@finalout
@end iftex
-@c SMALL BOOK version
+@c SMALL BOOK version
@c This edition has been formatted so that you can format and print it in
-@c the smallbook format.
+@c the smallbook format.
@c @smallbook
@c Set following if you have the new `shorttitlepage' command
@ifinfo
This file documents the Bison parser generator.
-Copyright (C) 1988, 89, 90, 91, 92, 93, 95, 98, 1999 Free Software Foundation, Inc.
+Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1995, 1998, 1999, 2000
+Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
@page
@vskip 0pt plus 1filll
-Copyright @copyright{} 1988, 89, 90, 91, 92, 93, 95, 98, 1999 Free Software
-Foundation
+Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1995, 1998,
+1999, 2000
+Free Software Foundation, Inc.
@sp 2
Published by the Free Software Foundation @*
59 Temple Place, Suite 330 @*
Boston, MA 02111-1307 USA @*
-Printed copies are available for $15 each.@*
-ISBN 1-882114-45-0
+Printed copies are available from the Free Software Foundation.@*
+ISBN 1-882114-44-2
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
@sp 2
Cover art by Etienne Suvasa.
@end titlepage
-@page
+
+@contents
@node Top, Introduction, (dir), (dir)
@end ifinfo
@menu
-* Introduction::
-* Conditions::
+* Introduction::
+* Conditions::
* Copying:: The GNU General Public License says
how you can copy and share Bison
Grammar Rules for @code{rpcalc}
-* Rpcalc Input::
-* Rpcalc Line::
-* Rpcalc Expr::
+* Rpcalc Input::
+* Rpcalc Line::
+* Rpcalc Expr::
Multi-Function Calculator: @code{mfcalc}
Parser C-Language Interface
* Parser Function:: How to call @code{yyparse} and what it returns.
-* Lexical:: You must supply a function @code{yylex}
+* Lexical:: You must supply a function @code{yylex}
which reads tokens.
* Error Reporting:: You must supply a function @code{yyerror}.
* Action Features:: Special features for use in actions.
* Pure Calling:: How the calling convention differs
in a pure parser (@pxref{Pure Decl, ,A Pure (Reentrant) Parser}).
-The Bison Parser Algorithm
+The Bison Parser Algorithm
* Look-Ahead:: Parser looks one token ahead when deciding what to do.
* Shift/Reduce:: Conflicts: when either shifting or reduction is valid.
Invoking Bison
-* Bison Options:: All the options described in detail,
+* Bison Options:: All the options described in detail,
in alphabetical order by short options.
* Option Cross Key:: Alphabetical list of long options.
* VMS Invocation:: Bison command syntax on VMS.
@unnumbered Conditions for Using Bison
As of Bison version 1.24, we have changed the distribution terms for
-@code{yyparse} to permit using Bison's output in non-free programs.
+@code{yyparse} to permit using Bison's output in nonfree programs.
Formerly, Bison parsers could be used only in programs that were free
software.
The other GNU programming tools, such as the GNU C compiler, have never
-had such a requirement. They could always be used for non-free
+had such a requirement. They could always be used for nonfree
software. The reason Bison was different was not due to a special
policy decision; it resulted from applying the usual General Public
License to all of the Bison source code.
@smallexample
Gnomovision version 69, Copyright (C) 19@var{yy} @var{name of author}
-Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
+Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
rule can have an @dfn{action} made up of C statements. Each time the
parser recognizes a match for that rule, the action is executed.
@xref{Actions}.
-
+
Most of the time, the purpose of an action is to compute the semantic value
of the whole construct from the semantic values of its parts. For example,
suppose we have a rule which says an expression can be the sum of two
rule are referred to as @code{$1}, @code{$2}, and so on.
@menu
-* Rpcalc Input::
-* Rpcalc Line::
-* Rpcalc Expr::
+* Rpcalc Input::
+* Rpcalc Line::
+* Rpcalc Expr::
@end menu
@node Rpcalc Input, Rpcalc Line, , Rpcalc Rules
@example
@group
-/* Lexical analyzer returns a double floating point
+/* 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
and tabs, returns 0 for EOF. */
@end group
@group
-yylex ()
+int
+yylex (void)
@{
int c;
/* skip white space */
- while ((c = getchar ()) == ' ' || c == '\t')
+ while ((c = getchar ()) == ' ' || c == '\t')
;
@end group
@group
/* process numbers */
- if (c == '.' || isdigit (c))
+ if (c == '.' || isdigit (c))
@{
ungetc (c, stdin);
scanf ("%lf", &yylval);
@end group
@group
/* return end-of-file */
- if (c == EOF)
+ if (c == EOF)
return 0;
/* return single chars */
- return c;
+ return c;
@}
@end group
@end example
@example
@group
-main ()
+int
+main (void)
@{
- yyparse ();
+ return yyparse ();
@}
@end group
@end example
@cindex error reporting routine
When @code{yyparse} detects a syntax error, it calls the error reporting
-function @code{yyerror} to print an error message (usually but not always
-@code{"parse error"}). It is up to the programmer to supply @code{yyerror}
-(@pxref{Interface, ,Parser C-Language Interface}), so here is the definition we will use:
+function @code{yyerror} to print an error message (usually but not
+always @code{"parse error"}). It is up to the programmer to supply
+@code{yyerror} (@pxref{Interface, ,Parser C-Language Interface}), so
+here is the definition we will use:
@example
@group
#include <stdio.h>
-yyerror (s) /* Called by yyparse on error */
- char *s;
+void
+yyerror (const char *s) /* Called by yyparse on error */
@{
printf ("%s\n", s);
@}
(@pxref{Error Recovery}). Otherwise, @code{yyparse} returns nonzero. We
have not written any error rules in this example, so any invalid input will
cause the calculator program to exit. This is not clean behavior for a
-real calculator, but it is adequate in the first example.
+real calculator, but it is adequate for the first example.
@node Rpcalc Gen, Rpcalc Compile, Rpcalc Error, RPN Calc
@subsection Running Bison to Make the Parser
@cindex running Bison (introduction)
-Before running Bison to produce a parser, we need to decide how to arrange
-all the source code in one or more source files. For such a simple example,
-the easiest thing is to put everything in one file. The definitions of
-@code{yylex}, @code{yyerror} and @code{main} go at the end, in the
-``additional C code'' section of the file (@pxref{Grammar Layout, ,The Overall Layout of a Bison Grammar}).
+Before running Bison to produce a parser, we need to decide how to
+arrange all the source code in one or more source files. For such a
+simple example, the easiest thing is to put everything in one file. The
+definitions of @code{yylex}, @code{yyerror} and @code{main} go at the
+end, in the ``additional C code'' section of the file (@pxref{Grammar
+Layout, ,The Overall Layout of a Bison Grammar}).
For a large project, you would probably have several source files, and use
@code{make} to arrange to recompile them.
@end example
@noindent
-The functions @code{yylex}, @code{yyerror} and @code{main} can be the same
-as before.
+The functions @code{yylex}, @code{yyerror} and @code{main} can be the
+same as before.
There are two important new features shown in this code.
Up to this point, this manual has not addressed the issue of @dfn{error
recovery}---how to continue parsing after the parser detects a syntax
-error. All we have handled is error reporting with @code{yyerror}. Recall
-that by default @code{yyparse} returns after calling @code{yyerror}. This
-means that an erroneous input line causes the calculator program to exit.
-Now we show how to rectify this deficiency.
+error. All we have handled is error reporting with @code{yyerror}.
+Recall that by default @code{yyparse} returns after calling
+@code{yyerror}. This means that an erroneous input line causes the
+calculator program to exit. Now we show how to rectify this deficiency.
The Bison language itself includes the reserved word @code{error}, which
may be included in the grammar rules. In the example below it has
@end group
@end example
-This addition to the grammar allows for simple error recovery in the event
-of a parse error. If an expression that cannot be evaluated is read, the
-error will be recognized by the third rule for @code{line}, and parsing
-will continue. (The @code{yyerror} function is still called upon to print
-its message as well.) The action executes the statement @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
+This addition to the grammar allows for simple error recovery in the
+event of a parse error. If an expression that cannot be evaluated is
+read, the error will be recognized by the third rule for @code{line},
+and parsing will continue. (The @code{yyerror} function is still called
+upon to print its message as well.) The action executes the statement
+@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
This form of error recovery deals with syntax errors. There are other
kinds of errors; for example, division by zero, which raises an exception
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 non-number characters as tokens, so new grammar rules suffice for
+back all nonnumber 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:
definition, which is kept in the header @file{calc.h}, is as follows. It
provides for either functions or variables to be placed in the table.
+@c FIXME: ANSIfy the prototypes for FNCTPTR etc.
@smallexample
@group
/* Data type for links in the chain of symbols. */
@group
#include <stdio.h>
-main ()
+int
+main (void)
@{
init_table ();
- yyparse ();
+ return yyparse ();
@}
@end group
@group
-yyerror (s) /* Called by yyparse on error */
- char *s;
+void
+yyerror (const char *s) /* Called by yyparse on error */
@{
printf ("%s\n", s);
@}
@end group
@group
-struct init arith_fncts[]
- = @{
- "sin", sin,
- "cos", cos,
- "atan", atan,
- "ln", log,
- "exp", exp,
- "sqrt", sqrt,
- 0, 0
- @};
+struct init arith_fncts[] =
+@{
+ "sin", sin,
+ "cos", cos,
+ "atan", atan,
+ "ln", log,
+ "exp", exp,
+ "sqrt", sqrt,
+ 0, 0
+@};
/* The symbol table: a chain of `struct symrec'. */
symrec *sym_table = (symrec *)0;
@end group
@group
-init_table () /* puts arithmetic functions in table. */
+/* Put arithmetic functions in table. */
+void
+init_table (void)
@{
int i;
symrec *ptr;
@smallexample
symrec *
-putsym (sym_name,sym_type)
- char *sym_name;
- int sym_type;
+putsym (char *sym_name, int sym_type)
@{
symrec *ptr;
ptr = (symrec *) malloc (sizeof (symrec));
@}
symrec *
-getsym (sym_name)
- char *sym_name;
+getsym (const char *sym_name)
@{
symrec *ptr;
for (ptr = sym_table; ptr != (symrec *) 0;
@smallexample
@group
#include <ctype.h>
-yylex ()
+
+int
+yylex (void)
@{
int c;
@cindex additional C code section
@cindex C code, section for additional
-The @var{additional C code} section is copied verbatim to the end of
-the parser file, just as the @var{C declarations} section is copied to
-the beginning. This is the most convenient place to put anything
-that you want to have in the parser file but which need not come before
-the definition of @code{yyparse}. For example, the definitions of
-@code{yylex} and @code{yyerror} often go here. @xref{Interface, ,Parser C-Language Interface}.
+The @var{additional C code} section is copied verbatim to the end of the
+parser file, just as the @var{C declarations} section is copied to the
+beginning. This is the most convenient place to put anything that you
+want to have in the parser file but which need not come before the
+definition of @code{yyparse}. For example, the definitions of
+@code{yylex} and @code{yyerror} often go here. @xref{Interface, ,Parser
+C-Language Interface}.
If the last section is empty, you may omit the @samp{%%} that separates it
from the grammar rules.
@item
@cindex string token
@cindex literal string token
-@cindex multi-character literal
+@cindex multicharacter literal
A @dfn{literal string token} is written like a C string constant; for
example, @code{"<="} is a literal string token. A literal string token
doesn't need to be declared unless you need to specify its semantic
By convention, a literal string token is used only to represent a token
that consists of that particular string. Thus, you should use the token
type @code{"<="} to represent the string @samp{<=} as a token. Bison
-does not enforces this convention, but if you depart from it, people who
+does not enforce this convention, but if you depart from it, people who
read your program will be confused.
All the escape sequences used in string literals in C can be used in
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.
-(This is why periods don't make sense in terminal symbols.)
+(This is why periods don't make sense in terminal symbols.)
@xref{Calling Convention, ,Calling Convention for @code{yylex}}.
If @code{yylex} is defined in a separate file, you need to arrange for the
@end example
@noindent
-where @var{result} is the nonterminal symbol that this rule describes
+where @var{result} is the nonterminal symbol that this rule describes,
and @var{components} are various terminal and nonterminal symbols that
-are put together by this rule (@pxref{Symbols}).
+are put together by this rule (@pxref{Symbols}).
For example,
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 somethings. Consider this recursive definition of a comma-separated
-sequence of one or more expressions:
+of a particular thing. Consider this recursive definition of a
+comma-separated sequence of one or more expressions:
@example
@group
@dfn{Indirect} or @dfn{mutual} recursion occurs when the result of the
rule does not appear directly on its right hand side, but does appear
in rules for other nonterminals which do appear on its right hand
-side.
+side.
For example:
@node Semantics, Declarations, Recursion, Grammar File
@section Defining Language Semantics
@cindex defining language semantics
-@cindex language semantics, defining
+@cindex language semantics, defining
The grammar rules for a language determine only the syntax. The semantics
are determined by the semantic values associated with various tokens and
can use the name @var{name} to stand for this token type's code.
Alternatively, you can use @code{%left}, @code{%right}, or @code{%nonassoc}
-instead of @code{%token}, if you wish to specify precedence.
+instead of @code{%token}, if you wish to specify associativity and precedence.
@xref{Precedence Decl, ,Operator Precedence}.
You can explicitly specify the numeric code for a token type by appending
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:
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.
+C.
For example:
The output file @file{@var{name}.h} normally defines the tokens with
Yacc-compatible token numbers. If this option is specified, the
internal Bison numbers are used instead. (Yacc-compatible numbers start
-at 257 except for single character tokens; Bison assigns token numbers
+at 257 except for single-character tokens; Bison assigns token numbers
sequentially for all tokens starting at 3.)
@item %token_table
@item YYNTOKENS
The highest token number, plus one.
@item YYNNTS
-The number of non-terminal symbols.
+The number of nonterminal symbols.
@item YYNRULES
The number of grammar rules,
@item YYNSTATES
@menu
* Parser Function:: How to call @code{yyparse} and what it returns.
-* Lexical:: You must supply a function @code{yylex}
+* Lexical:: You must supply a function @code{yylex}
which reads tokens.
* Error Reporting:: You must supply a function @code{yyerror}.
* Action Features:: Special features for use in actions.
Here is an example showing these things:
@example
-yylex ()
+int
+yylex (void)
@{
@dots{}
if (c == EOF) /* Detect end of file. */
the grammar file has no effect on @code{yylex}.
@item
-@code{yylex} can find the multi-character token in the @code{yytname}
+@code{yylex} can find the multicharacter token in the @code{yytname}
table. The index of the token in the table is the token type's code.
-The name of a multi-character token is recorded in @code{yytname} with a
+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.
pointers.
@example
-yylex (lvalp, llocp)
- YYSTYPE *lvalp;
- YYLTYPE *llocp;
+int
+yylex (YYSTYPE *lvalp, YYLTYPE *llocp)
@{
@dots{}
*lvalp = value; /* Put value onto Bison stack. */
@cindex syntax error
The Bison parser detects a @dfn{parse error} or @dfn{syntax error}
-whenever it reads a token which cannot satisfy any syntax rule. A
+whenever it reads a token which cannot satisfy any syntax rule. An
action in the grammar can also explicitly proclaim an error, using the
-macro @code{YYERROR} (@pxref{Action Features, ,Special Features for Use in Actions}).
+macro @code{YYERROR} (@pxref{Action Features, ,Special Features for Use
+in Actions}).
The Bison parser expects to report the error by calling an error
reporting function named @code{yyerror}, which you must supply. It is
@findex YYERROR_VERBOSE
If you define the macro @code{YYERROR_VERBOSE} in the Bison declarations
-section (@pxref{Bison Declarations, ,The Bison Declarations Section}), then Bison provides a more verbose
-and specific error message string instead of just plain @w{@code{"parse
-error"}}. It doesn't matter what definition you use for
-@code{YYERROR_VERBOSE}, just whether you define it.
+section (@pxref{Bison Declarations, ,The Bison Declarations Section}),
+then Bison provides a more verbose and specific error message string
+instead of just plain @w{@code{"parse error"}}. It doesn't matter what
+definition you use for @code{YYERROR_VERBOSE}, just whether you define
+it.
The parser can detect one other kind of error: stack overflow. This
happens when the input contains constructions that are very deeply
@example
@group
-yyerror (s)
- char *s;
+void
+yyerror (char *s)
@{
@end group
@group
@item $<@var{typealt}>@var{n}
Like @code{$@var{n}} but specifies alternative @var{typealt} in the
-union specified by the @code{%union} declaration.
+union specified by the @code{%union} declaration.
@xref{Action Types, ,Data Types of Values in Actions}.@refill
@item YYABORT;
@item yyerrok;
Resume generating error messages immediately for subsequent syntax
-errors. This is useful primarily in error rules.
+errors. This is useful primarily in error rules.
@xref{Error Recovery}.
@item @@@var{n}
@end table
@node Algorithm, Error Recovery, Interface, Top
-@chapter The Bison Parser Algorithm
-@cindex Bison parser algorithm
+@chapter The Bison Parser Algorithm
+@cindex Bison parser algorithm
@cindex algorithm of parser
@cindex shifting
@cindex reduction
@noindent
Suppose the parser has seen the tokens @samp{1}, @samp{-} and @samp{2};
-should it reduce them via the rule for the addition operator? It depends
+should it reduce them via the rule for the subtraction operator? It depends
on the next token. Of course, if the next token is @samp{)}, we must
reduce; shifting is invalid because no single rule can reduce the token
sequence @w{@samp{- 2 )}} or anything starting with that. But if the next
To decide which one Bison should do, we must consider the
results. If the next operator token @var{op} is shifted, then it
must be reduced first in order to permit another opportunity to
-reduce the sum. The result is (in effect) @w{@samp{1 - (2
+reduce the difference. The result is (in effect) @w{@samp{1 - (2
@var{op} 3)}}. On the other hand, if the subtraction is reduced
before shifting @var{op}, the result is @w{@samp{(1 - 2) @var{op}
3}}. Clearly, then, the choice of shift or reduce should depend
@end example
It would seem that this grammar can be parsed with only a single token
-of look-ahead: when a @code{param_spec} is being read, an @code{ID} is
+of look-ahead: when a @code{param_spec} is being read, an @code{ID} is
a @code{name} if a comma or colon follows, or a @code{type} if another
@code{ID} follows. In other words, this grammar is LR(1).
is always defined (you need not declare it) and reserved for error
handling. The Bison parser generates an @code{error} token whenever a
syntax error happens; if you have provided a rule to recognize this token
-in the current context, the parse can continue.
+in the current context, the parse can continue.
For example:
Unfortunately, the name being declared is separated from the declaration
construct itself by a complicated syntactic structure---the ``declarator''.
-As a result, the part of Bison parser for C needs to be duplicated, with
+As a result, part of the Bison parser for C needs to be duplicated, with
all the nonterminal names changed: once for parsing a declaration in which
a typedef name can be redefined, and once for parsing a declaration in
which that can't be done. Here is a part of the duplication, with actions
with letters are parsed as integers if possible.
The declaration of @code{hexflag} shown in the C declarations section of
-the parser file is needed to make it accessible to the actions
+the parser file is needed to make it accessible to the actions
(@pxref{C Declarations, ,The C Declarations Section}). You must also write the code in @code{yylex}
to obey the flag.
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 C declarations section of the grammar file
+YYDEBUG 1} in the C declarations section of the grammar file
(@pxref{C Declarations, ,The C Declarations Section}). 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.
#define YYPRINT(file, type, value) yyprint (file, type, value)
static void
-yyprint (file, type, value)
- FILE *file;
- int type;
- YYSTYPE value;
+yyprint (FILE *file, int type, YYSTYPE value)
@{
if (type == VAR)
fprintf (file, " %s", value.tptr->name);
@file{hack/foo.tab.c}.@refill
@menu
-* Bison Options:: All the options described in detail,
+* Bison Options:: All the options described in detail,
in alphabetical order by short options.
+* Environment Variables:: Variables which affect Bison execution.
* Option Cross Key:: Alphabetical list of long options.
* VMS Invocation:: Bison command syntax on VMS.
@end menu
-@node Bison Options, Option Cross Key, , Invocation
+@node Bison Options, Environment Variables, , Invocation
@section Bison Options
Bison supports both traditional single-letter options and mnemonic long
@end example
@end table
-@node Option Cross Key, VMS Invocation, Bison Options, Invocation
+@node Environment Variables, Option Cross Key, Bison Options, Invocation
+@section Environment Variables
+@cindex environment variables
+@cindex BISON_HAIRY
+@cindex BISON_SIMPLE
+
+Here is a list of environment variables which affect the way Bison
+runs.
+
+@table @samp
+@item BISON_SIMPLE
+@itemx BISON_HAIRY
+Much of the parser generated by Bison is copied verbatim from a file
+called @file{bison.simple}. If Bison cannot find that file, or if you
+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.
+
+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.
+
+@end table
+
+@node Option Cross Key, VMS Invocation, Environment Variables, Invocation
@section Option Cross Key
Here is a list of options, alphabetized by long option, to help you find
--no-lines -l
--no-parser -n
--output-file=@var{outfile} -o @var{outfile}
---raw -r
+--raw -r
--token-table -k
--verbose -v
--version -V
@item YYABORT
Macro to pretend that an unrecoverable syntax error has occurred, by
making @code{yyparse} return 1 immediately. The error reporting
-function @code{yyerror} is not called. @xref{Parser Function, ,The Parser Function @code{yyparse}}.
+function @code{yyerror} is not called. @xref{Parser Function, ,The
+Parser Function @code{yyparse}}.
@item YYACCEPT
Macro to pretend that a complete utterance of the language has been
-read, by making @code{yyparse} return 0 immediately.
+read, by making @code{yyparse} return 0 immediately.
@xref{Parser Function, ,The Parser Function @code{yyparse}}.
@item YYBACKUP
@xref{Value Type, ,Data Types of Semantic Values}.
@item yychar
-External integer variable that contains the integer value of the
-current look-ahead token. (In a pure parser, it is a local variable
-within @code{yyparse}.) Error-recovery rule actions may examine this
-variable. @xref{Action Features, ,Special Features for Use in Actions}.
+External integer variable that contains the integer value of the current
+look-ahead token. (In a pure parser, it is a local variable within
+@code{yyparse}.) Error-recovery rule actions may examine this variable.
+@xref{Action Features, ,Special Features for Use in Actions}.
@item yyclearin
Macro used in error-recovery rule actions. It clears the previous
@item yyerror
User-supplied function to be called by @code{yyparse} on error. The
function receives one argument, a pointer to a character string
-containing an error message. @xref{Error Reporting, ,The Error Reporting Function @code{yyerror}}.
+containing an error message. @xref{Error Reporting, ,The Error
+Reporting Function @code{yyerror}}.
@item yylex
User-supplied lexical analyzer function, called with no arguments
@code{yylex}.) @xref{Token Values, ,Semantic Values of Tokens}.
@item yylloc
-External variable in which @code{yylex} should place the line and
-column numbers associated with a token. (In a pure parser, it is a
-local variable within @code{yyparse}, and its address is passed to
+External variable in which @code{yylex} should place the line and column
+numbers associated with a token. (In a pure parser, it is a local
+variable within @code{yyparse}, and its address is passed to
@code{yylex}.) You can ignore this variable if you don't use the
-@samp{@@} feature in the grammar actions. @xref{Token Positions, ,Textual Positions of Tokens}.
+@samp{@@} feature in the grammar actions. @xref{Token Positions,
+,Textual Positions of Tokens}.
@item yynerrs
-Global variable which Bison increments each time there is a parse
-error. (In a pure parser, it is a local variable within
-@code{yyparse}.) @xref{Error Reporting, ,The Error Reporting Function @code{yyerror}}.
+Global variable which Bison increments each time there is a parse error.
+(In a pure parser, it is a local variable within @code{yyparse}.)
+@xref{Error Reporting, ,The Error Reporting Function @code{yyerror}}.
@item yyparse
The parser function produced by Bison; call this function to start
@item Grouping
A language construct that is (in general) grammatically divisible;
-for example, `expression' or `declaration' in C.
+for example, `expression' or `declaration' in C.
@xref{Language and Grammar, ,Languages and Context-Free Grammars}.
@item Infix operator
tokens are parsed. @xref{Lexical Tie-ins}.
@item Literal string token
-A token which constists of two or more fixed characters.
+A token which consists of two or more fixed characters.
@xref{Symbols}.
@item Look-ahead token
@item Start symbol
The nonterminal symbol that stands for a complete valid utterance in
the language being parsed. The start symbol is usually listed as the
-first nonterminal symbol in a language specification.
+first nonterminal symbol in a language specification.
@xref{Start Decl, ,The Start-Symbol}.
@item Symbol table
@printindex cp
-@contents
-
@bye
-
-
-\f
-
-@c old menu
-
-* Introduction::
-* Conditions::
-* Copying:: The GNU General Public License says
- how you can copy and share Bison
-
-Tutorial sections:
-* Concepts:: Basic concepts for understanding Bison.
-* Examples:: Three simple explained examples of using Bison.
-
-Reference sections:
-* Grammar File:: Writing Bison declarations and rules.
-* Interface:: C-language interface to the parser function @code{yyparse}.
-* Algorithm:: How the Bison parser works at run-time.
-* Error Recovery:: Writing rules for error recovery.
-* Context Dependency::What to do if your language syntax is too
- messy for Bison to handle straightforwardly.
-* Debugging:: Debugging Bison parsers that parse wrong.
-* Invocation:: How to run Bison (to produce the parser source file).
-* Table of Symbols:: All the keywords of the Bison language are explained.
-* Glossary:: Basic concepts are explained.
-* Index:: Cross-references to the text.
-
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