism 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 @acronym{LALR}(1) portions of a
 grammar, in particular, it is only slightly slower than with the default
 doubt'' only for a few tokens at a time.  Therefore, the current data
 structure should generally be adequate.  On @acronym{LALR}(1) portions of a
 grammar, in particular, it is only slightly slower than with the default


@@ -5672,16 +5846,17 @@ London, Department of Computer Science, TR-00-12,
 @uref{http://www.cs.rhul.ac.uk/research/languages/publications/tomita_style_1.ps},
 (2000-12-24).
 
 @uref{http://www.cs.rhul.ac.uk/research/languages/publications/tomita_style_1.ps},
 (2000-12-24).
 

-@node Stack Overflow
-@section Stack Overflow, and How to Avoid It
+@node Memory Management
+@section Memory Management, and How to Avoid Memory Exhaustion
+@cindex memory exhaustion
+@cindex memory management

 @cindex stack overflow
 @cindex parser stack overflow
 @cindex overflow of parser stack
 
 @cindex stack overflow
 @cindex parser stack overflow
 @cindex overflow of parser stack
 

-The Bison parser stack can overflow if too many tokens are shifted and
+The Bison parser stack can run out of memory if too many tokens are shifted and

 not reduced.  When this happens, the parser function @code{yyparse}
 not reduced.  When this happens, the parser function @code{yyparse}

-returns a nonzero value, pausing only to call @code{yyerror} to report
-the overflow.
+calls @code{yyerror} and then returns 2.

 
 Because Bison parsers have growing stacks, hitting the upper limit
 usually results from using a right recursion instead of a left
 
 Because Bison parsers have growing stacks, hitting the upper limit
 usually results from using a right recursion instead of a left


@@ -5689,12 +5864,12 @@ recursion, @xref{Recursion, ,Recursive Rules}.
 
 @vindex YYMAXDEPTH
 By defining the macro @code{YYMAXDEPTH}, you can control how deep 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
+parser stack can become before memory is exhausted.  Define the

 macro with a value that is an integer.  This value is the maximum number
 of tokens that can be shifted (and not reduced) before overflow.
 
 The stack space allowed is not necessarily allocated.  If you specify a
 macro with a value that is an integer.  This value is the maximum number
 of tokens that can be shifted (and not reduced) before overflow.
 
 The stack space allowed is not necessarily allocated.  If you specify a

-large value for @code{YYMAXDEPTH}, the parser actually allocates a small
+large value for @code{YYMAXDEPTH}, the parser normally allocates a small

 stack at first, and then makes it bigger by stages as needed.  This
 increasing allocation happens automatically and silently.  Therefore,
 you do not need to make @code{YYMAXDEPTH} painfully small merely to save
 stack at first, and then makes it bigger by stages as needed.  This
 increasing allocation happens automatically and silently.  Therefore,
 you do not need to make @code{YYMAXDEPTH} painfully small merely to save


@@ -5716,17 +5891,14 @@ macro @code{YYINITDEPTH} to a positive integer.  For the C
 unless you are assuming C99 or some other target language or compiler
 that allows variable-length arrays.  The default is 200.
 
 unless you are assuming C99 or some other target language or compiler
 that allows variable-length arrays.  The default is 200.
 

-Do not allow @code{YYINITDEPTH} to be a value so large that arithmetic
-overflow would occur when calculating the size of the stack space.
-Also, do not allow @code{YYINITDEPTH} to be greater than
-@code{YYMAXDEPTH}.
+Do not allow @code{YYINITDEPTH} to be greater than @code{YYMAXDEPTH}.

 
 @c FIXME: C++ output.
 Because of semantical differences between C and C++, the
 
 @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.
+@acronym{LALR}(1) parsers in C produced by Bison cannot grow when compiled
+by C++ compilers.  In this precise case (compiling a C parser as C++) you are
+suggested to grow @code{YYINITDEPTH}.  The Bison maintainers hope to fix
+this deficiency in a future release.

 
 @node Error Recovery
 @chapter Error Recovery
 
 @node Error Recovery
 @chapter Error Recovery


@@ -5835,6 +6007,7 @@ The previous look-ahead token is reanalyzed immediately after an error.  If
 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 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.

+@xref{Action Features, ,Special Features for Use in Actions}.

 
 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
 
 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


@@ -6597,14 +6770,15 @@ bison @var{infile}
 
 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}
 
 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
-@file{hack/foo.tab.c}.  It's also possible, in case you are writing
+with @samp{.tab.c} and removing any leading directory.  Thus, the
+@samp{bison foo.y} file name yields
+@file{foo.tab.c}, and the @samp{bison hack/foo.y} file name yields
+@file{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}
 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++}).
 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 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
+This feature takes effect with all options that manipulate file names like

 @samp{-o} or @samp{-d}.
 
 For example :
 @samp{-o} or @samp{-d}.
 
 For example :


@@ -6661,13 +6835,14 @@ Print the version number of Bison and exit.
 @item --print-localedir
 Print the name of the directory containing locale-dependent data.
 
 @item --print-localedir
 Print the name of the directory containing locale-dependent data.
 

-@need 1750

 @item -y
 @itemx --yacc
 @item -y
 @itemx --yacc

-Equivalent to @samp{-o y.tab.c}; the parser output file is called
+Act more like the traditional Yacc command.  This can cause
+different diagnostics to be generated, and may change behavior in
+other minor ways.  Most importantly, imitate Yacc's output
+file name conventions, so that the parser output file is called

 @file{y.tab.c}, and the other outputs are called @file{y.output} and
 @file{y.tab.c}, and the other outputs are called @file{y.output} and

-@file{y.tab.h}.  The purpose of this option is to imitate Yacc's output
-file name conventions.  Thus, the following shell script can substitute
+@file{y.tab.h}.  Thus, the following shell script can substitute

 for Yacc, and the Bison distribution contains such a script for
 compatibility with @acronym{POSIX}:
 
 for Yacc, and the Bison distribution contains such a script for
 compatibility with @acronym{POSIX}:
 


@@ -6675,6 +6850,12 @@ compatibility with @acronym{POSIX}:
 #! /bin/sh
 bison -y "$@@"
 @end example
 #! /bin/sh
 bison -y "$@@"
 @end example

+
+The @option{-y}/@option{--yacc} option is intended for use with
+traditional Yacc grammars.  If your grammar uses a Bison extension
+like @samp{%glr-parser}, Bison might not be Yacc-compatible even if
+this option is specified.
+

 @end table
 
 @noindent
 @end table
 
 @noindent


@@ -6754,19 +6935,17 @@ Implies @code{state} and augments the description of the automaton with
 the full set of items for each state, instead of its core only.
 @end table
 
 the full set of items for each state, instead of its core only.
 @end table
 

-For instance, on the following grammar
-

 @item -v
 @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}.
 
 @item -v
 @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}.
 

-@item -o @var{filename}
-@itemx --output=@var{filename}
-Specify the @var{filename} for the parser file.
+@item -o @var{file}
+@itemx --output=@var{file}
+Specify the @var{file} for the parser file.

 
 

-The other output files' names are constructed from @var{filename} as
+The other output files' names are constructed from @var{file} as

 described under the @samp{-v} and @samp{-d} options.
 
 @item -g
 described under the @samp{-v} and @samp{-d} options.
 
 @item -g


@@ -6778,7 +6957,7 @@ be @file{foo.vcg}.
 @item --graph=@var{graph-file}
 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
 @item --graph=@var{graph-file}
 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.
+the output graph file.

 @end table
 
 @node Option Cross Key
 @end table
 
 @node Option Cross Key


@@ -6894,13 +7073,13 @@ used for location tracking.  @xref{C++ Location Values}.
 @item stack.hh
 An auxiliary class @code{stack} used by the parser.
 
 @item stack.hh
 An auxiliary class @code{stack} used by the parser.
 

-@item @var{filename}.hh
-@itemx @var{filename}.cc
+@item @var{file}.hh
+@itemx @var{file}.cc

 The declaration and implementation of the C++ parser class.
 The declaration and implementation of the C++ parser class.

-@var{filename} is the name of the output file.  It follows the same
+@var{file} is the name of the output file.  It follows the same

 rules as with regular C parsers.
 
 rules as with regular C parsers.
 

-Note that @file{@var{filename}.hh} is @emph{mandatory}, the C++ cannot
+Note that @file{@var{file}.hh} is @emph{mandatory}, the C++ cannot

 work without the parser class declaration.  Therefore, you must either
 pass @option{-d}/@option{--defines} to @command{bison}, or use the
 @samp{%defines} directive.
 work without the parser class declaration.  Therefore, you must either
 pass @option{-d}/@option{--defines} to @command{bison}, or use the
 @samp{%defines} directive.


@@ -6918,12 +7097,13 @@ for a complete and accurate documentation.
 The @code{%union} directive works as for C, see @ref{Union Decl, ,The
 Collection of Value Types}.  In particular it produces a genuine
 @code{union}@footnote{In the future techniques to allow complex types
 The @code{%union} directive works as for C, see @ref{Union Decl, ,The
 Collection of Value Types}.  In particular it produces a genuine
 @code{union}@footnote{In the future techniques to allow complex types

-within pseudo-unions (variants) might be implemented to alleviate
-these issues.}, which have a few specific features in C++.
+within pseudo-unions (similar to Boost variants) might be implemented to
+alleviate these issues.}, which have a few specific features in C++.

 @itemize @minus
 @item
 @itemize @minus
 @item

-The name @code{YYSTYPE} also denotes @samp{union YYSTYPE}.  You may
-forward declare it just with @samp{union YYSTYPE;}.
+The type @code{YYSTYPE} is defined but its use is discouraged: rather
+you should refer to the parser's encapsulated type
+@code{yy::parser::semantic_type}.

 @item
 Non POD (Plain Old Data) types cannot be used.  C++ forbids any
 instance of classes with constructors in unions: only @emph{pointers}
 @item
 Non POD (Plain Old Data) types cannot be used.  C++ forbids any
 instance of classes with constructors in unions: only @emph{pointers}


@@ -6949,7 +7129,7 @@ auxiliary classes define a @code{position}, a single point in a file,
 and a @code{location}, a range composed of a pair of
 @code{position}s (possibly spanning several files).
 
 and a @code{location}, a range composed of a pair of
 @code{position}s (possibly spanning several files).
 

-@deftypemethod {position} {std::string*} filename
+@deftypemethod {position} {std::string*} file

 The name of the file.  It will always be handled as a pointer, the
 parser will never duplicate nor deallocate it.  As an experimental
 feature you may change it to @samp{@var{type}*} using @samp{%define
 The name of the file.  It will always be handled as a pointer, the
 parser will never duplicate nor deallocate it.  As an experimental
 feature you may change it to @samp{@var{type}*} using @samp{%define


@@ -6981,8 +7161,8 @@ Various forms of syntactic sugar for @code{columns}.
 
 @deftypemethod {position} {position} operator<< (std::ostream @var{o}, const position& @var{p})
 Report @var{p} on @var{o} like this:
 
 @deftypemethod {position} {position} operator<< (std::ostream @var{o}, const position& @var{p})
 Report @var{p} on @var{o} like this:

-@samp{@var{filename}:@var{line}.@var{column}}, or
-@samp{@var{line}.@var{column}} if @var{filename} is null.
+@samp{@var{file}:@var{line}.@var{column}}, or
+@samp{@var{line}.@var{column}} if @var{file} is null.

 @end deftypemethod
 
 @deftypemethod {location} {position} begin
 @end deftypemethod
 
 @deftypemethod {location} {position} begin


@@ -7018,7 +7198,7 @@ The output files @file{@var{output}.hh} and @file{@var{output}.cc}
 declare and define the parser class in the namespace @code{yy}.  The
 class name defaults to @code{parser}, but may be changed using
 @samp{%define "parser_class_name" "@var{name}"}.  The interface of
 declare and define the parser class in the namespace @code{yy}.  The
 class name defaults to @code{parser}, but may be changed using
 @samp{%define "parser_class_name" "@var{name}"}.  The interface of

-this class is detailled below.  It can be extended using the
+this class is detailed below.  It can be extended using the

 @code{%parse-param} feature: its semantics is slightly changed since
 it describes an additional member of the parser class, and an
 additional argument for its constructor.
 @code{%parse-param} feature: its semantics is slightly changed since
 it describes an additional member of the parser class, and an
 additional argument for its constructor.


@@ -7046,7 +7226,7 @@ Get or set the stream used for tracing the parsing.  It defaults to
 @deftypemethod {parser} {debug_level_type} debug_level ()
 @deftypemethodx {parser} {void} set_debug_level (debug_level @var{l})
 Get or set the tracing level.  Currently its value is either 0, no trace,
 @deftypemethod {parser} {debug_level_type} debug_level ()
 @deftypemethodx {parser} {void} set_debug_level (debug_level @var{l})
 Get or set the tracing level.  Currently its value is either 0, no trace,

-or non-zero, full tracing.
+or nonzero, full tracing.

 @end deftypemethod
 
 @deftypemethod {parser} {void} error (const location_type& @var{l}, const std::string& @var{m})
 @end deftypemethod
 
 @deftypemethod {parser} {void} error (const location_type& @var{l}, const std::string& @var{m})


@@ -7097,7 +7277,7 @@ actually easier to interface with.
 @subsection Calc++ --- C++ Calculator
 
 Of course the grammar is dedicated to arithmetics, a single
 @subsection Calc++ --- C++ Calculator
 
 Of course the grammar is dedicated to arithmetics, a single

-expression, possibily preceded by variable assignments.  An
+expression, possibly preceded by variable assignments.  An

 environment containing possibly predefined variables such as
 @code{one} and @code{two}, is exchanged with the parser.  An example
 of valid input follows.
 environment containing possibly predefined variables such as
 @code{one} and @code{two}, is exchanged with the parser.  An example
 of valid input follows.


@@ -7124,7 +7304,8 @@ transforming the simple parsing context structure into a fully blown
 
 The declaration of this driver class, @file{calc++-driver.hh}, is as
 follows.  The first part includes the CPP guard and imports the
 
 The declaration of this driver class, @file{calc++-driver.hh}, is as
 follows.  The first part includes the CPP guard and imports the

-required standard library components.
+required standard library components, and the declaration of the parser
+class.

 
 @comment file: calc++-driver.hh
 @example
 
 @comment file: calc++-driver.hh
 @example


@@ -7132,26 +7313,9 @@ required standard library components.
 # define CALCXX_DRIVER_HH
 # include <string>
 # include <map>
 # define CALCXX_DRIVER_HH
 # include <string>
 # include <map>

+# include "calc++-parser.hh"

 @end example
 
 @end example
 

-@noindent
-Then come forward declarations.  Because the parser uses the parsing
-driver and reciprocally, simple inclusions of header files will not
-do.  Because the driver's declaration is the one that will be imported
-by the rest of the project, it is saner to forward declare the
-parser's information here.
-
-@comment file: calc++-driver.hh
-@example
-// Forward declarations.
-union YYSTYPE;
-namespace yy
-@{
-  class location;
-  class calcxx_parser;
-@}
-class calcxx_driver;
-@end example

 
 @noindent
 Then comes the declaration of the scanning function.  Flex expects
 
 @noindent
 Then comes the declaration of the scanning function.  Flex expects


@@ -7163,7 +7327,9 @@ factor both as follows.
 @example
 // Announce to Flex the prototype we want for lexing function, ...
 # define YY_DECL                                                \
 @example
 // Announce to Flex the prototype we want for lexing function, ...
 # define YY_DECL                                                \

-  int yylex (YYSTYPE* yylval, yy::location* yylloc, calcxx_driver& driver)
+  int yylex (yy::calcxx_parser::semantic_type* yylval,           \
+             yy::calcxx_parser::location_type* yylloc,           \
+             calcxx_driver& driver)

 // ... and declare it for the parser's sake.
 YY_DECL;
 @end example
 // ... and declare it for the parser's sake.
 YY_DECL;
 @end example


@@ -7273,19 +7439,33 @@ calcxx_driver::error (const std::string& m)
 @node Calc++ Parser
 @subsection Calc++ Parser
 
 @node Calc++ Parser
 @subsection Calc++ Parser
 

-The parser definition file @file{calc++-parser.yy} starts by asking
-for the C++ skeleton, the creation of the parser header file, and
-specifies the name of the parser class.  It then includes the required
-headers.
+The parser definition file @file{calc++-parser.yy} starts by asking for
+the C++ LALR(1) skeleton, the creation of the parser header file, and
+specifies the name of the parser class.  Because the C++ skeleton
+changed several times, it is safer to require the version you designed
+the grammar for.

 
 @comment file: calc++-parser.yy
 @example
 %skeleton "lalr1.cc"                          /*  -*- C++ -*- */
 
 @comment file: calc++-parser.yy
 @example
 %skeleton "lalr1.cc"                          /*  -*- C++ -*- */

-%define "parser_class_name" "calcxx_parser"
+%require "2.1a"

 %defines
 %defines

+%define "parser_class_name" "calcxx_parser"
+@end example
+
+@noindent
+Then come the declarations/inclusions needed to define the
+@code{%union}.  Because the parser uses the parsing driver and
+reciprocally, both cannot include the header of the other.  Because the
+driver's header needs detailed knowledge about the parser class (in
+particular its inner types), it is the parser's header which will simply
+use a forward declaration of the driver.
+
+@comment file: calc++-parser.yy
+@example

 %@{
 # include <string>
 %@{
 # include <string>

-# include "calc++-driver.hh"
+class calcxx_driver;

 %@}
 @end example
 
 %@}
 @end example
 


@@ -7341,6 +7521,19 @@ them.
 @};
 @end example
 
 @};
 @end example
 

+@noindent
+The code between @samp{%@{} and @samp{%@}} after the introduction of the
+@samp{%union} is output in the @file{*.cc} file; it needs detailed
+knowledge about the driver.
+
+@comment file: calc++-parser.yy
+@example
+%@{
+# include "calc++-driver.hh"
+%@}
+@end example
+
+

 @noindent
 The token numbered as 0 corresponds to end of file; the following line
 allows for nicer error messages referring to ``end of file'' instead
 @noindent
 The token numbered as 0 corresponds to end of file; the following line
 allows for nicer error messages referring to ``end of file'' instead


@@ -7350,17 +7543,18 @@ avoid name clashes.
 
 @comment file: calc++-parser.yy
 @example
 
 @comment file: calc++-parser.yy
 @example

-%token        YYEOF          0 "end of file"
-%token        TOKEN_ASSIGN     ":="
-%token <sval> TOKEN_IDENTIFIER "identifier"
-%token <ival> TOKEN_NUMBER     "number"
-%type  <ival> exp              "expression"
+%token        END      0 "end of file"
+%token        ASSIGN     ":="
+%token <sval> IDENTIFIER "identifier"
+%token <ival> NUMBER     "number"
+%type  <ival> exp        "expression"

 @end example
 
 @noindent
 To enable memory deallocation during error recovery, use
 @code{%destructor}.
 
 @end example
 
 @noindent
 To enable memory deallocation during error recovery, use
 @code{%destructor}.
 

+@c FIXME: Document %printer, and mention that it takes a braced-code operand.

 @comment file: calc++-parser.yy
 @example
 %printer    @{ debug_stream () << *$$; @} "identifier"
 @comment file: calc++-parser.yy
 @example
 %printer    @{ debug_stream () << *$$; @} "identifier"


@@ -7379,9 +7573,9 @@ The grammar itself is straightforward.
 unit: assignments exp  @{ driver.result = $2; @};
 
 assignments: assignments assignment @{@}
 unit: assignments exp  @{ driver.result = $2; @};
 
 assignments: assignments assignment @{@}

-           | /* Nothing. */         @{@};
+           | /* Nothing.  */        @{@};

 
 

-assignment: TOKEN_IDENTIFIER ":=" exp @{ driver.variables[*$1] = $3; @};
+assignment: "identifier" ":=" exp @{ driver.variables[*$1] = $3; @};

 
 %left '+' '-';
 %left '*' '/';
 
 %left '+' '-';
 %left '*' '/';


@@ -7389,8 +7583,8 @@ exp: exp '+' exp   @{ $$ = $1 + $3; @}
    | exp '-' exp   @{ $$ = $1 - $3; @}
    | exp '*' exp   @{ $$ = $1 * $3; @}
    | exp '/' exp   @{ $$ = $1 / $3; @}
    | exp '-' exp   @{ $$ = $1 - $3; @}
    | exp '*' exp   @{ $$ = $1 * $3; @}
    | exp '/' exp   @{ $$ = $1 / $3; @}

-   | TOKEN_IDENTIFIER  @{ $$ = driver.variables[*$1]; @}
-   | TOKEN_NUMBER      @{ $$ = $1; @};
+   | "identifier"  @{ $$ = driver.variables[*$1]; @}
+   | "number"      @{ $$ = $1; @};

 %%
 @end example
 
 %%
 @end example
 


@@ -7417,9 +7611,16 @@ parser's to get the set of defined tokens.
 @comment file: calc++-scanner.ll
 @example
 %@{                                            /* -*- C++ -*- */
 @comment file: calc++-scanner.ll
 @example
 %@{                                            /* -*- C++ -*- */

+# include <cstdlib>
+# include <errno.h>
+# include <limits.h>

 # include <string>
 # include "calc++-driver.hh"
 # include "calc++-parser.hh"
 # include <string>
 # include "calc++-driver.hh"
 # include "calc++-parser.hh"

+/* Work around a bug in flex 2.5.31.  See Debian bug 333231
+  <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=333231>.  */
+# undef yywrap
+# define yywrap() 1

 %@}
 @end example
 
 %@}
 @end example
 


@@ -7445,7 +7646,7 @@ blank [ \t]
 @end example
 
 @noindent
 @end example
 
 @noindent

-The following paragraph suffices to track locations acurately.  Each
+The following paragraph suffices to track locations accurately.  Each

 time @code{yylex} is invoked, the begin position is moved onto the end
 position.  Then when a pattern is matched, the end position is
 advanced of its width.  In case it matched ends of lines, the end
 time @code{yylex} is invoked, the begin position is moved onto the end
 position.  Then when a pattern is matched, the end position is
 advanced of its width.  In case it matched ends of lines, the end


@@ -7467,15 +7668,28 @@ preceding tokens.  Comments would be treated equally.
 @end example
 
 @noindent
 @end example
 
 @noindent

-The rules are simple, just note the use of the driver to report
-errors.
+The rules are simple, just note the use of the driver to report errors.
+It is convenient to use a typedef to shorten
+@code{yy::calcxx_parser::token::identifier} into
+@code{token::identifier} for instance.

 
 @comment file: calc++-scanner.ll
 @example
 
 @comment file: calc++-scanner.ll
 @example

+%@{
+  typedef yy::calcxx_parser::token token;
+%@}
+

 [-+*/]     return yytext[0];
 [-+*/]     return yytext[0];

-":="       return TOKEN_ASSIGN;
-@{int@}      yylval->ival = atoi (yytext); return TOKEN_NUMBER;
-@{id@}       yylval->sval = new std::string (yytext); return TOKEN_IDENTIFIER;
+":="       return token::ASSIGN;
+@{int@}      @{
+  errno = 0;
+  long n = strtol (yytext, NULL, 10);
+  if (! (INT_MIN <= n && n <= INT_MAX && errno != ERANGE))
+    driver.error (*yylloc, "integer is out of range");
+  yylval->ival = n;
+  return token::NUMBER;
+@}
+@{id@}       yylval->sval = new std::string (yytext); return token::IDENTIFIER;

 .          driver.error (*yylloc, "invalid character");
 %%
 @end example
 .          driver.error (*yylloc, "invalid character");
 %%
 @end example


@@ -7512,7 +7726,7 @@ The top level file, @file{calc++.cc}, poses no problem.
 #include "calc++-driver.hh"
 
 int
 #include "calc++-driver.hh"
 
 int

-main (int argc, const char* argv[])
+main (int argc, char *argv[])

 @{
   calcxx_driver driver;
   for (++argv; argv[0]; ++argv)
 @{
   calcxx_driver driver;
   for (++argv; argv[0]; ++argv)


@@ -7539,17 +7753,17 @@ Several questions about Bison come up occasionally.  Here some of them
 are addressed.
 
 @menu
 are addressed.
 
 @menu

-* Parser Stack Overflow::      Breaking the Stack Limits
+* Memory Exhausted::           Breaking the Stack Limits

 * How Can I Reset the Parser:: @code{yyparse} Keeps some State
 * Strings are Destroyed::      @code{yylval} Loses Track of Strings
 * Implementing Gotos/Loops::   Control Flow in the Calculator
 @end menu
 
 * How Can I Reset the Parser:: @code{yyparse} Keeps some State
 * Strings are Destroyed::      @code{yylval} Loses Track of Strings
 * Implementing Gotos/Loops::   Control Flow in the Calculator
 @end menu
 

-@node Parser Stack Overflow
-@section Parser Stack Overflow
+@node Memory Exhausted
+@section Memory Exhausted

 
 @display
 
 @display

-My parser returns with error with a @samp{parser stack overflow}
+My parser returns with error with a @samp{memory exhausted}

 message.  What can I do?
 @end display
 
 message.  What can I do?
 @end display
 


@@ -7820,7 +8034,7 @@ Bison declaration to create a header file meant for the scanner.
 @end deffn
 
 @deffn {Directive} %destructor
 @end deffn
 
 @deffn {Directive} %destructor

-Specifying how the parser should reclaim the memory associated to
+Specify how the parser should reclaim the memory associated to

 discarded symbols.  @xref{Destructor Decl, , Freeing Discarded Symbols}.
 @end deffn
 
 discarded symbols.  @xref{Destructor Decl, , Freeing Discarded Symbols}.
 @end deffn
 


@@ -7901,11 +8115,11 @@ parser file.  @xref{Decl Summary}.
 @end deffn
 
 @deffn {Directive} %nonassoc
 @end deffn
 
 @deffn {Directive} %nonassoc

-Bison declaration to assign non-associativity to token(s).
+Bison declaration to assign nonassociativity to token(s).

 @xref{Precedence Decl, ,Operator Precedence}.
 @end deffn
 
 @xref{Precedence Decl, ,Operator Precedence}.
 @end deffn
 

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

 Bison declaration to set the name of the parser file.  @xref{Decl
 Summary}.
 @end deffn
 Bison declaration to set the name of the parser file.  @xref{Decl
 Summary}.
 @end deffn


@@ -7926,6 +8140,11 @@ Bison declaration to request a pure (reentrant) parser.
 @xref{Pure Decl, ,A Pure (Reentrant) Parser}.
 @end deffn
 
 @xref{Pure Decl, ,A Pure (Reentrant) Parser}.
 @end deffn
 

+@deffn {Directive} %require "@var{version}"
+Require version @var{version} or higher of Bison.  @xref{Require Decl, ,
+Require a Version of Bison}.
+@end deffn
+

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


@@ -7981,7 +8200,7 @@ token.  @xref{Action Features, ,Special Features for Use in Actions}.
 @end deffn
 
 @deffn {Variable} yychar
 @end deffn
 
 @deffn {Variable} yychar

-External integer variable that contains the integer value of the current
+External integer variable that contains the integer value of the

 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}.
 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}.


@@ -8031,7 +8250,7 @@ use for @code{YYERROR_VERBOSE}, just whether you define it.  Using
 
 @deffn {Macro} YYINITDEPTH
 Macro for specifying the initial size of the parser stack.
 
 @deffn {Macro} YYINITDEPTH
 Macro for specifying the initial size of the parser stack.

-@xref{Stack Overflow}.
+@xref{Memory Management}.

 @end deffn
 
 @deffn {Function} yylex
 @end deffn
 
 @deffn {Function} yylex


@@ -8042,7 +8261,7 @@ the next token.  @xref{Lexical, ,The Lexical Analyzer Function
 
 @deffn {Macro} YYLEX_PARAM
 An obsolete macro for specifying an extra argument (or list of extra
 
 @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
+arguments) for @code{yyparse} to pass to @code{yylex}.  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
 macro is deprecated, and is supported only for Yacc like parsers.
 @xref{Pure Calling,, Calling Conventions for Pure Parsers}.
 @end deffn


@@ -8051,9 +8270,12 @@ macro is deprecated, and is supported only for Yacc like parsers.
 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
 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 Locations,
-,Textual Locations of Tokens}.
+@code{yylex}.)
+You can ignore this variable if you don't use the @samp{@@} feature in the
+grammar actions.
+@xref{Token Locations, ,Textual Locations of Tokens}.
+In semantic actions, it stores the location of the look-ahead token.
+@xref{Actions and Locations, ,Actions and Locations}.

 @end deffn
 
 @deffn {Type} YYLTYPE
 @end deffn
 
 @deffn {Type} YYLTYPE


@@ -8065,16 +8287,19 @@ members.  @xref{Location Type, , Data Types of Locations}.
 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
 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}.
+@code{yylex}.)
+@xref{Token Values, ,Semantic Values of Tokens}.
+In semantic actions, it stores the semantic value of the look-ahead token.
+@xref{Actions, ,Actions}.

 @end deffn
 
 @deffn {Macro} YYMAXDEPTH
 @end deffn
 
 @deffn {Macro} YYMAXDEPTH

-Macro for specifying the maximum size of the parser stack.  @xref{Stack
-Overflow}.
+Macro for specifying the maximum size of the parser stack.  @xref{Memory
+Management}.

 @end deffn
 
 @deffn {Variable} yynerrs
 @end deffn
 
 @deffn {Variable} yynerrs

-Global variable which Bison increments each time there is a syntax error.
+Global variable which Bison increments each time it reports a syntax error.

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


@@ -8104,10 +8329,7 @@ the parser will use @code{malloc} to extend its stacks.  If defined to
 reserved for future Bison extensions.  If not defined,
 @code{YYSTACK_USE_ALLOCA} defaults to 0.
 
 reserved for future Bison extensions.  If not defined,
 @code{YYSTACK_USE_ALLOCA} defaults to 0.
 

-If you define @code{YYSTACK_USE_ALLOCA} to 1, it is your
-responsibility to make sure that @code{alloca} is visible, e.g., by
-using @acronym{GCC} or by including @code{<stdlib.h>}.  Furthermore,
-in the all-too-common case where your code may run on a host with a
+In the all-too-common case where your code may run on a host with a

 limited stack and with unreliable stack-overflow checking, you should
 set @code{YYMAXDEPTH} to a value that cannot possibly result in
 unchecked stack overflow on any of your target hosts when
 limited stack and with unreliable stack-overflow checking, you should
 set @code{YYMAXDEPTH} to a value that cannot possibly result in
 unchecked stack overflow on any of your target hosts when


@@ -8329,7 +8551,7 @@ grammatically indivisible.  The piece of text it represents is a token.
 @c LocalWords: yychar yydebug msg YYNTOKENS YYNNTS YYNRULES YYNSTATES
 @c LocalWords: cparse clex deftypefun NE defmac YYACCEPT YYABORT param
 @c LocalWords: strncmp intval tindex lvalp locp llocp typealt YYBACKUP
 @c LocalWords: yychar yydebug msg YYNTOKENS YYNNTS YYNRULES YYNSTATES
 @c LocalWords: cparse clex deftypefun NE defmac YYACCEPT YYABORT param
 @c LocalWords: strncmp intval tindex lvalp locp llocp typealt YYBACKUP

-@c LocalWords: YYEMPTY YYRECOVERING yyclearin GE def UMINUS maybeword
+@c LocalWords: YYEMPTY YYEOF YYRECOVERING yyclearin GE def UMINUS maybeword

 @c LocalWords: Johnstone Shamsa Sadaf Hussain Tomita TR uref YYMAXDEPTH
 @c LocalWords: YYINITDEPTH stmnts ref stmnt initdcl maybeasm VCG notype
 @c LocalWords: hexflag STR exdent itemset asis DYYDEBUG YYFPRINTF args
 @c LocalWords: Johnstone Shamsa Sadaf Hussain Tomita TR uref YYMAXDEPTH
 @c LocalWords: YYINITDEPTH stmnts ref stmnt initdcl maybeasm VCG notype
 @c LocalWords: hexflag STR exdent itemset asis DYYDEBUG YYFPRINTF args