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Minor spelling, grammar, and white space fixes.

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(Symbols): Mention that any negative value returned from yylex
signifies end-of-input.  Warn about negative chars.  Mention
the portable Standard C character set.
This commit is contained in:
Paul Eggert
2002-10-05 04:45:45 +00:00
parent ff68026d4f
commit 72d2299ca0
1 changed files with 108 additions and 95 deletions
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doc/bison.texinfo
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@@ -806,25 +806,25 @@ as both an @code{expr} and a @code{decl}, and print
@cindex position, textual @cindex position, textual
Many applications, like interpreters or compilers, have to produce verbose Many applications, like interpreters or compilers, have to produce verbose
and useful error messages. To achieve this, one must be able to keep track of and useful error messages. To achieve this, one must be able to keep track of
the @dfn{textual position}, or @dfn{location}, of each syntactic construct. the @dfn{textual position}, or @dfn{location}, of each syntactic construct.
Bison provides a mechanism for handling these locations. Bison provides a mechanism for handling these locations.
Each token has a semantic value. In a similar fashion, each token has an Each token has a semantic value. In a similar fashion, each token has an
associated location, but the type of locations is the same for all tokens and associated location, but the type of locations is the same for all tokens and
groupings. Moreover, the output parser is equipped with a default data groupings. Moreover, the output parser is equipped with a default data
structure for storing locations (@pxref{Locations}, for more details). structure for storing locations (@pxref{Locations}, for more details).
Like semantic values, locations can be reached in actions using a dedicated Like semantic values, locations can be reached in actions using a dedicated
set of constructs. In the example above, the location of the whole grouping set of constructs. In the example above, the location of the whole grouping
is @code{@@$}, while the locations of the subexpressions are @code{@@1} and is @code{@@$}, while the locations of the subexpressions are @code{@@1} and
@code{@@3}. @code{@@3}.
When a rule is matched, a default action is used to compute the semantic value When a rule is matched, a default action is used to compute the semantic value
of its left hand side (@pxref{Actions}). In the same way, another default of its left hand side (@pxref{Actions}). In the same way, another default
action is used for locations. However, the action for locations is general action is used for locations. However, the action for locations is general
enough for most cases, meaning there is usually no need to describe for each enough for most cases, meaning there is usually no need to describe for each
rule how @code{@@$} should be formed. When building a new location for a given rule how @code{@@$} should be formed. When building a new location for a given
grouping, the default behavior of the output parser is to take the beginning grouping, the default behavior of the output parser is to take the beginning
of the first symbol, and the end of the last symbol. of the first symbol, and the end of the last symbol.
@@ -952,7 +952,7 @@ general form of a Bison grammar file is as follows:
The @samp{%%}, @samp{%@{} and @samp{%@}} are punctuation that appears The @samp{%%}, @samp{%@{} and @samp{%@}} are punctuation that appears
in every Bison grammar file to separate the sections. in every Bison grammar file to separate the sections.
The prologue may define types and variables used in the actions. You can The prologue may define types and variables used in the actions. You can
also use preprocessor commands to define macros used there, and use also use preprocessor commands to define macros used there, and use
@code{#include} to include header files that do any of these things. @code{#include} to include header files that do any of these things.
@@ -963,7 +963,7 @@ semantic values of various symbols.
The grammar rules define how to construct each nonterminal symbol from its The grammar rules define how to construct each nonterminal symbol from its
parts. parts.
The epilogue can contain any code you want to use. Often the definition of The epilogue can contain any code you want to use. Often the definition of
the lexical analyzer @code{yylex} goes here, plus subroutines called by the the lexical analyzer @code{yylex} goes here, plus subroutines called by the
actions in the grammar rules. In a simple program, all the rest of the actions in the grammar rules. In a simple program, all the rest of the
program can go here. program can go here.
@@ -1030,7 +1030,7 @@ Here are the C and Bison declarations for the reverse polish notation
calculator. As in C, comments are placed between @samp{/*@dots{}*/}. calculator. As in C, comments are placed between @samp{/*@dots{}*/}.
@example @example
/* Reverse polish notation calculator. */ /* Reverse polish notation calculator. */
%@{ %@{
#define YYSTYPE double #define YYSTYPE double
@@ -1039,7 +1039,7 @@ calculator. As in C, comments are placed between @samp{/*@dots{}*/}.
%token NUM %token NUM
%% /* Grammar rules and actions follow */ %% /* Grammar rules and actions follow. */
@end example @end example
The declarations section (@pxref{Prologue, , The prologue}) contains two The declarations section (@pxref{Prologue, , The prologue}) contains two
@@ -1148,7 +1148,7 @@ more times.
The parser function @code{yyparse} continues to process input until a The parser function @code{yyparse} continues to process input until a
grammatical error is seen or the lexical analyzer says there are no more grammatical error is seen or the lexical analyzer says there are no more
input tokens; we will arrange for the latter to happen at end of file. input tokens; we will arrange for the latter to happen at end-of-input.
@node Rpcalc Line @node Rpcalc Line
@subsubsection Explanation of @code{line} @subsubsection Explanation of @code{line}
@@ -1215,7 +1215,7 @@ action, Bison by default copies the value of @code{$1} into @code{$$}.
This is what happens in the first rule (the one that uses @code{NUM}). This is what happens in the first rule (the one that uses @code{NUM}).
The formatting shown here is the recommended convention, but Bison does The formatting shown here is the recommended convention, but Bison does
not require it. You can add or change whitespace as much as you wish. not require it. You can add or change white space as much as you wish.
For example, this: For example, this:
@example @example
@@ -1266,18 +1266,17 @@ for it. (The C data type of @code{yylval} is @code{YYSTYPE}, which was
defined at the beginning of the grammar; @pxref{Rpcalc Decls, defined at the beginning of the grammar; @pxref{Rpcalc Decls,
,Declarations for @code{rpcalc}}.) ,Declarations for @code{rpcalc}}.)
A token type code of zero is returned if the end-of-file is encountered. A token type code of zero is returned if the end-of-input is encountered.
(Bison recognizes any nonpositive value as indicating the end of the (Bison recognizes any nonpositive value as indicating end-of-input.)
input.)
Here is the code for the lexical analyzer: Here is the code for the lexical analyzer:
@example @example
@group @group
/* Lexical analyzer returns a double floating point /* The lexical analyzer returns a double floating point
number on the stack and the token NUM, or the numeric code number on the stack and the token NUM, or the numeric code
of the character read if not a number. Skips all blanks of the character read if not a number. It skips all blanks
and tabs, returns 0 for EOF. */ and tabs, and returns 0 for end-of-input. */
#include <ctype.h> #include <ctype.h>
@end group @end group
@@ -1288,12 +1287,12 @@ yylex (void)
@{ @{
int c; int c;
/* skip white space */ /* Skip white space. */
while ((c = getchar ()) == ' ' || c == '\t') while ((c = getchar ()) == ' ' || c == '\t')
; ;
@end group @end group
@group @group
/* process numbers */ /* Process numbers. */
if (c == '.' || isdigit (c)) if (c == '.' || isdigit (c))
@{ @{
ungetc (c, stdin); ungetc (c, stdin);
@@ -1302,10 +1301,10 @@ yylex (void)
@} @}
@end group @end group
@group @group
/* return end-of-file */ /* Return end-of-input. */
if (c == EOF) if (c == EOF)
return 0; return 0;
/* return single chars */ /* Return a single char. */
return c; return c;
@} @}
@end group @end group
@@ -1345,7 +1344,7 @@ here is the definition we will use:
#include <stdio.h> #include <stdio.h>
void void
yyerror (const char *s) /* Called by yyparse on error */ yyerror (const char *s) /* called by yyparse on error */
@{ @{
printf ("%s\n", s); printf ("%s\n", s);
@} @}
@@ -1383,7 +1382,7 @@ bison @var{file_name}.y
@noindent @noindent
In this example the file was called @file{rpcalc.y} (for ``Reverse Polish In this example the file was called @file{rpcalc.y} (for ``Reverse Polish
CALCulator''). Bison produces a file named @file{@var{file_name}.tab.c}, CALCulator''). Bison produces a file named @file{@var{file_name}.tab.c},
removing the @samp{.y} from the original file name. The file output by removing the @samp{.y} from the original file name. The file output by
Bison contains the source code for @code{yyparse}. The additional Bison contains the source code for @code{yyparse}. The additional
functions in the input file (@code{yylex}, @code{yyerror} and @code{main}) functions in the input file (@code{yylex}, @code{yyerror} and @code{main})
are copied verbatim to the output. are copied verbatim to the output.
@@ -1573,7 +1572,7 @@ This example extends the infix notation calculator with location
tracking. This feature will be used to improve the error messages. For tracking. This feature will be used to improve the error messages. For
the sake of clarity, this example is a simple integer calculator, since the sake of clarity, this example is a simple integer calculator, since
most of the work needed to use locations will be done in the lexical most of the work needed to use locations will be done in the lexical
analyser. analyzer.
@menu @menu
* Decls: Ltcalc Decls. Bison and C declarations for ltcalc. * Decls: Ltcalc Decls. Bison and C declarations for ltcalc.
@@ -1681,7 +1680,7 @@ hand.
@subsection The @code{ltcalc} Lexical Analyzer. @subsection The @code{ltcalc} Lexical Analyzer.
Until now, we relied on Bison's defaults to enable location Until now, we relied on Bison's defaults to enable location
tracking. The next step is to rewrite the lexical analyser, and make it tracking. The next step is to rewrite the lexical analyzer, and make it
able to feed the parser with the token locations, as it already does for able to feed the parser with the token locations, as it already does for
semantic values. semantic values.
@@ -1695,17 +1694,17 @@ yylex (void)
@{ @{
int c; int c;
/* skip white space */ /* Skip white space. */
while ((c = getchar ()) == ' ' || c == '\t') while ((c = getchar ()) == ' ' || c == '\t')
++yylloc.last_column; ++yylloc.last_column;
/* step */ /* Step. */
yylloc.first_line = yylloc.last_line; yylloc.first_line = yylloc.last_line;
yylloc.first_column = yylloc.last_column; yylloc.first_column = yylloc.last_column;
@end group @end group
@group @group
/* process numbers */ /* Process numbers. */
if (isdigit (c)) if (isdigit (c))
@{ @{
yylval = c - '0'; yylval = c - '0';
@@ -1720,11 +1719,11 @@ yylex (void)
@} @}
@end group @end group
/* return end-of-file */ /* Return end-of-input. */
if (c == EOF) if (c == EOF)
return 0; return 0;
/* return single chars and update location */ /* Return a single char, and update location. */
if (c == '\n') if (c == '\n')
@{ @{
++yylloc.last_line; ++yylloc.last_line;
@@ -1742,7 +1741,7 @@ In addition, it updates @code{yylloc}, the global variable (of type
@code{YYLTYPE}) containing the token's location. @code{YYLTYPE}) containing the token's location.
Now, each time this function returns a token, the parser has its number Now, each time this function returns a token, the parser has its number
as well as its semantic value, and its location in the text. The last as well as its semantic value, and its location in the text. The last
needed change is to initialize @code{yylloc}, for example in the needed change is to initialize @code{yylloc}, for example in the
controlling function: controlling function:
@@ -1821,7 +1820,7 @@ Here are the C and Bison declarations for the multi-function calculator.
@smallexample @smallexample
%@{ %@{
#include <math.h> /* For math functions, cos(), sin(), etc. */ #include <math.h> /* For math functions, cos(), sin(), etc. */
#include "calc.h" /* Contains definition of `symrec' */ #include "calc.h" /* Contains definition of `symrec' */
%@} %@}
%union @{ %union @{
@@ -1915,7 +1914,7 @@ provides for either functions or variables to be placed in the table.
@smallexample @smallexample
@group @group
/* Fonctions type. */ /* Function type. */
typedef double (*func_t) (double); typedef double (*func_t) (double);
/* Data type for links in the chain of symbols. */ /* Data type for links in the chain of symbols. */
@@ -1990,7 +1989,7 @@ symrec *sym_table = (symrec *) 0;
@end group @end group
@group @group
/* Put arithmetic functions in table. */ /* Put arithmetic functions in table. */
void void
init_table (void) init_table (void)
@{ @{
@@ -2024,7 +2023,7 @@ putsym (char *sym_name, int sym_type)
ptr->name = (char *) malloc (strlen (sym_name) + 1); ptr->name = (char *) malloc (strlen (sym_name) + 1);
strcpy (ptr->name,sym_name); strcpy (ptr->name,sym_name);
ptr->type = sym_type; ptr->type = sym_type;
ptr->value.var = 0; /* set value to 0 even if fctn. */ ptr->value.var = 0; /* Set value to 0 even if fctn. */
ptr->next = (struct symrec *)sym_table; ptr->next = (struct symrec *)sym_table;
sym_table = ptr; sym_table = ptr;
return ptr; return ptr;
@@ -2066,7 +2065,7 @@ yylex (void)
@{ @{
int c; int c;
/* Ignore whitespace, get first nonwhite character. */ /* Ignore white space, get first nonwhite character. */
while ((c = getchar ()) == ' ' || c == '\t'); while ((c = getchar ()) == ' ' || c == '\t');
if (c == EOF) if (c == EOF)
@@ -2117,7 +2116,7 @@ yylex (void)
@} @}
@end group @end group
@group @group
while (c != EOF && isalnum (c)); while (isalnum (c));
ungetc (c, stdin); ungetc (c, stdin);
symbuf[i] = '\0'; symbuf[i] = '\0';
@@ -2137,7 +2136,7 @@ yylex (void)
@end group @end group
@end smallexample @end smallexample
This program is both powerful and flexible. You may easily add new This program is both powerful and flexible. You may easily add new
functions, and it is a simple job to modify this code to install functions, and it is a simple job to modify this code to install
predefined variables such as @code{pi} or @code{e} as well. predefined variables such as @code{pi} or @code{e} as well.
@@ -2346,8 +2345,8 @@ your program will confuse other readers.
All the usual escape sequences used in character literals in C can be 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 used in Bison as well, but you must not use the null character as a
character literal because its numeric code, zero, is the code @code{yylex} character literal because its numeric code, zero, signifies
returns for end-of-input (@pxref{Calling Convention, ,Calling Convention end-of-input (@pxref{Calling Convention, ,Calling Convention
for @code{yylex}}). for @code{yylex}}).
@item @item
@@ -2384,12 +2383,15 @@ How you choose to write a terminal symbol has no effect on its
grammatical meaning. That depends only on where it appears in rules and grammatical meaning. That depends only on where it appears in rules and
on when the parser function returns that symbol. on when the parser function returns that symbol.
The value returned by @code{yylex} is always one of the terminal symbols The value returned by @code{yylex} is always one of the terminal
(or 0 for end-of-input). Whichever way you write the token type in the symbols, except that a zero or negative value signifies end-of-input.
grammar rules, you write it the same way in the definition of @code{yylex}. Whichever way you write the token type in the grammar rules, you write
The numeric code for a character token type is simply the numeric code of it the same way in the definition of @code{yylex}. The numeric code
the character, so @code{yylex} can use the identical character constant to for a character token type is simply the positive numeric code of the
generate the requisite code. Each named token type becomes a C macro in character, so @code{yylex} can use the identical value to generate the
requisite code, though you may need to convert it to @code{unsigned
char} to avoid sign-extension on hosts where @code{char} is signed.
Each named token type becomes a C macro in
the parser file, so @code{yylex} can use the name to stand for the code. 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}}. @xref{Calling Convention, ,Calling Convention for @code{yylex}}.
@@ -2400,15 +2402,23 @@ 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 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}. in the other source files that need it. @xref{Invocation, ,Invoking Bison}.
The @code{yylex} function must use the same character set and encoding If you want to write a grammar that is portable to any Standard C
that was used by Bison. For example, if you run Bison in an host, you must use only non-null character tokens taken from the basic
execution character set of Standard C. This set consists of the ten
digits, the 52 lower- and upper-case English letters, and the
characters in the following C-language string:
@example
"\a\b\t\n\v\f\r !\"#%&'()*+,-./:;<=>?[\\]^_@{|@}~"
@end example
The @code{yylex} function and Bison must use a consistent character
set and encoding for character tokens. For example, if you run Bison in an
@sc{ascii} environment, but then compile and run the resulting program @sc{ascii} environment, but then compile and run the resulting program
in an environment that uses an incompatible character set like in an environment that uses an incompatible character set like
@sc{ebcdic}, the resulting program will probably not work because the @sc{ebcdic}, the resulting program may not work because the
tables generated by Bison will assume @sc{ascii} numeric values for tables generated by Bison will assume @sc{ascii} numeric values for
character tokens. Portable grammars should avoid non-@sc{ascii} character tokens. It is standard
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 practice for software distributions to contain C source files that
were generated by Bison in an @sc{ascii} environment, so installers on were generated by Bison in an @sc{ascii} environment, so installers on
platforms that are incompatible with @sc{ascii} must rebuild those platforms that are incompatible with @sc{ascii} must rebuild those
@@ -2453,8 +2463,8 @@ exp: exp '+' exp
says that two groupings of type @code{exp}, with a @samp{+} token in between, says that two groupings of type @code{exp}, with a @samp{+} token in between,
can be combined into a larger grouping of type @code{exp}. can be combined into a larger grouping of type @code{exp}.
Whitespace in rules is significant only to separate symbols. You can add White space in rules is significant only to separate symbols. You can add
extra whitespace as you wish. extra white space as you wish.
Scattered among the components can be @var{actions} that determine Scattered among the components can be @var{actions} that determine
the semantics of the rule. An action looks like this: the semantics of the rule. An action looks like this:
@@ -2959,7 +2969,7 @@ actually does to implement mid-rule actions.
@cindex position, textual @cindex position, textual
Though grammar rules and semantic actions are enough to write a fully Though grammar rules and semantic actions are enough to write a fully
functional parser, it can be useful to process some additionnal informations, functional parser, it can be useful to process some additional information,
especially symbol locations. especially symbol locations.
@c (terminal or not) ? @c (terminal or not) ?
@@ -3006,7 +3016,7 @@ Actions are not only useful for defining language semantics, but also for
describing the behavior of the output parser with locations. describing the behavior of the output parser with locations.
The most obvious way for building locations of syntactic groupings is very The most obvious way for building locations of syntactic groupings is very
similar to the way semantic values are computed. In a given rule, several similar to the way semantic values are computed. In a given rule, several
constructs can be used to access the locations of the elements being matched. constructs can be used to access the locations of the elements being matched.
The location of the @var{n}th component of the right hand side is The location of the @var{n}th component of the right hand side is
@code{@@@var{n}}, while the location of the left hand side grouping is @code{@@@var{n}}, while the location of the left hand side grouping is
@@ -3037,11 +3047,11 @@ exp: @dots{}
@end example @end example
As for semantic values, there is a default action for locations that is As for semantic values, there is a default action for locations that is
run each time a rule is matched. It sets the beginning of @code{@@$} to the run each time a rule is matched. It sets the beginning of @code{@@$} to the
beginning of the first symbol, and the end of @code{@@$} to the end of the beginning of the first symbol, and the end of @code{@@$} to the end of the
last symbol. last symbol.
With this default action, the location tracking can be fully automatic. The With this default action, the location tracking can be fully automatic. The
example above simply rewrites this way: example above simply rewrites this way:
@example @example
@@ -3066,19 +3076,19 @@ exp: @dots{}
@subsection Default Action for Locations @subsection Default Action for Locations
@vindex YYLLOC_DEFAULT @vindex YYLLOC_DEFAULT
Actually, actions are not the best place to compute locations. Since Actually, actions are not the best place to compute locations. Since
locations are much more general than semantic values, there is room in locations are much more general than semantic values, there is room in
the output parser to redefine the default action to take for each the output parser to redefine the default action to take for each
rule. The @code{YYLLOC_DEFAULT} macro is invoked each time a rule is rule. The @code{YYLLOC_DEFAULT} macro is invoked each time a rule is
matched, before the associated action is run. matched, before the associated action is run.
Most of the time, this macro is general enough to suppress location Most of the time, this macro is general enough to suppress location
dedicated code from semantic actions. dedicated code from semantic actions.
The @code{YYLLOC_DEFAULT} macro takes three parameters. The first one is The @code{YYLLOC_DEFAULT} macro takes three parameters. The first one is
the location of the grouping (the result of the computation). The second one the location of the grouping (the result of the computation). The second one
is an array holding locations of all right hand side elements of the rule is an array holding locations of all right hand side elements of the rule
being matched. The last one is the size of the right hand side rule. being matched. The last one is the size of the right hand side rule.
By default, it is defined this way for simple LALR(1) parsers: By default, it is defined this way for simple LALR(1) parsers:
@@ -3109,7 +3119,7 @@ When defining @code{YYLLOC_DEFAULT}, you should consider that:
@itemize @bullet @itemize @bullet
@item @item
All arguments are free of side-effects. However, only the first one (the All arguments are free of side-effects. However, only the first one (the
result) should be modified by @code{YYLLOC_DEFAULT}. result) should be modified by @code{YYLLOC_DEFAULT}.
@item @item
@@ -3597,7 +3607,7 @@ The number of parser states (@pxref{Parser States}).
@item %verbose @item %verbose
Write an extra output file containing verbose descriptions of the Write an extra output file containing verbose descriptions of the
parser states and what is done for each type of look-ahead token in parser states and what is done for each type of look-ahead token in
that state. @xref{Understanding, , Understanding Your Parser}, for more that state. @xref{Understanding, , Understanding Your Parser}, for more
information. information.
@@ -3722,8 +3732,9 @@ that need it. @xref{Invocation, ,Invoking Bison}.
@node Calling Convention @node Calling Convention
@subsection Calling Convention for @code{yylex} @subsection Calling Convention for @code{yylex}
The value that @code{yylex} returns must be the numeric code for the type The value that @code{yylex} returns must be the positive numeric code
of token it has just found, or 0 for end-of-input. for the type of token it has just found; a zero or negative value
signifies end-of-input.
When a token is referred to in the grammar rules by a name, that name When a token is referred to in the grammar rules by a name, that name
in the parser file becomes a C macro whose definition is the proper in the parser file becomes a C macro whose definition is the proper
@@ -3732,8 +3743,9 @@ to indicate that type. @xref{Symbols}.
When a token is referred to in the grammar rules by a character literal, When a token is referred to in the grammar rules by a character literal,
the numeric code for that character is also the code for the token type. the numeric code for that character is also the code for the token type.
So @code{yylex} can simply return that character code. The null character So @code{yylex} can simply return that character code, possibly converted
must not be used this way, because its code is zero and that is what to @code{unsigned char} to avoid sign-extension. The null character
must not be used this way, because its code is zero and that
signifies end-of-input. signifies end-of-input.
Here is an example showing these things: Here is an example showing these things:
@@ -3743,13 +3755,13 @@ int
yylex (void) yylex (void)
@{ @{
@dots{} @dots{}
if (c == EOF) /* Detect end of file. */ if (c == EOF) /* Detect end-of-input. */
return 0; return 0;
@dots{} @dots{}
if (c == '+' || c == '-') if (c == '+' || c == '-')
return c; /* Assume token type for `+' is '+'. */ return c; /* Assume token type for `+' is '+'. */
@dots{} @dots{}
return INT; /* Return the type of the token. */ return INT; /* Return the type of the token. */
@dots{} @dots{}
@} @}
@end example @end example
@@ -3809,8 +3821,8 @@ Thus, if the type is @code{int} (the default), you might write this in
@example @example
@group @group
@dots{} @dots{}
yylval = value; /* Put value onto Bison stack. */ yylval = value; /* Put value onto Bison stack. */
return INT; /* Return the type of the token. */ return INT; /* Return the type of the token. */
@dots{} @dots{}
@end group @end group
@end example @end example
@@ -3837,8 +3849,8 @@ then the code in @code{yylex} might look like this:
@example @example
@group @group
@dots{} @dots{}
yylval.intval = value; /* Put value onto Bison stack. */ yylval.intval = value; /* Put value onto Bison stack. */
return INT; /* Return the type of the token. */ return INT; /* Return the type of the token. */
@dots{} @dots{}
@end group @end group
@end example @end example
@@ -4989,7 +5001,7 @@ error recovery. A simple and useful strategy is simply to skip the rest of
the current input line or current statement if an error is detected: the current input line or current statement if an error is detected:
@example @example
stmnt: error ';' /* on error, skip until ';' is read */ stmnt: error ';' /* On error, skip until ';' is read. */
@end example @end example
It is also useful to recover to the matching close-delimiter of an It is also useful to recover to the matching close-delimiter of an
@@ -5783,10 +5795,11 @@ Here @var{infile} is the grammar file name, which usually ends in
@samp{.y}. The parser file's name is made by replacing the @samp{.y} @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 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{foo.tab.c}, and the @samp{bison hack/foo.y} filename yields
@file{hack/foo.tab.c}. It's is also possible, in case you are writing @file{hack/foo.tab.c}. It's also possible, in case you are writing
C++ code instead of C in your grammar file, to name it @file{foo.ypp} C++ code instead of C in your grammar file, to name it @file{foo.ypp}
or @file{foo.y++}. Then, the output files will take an extention like or @file{foo.y++}. Then, the output files will take an extension like
the given one as input (repectively @file{foo.tab.cpp} and @file{foo.tab.c++}). 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 filenames like
@samp{-o} or @samp{-d}. @samp{-o} or @samp{-d}.
@@ -5796,7 +5809,7 @@ For example :
bison -d @var{infile.yxx} bison -d @var{infile.yxx}
@end example @end example
@noindent @noindent
will produce @file{infile.tab.cxx} and @file{infile.tab.hxx}. and will produce @file{infile.tab.cxx} and @file{infile.tab.hxx}, and
@example @example
bison -d @var{infile.y} -o @var{output.c++} bison -d @var{infile.y} -o @var{output.c++}
@@ -5908,7 +5921,7 @@ Same as above, but save in the file @var{defines-file}.
@item -b @var{file-prefix} @item -b @var{file-prefix}
@itemx --file-prefix=@var{prefix} @itemx --file-prefix=@var{prefix}
Pretend that @code{%verbose} was specified, i.e, specify prefix to use Pretend that @code{%verbose} was specified, i.e, specify prefix to use
for all Bison output file names. @xref{Decl Summary}. for all Bison output file names. @xref{Decl Summary}.
@item -r @var{things} @item -r @var{things}
@itemx --report=@var{things} @itemx --report=@var{things}
@@ -5935,7 +5948,7 @@ For instance, on the following grammar
@itemx --verbose @itemx --verbose
Pretend that @code{%verbose} was specified, i.e, write an extra output Pretend that @code{%verbose} was specified, i.e, write an extra output
file containing verbose descriptions of the grammar and file containing verbose descriptions of the grammar and
parser. @xref{Decl Summary}. parser. @xref{Decl Summary}.
@item -o @var{filename} @item -o @var{filename}
@itemx --output=@var{filename} @itemx --output=@var{filename}
@@ -5946,12 +5959,12 @@ described under the @samp{-v} and @samp{-d} options.
@item -g @item -g
Output a VCG definition of the LALR(1) grammar automaton computed by Output a VCG definition of the LALR(1) grammar automaton computed by
Bison. If the grammar file is @file{foo.y}, the VCG output file will Bison. If the grammar file is @file{foo.y}, the VCG output file will
be @file{foo.vcg}. be @file{foo.vcg}.
@item --graph=@var{graph-file} @item --graph=@var{graph-file}
The behaviour of @var{--graph} is the same than @samp{-g}. The only The behavior of @var{--graph} is the same than @samp{-g}. The only
difference is that it has an optionnal argument which is the name of difference is that it has an optional argument which is the name of
the output graph filename. the output graph filename.
@end table @end table
@@ -6116,7 +6129,7 @@ Macro to discard a value from the parser stack and fake a look-ahead
token. @xref{Action Features, ,Special Features for Use in Actions}. token. @xref{Action Features, ,Special Features for Use in Actions}.
@item YYDEBUG @item YYDEBUG
Macro to define to equip the parser with tracing code. @xref{Tracing, Macro to define to equip the parser with tracing code. @xref{Tracing,
,Tracing Your Parser}. ,Tracing Your Parser}.
@item YYERROR @item YYERROR
@@ -6159,9 +6172,9 @@ Macro whose value indicates whether the parser is recovering from a
syntax error. @xref{Action Features, ,Special Features for Use in Actions}. syntax error. @xref{Action Features, ,Special Features for Use in Actions}.
@item YYSTACK_USE_ALLOCA @item YYSTACK_USE_ALLOCA
Macro used to control the use of @code{alloca}. If defined to @samp{0}, Macro used to control the use of @code{alloca}. If defined to @samp{0},
the parser will not use @code{alloca} but @code{malloc} when trying to the parser will not use @code{alloca} but @code{malloc} when trying to
grow its internal stacks. Do @emph{not} define @code{YYSTACK_USE_ALLOCA} grow its internal stacks. Do @emph{not} define @code{YYSTACK_USE_ALLOCA}
to anything else. to anything else.
@item YYSTYPE @item YYSTYPE
@@ -6233,7 +6246,7 @@ Bison declaration to assign a precedence to a rule that is used at parse
time to resolve reduce/reduce conflicts. @xref{GLR Parsers}. time to resolve reduce/reduce conflicts. @xref{GLR Parsers}.
@item %file-prefix="@var{prefix}" @item %file-prefix="@var{prefix}"
Bison declaration to set the prefix of the output files. @xref{Decl Bison declaration to set the prefix of the output files. @xref{Decl
Summary}. Summary}.
@item %glr-parser @item %glr-parser
@@ -6245,7 +6258,7 @@ Bison declaration to produce a GLR parser. @xref{GLR Parsers}.
@c @c
@c @item %header-extension @c @item %header-extension
@c Bison declaration to specify the generated parser header file extension @c Bison declaration to specify the generated parser header file extension
@c if required. @xref{Decl Summary}. @c if required. @xref{Decl Summary}.
@item %left @item %left
Bison declaration to assign left associativity to token(s). Bison declaration to assign left associativity to token(s).
@@ -6258,7 +6271,7 @@ function is applied to the two semantic values to get a single result.
@xref{GLR Parsers}. @xref{GLR Parsers}.
@item %name-prefix="@var{prefix}" @item %name-prefix="@var{prefix}"
Bison declaration to rename the external symbols. @xref{Decl Summary}. Bison declaration to rename the external symbols. @xref{Decl Summary}.
@item %no-lines @item %no-lines
Bison declaration to avoid generating @code{#line} directives in the Bison declaration to avoid generating @code{#line} directives in the
@@ -6269,7 +6282,7 @@ Bison declaration to assign non-associativity to token(s).
@xref{Precedence Decl, ,Operator Precedence}. @xref{Precedence Decl, ,Operator Precedence}.
@item %output="@var{filename}" @item %output="@var{filename}"
Bison declaration to set the name of the parser file. @xref{Decl Bison declaration to set the name of the parser file. @xref{Decl
Summary}. Summary}.
@item %prec @item %prec