* bootstrap (gnulib_modules): Add strverscmp.

[bison.git] / doc / bison.texinfo

diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index 5f6f597a81e0d78497da093d89eae6797a8f3ceb..69eb649fe3b386f341170fac81631c7e547bb76c 100644 (file)
--- a/doc/bison.texinfo
+++ b/doc/bison.texinfo
@@ -145,9 +145,9 @@ The Concepts of Bison
 
 Writing @acronym{GLR} Parsers
 
 
 Writing @acronym{GLR} Parsers
 

-* Simple GLR Parsers::          Using @acronym{GLR} parsers on unambiguous grammars
-* Merging GLR Parses::          Using @acronym{GLR} parsers to resolve ambiguities
-* Compiler Requirements::       @acronym{GLR} parsers require a modern C compiler
+* Simple GLR Parsers::       Using @acronym{GLR} parsers on unambiguous grammars
+* Merging GLR Parses::       Using @acronym{GLR} parsers to resolve ambiguities
+* Compiler Requirements::    @acronym{GLR} parsers require a modern C compiler

 
 Examples
 
 
 Examples
 


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

+* Require Decl::      Requiring a Bison version.

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


@@ -732,9 +733,9 @@ user-defined function on the resulting values to produce an arbitrary
 merged result.
 
 @menu
 merged result.
 
 @menu

-* Simple GLR Parsers::          Using @acronym{GLR} parsers on unambiguous grammars
-* Merging GLR Parses::          Using @acronym{GLR} parsers to resolve ambiguities
-* Compiler Requirements::       @acronym{GLR} parsers require a modern C compiler
+* Simple GLR Parsers::       Using @acronym{GLR} parsers on unambiguous grammars
+* Merging GLR Parses::       Using @acronym{GLR} parsers to resolve ambiguities
+* Compiler Requirements::    @acronym{GLR} parsers require a modern C compiler

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


@@ -1197,11 +1198,13 @@ function @code{yyerror} and the parser function @code{yyparse} itself.
 This also includes numerous identifiers used for internal purposes.
 Therefore, you should avoid using C identifiers starting with @samp{yy}
 or @samp{YY} in the Bison grammar file except for the ones defined in
 This also includes numerous identifiers used for internal purposes.
 Therefore, you should avoid using C identifiers starting with @samp{yy}
 or @samp{YY} in the Bison grammar file except for the ones defined in

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

 
 In some cases the Bison parser file includes system headers, and in
 those cases your code should respect the identifiers reserved by those
 
 In some cases the Bison parser file includes system headers, and in
 those cases your code should respect the identifiers reserved by those

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

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


@@ -1716,12 +1719,12 @@ With all the source in a single file, you use the following command to
 convert it into a parser file:
 
 @example
 convert it into a parser file:
 
 @example

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

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

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

 removing the @samp{.y} from the original file name.  The file output by
 Bison contains the source code for @code{yyparse}.  The additional
 functions in the input file (@code{yylex}, @code{yyerror} and @code{main})
 removing the @samp{.y} from the original file name.  The file output by
 Bison contains the source code for @code{yyparse}.  The additional
 functions in the input file (@code{yylex}, @code{yyerror} and @code{main})


@@ -3546,6 +3549,7 @@ it explicitly (@pxref{Language and Grammar, ,Languages and Context-Free
 Grammars}).
 
 @menu
 Grammars}).
 
 @menu

+* Require Decl::      Requiring a Bison version.

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


@@ -3558,6 +3562,19 @@ Grammars}).
 * Decl Summary::      Table of all Bison declarations.
 @end menu
 
 * Decl Summary::      Table of all Bison declarations.
 @end menu
 

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

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


@@ -3779,10 +3796,10 @@ Declare that the @var{code} must be invoked before parsing each time
 For instance, if your locations use a file name, you may use
 
 @example
 For instance, if your locations use a file name, you may use
 
 @example

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

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

-  @@$.begin.filename = @@$.end.filename = filename;
+  @@$.begin.filename = @@$.end.filename = file_name;

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


@@ -3792,28 +3809,31 @@ For instance, if your locations use a file name, you may use
 @cindex freeing discarded symbols
 @findex %destructor
 
 @cindex freeing discarded symbols
 @findex %destructor
 

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

 
 

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

 
 @deffn {Directive} %destructor @{ @var{code} @} @var{symbols}
 @findex %destructor
 
 @deffn {Directive} %destructor @{ @var{code} @} @var{symbols}
 @findex %destructor

-Declare that the @var{code} must be invoked for each of the
-@var{symbols} that will be discarded by the parser.  The @var{code}
-should use @code{$$} to designate the semantic value associated to the
-@var{symbols}.  The additional parser parameters are also available
+Invoke @var{code} whenever the parser discards one of the
+@var{symbols}.  Within @var{code}, @code{$$} designates the semantic
+value associated with the discarded symbol.  The additional
+parser parameters are also available

 (@pxref{Parser Function, , The Parser Function @code{yyparse}}).
 
 (@pxref{Parser Function, , The Parser Function @code{yyparse}}).
 

-@strong{Warning:} as of Bison 1.875, this feature is still considered as
-experimental, as there was not enough user feedback.  In particular,
+@strong{Warning:} as of Bison 2.1, this feature is still
+experimental, as there has not been enough user feedback.  In particular,

 the syntax might still change.
 @end deffn
 
 the syntax might still change.
 @end deffn
 


@@ -3830,7 +3850,7 @@ For instance:
 @end smallexample
 
 @noindent
 @end smallexample
 
 @noindent

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

 its associated memory will be freed.
 
 Note that in the future, Bison might also consider that right hand side
 its associated memory will be freed.
 
 Note that in the future, Bison might also consider that right hand side


@@ -3862,8 +3882,11 @@ stacked symbols popped during the first phase of error recovery,
 @item
 incoming terminals during the second phase of error recovery,
 @item
 @item
 incoming terminals during the second phase of error recovery,
 @item

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

 @end itemize
 
 
 @end itemize
 
 


@@ -4085,7 +4108,7 @@ above-mentioned declarations and to the token type codes.
 @end deffn
 
 @deffn {Directive} %destructor
 @end deffn
 
 @deffn {Directive} %destructor

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

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


@@ -4127,7 +4150,7 @@ parser file contains just @code{#define} directives and static variable
 declarations.
 
 This option also tells Bison to write the C code for the grammar actions
 declarations.
 
 This option also tells Bison to write the C code for the grammar actions

-into a file named @file{@var{filename}.act}, in the form of a
+into a file named @file{@var{file}.act}, in the form of a

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


@@ -4140,8 +4163,8 @@ associate errors with the parser file, treating it an independent source
 file in its own right.
 @end deffn
 
 file in its own right.
 @end deffn
 

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

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


@@ -4149,6 +4172,12 @@ Request a pure (reentrant) parser program (@pxref{Pure Decl, ,A Pure
 (Reentrant) Parser}).
 @end deffn
 
 (Reentrant) Parser}).
 @end deffn
 

+@deffn {Directive} %require "@var{version}"
+Specify that version @var{version} or higher of Bison required for the
+grammar.
+@xref{Require Decl, , Require a Version of Bison}.
+@end deffn
+

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


@@ -4158,15 +4187,14 @@ three elements of @code{yytname} correspond to the predefined tokens
 @code{"error"}, and @code{"$undefined"}; after these come the symbols
 defined in the grammar file.
 
 @code{"error"}, and @code{"$undefined"}; after these come the symbols
 defined in the grammar file.
 

-For single-character literal tokens and literal string tokens, the name
-in the table includes the single-quote or double-quote characters: for
-example, @code{"'+'"} is a single-character literal and @code{"\"<=\""}
-is a literal string token.  All the characters of the literal string
-token appear verbatim in the string found in the table; even
-double-quote characters are not escaped.  For example, if the token
-consists of three characters @samp{*"*}, its string in @code{yytname}
-contains @samp{"*"*"}.  (In C, that would be written as
-@code{"\"*\"*\""}).
+The name in the table includes all the characters needed to represent
+the token in Bison.  For single-character literals and literal
+strings, this includes the surrounding quoting characters and any
+escape sequences.  For example, the Bison single-character literal
+@code{'+'} corresponds to a three-character name, represented in C as
+@code{"'+'"}; and the Bison two-character literal string @code{"\\/"}
+corresponds to a five-character name, represented in C as
+@code{"\"\\\\/\""}.

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


@@ -4266,7 +4294,11 @@ without reading further.
 The value returned by @code{yyparse} is 0 if parsing was successful (return
 is due to end-of-input).
 
 The value returned by @code{yyparse} is 0 if parsing was successful (return
 is due to end-of-input).
 

-The value is 1 if parsing failed (return is due to a syntax error).
+The value is 1 if parsing failed because of invalid input, i.e., input
+that contains a syntax error or that causes @code{YYABORT} to be
+invoked.
+
+The value is 2 if parsing failed due to memory exhaustion.

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


@@ -4407,11 +4439,13 @@ the grammar file has no effect on @code{yylex}.
 table.  The index of the token in the table is the token type's code.
 The name of a multicharacter token is recorded in @code{yytname} with a
 double-quote, the token's characters, and another double-quote.  The
 table.  The index of the token in the table is the token type's code.
 The name of a multicharacter token is recorded in @code{yytname} with a
 double-quote, the token's characters, and another double-quote.  The

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

 
 

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

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


@@ -4682,7 +4716,7 @@ preferable since it more accurately describes the return type for
 
 @vindex yynerrs
 The variable @code{yynerrs} contains the number of syntax errors
 
 @vindex yynerrs
 The variable @code{yynerrs} contains the number of syntax errors

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

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


@@ -6598,14 +6632,15 @@ bison @var{infile}
 
 Here @var{infile} is the grammar file name, which usually ends in
 @samp{.y}.  The parser file's name is made by replacing the @samp{.y}
 
 Here @var{infile} is the grammar file name, which usually ends in
 @samp{.y}.  The parser file's name is made by replacing the @samp{.y}

-with @samp{.tab.c}.  Thus, the @samp{bison foo.y} filename yields
-@file{foo.tab.c}, and the @samp{bison hack/foo.y} filename yields
-@file{hack/foo.tab.c}.  It's also possible, in case you are writing
+with @samp{.tab.c} and removing any leading directory.  Thus, the
+@samp{bison foo.y} file name yields
+@file{foo.tab.c}, and the @samp{bison hack/foo.y} file name yields
+@file{foo.tab.c}.  It's also possible, in case you are writing

 C++ code instead of C in your grammar file, to name it @file{foo.ypp}
 or @file{foo.y++}.  Then, the output files will take an extension like
 the given one as input (respectively @file{foo.tab.cpp} and
 @file{foo.tab.c++}).
 C++ code instead of C in your grammar file, to name it @file{foo.ypp}
 or @file{foo.y++}.  Then, the output files will take an extension like
 the given one as input (respectively @file{foo.tab.cpp} and
 @file{foo.tab.c++}).

-This feature takes effect with all options that manipulate filenames like
+This feature takes effect with all options that manipulate file names like

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


@@ -6763,11 +6798,11 @@ Pretend that @code{%verbose} was specified, i.e, write an extra output
 file containing verbose descriptions of the grammar and
 parser.  @xref{Decl Summary}.
 
 file containing verbose descriptions of the grammar and
 parser.  @xref{Decl Summary}.
 

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

 
 

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

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


@@ -6779,7 +6814,7 @@ be @file{foo.vcg}.
 @item --graph=@var{graph-file}
 The behavior of @var{--graph} is the same than @samp{-g}.  The only
 difference is that it has an optional argument which is the name of
 @item --graph=@var{graph-file}
 The behavior of @var{--graph} is the same than @samp{-g}.  The only
 difference is that it has an optional argument which is the name of

-the output graph filename.
+the output graph file.

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


@@ -6895,13 +6930,13 @@ used for location tracking.  @xref{C++ Location Values}.
 @item stack.hh
 An auxiliary class @code{stack} used by the parser.
 
 @item stack.hh
 An auxiliary class @code{stack} used by the parser.
 

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

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

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

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

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

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


@@ -6919,12 +6954,13 @@ for a complete and accurate documentation.
 The @code{%union} directive works as for C, see @ref{Union Decl, ,The
 Collection of Value Types}.  In particular it produces a genuine
 @code{union}@footnote{In the future techniques to allow complex types
 The @code{%union} directive works as for C, see @ref{Union Decl, ,The
 Collection of Value Types}.  In particular it produces a genuine
 @code{union}@footnote{In the future techniques to allow complex types

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

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

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

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


@@ -6950,7 +6986,7 @@ auxiliary classes define a @code{position}, a single point in a file,
 and a @code{location}, a range composed of a pair of
 @code{position}s (possibly spanning several files).
 
 and a @code{location}, a range composed of a pair of
 @code{position}s (possibly spanning several files).
 

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

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


@@ -6982,8 +7018,8 @@ Various forms of syntactic sugar for @code{columns}.
 
 @deftypemethod {position} {position} operator<< (std::ostream @var{o}, const position& @var{p})
 Report @var{p} on @var{o} like this:
 
 @deftypemethod {position} {position} operator<< (std::ostream @var{o}, const position& @var{p})
 Report @var{p} on @var{o} like this:

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

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


@@ -7125,7 +7161,8 @@ transforming the simple parsing context structure into a fully blown
 
 The declaration of this driver class, @file{calc++-driver.hh}, is as
 follows.  The first part includes the CPP guard and imports the
 
 The declaration of this driver class, @file{calc++-driver.hh}, is as
 follows.  The first part includes the CPP guard and imports the

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

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


@@ -7133,26 +7170,9 @@ required standard library components.
 # define CALCXX_DRIVER_HH
 # include <string>
 # include <map>
 # define CALCXX_DRIVER_HH
 # include <string>
 # include <map>

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

 @end example
 
 @end example
 

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

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


@@ -7164,7 +7184,9 @@ factor both as follows.
 @example
 // Announce to Flex the prototype we want for lexing function, ...
 # define YY_DECL                                                \
 @example
 // Announce to Flex the prototype we want for lexing function, ...
 # define YY_DECL                                                \

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

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


@@ -7274,19 +7296,33 @@ calcxx_driver::error (const std::string& m)
 @node Calc++ Parser
 @subsection Calc++ Parser
 
 @node Calc++ Parser
 @subsection Calc++ Parser
 

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

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

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

 %defines
 %defines

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

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

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

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


@@ -7342,6 +7378,19 @@ them.
 @};
 @end example
 
 @};
 @end example
 

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

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


@@ -7351,11 +7400,11 @@ avoid name clashes.
 
 @comment file: calc++-parser.yy
 @example
 
 @comment file: calc++-parser.yy
 @example

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

 @end example
 
 @noindent
 @end example
 
 @noindent


@@ -7382,7 +7431,7 @@ unit: assignments exp  @{ driver.result = $2; @};
 assignments: assignments assignment @{@}
            | /* Nothing. */         @{@};
 
 assignments: assignments assignment @{@}
            | /* Nothing. */         @{@};
 

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

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


@@ -7390,8 +7439,8 @@ exp: exp '+' exp   @{ $$ = $1 + $3; @}
    | exp '-' exp   @{ $$ = $1 - $3; @}
    | exp '*' exp   @{ $$ = $1 * $3; @}
    | exp '/' exp   @{ $$ = $1 / $3; @}
    | exp '-' exp   @{ $$ = $1 - $3; @}
    | exp '*' exp   @{ $$ = $1 * $3; @}
    | exp '/' exp   @{ $$ = $1 / $3; @}

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

 %%
 @end example
 
 %%
 @end example
 


@@ -7418,6 +7467,9 @@ parser's to get the set of defined tokens.
 @comment file: calc++-scanner.ll
 @example
 %@{                                            /* -*- C++ -*- */
 @comment file: calc++-scanner.ll
 @example
 %@{                                            /* -*- C++ -*- */

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

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


@@ -7468,15 +7520,28 @@ preceding tokens.  Comments would be treated equally.
 @end example
 
 @noindent
 @end example
 
 @noindent

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

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

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

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

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

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


@@ -7513,7 +7578,7 @@ The top level file, @file{calc++.cc}, poses no problem.
 #include "calc++-driver.hh"
 
 int
 #include "calc++-driver.hh"
 
 int

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

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


@@ -7821,7 +7886,7 @@ Bison declaration to create a header file meant for the scanner.
 @end deffn
 
 @deffn {Directive} %destructor
 @end deffn
 
 @deffn {Directive} %destructor

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

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


@@ -7906,7 +7971,7 @@ Bison declaration to assign non-associativity to token(s).
 @xref{Precedence Decl, ,Operator Precedence}.
 @end deffn
 
 @xref{Precedence Decl, ,Operator Precedence}.
 @end deffn
 

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

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


@@ -7927,6 +7992,12 @@ Bison declaration to request a pure (reentrant) parser.
 @xref{Pure Decl, ,A Pure (Reentrant) Parser}.
 @end deffn
 
 @xref{Pure Decl, ,A Pure (Reentrant) Parser}.
 @end deffn
 

+@deffn {Directive} %require "@var{version}"
+Specify that version @var{version} or higher of Bison required for the
+grammar.
+@xref{Require Decl, , Require a Version of Bison}.
+@end deffn
+

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


@@ -8075,7 +8146,7 @@ Management}.
 @end deffn
 
 @deffn {Variable} yynerrs
 @end deffn
 
 @deffn {Variable} yynerrs

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

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


@@ -8105,10 +8176,7 @@ the parser will use @code{malloc} to extend its stacks.  If defined to
 reserved for future Bison extensions.  If not defined,
 @code{YYSTACK_USE_ALLOCA} defaults to 0.
 
 reserved for future Bison extensions.  If not defined,
 @code{YYSTACK_USE_ALLOCA} defaults to 0.
 

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

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