Point to an official beta.

[bison.git] / doc / bison.texinfo

diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index 609f870bcfb5916b92ffde7b6e2d8e6f0dcbd07e..84a4ae8ebdb9fcdf58a7c7dff84e1380d2665d86 100644 (file)
--- a/doc/bison.texinfo
+++ b/doc/bison.texinfo
@@ -47,7 +47,7 @@ END-INFO-DIR-ENTRY
 This file documents the Bison parser generator.
 
 Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1995, 1998, 1999,
 This file documents the Bison parser generator.
 
 Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1995, 1998, 1999,

-2000, 2001
+2000, 2001, 2002

 Free Software Foundation, Inc.
 
 Permission is granted to make and distribute verbatim copies of
 Free Software Foundation, Inc.
 
 Permission is granted to make and distribute verbatim copies of


@@ -89,7 +89,7 @@ instead of in the original English.
 @page
 @vskip 0pt plus 1filll
 Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1995, 1998,
 @page
 @vskip 0pt plus 1filll
 Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1995, 1998,

-1999, 2000, 2001
+1999, 2000, 2001, 2002

 Free Software Foundation, Inc.
 
 @sp 2
 Free Software Foundation, Inc.
 
 @sp 2


@@ -433,7 +433,7 @@ smaller constructs according to grammatical rules are called
 @dfn{nonterminal symbols}; those which can't be subdivided are called
 @dfn{terminal symbols} or @dfn{token types}.  We call a piece of input
 corresponding to a single terminal symbol a @dfn{token}, and a piece
 @dfn{nonterminal symbols}; those which can't be subdivided are called
 @dfn{terminal symbols} or @dfn{token types}.  We call a piece of input
 corresponding to a single terminal symbol a @dfn{token}, and a piece

-corresponding to a single nonterminal symbol a @dfn{grouping}.@refill
+corresponding to a single nonterminal symbol a @dfn{grouping}.

 
 We can use the C language as an example of what symbols, terminal and
 nonterminal, mean.  The tokens of C are identifiers, constants (numeric and
 
 We can use the C language as an example of what symbols, terminal and
 nonterminal, mean.  The tokens of C are identifiers, constants (numeric and


@@ -565,7 +565,7 @@ if a rule mentions the terminal symbol `integer constant', it means that
 @emph{any} integer constant is grammatically valid in that position.  The
 precise value of the constant is irrelevant to how to parse the input: if
 @samp{x+4} is grammatical then @samp{x+1} or @samp{x+3989} is equally
 @emph{any} integer constant is grammatically valid in that position.  The
 precise value of the constant is irrelevant to how to parse the input: if
 @samp{x+4} is grammatical then @samp{x+1} or @samp{x+3989} is equally

-grammatical.@refill
+grammatical.

 
 But the precise value is very important for what the input means once it is
 parsed.  A compiler is useless if it fails to distinguish between 4, 1 and
 
 But the precise value is very important for what the input means once it is
 parsed.  A compiler is useless if it fails to distinguish between 4, 1 and


@@ -577,7 +577,7 @@ The token type is a terminal symbol defined in the grammar, such as
 @code{INTEGER}, @code{IDENTIFIER} or @code{','}.  It tells everything
 you need to know to decide where the token may validly appear and how to
 group it with other tokens.  The grammar rules know nothing about tokens
 @code{INTEGER}, @code{IDENTIFIER} or @code{','}.  It tells everything
 you need to know to decide where the token may validly appear and how to
 group it with other tokens.  The grammar rules know nothing about tokens

-except their types.@refill
+except their types.

 
 The semantic value has all the rest of the information about the
 meaning of the token, such as the value of an integer, or the name of an
 
 The semantic value has all the rest of the information about the
 meaning of the token, such as the value of an integer, or the name of an


@@ -676,12 +676,13 @@ the grammar rules---for example, to build identifiers and operators into
 expressions.  As it does this, it runs the actions for the grammar rules it
 uses.
 
 expressions.  As it does this, it runs the actions for the grammar rules it
 uses.
 

-The tokens come from a function called the @dfn{lexical analyzer} that you
-must supply in some fashion (such as by writing it in C).  The Bison parser
-calls the lexical analyzer each time it wants a new token.  It doesn't know
-what is ``inside'' the tokens (though their semantic values may reflect
-this).  Typically the lexical analyzer makes the tokens by parsing
-characters of text, but Bison does not depend on this.  @xref{Lexical, ,The Lexical Analyzer Function @code{yylex}}.
+The tokens come from a function called the @dfn{lexical analyzer} that
+you must supply in some fashion (such as by writing it in C).  The Bison
+parser calls the lexical analyzer each time it wants a new token.  It
+doesn't know what is ``inside'' the tokens (though their semantic values
+may reflect this).  Typically the lexical analyzer makes the tokens by
+parsing characters of text, but Bison does not depend on this.
+@xref{Lexical, ,The Lexical Analyzer Function @code{yylex}}.

 
 The Bison parser file is C code which defines a function named
 @code{yyparse} which implements that grammar.  This function does not make
 
 The Bison parser file is C code which defines a function named
 @code{yyparse} which implements that grammar.  This function does not make


@@ -706,10 +707,9 @@ In some cases the Bison parser file includes system headers, and in
 those cases your code should respect the identifiers reserved by those
 headers.  On some non-@sc{gnu} hosts, @code{<alloca.h>},
 @code{<stddef.h>}, and @code{<stdlib.h>} are included as needed to
 those cases your code should respect the identifiers reserved by those
 headers.  On some non-@sc{gnu} hosts, @code{<alloca.h>},
 @code{<stddef.h>}, and @code{<stdlib.h>} are included as needed to

-declare memory allocators and related types.  In the same situation,
-C++ parsers may include @code{<cstddef>} and @code{<cstdlib>} instead.
-Other system headers may be included if you define @code{YYDEBUG}
-(@pxref{Debugging, ,Debugging Your Parser}).
+declare memory allocators and related types.
+Other system headers may be included if you define @code{YYDEBUG} to a
+nonzero value (@pxref{Debugging, ,Debugging Your Parser}).

 
 @node Stages
 @section Stages in Using Bison
 
 @node Stages
 @section Stages in Using Bison


@@ -722,15 +722,16 @@ to a working compiler or interpreter, has these parts:
 @enumerate
 @item
 Formally specify the grammar in a form recognized by Bison
 @enumerate
 @item
 Formally specify the grammar in a form recognized by Bison

-(@pxref{Grammar File, ,Bison Grammar Files}).  For each grammatical rule in the language,
-describe the action that is to be taken when an instance of that rule
-is recognized.  The action is described by a sequence of C statements.
+(@pxref{Grammar File, ,Bison Grammar Files}).  For each grammatical rule
+in the language, describe the action that is to be taken when an
+instance of that rule is recognized.  The action is described by a
+sequence of C statements.

 
 @item
 
 @item

-Write a lexical analyzer to process input and pass tokens to the
-parser.  The lexical analyzer may be written by hand in C
-(@pxref{Lexical, ,The Lexical Analyzer Function @code{yylex}}).  It could also be produced using Lex, but the use
-of Lex is not discussed in this manual.
+Write a lexical analyzer to process input and pass tokens to the parser.
+The lexical analyzer may be written by hand in C (@pxref{Lexical, ,The
+Lexical Analyzer Function @code{yylex}}).  It could also be produced
+using Lex, but the use of Lex is not discussed in this manual.

 
 @item
 Write a controlling function that calls the Bison-produced parser.
 
 @item
 Write a controlling function that calls the Bison-produced parser.


@@ -884,9 +885,10 @@ which is a floating point number.
 The @code{#include} directive is used to declare the exponentiation
 function @code{pow}.
 
 The @code{#include} directive is used to declare the exponentiation
 function @code{pow}.
 

-The second section, Bison declarations, provides information to Bison about
-the token types (@pxref{Bison Declarations, ,The Bison Declarations Section}).  Each terminal symbol that is
-not a single-character literal must be declared here.  (Single-character
+The second section, Bison declarations, provides information to Bison
+about the token types (@pxref{Bison Declarations, ,The Bison
+Declarations Section}).  Each terminal symbol that is not a
+single-character literal must be declared here.  (Single-character

 literals normally don't need to be declared.)  In this example, all the
 arithmetic operators are designated by single-character literals, so the
 only terminal symbol that needs to be declared is @code{NUM}, the token
 literals normally don't need to be declared.)  In this example, all the
 arithmetic operators are designated by single-character literals, so the
 only terminal symbol that needs to be declared is @code{NUM}, the token


@@ -1066,9 +1068,10 @@ The latter, however, is much more readable.
 @cindex writing a lexical analyzer
 @cindex lexical analyzer, writing
 
 @cindex writing a lexical analyzer
 @cindex lexical analyzer, writing
 

-The lexical analyzer's job is low-level parsing: converting characters or
-sequences of characters into tokens.  The Bison parser gets its tokens by
-calling the lexical analyzer.  @xref{Lexical, ,The Lexical Analyzer Function @code{yylex}}.
+The lexical analyzer's job is low-level parsing: converting characters
+or sequences of characters into tokens.  The Bison parser gets its
+tokens by calling the lexical analyzer.  @xref{Lexical, ,The Lexical
+Analyzer Function @code{yylex}}.

 
 Only a simple lexical analyzer is needed for the RPN calculator.  This
 lexical analyzer skips blanks and tabs, then reads in numbers as
 
 Only a simple lexical analyzer is needed for the RPN calculator.  This
 lexical analyzer skips blanks and tabs, then reads in numbers as


@@ -1080,7 +1083,7 @@ The return value of the lexical analyzer function is a numeric code which
 represents a token type.  The same text used in Bison rules to stand for
 this token type is also a C expression for the numeric code for the type.
 This works in two ways.  If the token type is a character literal, then its
 represents a token type.  The same text used in Bison rules to stand for
 this token type is also a C expression for the numeric code for the type.
 This works in two ways.  If the token type is a character literal, then its

-numeric code is the ASCII code for that character; you can use the same
+numeric code is that of the character; you can use the same

 character literal in the lexical analyzer to express the number.  If the
 token type is an identifier, that identifier is defined by Bison as a C
 macro whose definition is the appropriate number.  In this example,
 character literal in the lexical analyzer to express the number.  If the
 token type is an identifier, that identifier is defined by Bison as a C
 macro whose definition is the appropriate number.  In this example,


@@ -1101,8 +1104,8 @@ Here is the code for the lexical analyzer:
 @example
 @group
 /* Lexical analyzer returns a double floating point
 @example
 @group
 /* Lexical analyzer returns a double floating point

-   number on the stack and the token NUM, or the ASCII
-   character read if not a number.  Skips all blanks
+   number on the stack and the token NUM, or the numeric code
+   of the character read if not a number.  Skips all blanks

    and tabs, returns 0 for EOF. */
 
 #include <ctype.h>
    and tabs, returns 0 for EOF. */
 
 #include <ctype.h>


@@ -1325,12 +1328,14 @@ Operator precedence is determined by the line ordering of the
 declarations; the higher the line number of the declaration (lower on
 the page or screen), the higher the precedence.  Hence, exponentiation
 has the highest precedence, unary minus (@code{NEG}) is next, followed
 declarations; the higher the line number of the declaration (lower on
 the page or screen), the higher the precedence.  Hence, exponentiation
 has the highest precedence, unary minus (@code{NEG}) is next, followed

-by @samp{*} and @samp{/}, and so on.  @xref{Precedence, ,Operator Precedence}.
+by @samp{*} and @samp{/}, and so on.  @xref{Precedence, ,Operator
+Precedence}.

 
 

-The other important new feature is the @code{%prec} in the grammar section
-for the unary minus operator.  The @code{%prec} simply instructs Bison that
-the rule @samp{| '-' exp} has the same precedence as @code{NEG}---in this
-case the next-to-highest.  @xref{Contextual Precedence, ,Context-Dependent Precedence}.
+The other important new feature is the @code{%prec} in the grammar
+section for the unary minus operator.  The @code{%prec} simply instructs
+Bison that the rule @samp{| '-' exp} has the same precedence as
+@code{NEG}---in this case the next-to-highest.  @xref{Contextual
+Precedence, ,Context-Dependent Precedence}.

 
 Here is a sample run of @file{calc.y}:
 
 
 Here is a sample run of @file{calc.y}:
 


@@ -1377,7 +1382,7 @@ upon to print its message as well.)  The action executes the statement
 @code{yyerrok}, a macro defined automatically by Bison; its meaning is
 that error recovery is complete (@pxref{Error Recovery}).  Note the
 difference between @code{yyerrok} and @code{yyerror}; neither one is a
 @code{yyerrok}, a macro defined automatically by Bison; its meaning is
 that error recovery is complete (@pxref{Error Recovery}).  Note the
 difference between @code{yyerrok} and @code{yyerror}; neither one is a

-misprint.@refill
+misprint.

 
 This form of error recovery deals with syntax errors.  There are other
 kinds of errors; for example, division by zero, which raises an exception
 
 This form of error recovery deals with syntax errors.  There are other
 kinds of errors; for example, division by zero, which raises an exception


@@ -1683,11 +1688,12 @@ are @code{NUM}, @code{VAR}, @code{FNCT}, and @code{exp}.  Their
 declarations are augmented with information about their data type (placed
 between angle brackets).
 
 declarations are augmented with information about their data type (placed
 between angle brackets).
 

-The Bison construct @code{%type} is used for declaring nonterminal symbols,
-just as @code{%token} is used for declaring token types.  We have not used
-@code{%type} before because nonterminal symbols are normally declared
-implicitly by the rules that define them.  But @code{exp} must be declared
-explicitly so we can specify its value type.  @xref{Type Decl, ,Nonterminal Symbols}.
+The Bison construct @code{%type} is used for declaring nonterminal
+symbols, just as @code{%token} is used for declaring token types.  We
+have not used @code{%type} before because nonterminal symbols are
+normally declared implicitly by the rules that define them.  But
+@code{exp} must be declared explicitly so we can specify its value type.
+@xref{Type Decl, ,Nonterminal Symbols}.

 
 @node Mfcalc Rules
 @subsection Grammar Rules for @code{mfcalc}
 
 @node Mfcalc Rules
 @subsection Grammar Rules for @code{mfcalc}


@@ -1875,7 +1881,7 @@ the name appears in the table, a pointer to its location and its type
 (@code{VAR} or @code{FNCT}) is returned to @code{yyparse}.  If it is not
 already in the table, then it is installed as a @code{VAR} using
 @code{putsym}.  Again, a pointer and its type (which must be @code{VAR}) is
 (@code{VAR} or @code{FNCT}) is returned to @code{yyparse}.  If it is not
 already in the table, then it is installed as a @code{VAR} using
 @code{putsym}.  Again, a pointer and its type (which must be @code{VAR}) is

-returned to @code{yyparse}.@refill
+returned to @code{yyparse}.

 
 No change is needed in the handling of numeric values and arithmetic
 operators in @code{yylex}.
 
 No change is needed in the handling of numeric values and arithmetic
 operators in @code{yylex}.


@@ -1961,8 +1967,8 @@ yylex (void)
 @end smallexample
 
 This program is both powerful and flexible. You may easily add new
 @end smallexample
 
 This program is both powerful and flexible. You may easily add new

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

 
 @node Exercises
 @section Exercises
 
 @node Exercises
 @section Exercises


@@ -2142,7 +2148,7 @@ your program will confuse other readers.
 
 All the usual escape sequences used in character literals in C can be
 used in Bison as well, but you must not use the null character as a
 
 All the usual escape sequences used in character literals in C can be
 used in Bison as well, but you must not use the null character as a

-character literal because its ASCII code, zero, is the code @code{yylex}
+character literal because its numeric code, zero, is the code @code{yylex}

 returns for end-of-input (@pxref{Calling Convention, ,Calling Convention
 for @code{yylex}}).
 
 returns for end-of-input (@pxref{Calling Convention, ,Calling Convention
 for @code{yylex}}).
 


@@ -2183,7 +2189,7 @@ on when the parser function returns that symbol.
 The value returned by @code{yylex} is always one of the terminal symbols
 (or 0 for end-of-input).  Whichever way you write the token type in the
 grammar rules, you write it the same way in the definition of @code{yylex}.
 The value returned by @code{yylex} is always one of the terminal symbols
 (or 0 for end-of-input).  Whichever way you write the token type in the
 grammar rules, you write it the same way in the definition of @code{yylex}.

-The numeric code for a character token type is simply the ASCII code for
+The numeric code for a character token type is simply the numeric code of

 the character, so @code{yylex} can use the identical character constant to
 generate the requisite code.  Each named token type becomes a C macro in
 the parser file, so @code{yylex} can use the name to stand for the code.
 the character, so @code{yylex} can use the identical character constant to
 generate the requisite code.  Each named token type becomes a C macro in
 the parser file, so @code{yylex} can use the name to stand for the code.


@@ -2196,9 +2202,25 @@ option when you run Bison, so that it will write these macro definitions
 into a separate header file @file{@var{name}.tab.h} which you can include
 in the other source files that need it.  @xref{Invocation, ,Invoking Bison}.
 
 into a separate header file @file{@var{name}.tab.h} which you can include
 in the other source files that need it.  @xref{Invocation, ,Invoking Bison}.
 

+The @code{yylex} function must use the same character set and encoding
+that was used by Bison.  For example, if you run Bison in an
+@sc{ascii} environment, but then compile and run the resulting program
+in an environment that uses an incompatible character set like
+@sc{ebcdic}, the resulting program will probably not work because the
+tables generated by Bison will assume @sc{ascii} numeric values for
+character tokens.  Portable grammars should avoid non-@sc{ascii}
+character tokens, as implementations in practice often use different
+and incompatible extensions in this area.  However, it is standard
+practice for software distributions to contain C source files that
+were generated by Bison in an @sc{ascii} environment, so installers on
+platforms that are incompatible with @sc{ascii} must rebuild those
+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.

-In particular, @code{yylex} should never return this value.
+In particular, @code{yylex} should never return this value.  The default
+value of the error token is 256, unless you explicitly assigned 256 to
+one of your tokens with a @code{%token} declaration.

 
 @node Rules
 @section Syntax of Grammar Rules
 
 @node Rules
 @section Syntax of Grammar Rules


@@ -2425,7 +2447,8 @@ requires you to do two things:
 @itemize @bullet
 @item
 Specify the entire collection of possible data types, with the
 @itemize @bullet
 @item
 Specify the entire collection of possible data types, with the

-@code{%union} Bison declaration (@pxref{Union Decl, ,The Collection of Value Types}).
+@code{%union} Bison declaration (@pxref{Union Decl, ,The Collection of
+Value Types}).

 
 @item
 Choose one of those types for each symbol (terminal or nonterminal) for
 
 @item
 Choose one of those types for each symbol (terminal or nonterminal) for


@@ -2447,10 +2470,11 @@ is to compute a semantic value for the grouping built by the rule from the
 semantic values associated with tokens or smaller groupings.
 
 An action consists of C statements surrounded by braces, much like a
 semantic values associated with tokens or smaller groupings.
 
 An action consists of C statements surrounded by braces, much like a

-compound statement in C.  It can be placed at any position in the rule; 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 Actions, ,Actions in Mid-Rule}).
+compound statement in C.  It 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
+Actions, ,Actions in Mid-Rule}).

 
 The C code in an action can refer to the semantic values of the components
 matched by the rule with the construct @code{$@var{n}}, which stands for
 
 The C code in an action can refer to the semantic values of the components
 matched by the rule with the construct @code{$@var{n}}, which stands for


@@ -2477,7 +2501,19 @@ which are the first and third symbols on the right hand side of the rule.
 The sum is stored into @code{$$} so that it becomes the semantic value of
 the addition-expression just recognized by the rule.  If there were a
 useful semantic value associated with the @samp{+} token, it could be
 The sum is stored into @code{$$} so that it becomes the semantic value of
 the addition-expression just recognized by the rule.  If there were a
 useful semantic value associated with the @samp{+} token, it could be

-referred to as @code{$2}.@refill
+referred to as @code{$2}.
+
+Note that the vertical-bar character @samp{|} is really a rule
+separator, and actions are attached to a single rule.  This is a
+difference with tools like Flex, for which @samp{|} stands for either
+``or'', or ``the same action as that of the next rule''.  In the
+following example, the action is triggered only when @samp{b} is found:
+
+@example
+@group
+a-or-b: 'a'|'b'   @{ a_or_b_found = 1; @};
+@end group
+@end example

 
 @cindex default action
 If you don't specify an action for a rule, Bison supplies a default:
 
 @cindex default action
 If you don't specify an action for a rule, Bison supplies a default:


@@ -2523,7 +2559,7 @@ If you have used @code{%union} to specify a variety of data types, then you
 must declare a choice among these types for each terminal or nonterminal
 symbol that can have a semantic value.  Then each time you use @code{$$} or
 @code{$@var{n}}, its data type is determined by which symbol it refers to
 must declare a choice among these types for each terminal or nonterminal
 symbol that can have a semantic value.  Then each time you use @code{$$} or
 @code{$@var{n}}, its data type is determined by which symbol it refers to

-in the rule.  In this example,@refill
+in the rule.  In this example,

 
 @example
 @group
 
 @example
 @group


@@ -2537,7 +2573,7 @@ exp:    @dots{}
 @code{$1} and @code{$3} refer to instances of @code{exp}, so they all
 have the data type declared for the nonterminal symbol @code{exp}.  If
 @code{$2} were used, it would have the data type declared for the
 @code{$1} and @code{$3} refer to instances of @code{exp}, so they all
 have the data type declared for the nonterminal symbol @code{exp}.  If
 @code{$2} were used, it would have the data type declared for the

-terminal symbol @code{'+'}, whatever that might be.@refill
+terminal symbol @code{'+'}, whatever that might be.

 
 Alternatively, you can specify the data type when you refer to the value,
 by inserting @samp{<@var{type}>} after the @samp{$} at the beginning of the
 
 Alternatively, you can specify the data type when you refer to the value,
 by inserting @samp{<@var{type}>} after the @samp{$} at the beginning of the


@@ -2730,8 +2766,8 @@ especially symbol locations.
 
 @c (terminal or not) ?
 
 
 @c (terminal or not) ?
 

-The way locations are handled is defined by providing a data type, and actions
-to take when rules are matched.
+The way locations are handled is defined by providing a data type, and
+actions to take when rules are matched.

 
 @menu
 * Location Type::               Specifying a data type for locations.
 
 @menu
 * Location Type::               Specifying a data type for locations.


@@ -2832,11 +2868,11 @@ exp:    @dots{}
 @subsection Default Action for Locations
 @vindex YYLLOC_DEFAULT
 
 @subsection Default Action for Locations
 @vindex YYLLOC_DEFAULT
 

-Actually, actions are not the best place to compute locations. Since locations
-are much more general than semantic values, there is room in the output parser
-to redefine the default action to take for each rule. The
-@code{YYLLOC_DEFAULT} macro is called each time a rule is matched, before the
-associated action is run.
+Actually, actions are not the best place to compute locations. Since
+locations are much more general than semantic values, there is room in
+the output parser to redefine the default action to take for each
+rule. The @code{YYLLOC_DEFAULT} macro is invoked each time a rule is
+matched, before the associated action is run.

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


@@ -2888,7 +2924,8 @@ value (@pxref{Multiple Types, ,More Than One Value Type}).
 
 The first rule in the file also specifies the start symbol, by default.
 If you want some other symbol to be the start symbol, you must declare
 
 The first rule in the file also specifies the start symbol, by default.
 If you want some other symbol to be the start symbol, you must declare

-it explicitly (@pxref{Language and Grammar, ,Languages and Context-Free Grammars}).
+it explicitly (@pxref{Language and Grammar, ,Languages and Context-Free
+Grammars}).

 
 @menu
 * Token Decl::        Declaring terminal symbols.
 
 @menu
 * Token Decl::        Declaring terminal symbols.


@@ -2933,11 +2970,12 @@ an integer value in the field immediately following the token name:
 @noindent
 It is generally best, however, to let Bison choose the numeric codes for
 all token types.  Bison will automatically select codes that don't conflict
 @noindent
 It is generally best, however, to let Bison choose the numeric codes for
 all token types.  Bison will automatically select codes that don't conflict

-with each other or with ASCII characters.
+with each other or with normal characters.

 
 In the event that the stack type is a union, you must augment the
 @code{%token} or other token declaration to include the data type
 
 In the event that the stack type is a union, you must augment the
 @code{%token} or other token declaration to include the data type

-alternative delimited by angle-brackets (@pxref{Multiple Types, ,More Than One Value Type}).
+alternative delimited by angle-brackets (@pxref{Multiple Types, ,More
+Than One Value Type}).

 
 For example:
 
 
 For example:
 


@@ -2984,7 +3022,8 @@ obtain the token type code number (@pxref{Calling Convention}).
 Use the @code{%left}, @code{%right} or @code{%nonassoc} declaration to
 declare a token and specify its precedence and associativity, all at
 once.  These are called @dfn{precedence declarations}.
 Use the @code{%left}, @code{%right} or @code{%nonassoc} declaration to
 declare a token and specify its precedence and associativity, all at
 once.  These are called @dfn{precedence declarations}.

-@xref{Precedence, ,Operator Precedence}, for general information on operator precedence.
+@xref{Precedence, ,Operator Precedence}, for general information on
+operator precedence.

 
 The syntax of a precedence declaration is the same as that of
 @code{%token}: either
 
 The syntax of a precedence declaration is the same as that of
 @code{%token}: either


@@ -3071,11 +3110,12 @@ used.  This is done with a @code{%type} declaration, like this:
 @end example
 
 @noindent
 @end example
 
 @noindent

-Here @var{nonterminal} is the name of a nonterminal symbol, and @var{type}
-is the name given in the @code{%union} to the alternative that you want
-(@pxref{Union Decl, ,The Collection of Value Types}).  You can give any number of nonterminal symbols in
-the same @code{%type} declaration, if they have the same value type.  Use
-spaces to separate the symbol names.
+Here @var{nonterminal} is the name of a nonterminal symbol, and
+@var{type} is the name given in the @code{%union} to the alternative
+that you want (@pxref{Union Decl, ,The Collection of Value Types}).  You
+can give any number of nonterminal symbols in the same @code{%type}
+declaration, if they have the same value type.  Use spaces to separate
+the symbol names.

 
 You can also declare the value type of a terminal symbol.  To do this,
 use the same @code{<@var{type}>} construction in a declaration for the
 
 You can also declare the value type of a terminal symbol.  To do this,
 use the same @code{<@var{type}>} construction in a declaration for the


@@ -3150,7 +3190,7 @@ may override this restriction with the @code{%start} declaration as follows:
 @subsection A Pure (Reentrant) Parser
 @cindex reentrant parser
 @cindex pure parser
 @subsection A Pure (Reentrant) Parser
 @cindex reentrant parser
 @cindex pure parser

-@findex %pure_parser
+@findex %pure-parser

 
 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)
 
 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)


@@ -3166,11 +3206,11 @@ statically allocated variables for communication with @code{yylex},
 including @code{yylval} and @code{yylloc}.)
 
 Alternatively, you can generate a pure, reentrant parser.  The Bison
 including @code{yylval} and @code{yylloc}.)
 
 Alternatively, you can generate a pure, reentrant parser.  The Bison

-declaration @code{%pure_parser} says that you want the parser to be
+declaration @code{%pure-parser} says that you want the parser to be

 reentrant.  It looks like this:
 
 @example
 reentrant.  It looks like this:
 
 @example

-%pure_parser
+%pure-parser

 @end example
 
 The result is that the communication variables @code{yylval} and
 @end example
 
 The result is that the communication variables @code{yylval} and


@@ -3236,9 +3276,9 @@ directives:
 
 @table @code
 @item %debug
 
 @table @code
 @item %debug

-Output a definition of the macro @code{YYDEBUG} into the parser file, so
-that the debugging facilities are compiled.  @xref{Debugging, ,Debugging
-Your Parser}.
+In the parser file, define the macro @code{YYDEBUG} to 1 if it is not
+already defined, so that the debugging facilities are compiled.
+@xref{Debugging, ,Debugging Your Parser}.

 
 @item %defines
 Write an extra output file containing macro definitions for the token
 
 @item %defines
 Write an extra output file containing macro definitions for the token


@@ -3246,23 +3286,23 @@ type names defined in the grammar and the semantic value type
 @code{YYSTYPE}, as well as a few @code{extern} variable declarations.
 
 If the parser output file is named @file{@var{name}.c} then this file
 @code{YYSTYPE}, as well as a few @code{extern} variable declarations.
 
 If the parser output file is named @file{@var{name}.c} then this file

-is named @file{@var{name}.h}.@refill
+is named @file{@var{name}.h}.

 
 This output file is essential if you wish to put the definition of
 @code{yylex} in a separate source file, because @code{yylex} needs to
 be able to refer to token type codes and the variable
 
 This output file is essential if you wish to put the definition of
 @code{yylex} in a separate source file, because @code{yylex} needs to
 be able to refer to token type codes and the variable

-@code{yylval}.  @xref{Token Values, ,Semantic Values of Tokens}.@refill
+@code{yylval}.  @xref{Token Values, ,Semantic Values of Tokens}.

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

-@c @item %header_extension
+@c @item %header-extension

 @c Specify the extension of the parser header file generated when
 @c @code{%define} or @samp{-d} are used.
 @c
 @c For example, a grammar file named @file{foo.ypp} and containing a
 @c Specify the extension of the parser header file generated when
 @c @code{%define} or @samp{-d} are used.
 @c
 @c For example, a grammar file named @file{foo.ypp} and containing a

-@c @code{%header_extension .hh} directive will produce a header file
+@c @code{%header-extension .hh} directive will produce a header file

 @c named @file{foo.tab.hh}
 
 @item %locations
 @c named @file{foo.tab.hh}
 
 @item %locations


@@ -3276,10 +3316,10 @@ accurate parse error messages.
 Rename the external symbols used in the parser so that they start with
 @var{prefix} instead of @samp{yy}.  The precise list of symbols renamed
 is @code{yyparse}, @code{yylex}, @code{yyerror}, @code{yynerrs},
 Rename the external symbols used in the parser so that they start with
 @var{prefix} instead of @samp{yy}.  The precise list of symbols renamed
 is @code{yyparse}, @code{yylex}, @code{yyerror}, @code{yynerrs},

-@code{yylval}, @code{yychar} and @code{yydebug}.  For example, if you
-use @samp{%name-prefix="c_"}, the names become @code{c_parse},
-@code{c_lex}, and so on.  @xref{Multiple Parsers, ,Multiple Parsers in
-the Same Program}.
+@code{yylval}, @code{yychar}, @code{yydebug}, and possible
+@code{yylloc}.  For example, if you use @samp{%name-prefix="c_"}, the
+names become @code{c_parse}, @code{c_lex}, and so on.  @xref{Multiple
+Parsers, ,Multiple Parsers in the Same Program}.

 
 @item %no-parser
 Do not include any C code in the parser file; generate tables only.  The
 
 @item %no-parser
 Do not include any C code in the parser file; generate tables only.  The


@@ -3305,14 +3345,14 @@ Specify the @var{filename} for the parser file.
 Request a pure (reentrant) parser program (@pxref{Pure Decl, ,A Pure
 (Reentrant) Parser}).
 
 Request a pure (reentrant) parser program (@pxref{Pure Decl, ,A Pure
 (Reentrant) Parser}).
 

-@c @item %source_extension
+@c @item %source-extension

 @c Specify the extension of the parser output file.
 @c
 @c For example, a grammar file named @file{foo.yy} and containing a
 @c Specify the extension of the parser output file.
 @c
 @c For example, a grammar file named @file{foo.yy} and containing a

-@c @code{%source_extension .cpp} directive will produce a parser file
+@c @code{%source-extension .cpp} directive will produce a parser file

 @c named @file{foo.tab.cpp}
 
 @c named @file{foo.tab.cpp}
 

-@item %token_table
+@item %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
 token whose internal Bison token code number is @var{i}.  The first three
 Generate an array of token names in the parser file.  The name of the
 array is @code{yytname}; @code{yytname[@var{i}]} is the name of the
 token whose internal Bison token code number is @var{i}.  The first three


@@ -3330,7 +3370,7 @@ consists of three characters @samp{*"*}, its string in @code{yytname}
 contains @samp{"*"*"}.  (In C, that would be written as
 @code{"\"*\"*\""}).
 
 contains @samp{"*"*"}.  (In C, that would be written as
 @code{"\"*\"*\""}).
 

-When you specify @code{%token_table}, Bison also generates macro
+When you specify @code{%token-table}, Bison also generates macro

 definitions for macros @code{YYNTOKENS}, @code{YYNNTS}, and
 @code{YYNRULES}, and @code{YYNSTATES}:
 
 definitions for macros @code{YYNTOKENS}, @code{YYNNTS}, and
 @code{YYNRULES}, and @code{YYNSTATES}:
 


@@ -3354,14 +3394,13 @@ This file also describes all the conflicts, both those resolved by
 operator precedence and the unresolved ones.
 
 The file's name is made by removing @samp{.tab.c} or @samp{.c} from
 operator precedence and the unresolved ones.
 
 The file's name is made by removing @samp{.tab.c} or @samp{.c} from

-the parser output file name, and adding @samp{.output} instead.@refill
+the parser output file name, and adding @samp{.output} instead.

 
 Therefore, if the input file is @file{foo.y}, then the parser file is
 called @file{foo.tab.c} by default.  As a consequence, the verbose
 
 Therefore, if the input file is @file{foo.y}, then the parser file is
 called @file{foo.tab.c} by default.  As a consequence, the verbose

-output file is called @file{foo.output}.@refill
+output file is called @file{foo.output}.

 
 @item %yacc
 
 @item %yacc

-@itemx %fixed-output-files

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


@@ -3378,10 +3417,10 @@ language with the same program?  Then you need to avoid a name conflict
 between different definitions of @code{yyparse}, @code{yylval}, and so on.
 
 The easy way to do this is to use the option @samp{-p @var{prefix}}
 between different definitions of @code{yyparse}, @code{yylval}, and so on.
 
 The easy way to do this is to use the option @samp{-p @var{prefix}}

-(@pxref{Invocation, ,Invoking Bison}).  This renames the interface functions and
-variables of the Bison parser to start with @var{prefix} instead of
-@samp{yy}.  You can use this to give each parser distinct names that do
-not conflict.
+(@pxref{Invocation, ,Invoking Bison}).  This renames the interface
+functions and variables of the Bison parser to start with @var{prefix}
+instead of @samp{yy}.  You can use this to give each parser distinct
+names that do not conflict.

 
 The precise list of symbols renamed is @code{yyparse}, @code{yylex},
 @code{yyerror}, @code{yynerrs}, @code{yylval}, @code{yychar} and
 
 The precise list of symbols renamed is @code{yyparse}, @code{yylex},
 @code{yyerror}, @code{yynerrs}, @code{yylval}, @code{yychar} and


@@ -3465,7 +3504,7 @@ need to arrange for the token-type macro definitions to be available there.
 To do this, use the @samp{-d} option when you run Bison, so that it will
 write these macro definitions into a separate header file
 @file{@var{name}.tab.h} which you can include in the other source files
 To do this, use the @samp{-d} option when you run Bison, so that it will
 write these macro definitions into a separate header file
 @file{@var{name}.tab.h} which you can include in the other source files

-that need it.  @xref{Invocation, ,Invoking Bison}.@refill
+that need it.  @xref{Invocation, ,Invoking Bison}.

 
 @menu
 * Calling Convention::  How @code{yyparse} calls @code{yylex}.
 
 @menu
 * Calling Convention::  How @code{yyparse} calls @code{yylex}.


@@ -3552,7 +3591,7 @@ for (i = 0; i < YYNTOKENS; i++)
 @end smallexample
 
 The @code{yytname} table is generated only if you use the
 @end smallexample
 
 The @code{yytname} table is generated only if you use the

-@code{%token_table} declaration.  @xref{Decl Summary}.
+@code{%token-table} declaration.  @xref{Decl Summary}.

 @end itemize
 
 @node Token Values
 @end itemize
 
 @node Token Values


@@ -3575,9 +3614,10 @@ Thus, if the type is @code{int} (the default), you might write this in
 @end example
 
 When you are using multiple data types, @code{yylval}'s type is a union
 @end example
 
 When you are using multiple data types, @code{yylval}'s type is a union

-made from the @code{%union} declaration (@pxref{Union Decl, ,The Collection of Value Types}).  So when
-you store a token's value, you must use the proper member of the union.
-If the @code{%union} declaration looks like this:
+made from the @code{%union} declaration (@pxref{Union Decl, ,The
+Collection of Value Types}).  So when you store a token's value, you
+must use the proper member of the union.  If the @code{%union}
+declaration looks like this:

 
 @example
 @group
 
 @example
 @group


@@ -3625,7 +3665,7 @@ The data type of @code{yylloc} has the name @code{YYLTYPE}.
 @node Pure Calling
 @subsection Calling Conventions for Pure Parsers
 
 @node Pure Calling
 @subsection Calling Conventions for Pure Parsers
 

-When you use the Bison declaration @code{%pure_parser} to request a
+When you use the Bison declaration @code{%pure-parser} to request a

 pure, reentrant parser, the global communication variables @code{yylval}
 and @code{yylloc} cannot be used.  (@xref{Pure Decl, ,A Pure (Reentrant)
 Parser}.)  In such parsers the two global variables are replaced by
 pure, reentrant parser, the global communication variables @code{yylval}
 and @code{yylloc} cannot be used.  (@xref{Pure Decl, ,A Pure (Reentrant)
 Parser}.)  In such parsers the two global variables are replaced by


@@ -3725,7 +3765,7 @@ arguments in total, depending on whether an argument of type
 the proper object type, or you can declare it as @code{void *} and
 access the contents as shown above.
 
 the proper object type, or you can declare it as @code{void *} and
 access the contents as shown above.
 

-You can use @samp{%pure_parser} to request a reentrant parser without
+You can use @samp{%pure-parser} to request a reentrant parser without

 also using @code{YYPARSE_PARAM}.  Then you should call @code{yyparse}
 with no arguments, as usual.
 
 also using @code{YYPARSE_PARAM}.  Then you should call @code{yyparse}
 with no arguments, as usual.
 


@@ -3786,8 +3826,8 @@ immediately return 1.
 @vindex yynerrs
 The variable @code{yynerrs} contains the number of syntax errors
 encountered so far.  Normally this variable is global; but if you
 @vindex yynerrs
 The variable @code{yynerrs} contains the number of syntax errors
 encountered so far.  Normally this variable is global; but if you

-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.

 
 @node Action Features
 @section Special Features for Use in Actions
 
 @node Action Features
 @section Special Features for Use in Actions


@@ -3808,12 +3848,13 @@ Acts like a variable that contains the semantic value for the
 
 @item $<@var{typealt}>$
 Like @code{$$} but specifies alternative @var{typealt} in the union
 
 @item $<@var{typealt}>$
 Like @code{$$} but specifies alternative @var{typealt} in the union

-specified by the @code{%union} declaration.  @xref{Action Types, ,Data Types of Values in Actions}.
+specified by the @code{%union} declaration.  @xref{Action Types, ,Data
+Types of Values in Actions}.

 
 @item $<@var{typealt}>@var{n}
 Like @code{$@var{n}} but specifies alternative @var{typealt} in the
 union specified by the @code{%union} declaration.
 
 @item $<@var{typealt}>@var{n}
 Like @code{$@var{n}} but specifies alternative @var{typealt} in the
 union specified by the @code{%union} declaration.

-@xref{Action Types, ,Data Types of Values in Actions}.@refill
+@xref{Action Types, ,Data Types of Values in Actions}.

 
 @item YYABORT;
 Return immediately from @code{yyparse}, indicating failure.
 
 @item YYABORT;
 Return immediately from @code{yyparse}, indicating failure.


@@ -4237,18 +4278,19 @@ and therefore are represented by names, not character literals.)
 
 The first effect of the precedence declarations is to assign precedence
 levels to the terminal symbols declared.  The second effect is to assign
 
 The first effect of the precedence declarations is to assign precedence
 levels to the terminal symbols declared.  The second effect is to assign

-precedence levels to certain rules: each rule gets its precedence from the
-last terminal symbol mentioned in the components.  (You can also specify
-explicitly the precedence of a rule.  @xref{Contextual Precedence, ,Context-Dependent Precedence}.)
-
-Finally, the resolution of conflicts works by comparing the
-precedence of the rule being considered with that of the
-look-ahead token.  If the token's precedence is higher, the
-choice is to shift.  If the rule's precedence is higher, the
-choice is to reduce.  If they have equal precedence, the choice
-is made based on the associativity of that precedence level.  The
-verbose output file made by @samp{-v} (@pxref{Invocation, ,Invoking Bison}) says
-how each conflict was resolved.
+precedence levels to certain rules: each rule gets its precedence from
+the last terminal symbol mentioned in the components.  (You can also
+specify explicitly the precedence of a rule.  @xref{Contextual
+Precedence, ,Context-Dependent Precedence}.)
+
+Finally, the resolution of conflicts works by comparing the precedence
+of the rule being considered with that of the look-ahead token.  If the
+token's precedence is higher, the choice is to shift.  If the rule's
+precedence is higher, the choice is to reduce.  If they have equal
+precedence, the choice is made based on the associativity of that
+precedence level.  The verbose output file made by @samp{-v}
+(@pxref{Invocation, ,Invoking Bison}) says how each conflict was
+resolved.

 
 Not all rules and not all tokens have precedence.  If either the rule or
 the look-ahead token has no precedence, then the default is to shift.
 
 Not all rules and not all tokens have precedence.  If either the rule or
 the look-ahead token has no precedence, then the default is to shift.


@@ -4270,7 +4312,7 @@ The Bison precedence declarations, @code{%left}, @code{%right} and
 @code{%nonassoc}, can only be used once for a given token; so a token has
 only one precedence declared in this way.  For context-dependent
 precedence, you need to use an additional mechanism: the @code{%prec}
 @code{%nonassoc}, can only be used once for a given token; so a token has
 only one precedence declared in this way.  For context-dependent
 precedence, you need to use an additional mechanism: the @code{%prec}

-modifier for rules.@refill
+modifier for rules.

 
 The @code{%prec} modifier declares the precedence of a particular rule by
 specifying a terminal symbol whose precedence should be used for that rule.
 
 The @code{%prec} modifier declares the precedence of a particular rule by
 specifying a terminal symbol whose precedence should be used for that rule.


@@ -4916,7 +4958,6 @@ clear the flag.
 
 @node Debugging
 @chapter Debugging Your Parser
 
 @node Debugging
 @chapter Debugging Your Parser

-@findex YYDEBUG

 @findex yydebug
 @cindex debugging
 @cindex tracing the parser
 @findex yydebug
 @cindex debugging
 @cindex tracing the parser


@@ -4924,21 +4965,39 @@ clear the flag.
 If a Bison grammar compiles properly but doesn't do what you want when it
 runs, the @code{yydebug} parser-trace feature can help you figure out why.
 
 If a Bison grammar compiles properly but doesn't do what you want when it
 runs, the @code{yydebug} parser-trace feature can help you figure out why.
 

-To enable compilation of trace facilities, you must define the macro
-@code{YYDEBUG} when you compile the parser.  You could use @samp{-DYYDEBUG=1}
-as a compiler option or you could put @samp{#define YYDEBUG 1} in the prologue
-of the grammar file (@pxref{Prologue, , The Prologue}). Alternatively, use the
-@samp{-t} option when you run Bison (@pxref{Invocation, ,Invoking Bison}).
-We always define @code{YYDEBUG} so that debugging is always possible.
+There are several means to enable compilation of trace facilities:
+
+@table @asis
+@item the macro @code{YYDEBUG}
+@findex YYDEBUG
+Define the macro @code{YYDEBUG} to a nonzero value when you compile the
+parser.  This is compliant with POSIX Yacc.  You could use
+@samp{-DYYDEBUG=1} as a compiler option or you could put @samp{#define
+YYDEBUG 1} in the prologue of the grammar file (@pxref{Prologue, , The
+Prologue}).
+
+@item the option @option{-t}, @option{--debug}
+Use the @samp{-t} option when you run Bison (@pxref{Invocation,
+,Invoking Bison}).  This is POSIX compliant too.
+
+@item the directive @samp{%debug}
+@findex %debug
+Add the @code{%debug} directive (@pxref{Decl Summary, ,Bison
+Declaration Summary}).  This is a Bison extension, which will prove
+useful when Bison will output parsers for languages that don't use a
+preprocessor.  Useless POSIX and Yacc portability matter to you, this is
+the preferred solution.
+@end table
+
+We suggest that you always enable the debug option so that debugging is
+always possible.

 
 The trace facility outputs messages with macro calls of the form
 
 The trace facility outputs messages with macro calls of the form

-@code{YYFPRINTF (YYSTDERR, @var{format}, @var{args})} where
+@code{YYFPRINTF (stderr, @var{format}, @var{args})} where

 @var{format} and @var{args} are the usual @code{printf} format and
 @var{format} and @var{args} are the usual @code{printf} format and

-arguments.  If you define @code{YYDEBUG} but do not define
-@code{YYFPRINTF}, @code{<stdio.h>} is automatically included and the
-macros are defined to @code{fprintf} and @code{stderr}.  In the same
-situation, C++ parsers include @code{<cstdio.h>} instead, and use
-@code{std::fprintf} and @code{std::stderr}.
+arguments.  If you define @code{YYDEBUG} to a nonzero value but do not
+define @code{YYFPRINTF}, @code{<stdio.h>} is automatically included
+and @code{YYPRINTF} is defined to @code{fprintf}.

 
 Once you have compiled the program with trace facilities, the way to
 request a trace is to store a nonzero value in the variable @code{yydebug}.
 
 Once you have compiled the program with trace facilities, the way to
 request a trace is to store a nonzero value in the variable @code{yydebug}.


@@ -4963,13 +5022,14 @@ of the state stack afterward.
 @end itemize
 
 To make sense of this information, it helps to refer to the listing file
 @end itemize
 
 To make sense of this information, it helps to refer to the listing file

-produced by the Bison @samp{-v} option (@pxref{Invocation, ,Invoking Bison}).  This file
-shows the meaning of each state in terms of positions in various rules, and
-also what each state will do with each possible input token.  As you read
-the successive trace messages, you can see that the parser is functioning
-according to its specification in the listing file.  Eventually you will
-arrive at the place where something undesirable happens, and you will see
-which parts of the grammar are to blame.
+produced by the Bison @samp{-v} option (@pxref{Invocation, ,Invoking
+Bison}).  This file shows the meaning of each state in terms of
+positions in various rules, and also what each state will do with each
+possible input token.  As you read the successive trace messages, you
+can see that the parser is functioning according to its specification in
+the listing file.  Eventually you will arrive at the place where
+something undesirable happens, and you will see which parts of the
+grammar are to blame.

 
 The parser file is a C program and you can use C debuggers on it, but it's
 not easy to interpret what it is doing.  The parser function is a
 
 The parser file is a C program and you can use C debuggers on it, but it's
 not easy to interpret what it is doing.  The parser function is a


@@ -5076,12 +5136,11 @@ Print the version number of Bison and exit.
 @need 1750
 @item -y
 @itemx --yacc
 @need 1750
 @item -y
 @itemx --yacc

-@itemx --fixed-output-files

 Equivalent to @samp{-o y.tab.c}; the parser output file is called
 @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
 Equivalent to @samp{-o y.tab.c}; the parser output file is called
 @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

-for Yacc:@refill
+for Yacc:

 
 @example
 bison -y $*
 
 @example
 bison -y $*


@@ -5099,9 +5158,9 @@ you are developing Bison.
 
 @item -t
 @itemx --debug
 
 @item -t
 @itemx --debug

-Output a definition of the macro @code{YYDEBUG} into the parser file, so
-that the debugging facilities are compiled.  @xref{Debugging, ,Debugging
-Your Parser}.
+In the parser file, define the macro @code{YYDEBUG} to 1 if it is not
+already defined, so that the debugging facilities are compiled.
+@xref{Debugging, ,Debugging Your Parser}.

 
 @item --locations
 Pretend that @code{%locations} was specified.  @xref{Decl Summary}.
 
 @item --locations
 Pretend that @code{%locations} was specified.  @xref{Decl Summary}.


@@ -5189,7 +5248,7 @@ would like to direct Bison to use a different copy, setting the
 environment variable @code{BISON_SIMPLE} to the path of the file will
 cause Bison to use that copy instead.
 
 environment variable @code{BISON_SIMPLE} to the path of the file will
 cause Bison to use that copy instead.
 

-When the @samp{%semantic_parser} declaration is used, Bison copies from
+When the @samp{%semantic-parser} declaration is used, Bison copies from

 a file called @file{bison.hairy} instead.  The location of this file can
 also be specified or overridden in a similar fashion, with the
 @code{BISON_HAIRY} environment variable.
 a file called @file{bison.hairy} instead.  The location of this file can
 also be specified or overridden in a similar fashion, with the
 @code{BISON_HAIRY} environment variable.


@@ -5209,7 +5268,6 @@ the corresponding short option.
 \line{ --debug \leaderfill -t}
 \line{ --defines \leaderfill -d}
 \line{ --file-prefix \leaderfill -b}
 \line{ --debug \leaderfill -t}
 \line{ --defines \leaderfill -d}
 \line{ --file-prefix \leaderfill -b}

-\line{ --fixed-output-files \leaderfill -y}

 \line{ --graph \leaderfill -g}
 \line{ --help \leaderfill -h}
 \line{ --name-prefix \leaderfill -p}
 \line{ --graph \leaderfill -g}
 \line{ --help \leaderfill -h}
 \line{ --name-prefix \leaderfill -p}


@@ -5228,7 +5286,6 @@ the corresponding short option.
 --debug                               -t
 --defines=@var{defines-file}          -d
 --file-prefix=@var{prefix}                  -b @var{file-prefix}
 --debug                               -t
 --defines=@var{defines-file}          -d
 --file-prefix=@var{prefix}                  -b @var{file-prefix}

---fixed-output-files --yacc           -y

 --graph=@var{graph-file}              -d
 --help                                -h
 --name-prefix=@var{prefix}                  -p @var{name-prefix}
 --graph=@var{graph-file}              -d
 --help                                -h
 --name-prefix=@var{prefix}                  -p @var{name-prefix}


@@ -5238,6 +5295,7 @@ the corresponding short option.
 --token-table                         -k
 --verbose                             -v
 --version                             -V
 --token-table                         -k
 --verbose                             -v
 --version                             -V

+--yacc                                -y

 @end example
 @end ifinfo
 
 @end example
 @end ifinfo
 


@@ -5275,6 +5333,22 @@ would instead be named @file{foo_tab.c}.
 @cindex symbols in Bison, table of
 
 @table @code
 @cindex symbols in Bison, table of
 
 @table @code

+@item @@$
+In an action, the location of the left-hand side of the rule.
+  @xref{Locations, , Locations Overview}.
+
+@item @@@var{n}
+In an action, the location of the @var{n}-th symbol of the right-hand
+side of the rule.  @xref{Locations, , Locations Overview}.
+
+@item $$
+In an action, the semantic value of the left-hand side of the rule.
+@xref{Actions}.
+
+@item $@var{n}
+In an action, the semantic value of the @var{n}-th symbol of the
+right-hand side of the rule.  @xref{Actions}.
+

 @item error
 A token name reserved for error recovery.  This token may be used in
 grammar rules so as to allow the Bison parser to recognize an error in
 @item error
 A token name reserved for error recovery.  This token may be used in
 grammar rules so as to allow the Bison parser to recognize an error in


@@ -5300,6 +5374,10 @@ read, by making @code{yyparse} return 0 immediately.
 Macro to discard a value from the parser stack and fake a look-ahead
 token.  @xref{Action Features, ,Special Features for Use in Actions}.
 
 Macro to discard a value from the parser stack and fake a look-ahead
 token.  @xref{Action Features, ,Special Features for Use in Actions}.
 

+@item YYDEBUG
+Macro to define to equip the parser with tracing code. @xref{Debugging,
+,Debugging Your Parser}.
+

 @item YYERROR
 Macro to pretend that a syntax error has just been detected: call
 @code{yyerror} and then perform normal error recovery if possible
 @item YYERROR
 Macro to pretend that a syntax error has just been detected: call
 @code{yyerror} and then perform normal error recovery if possible


@@ -5375,8 +5453,9 @@ containing an error message.  @xref{Error Reporting, ,The Error
 Reporting Function @code{yyerror}}.
 
 @item yylex
 Reporting Function @code{yyerror}}.
 
 @item yylex

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

 
 @item yylval
 External variable in which @code{yylex} should place the semantic
 
 @item yylval
 External variable in which @code{yylex} should place the semantic


@@ -5412,11 +5491,11 @@ Bison declaration to create a header file meant for the scanner.
 Bison declaration to set tge prefix of the output files. @xref{Decl
 Summary}.
 
 Bison declaration to set tge prefix of the output files. @xref{Decl
 Summary}.
 

-@c @item %source_extension
+@c @item %source-extension

 @c Bison declaration to specify the generated parser output file extension.
 @c @xref{Decl Summary}.
 @c
 @c Bison declaration to specify the generated parser output file extension.
 @c @xref{Decl Summary}.
 @c

-@c @item %header_extension
+@c @item %header-extension

 @c Bison declaration to specify the generated parser header file extension
 @c if required. @xref{Decl Summary}.
 
 @c Bison declaration to specify the generated parser header file extension
 @c if required. @xref{Decl Summary}.
 


@@ -5452,7 +5531,8 @@ Bison declaration to assign right associativity to token(s).
 @xref{Precedence Decl, ,Operator Precedence}.
 
 @item %start
 @xref{Precedence Decl, ,Operator Precedence}.
 
 @item %start

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

 
 @item %token
 Bison declaration to declare token(s) without specifying precedence.
 
 @item %token
 Bison declaration to declare token(s) without specifying precedence.


@@ -5463,13 +5543,16 @@ Bison declaration to include a token name table in the parser file.
 @xref{Decl Summary}.
 
 @item %type
 @xref{Decl Summary}.
 
 @item %type

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

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

+@sp 1
+

 These are the punctuation and delimiters used in Bison input:
 
 @table @samp
 These are the punctuation and delimiters used in Bison input:
 
 @table @samp