X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/d59e456dbf5d9747e2fe0c0539f2ec670ce6f9c4..a6ca4ce2292277b4af21b5069bded9c73341d23a:/doc/bison.texinfo

diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index 18d40861..8f40afbe 100644
--- a/doc/bison.texinfo
+++ b/doc/bison.texinfo
@@ -4588,7 +4588,7 @@ The following Bison declaration says that you want the parser to be a push
 parser (@pxref{Decl Summary,,%define api.push-pull}):
 
 @example
-%define api.push-pull "push"
+%define api.push-pull push
 @end example
 
 In almost all cases, you want to ensure that your push parser is also
@@ -4599,7 +4599,7 @@ what you are doing, your declarations should look like this:
 
 @example
 %define api.pure
-%define api.push-pull "push"
+%define api.push-pull push
 @end example
 
 There is a major notable functional difference between the pure push parser
@@ -4648,14 +4648,14 @@ for use by the next invocation of the @code{yypush_parse} function.
 
 Bison also supports both the push parser interface along with the pull parser
 interface in the same generated parser.  In order to get this functionality,
-you should replace the @samp{%define api.push-pull "push"} declaration with the
-@samp{%define api.push-pull "both"} declaration.  Doing this will create all of
+you should replace the @samp{%define api.push-pull push} declaration with the
+@samp{%define api.push-pull both} declaration.  Doing this will create all of
 the symbols mentioned earlier along with the two extra symbols, @code{yyparse}
 and @code{yypull_parse}.  @code{yyparse} can be used exactly as it normally
 would be used.  However, the user should note that it is implemented in the
 generated parser by calling @code{yypull_parse}.
 This makes the @code{yyparse} function that is generated with the
-@samp{%define api.push-pull "both"} declaration slower than the normal
+@samp{%define api.push-pull both} declaration slower than the normal
 @code{yyparse} function.  If the user
 calls the @code{yypull_parse} function it will parse the rest of the input
 stream.  It is possible to @code{yypush_parse} tokens to select a subgrammar
@@ -4672,8 +4672,8 @@ yypstate_delete (ps);
 @end example
 
 Adding the @samp{%define api.pure} declaration does exactly the same thing to
-the generated parser with @samp{%define api.push-pull "both"} as it did for
-@samp{%define api.push-pull "push"}.
+the generated parser with @samp{%define api.push-pull both} as it did for
+@samp{%define api.push-pull push}.
 
 @node Decl Summary
 @subsection Bison Declaration Summary
@@ -4763,7 +4763,9 @@ use this form instead.
 
 @var{qualifier} identifies the purpose of @var{code} and thus the location(s)
 where Bison should generate it.
-Not all values of @var{qualifier} are available for all target languages:
+Not all @var{qualifier}s are accepted for all target languages.
+Unaccepted @var{qualifier}s produce an error.
+Some of the accepted @var{qualifier}s are:
 
 @itemize @bullet
 @item requires
@@ -4842,39 +4844,45 @@ parse.trace}.
 @end deffn
 
 @deffn {Directive} %define @var{variable}
+@deffnx {Directive} %define @var{variable} @var{value}
 @deffnx {Directive} %define @var{variable} "@var{value}"
 Define a variable to adjust Bison's behavior.
-The possible choices for @var{variable}, as well as their meanings, depend on
-the selected target language and/or the parser skeleton (@pxref{Decl
-Summary,,%language}, @pxref{Decl Summary,,%skeleton}).
 
 It is an error if a @var{variable} is defined by @code{%define} multiple
-times, but @ref{Bison Options,,-D @var{name}[=@var{value}]}.
+times, but see @ref{Bison Options,,-D @var{name}[=@var{value}]}.
 
-Omitting @code{"@var{value}"} is always equivalent to specifying it as
+@var{value} must be placed in quotation marks if it contains any
+character other than a letter, underscore, period, dash, or non-initial
+digit.
+
+Omitting @code{"@var{value}"} entirely is always equivalent to specifying
 @code{""}.
 
-Some @var{variable}s may be used as Booleans.
+Some @var{variable}s take Boolean values.
 In this case, Bison will complain if the variable definition does not meet one
 of the following four conditions:
 
 @enumerate
-@item @code{"@var{value}"} is @code{"true"}
+@item @code{@var{value}} is @code{true}
 
-@item @code{"@var{value}"} is omitted (or is @code{""}).
-This is equivalent to @code{"true"}.
+@item @code{@var{value}} is omitted (or @code{""} is specified).
+This is equivalent to @code{true}.
 
-@item @code{"@var{value}"} is @code{"false"}.
+@item @code{@var{value}} is @code{false}.
 
 @item @var{variable} is never defined.
-In this case, Bison selects a default value, which may depend on the selected
-target language and/or parser skeleton.
+In this case, Bison selects a default value.
 @end enumerate
 
+What @var{variable}s are accepted, as well as their meanings and default
+values, depend on the selected target language and/or the parser
+skeleton (@pxref{Decl Summary,,%language}, @pxref{Decl
+Summary,,%skeleton}).
+Unaccepted @var{variable}s produce an error.
 Some of the accepted @var{variable}s are:
 
 @table @code
-@c ================================================== namespace
+@c ================================================== api.namespace
 @item api.namespace
 @findex %define api.namespace
 @itemize
@@ -4940,7 +4948,7 @@ The parser namespace is @code{foo} and @code{yylex} is referenced as
 
 @item Accepted Values: Boolean
 
-@item Default Value: @code{"false"}
+@item Default Value: @code{false}
 @end itemize
 @c api.pure
 
@@ -4958,12 +4966,15 @@ The parser namespace is @code{foo} and @code{yylex} is referenced as
 (The current push parsing interface is experimental and may evolve.
 More user feedback will help to stabilize it.)
 
-@item Accepted Values: @code{"pull"}, @code{"push"}, @code{"both"}
+@item Accepted Values: @code{pull}, @code{push}, @code{both}
 
-@item Default Value: @code{"pull"}
+@item Default Value: @code{pull}
 @end itemize
 @c api.push-pull
 
+
+
+@c ================================================== api.tokens.prefix
 @item api.tokens.prefix
 @findex %define api.tokens.prefix
 
@@ -5001,6 +5012,30 @@ empty
 @c api.tokens.prefix
 
 
+@c ================================================== lex_symbol
+@item variant
+@findex %define lex_symbol
+
+@itemize @bullet
+@item Language(s):
+C++
+
+@item Purpose:
+When variant-based semantic values are enabled (@pxref{C++ Variants}),
+request that symbols be handled as a whole (type, value, and possibly
+location) in the scanner.  @xref{Complete Symbols}, for details.
+
+@item Accepted Values:
+Boolean.
+
+@item Default Value:
+@code{false}
+@end itemize
+@c lex_symbol
+
+
+@c ================================================== lr.default-reductions
+
 @item lr.default-reductions
 @cindex default reductions
 @findex %define lr.default-reductions
@@ -5025,7 +5060,7 @@ More user feedback will help to stabilize it.)
 
 @item Accepted Values:
 @itemize
-@item @code{"all"}.
+@item @code{all}.
 For @acronym{LALR} and @acronym{IELR} parsers (@pxref{Decl
 Summary,,lr.type}) by default, all states are permitted to contain
 default reductions.
@@ -5037,7 +5072,7 @@ That is, unlike in a canonical @acronym{LR} state, the lookahead sets of
 reductions in an @acronym{LALR} or @acronym{IELR} state can contain
 tokens that are syntactically incorrect for some left contexts.
 
-@item @code{"consistent"}.
+@item @code{consistent}.
 @cindex consistent states
 A consistent state is a state that has only one possible action.
 If that action is a reduction, then the parser does not need to request
@@ -5049,7 +5084,7 @@ states, then a canonical @acronym{LR} parser reports a syntax error as
 soon as it @emph{needs} the syntactically unacceptable token from the
 scanner.
 
-@item @code{"accepting"}.
+@item @code{accepting}.
 @cindex accepting state
 By default, the only default reduction permitted in a canonical
 @acronym{LR} parser is the accept action in the accepting state, which
@@ -5061,11 +5096,13 @@ without performing any extra reductions.
 
 @item Default Value:
 @itemize
-@item @code{"accepting"} if @code{lr.type} is @code{"canonical LR"}.
-@item @code{"all"} otherwise.
+@item @code{accepting} if @code{lr.type} is @code{canonical-lr}.
+@item @code{all} otherwise.
 @end itemize
 @end itemize
 
+@c ============================================ lr.keep-unreachable-states
+
 @item lr.keep-unreachable-states
 @findex %define lr.keep-unreachable-states
 
@@ -5083,7 +5120,7 @@ are useless in the generated parser.
 
 @item Accepted Values: Boolean
 
-@item Default Value: @code{"false"}
+@item Default Value: @code{false}
 
 @item Caveats:
 
@@ -5110,6 +5147,8 @@ However, Bison does not compute which goto actions are useless.
 @end itemize
 @c lr.keep-unreachable-states
 
+@c ================================================== lr.type
+
 @item lr.type
 @findex %define lr.type
 @cindex @acronym{LALR}
@@ -5126,7 +5165,7 @@ More user feedback will help to stabilize it.)
 
 @item Accepted Values:
 @itemize
-@item @code{"LALR"}.
+@item @code{lalr}.
 While Bison generates @acronym{LALR} parser tables by default for
 historical reasons, @acronym{IELR} or canonical @acronym{LR} is almost
 always preferable for deterministic parsers.
@@ -5155,7 +5194,7 @@ investigate such problems while ignoring the more subtle differences
 from @acronym{IELR} and canonical @acronym{LR}.
 @end itemize
 
-@item @code{"IELR"}.
+@item @code{ielr}.
 @acronym{IELR} is a minimal @acronym{LR} algorithm.
 That is, given any grammar (@acronym{LR} or non-@acronym{LR}),
 @acronym{IELR} and canonical @acronym{LR} always accept exactly the same
@@ -5169,7 +5208,7 @@ grammars, the number of conflicts for @acronym{IELR} is often an order
 of magnitude less as well.
 This can significantly reduce the complexity of developing of a grammar.
 
-@item @code{"canonical LR"}.
+@item @code{canonical-lr}.
 @cindex delayed syntax errors
 @cindex syntax errors delayed
 The only advantage of canonical @acronym{LR} over @acronym{IELR} is
@@ -5185,7 +5224,7 @@ Even when canonical @acronym{LR} behavior is ultimately desired,
 facilitate the development of a grammar.
 @end itemize
 
-@item Default Value: @code{"LALR"}
+@item Default Value: @code{lalr}
 @end itemize
 
 
@@ -5204,7 +5243,8 @@ Obsoleted by @code{api.namespace}
 @item Languages(s): C++
 
 @item Purpose: Issue runtime assertions to catch invalid uses.
-In C++, when variants are used, symbols must be constructed and
+In C++, when variants are used (@pxref{C++ Variants}), symbols must be
+constructed and
 destroyed properly.  This option checks these constraints.
 
 @item Accepted Values: Boolean
@@ -5226,10 +5266,10 @@ function.  @xref{Error Reporting, ,The Error Reporting Function
 @code{yyerror}}.
 @item Accepted Values:
 @itemize
-@item @code{"simple"}
+@item @code{simple}
 Error messages passed to @code{yyerror} are simply @w{@code{"syntax
 error"}}.
-@item @code{"verbose"}
+@item @code{verbose}
 Error messages report the unexpected token, and possibly the expected
 ones.
 @end itemize
@@ -5258,6 +5298,27 @@ is not already defined, so that the debugging facilities are compiled.
 @end itemize
 @c parse.trace
 
+@c ================================================== variant
+@item variant
+@findex %define variant
+
+@itemize @bullet
+@item Language(s):
+C++
+
+@item Purpose:
+Requests variant-based semantic values.
+@xref{C++ Variants}.
+
+@item Accepted Values:
+Boolean.
+
+@item Default Value:
+@code{false}
+@end itemize
+@c variant
+
+
 @end table
 @end deffn
 @c ----------------------------------------------------------   %define
@@ -5542,10 +5603,10 @@ If you use a reentrant parser, you can optionally pass additional
 parameter information to it in a reentrant way.  To do so, use the
 declaration @code{%parse-param}:
 
-@deffn {Directive} %parse-param @{@var{argument-declaration}@}
+@deffn {Directive} %parse-param @{@var{argument-declaration}@} @dots{}
 @findex %parse-param
-Declare that an argument declared by the braced-code
-@var{argument-declaration} is an additional @code{yyparse} argument.
+Declare that one or more
+@var{argument-declaration} are additional @code{yyparse} arguments.
 The @var{argument-declaration} is used when declaring
 functions or prototypes.  The last identifier in
 @var{argument-declaration} must be the argument name.
@@ -5554,8 +5615,7 @@ functions or prototypes.  The last identifier in
 Here's an example.  Write this in the parser:
 
 @example
-%parse-param @{int *nastiness@}
-%parse-param @{int *randomness@}
+%parse-param @{int *nastiness@} @{int *randomness@}
 @end example
 
 @noindent
@@ -5585,8 +5645,8 @@ exp: @dots{}    @{ @dots{}; *randomness += 1; @dots{} @}
 More user feedback will help to stabilize it.)
 
 You call the function @code{yypush_parse} to parse a single token.  This
-function is available if either the @samp{%define api.push-pull "push"} or
-@samp{%define api.push-pull "both"} declaration is used.
+function is available if either the @samp{%define api.push-pull push} or
+@samp{%define api.push-pull both} declaration is used.
 @xref{Push Decl, ,A Push Parser}.
 
 @deftypefun int yypush_parse (yypstate *yyps)
@@ -5603,7 +5663,7 @@ is required to finish parsing the grammar.
 More user feedback will help to stabilize it.)
 
 You call the function @code{yypull_parse} to parse the rest of the input
-stream.  This function is available if the @samp{%define api.push-pull "both"}
+stream.  This function is available if the @samp{%define api.push-pull both}
 declaration is used.
 @xref{Push Decl, ,A Push Parser}.
 
@@ -5619,12 +5679,12 @@ The value returned by @code{yypull_parse} is the same as for @code{yyparse}.
 More user feedback will help to stabilize it.)
 
 You call the function @code{yypstate_new} to create a new parser instance.
-This function is available if either the @samp{%define api.push-pull "push"} or
-@samp{%define api.push-pull "both"} declaration is used.
+This function is available if either the @samp{%define api.push-pull push} or
+@samp{%define api.push-pull both} declaration is used.
 @xref{Push Decl, ,A Push Parser}.
 
 @deftypefun yypstate *yypstate_new (void)
-The fuction will return a valid parser instance if there was memory available
+The function will return a valid parser instance if there was memory available
 or 0 if no memory was available.
 In impure mode, it will also return 0 if a parser instance is currently
 allocated.
@@ -5638,8 +5698,8 @@ allocated.
 More user feedback will help to stabilize it.)
 
 You call the function @code{yypstate_delete} to delete a parser instance.
-function is available if either the @samp{%define api.push-pull "push"} or
-@samp{%define api.push-pull "both"} declaration is used.
+function is available if either the @samp{%define api.push-pull push} or
+@samp{%define api.push-pull both} declaration is used.
 @xref{Push Decl, ,A Push Parser}.
 
 @deftypefun void yypstate_delete (yypstate *yyps)
@@ -5851,46 +5911,57 @@ textual locations, then the type @code{YYLTYPE} will not be defined.  In
 this case, omit the second argument; @code{yylex} will be called with
 only one argument.
 
-
-If you wish to pass the additional parameter data to @code{yylex}, use
+If you wish to pass additional arguments to @code{yylex}, use
 @code{%lex-param} just like @code{%parse-param} (@pxref{Parser
-Function}).
+Function}).  To pass additional arguments to both @code{yylex} and
+@code{yyparse}, use @code{%param}.
 
-@deffn {Directive} lex-param @{@var{argument-declaration}@}
+@deffn {Directive} %lex-param @{@var{argument-declaration}@} @dots{}
 @findex %lex-param
-Declare that the braced-code @var{argument-declaration} is an
-additional @code{yylex} argument declaration.
+Specify that @var{argument-declaration} are additional @code{yylex} argument
+declarations.  You may pass one or more such declarations, which is
+equivalent to repeating @code{%lex-param}.
+@end deffn
+
+@deffn {Directive} %param @{@var{argument-declaration}@} @dots{}
+@findex %param
+Specify that @var{argument-declaration} are additional
+@code{yylex}/@code{yyparse} argument declaration.  This is equivalent to
+@samp{%lex-param @{@var{argument-declaration}@} @dots{} %parse-param
+@{@var{argument-declaration}@} @dots{}}.  You may pass one or more
+declarations, which is equivalent to repeating @code{%param}.
 @end deffn
 
 For instance:
 
 @example
-%parse-param @{int *nastiness@}
-%lex-param   @{int *nastiness@}
-%parse-param @{int *randomness@}
+%lex-param   @{scanner_mode *mode@}
+%parse-param @{parser_mode *mode@}
+%param       @{environment_type *env@}
 @end example
 
 @noindent
 results in the following signature:
 
 @example
-int yylex   (int *nastiness);
-int yyparse (int *nastiness, int *randomness);
+int yylex   (scanner_mode *mode, environment_type *env);
+int yyparse (parser_mode *mode, environment_type *env);
 @end example
 
 If @samp{%define api.pure} is added:
 
 @example
-int yylex   (YYSTYPE *lvalp, int *nastiness);
-int yyparse (int *nastiness, int *randomness);
+int yylex   (YYSTYPE *lvalp, scanner_mode *mode, environment_type *env);
+int yyparse (parser_mode *mode, environment_type *env);
 @end example
 
 @noindent
 and finally, if both @samp{%define api.pure} and @code{%locations} are used:
 
 @example
-int yylex   (YYSTYPE *lvalp, YYLTYPE *llocp, int *nastiness);
-int yyparse (int *nastiness, int *randomness);
+int yylex   (YYSTYPE *lvalp, YYLTYPE *llocp,
+             scanner_mode *mode, environment_type *env);
+int yyparse (parser_mode *mode, environment_type *env);
 @end example
 
 @node Error Reporting
@@ -5913,7 +5984,7 @@ receives one argument.  For a syntax error, the string is normally
 @w{@code{"syntax error"}}.
 
 @findex %define parse.error
-If you invoke @samp{%define parse.error "verbose"} in the Bison
+If you invoke @samp{%define parse.error 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{"syntax error"}}.
@@ -6584,7 +6655,7 @@ conflict, precedence suffices.  In such a case, using @code{%left},
 related) conflicts that would remain hidden.
 
 The dangling @code{else} ambiguity (@pxref{Shift/Reduce, , Shift/Reduce
-Conflicts}) can be solved explictly.  This shift/reduce conflicts occurs
+Conflicts}) can be solved explicitly.  This shift/reduce conflicts occurs
 in the following situation, where the period denotes the current parsing
 state:
 
@@ -6607,7 +6678,7 @@ in an associativity related conflict, which can be specified as follows.
 
 The unary-minus is another typical example where associativity is
 usually over-specified, see @ref{Infix Calc, , Infix Notation
-Calculator: @code{calc}}.  The @code{%left} directive is traditionaly
+Calculator: @code{calc}}.  The @code{%left} directive is traditionally
 used to declare the precedence of @code{NEG}, which is more than needed
 since it also defines its associativity.  While this is harmless in the
 traditional example, who knows how @code{NEG} might be used in future
@@ -7140,7 +7211,7 @@ that allows variable-length arrays.  The default is 200.
 Do not allow @code{YYINITDEPTH} to be greater than @code{YYMAXDEPTH}.
 
 @c FIXME: C++ output.
-Because of semantical differences between C and C++, the deterministic
+Because of semantic differences between C and C++, the deterministic
 parsers in C produced by Bison cannot grow when compiled
 by C++ compilers.  In this precise case (compiling a C parser as C++) you are
 suggested to grow @code{YYINITDEPTH}.  The Bison maintainers hope to fix
@@ -8169,7 +8240,7 @@ already defined, so that the debugging facilities are compiled.
 
 @item -D @var{name}[=@var{value}]
 @itemx --define=@var{name}[=@var{value}]
-@item -F @var{name}[=@var{value}]
+@itemx -F @var{name}[=@var{value}]
 @itemx --force-define=@var{name}[=@var{value}]
 Each of these is equivalent to @samp{%define @var{name} "@var{value}"}
 (@pxref{Decl Summary, ,%define}) except that Bison processes multiple
@@ -8398,7 +8469,7 @@ The various classes are generated in the following files:
 @item position.hh
 @itemx location.hh
 The definition of the classes @code{position} and @code{location},
-used for location tracking.  @xref{C++ Location Values}.
+used for location tracking when enabled.  @xref{C++ Location Values}.
 
 @item stack.hh
 An auxiliary class @code{stack} used by the parser.
@@ -8424,11 +8495,22 @@ for a complete and accurate documentation.
 @c - YYSTYPE
 @c - Printer and destructor
 
+Bison supports two different means to handle semantic values in C++.  One is
+alike the C interface, and relies on unions (@pxref{C++ Unions}).  As C++
+practitioners know, unions are inconvenient in C++, therefore another
+approach is provided, based on variants (@pxref{C++ Variants}).
+
+@menu
+* C++ Unions::             Semantic values cannot be objects
+* C++ Variants::           Using objects as semantic values
+@end menu
+
+@node C++ Unions
+@subsubsection C++ Unions
+
 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 (similar to Boost variants) might be implemented to
-alleviate these issues.}, which have a few specific features in C++.
+@code{union}, which have a few specific features in C++.
 @itemize @minus
 @item
 The type @code{YYSTYPE} is defined but its use is discouraged: rather
@@ -8445,6 +8527,98 @@ reclaimed automatically: using the @code{%destructor} directive is the
 only means to avoid leaks.  @xref{Destructor Decl, , Freeing Discarded
 Symbols}.
 
+@node C++ Variants
+@subsubsection C++ Variants
+
+Starting with version 2.6, Bison provides a @emph{variant} based
+implementation of semantic values for C++.  This alleviates all the
+limitations reported in the previous section, and in particular, object
+types can be used without pointers.
+
+To enable variant-based semantic values, set @code{%define} variable
+@code{variant} (@pxref{Decl Summary, , variant}).  Once this defined,
+@code{%union} is ignored, and instead of using the name of the fields of the
+@code{%union} to ``type'' the symbols, use genuine types.
+
+For instance, instead of
+
+@example
+%union
+@{
+  int ival;
+  std::string* sval;
+@}
+%token <ival> NUMBER;
+%token <sval> STRING;
+@end example
+
+@noindent
+write
+
+@example
+%token <int> NUMBER;
+%token <std::string> STRING;
+@end example
+
+@code{STRING} is no longer a pointer, which should fairly simplify the user
+actions in the grammar and in the scanner (in particular the memory
+management).
+
+Since C++ features destructors, and since it is customary to specialize
+@code{operator<<} to support uniform printing of values, variants also
+typically simplify Bison printers and destructors.
+
+Variants are stricter than unions.  When based on unions, you may play any
+dirty game with @code{yylval}, say storing an @code{int}, reading a
+@code{char*}, and then storing a @code{double} in it.  This is no longer
+possible with variants: they must be initialized, then assigned to, and
+eventually, destroyed.
+
+@deftypemethod {semantic_type} {T&} build<T> ()
+Initialize, but leave empty.  Returns the address where the actual value may
+be stored.  Requires that the variant was not initialized yet.
+@end deftypemethod
+
+@deftypemethod {semantic_type} {T&} build<T> (const T& @var{t})
+Initialize, and copy-construct from @var{t}.
+@end deftypemethod
+
+
+@strong{Warning}: We do not use Boost.Variant, for two reasons.  First, it
+appeared unacceptable to require Boost on the user's machine (i.e., the
+machine on which the generated parser will be compiled, not the machine on
+which @command{bison} was run).  Second, for each possible semantic value,
+Boost.Variant not only stores the value, but also a tag specifying its
+type.  But the parser already ``knows'' the type of the semantic value, so
+that would be duplicating the information.
+
+Therefore we developed light-weight variants whose type tag is external (so
+they are really like @code{unions} for C++ actually).  But our code is much
+less mature that Boost.Variant.  So there is a number of limitations in
+(the current implementation of) variants:
+@itemize
+@item
+Alignment must be enforced: values should be aligned in memory according to
+the most demanding type.  Computing the smallest alignment possible requires
+meta-programming techniques that are not currently implemented in Bison, and
+therefore, since, as far as we know, @code{double} is the most demanding
+type on all platforms, alignments are enforced for @code{double} whatever
+types are actually used.  This may waste space in some cases.
+
+@item
+Our implementation is not conforming with strict aliasing rules.  Alias
+analysis is a technique used in optimizing compilers to detect when two
+pointers are disjoint (they cannot ``meet'').  Our implementation breaks
+some of the rules that G++ 4.4 uses in its alias analysis, so @emph{strict
+alias analysis must be disabled}.  Use the option
+@option{-fno-strict-aliasing} to compile the generated parser.
+
+@item
+There might be portability issues we are not aware of.
+@end itemize
+
+As far as we know, these limitations @emph{can} be alleviated.  All it takes
+is some time and/or some talented C++ hacker willing to contribute to Bison.
 
 @node C++ Location Values
 @subsection C++ Location Values
@@ -8533,9 +8707,19 @@ this class is detailed below.  It can be extended using the
 it describes an additional member of the parser class, and an
 additional argument for its constructor.
 
-@defcv {Type} {parser} {semantic_value_type}
-@defcvx {Type} {parser} {location_value_type}
-The types for semantics value and locations.
+@defcv {Type} {parser} {semantic_type}
+@defcvx {Type} {parser} {location_type}
+The types for semantic values and locations (if enabled).
+@end defcv
+
+@defcv {Type} {parser} {syntax_error}
+This class derives from @code{std::runtime_error}.  Throw instances of it
+from user actions to raise parse errors.  This is equivalent with first
+invoking @code{error} to report the location and message of the syntax
+error, and then to invoke @code{YYERROR} to enter the error-recovery mode.
+But contrary to @code{YYERROR} which can only be invoked from user actions
+(i.e., written in the action itself), the exception can be thrown from
+function invoked from the user action.
 @end defcv
 
 @deftypemethod {parser} {} parser (@var{type1} @var{arg1}, ...)
@@ -8543,6 +8727,11 @@ Build a new parser object.  There are no arguments by default, unless
 @samp{%parse-param @{@var{type1} @var{arg1}@}} was used.
 @end deftypemethod
 
+@deftypemethod {syntax_error} {} syntax_error (const location_type& @var{l}, const std::string& @var{m})
+@deftypemethodx {syntax_error} {} syntax_error (const std::string& @var{m})
+Instantiate a syntax-error exception.
+@end deftypemethod
+
 @deftypemethod {parser} {int} parse ()
 Run the syntactic analysis, and return 0 on success, 1 otherwise.
 @end deftypemethod
@@ -8560,9 +8749,11 @@ or nonzero, full tracing.
 @end deftypemethod
 
 @deftypemethod {parser} {void} error (const location_type& @var{l}, const std::string& @var{m})
+@deftypemethodx {parser} {void} error (const std::string& @var{m})
 The definition for this member function must be supplied by the user:
 the parser uses it to report a parser error occurring at @var{l},
-described by @var{m}.
+described by @var{m}.  If location tracking is not enabled, the second
+signature is used.
 @end deftypemethod
 
 
@@ -8574,25 +8765,143 @@ described by @var{m}.
 
 The parser invokes the scanner by calling @code{yylex}.  Contrary to C
 parsers, C++ parsers are always pure: there is no point in using the
-@samp{%define api.pure} directive.  Therefore the interface is as follows.
+@samp{%define api.pure} directive.  The actual interface with @code{yylex}
+depends whether you use unions, or variants.
 
-@deftypemethod {parser} {int} yylex (semantic_value_type& @var{yylval}, location_type& @var{yylloc}, @var{type1} @var{arg1}, ...)
-Return the next token.  Its type is the return value, its semantic
-value and location being @var{yylval} and @var{yylloc}.  Invocations of
+@menu
+* Split Symbols::         Passing symbols as two/three components
+* Complete Symbols::      Making symbols a whole
+@end menu
+
+@node Split Symbols
+@subsubsection Split Symbols
+
+Therefore the interface is as follows.
+
+@deftypemethod {parser} {int} yylex (semantic_type& @var{yylval}, location_type& @var{yylloc}, @var{type1} @var{arg1}, ...)
+@deftypemethodx {parser} {int} yylex (semantic_type& @var{yylval}, @var{type1} @var{arg1}, ...)
+Return the next token.  Its type is the return value, its semantic value and
+location (if enabled) being @var{yylval} and @var{yylloc}.  Invocations of
 @samp{%lex-param @{@var{type1} @var{arg1}@}} yield additional arguments.
 @end deftypemethod
 
+Note that when using variants, the interface for @code{yylex} is the same,
+but @code{yylval} is handled differently.
+
+Regular union-based code in Lex scanner typically look like:
+
+@example
+[0-9]+   @{
+           yylval.ival = text_to_int (yytext);
+           return yy::parser::INTEGER;
+         @}
+[a-z]+   @{
+           yylval.sval = new std::string (yytext);
+           return yy::parser::IDENTIFIER;
+         @}
+@end example
+
+Using variants, @code{yylval} is already constructed, but it is not
+initialized.  So the code would look like:
+
+@example
+[0-9]+   @{
+           yylval.build<int>() = text_to_int (yytext);
+           return yy::parser::INTEGER;
+         @}
+[a-z]+   @{
+           yylval.build<std::string> = yytext;
+           return yy::parser::IDENTIFIER;
+         @}
+@end example
+
+@noindent
+or
+
+@example
+[0-9]+   @{
+           yylval.build(text_to_int (yytext));
+           return yy::parser::INTEGER;
+         @}
+[a-z]+   @{
+           yylval.build(yytext);
+           return yy::parser::IDENTIFIER;
+         @}
+@end example
+
+
+@node Complete Symbols
+@subsubsection Complete Symbols
+
+If you specified both @code{%define variant} and @code{%define lex_symbol},
+the @code{parser} class also defines the class @code{parser::symbol_type}
+which defines a @emph{complete} symbol, aggregating its type (i.e., the
+traditional value returned by @code{yylex}), its semantic value (i.e., the
+value passed in @code{yylval}, and possibly its location (@code{yylloc}).
+
+@deftypemethod {symbol_type} {} symbol_type (token_type @var{type},  const semantic_type& @var{value}, const location_type& @var{location})
+Build a complete terminal symbol which token type is @var{type}, and which
+semantic value is @var{value}.  If location tracking is enabled, also pass
+the @var{location}.
+@end deftypemethod
+
+This interface is low-level and should not be used for two reasons.  First,
+it is inconvenient, as you still have to build the semantic value, which is
+a variant, and second, because consistency is not enforced: as with unions,
+it is still possible to give an integer as semantic value for a string.
+
+So for each token type, Bison generates named constructors as follows.
+
+@deftypemethod {symbol_type} {} make_@var{token} (const @var{value_type}& @var{value}, const location_type& @var{location})
+@deftypemethodx {symbol_type} {} make_@var{token} (const location_type& @var{location})
+Build a complete terminal symbol for the token type @var{token} (not
+including the @code{api.tokens.prefix}) whose possible semantic value is
+@var{value} of adequate @var{value_type}.  If location tracking is enabled,
+also pass the @var{location}.
+@end deftypemethod
+
+For instance, given the following declarations:
+
+@example
+%define api.tokens.prefix "TOK_"
+%token <std::string> IDENTIFIER;
+%token <int> INTEGER;
+%token COLON;
+@end example
+
+@noindent
+Bison generates the following functions:
+
+@example
+symbol_type make_IDENTIFIER(const std::string& v,
+                            const location_type& l);
+symbol_type make_INTEGER(const int& v,
+                         const location_type& loc);
+symbol_type make_COLON(const location_type& loc);
+@end example
+
+@noindent
+which should be used in a Lex-scanner as follows.
+
+@example
+[0-9]+   return yy::parser::make_INTEGER(text_to_int (yytext), loc);
+[a-z]+   return yy::parser::make_IDENTIFIER(yytext, loc);
+":"      return yy::parser::make_COLON(loc);
+@end example
+
+Tokens that do not have an identifier are not accessible: you cannot simply
+use characters such as @code{':'}, they must be declared with @code{%token}.
 
 @node A Complete C++ Example
 @subsection A Complete C++ Example
 
 This section demonstrates the use of a C++ parser with a simple but
 complete example.  This example should be available on your system,
-ready to compile, in the directory @dfn{../bison/examples/calc++}.  It
+ready to compile, in the directory @dfn{.../bison/examples/calc++}.  It
 focuses on the use of Bison, therefore the design of the various C++
 classes is very naive: no accessors, no encapsulation of members etc.
 We will use a Lex scanner, and more precisely, a Flex scanner, to
-demonstrate the various interaction.  A hand written scanner is
+demonstrate the various interactions.  A hand-written scanner is
 actually easier to interface with.
 
 @menu
@@ -8656,11 +8965,8 @@ factor both as follows.
 @comment file: calc++-driver.hh
 @example
 // Tell Flex the lexer's prototype ...
-# define YY_DECL                                        \
-  yy::calcxx_parser::token_type                         \
-  yylex (yy::calcxx_parser::semantic_type* yylval,      \
-         yy::calcxx_parser::location_type* yylloc,      \
-         calcxx_driver& driver)
+# define YY_DECL \
+  yy::calcxx_parser::symbol_type yylex (calcxx_driver& driver)
 // ... and declare it for the parser's sake.
 YY_DECL;
 @end example
@@ -8684,8 +8990,8 @@ public:
 @end example
 
 @noindent
-To encapsulate the coordination with the Flex scanner, it is useful to
-have two members function to open and close the scanning phase.
+To encapsulate the coordination with the Flex scanner, it is useful to have
+member functions to open and close the scanning phase.
 
 @comment file: calc++-driver.hh
 @example
@@ -8700,9 +9006,13 @@ Similarly for the parser itself.
 
 @comment file: calc++-driver.hh
 @example
-  // Run the parser.  Return 0 on success.
+  // Run the parser on file F.
+  // Return 0 on success.
   int parse (const std::string& f);
+  // The name of the file being parsed.
+  // Used later to pass the file name to the location tracker.
   std::string file;
+  // Whether parser traces should be generated.
   bool trace_parsing;
 @end example
 
@@ -8784,19 +9094,35 @@ the version you designed the grammar for.
 %define parser_class_name "calcxx_parser"
 @end example
 
+@noindent
+@findex %define variant
+@findex %define lex_symbol
+This example will use genuine C++ objects as semantic values, therefore, we
+require the variant-based interface.  To make sure we properly use it, we
+enable assertions.  To fully benefit from type-safety and more natural
+definition of ``symbol'', we enable @code{lex_symbol}.
+
+@comment file: calc++-parser.yy
+@example
+%define variant
+%define parse.assert
+%define lex_symbol
+@end example
+
 @noindent
 @findex %code requires
-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
+Then come the declarations/inclusions needed by the semantic values.
+Because the parser uses the parsing driver and reciprocally, both would like
+to include the header of the other, which is, of course, insane.  This
+mutual dependency will be broken using forward declarations.  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.
-@xref{Decl Summary, ,%code}.
+particular its inner types), it is the parser's header which will use a
+forward declaration of the driver.  @xref{Decl Summary, ,%code}.
 
 @comment file: calc++-parser.yy
 @example
-%code requires @{
+%code requires
+@{
 # include <string>
 class calcxx_driver;
 @}
@@ -8810,15 +9136,14 @@ global variables.
 @comment file: calc++-parser.yy
 @example
 // The parsing context.
-%parse-param @{ calcxx_driver& driver @}
-%lex-param   @{ calcxx_driver& driver @}
+%param @{ calcxx_driver& driver @}
 @end example
 
 @noindent
-Then we request the location tracking feature, and initialize the
-first location's file name.  Afterwards new locations are computed
+Then we request location tracking, and initialize the
+first location's file name.  Afterward new locations are computed
 relatively to the previous locations: the file name will be
-automatically propagated.
+propagated.
 
 @comment file: calc++-parser.yy
 @example
@@ -8831,27 +9156,13 @@ automatically propagated.
 @end example
 
 @noindent
-Use the two following directives to enable parser tracing and verbose
+Use the following two directives to enable parser tracing and verbose
 error messages.
 
 @comment file: calc++-parser.yy
 @example
 %define parse.trace
-%define parse.error "verbose"
-@end example
-
-@noindent
-Semantic values cannot use ``real'' objects, but only pointers to
-them.
-
-@comment file: calc++-parser.yy
-@example
-// Symbols.
-%union
-@{
-  int          ival;
-  std::string *sval;
-@};
+%define parse.error verbose
 @end example
 
 @noindent
@@ -8861,7 +9172,8 @@ The code between @samp{%code @{} and @samp{@}} is output in the
 
 @comment file: calc++-parser.yy
 @example
-%code @{
+%code
+@{
 # include "calc++-driver.hh"
 @}
 @end example
@@ -8877,28 +9189,45 @@ prefix tokens with @code{TOK_} (@pxref{Decl Summary,, api.tokens.prefix}).
 @comment file: calc++-parser.yy
 @example
 %define api.tokens.prefix "TOK_"
-%token        END      0 "end of file"
-%token        ASSIGN     ":="
-%token <sval> IDENTIFIER "identifier"
-%token <ival> NUMBER     "number"
-%type  <ival> exp
+%token
+  END  0  "end of file"
+  ASSIGN  ":="
+  MINUS   "-"
+  PLUS    "+"
+  STAR    "*"
+  SLASH   "/"
+  LPAREN  "("
+  RPAREN  ")"
+;
 @end example
 
 @noindent
-To enable memory deallocation during error recovery, use
-@code{%destructor}.
+Since we use variant-based semantic values, @code{%union} is not used, and
+both @code{%type} and @code{%token} expect genuine types, as opposed to type
+tags.
 
-@c FIXME: Document %printer, and mention that it takes a braced-code operand.
 @comment file: calc++-parser.yy
 @example
-%printer    @{ debug_stream () << *$$; @} "identifier"
-%destructor @{ delete $$; @} "identifier"
+%token <std::string> IDENTIFIER "identifier"
+%token <int> NUMBER "number"
+%type  <int> exp
+@end example
+
+@noindent
+No @code{%destructor} is needed to enable memory deallocation during error
+recovery; the memory, for strings for instance, will be reclaimed by the
+regular destructors.  All the values are printed using their
+@code{operator<<}.
 
-%printer    @{ debug_stream () << $$; @} <ival>
+@c FIXME: Document %printer, and mention that it takes a braced-code operand.
+@comment file: calc++-parser.yy
+@example
+%printer @{ debug_stream () << $$; @} <*>;
 @end example
 
 @noindent
-The grammar itself is straightforward.
+The grammar itself is straightforward (@pxref{Location Tracking Calc, ,
+Location Tracking Calculator: @code{ltcalc}}).
 
 @comment file: calc++-parser.yy
 @example
@@ -8911,19 +9240,18 @@ assignments:
 | /* Nothing.  */        @{@};
 
 assignment:
-  "identifier" ":=" exp
-       @{ driver.variables[*$1] = $3; delete $1; @};
+  "identifier" ":=" exp @{ driver.variables[$1] = $3; @};
 
-%left '+' '-';
-%left '*' '/';
+%left "+" "-";
+%left "*" "/";
 exp:
-  exp '+' exp   @{ $$ = $1 + $3; @}
-| exp '-' exp   @{ $$ = $1 - $3; @}
-| exp '*' exp   @{ $$ = $1 * $3; @}
-| exp '/' exp   @{ $$ = $1 / $3; @}
-| '(' exp ')'   @{ $$ = $2; @}
-| "identifier"  @{ $$ = driver.variables[*$1]; delete $1; @}
-| "number"      @{ $$ = $1; @};
+  exp "+" exp   @{ $$ = $1 + $3; @}
+| exp "-" exp   @{ $$ = $1 - $3; @}
+| exp "*" exp   @{ $$ = $1 * $3; @}
+| exp "/" exp   @{ $$ = $1 / $3; @}
+| "(" exp ")"   @{ std::swap($$, $2); @}
+| "identifier"  @{ $$ = driver.variables[$1]; @}
+| "number"      @{ std::swap($$, $1); @};
 %%
 @end example
 
@@ -8934,7 +9262,7 @@ driver.
 @comment file: calc++-parser.yy
 @example
 void
-yy::calcxx_parser::error (const yy::calcxx_parser::location_type& l,
+yy::calcxx_parser::error (const location_type& l,
                           const std::string& m)
 @{
   driver.error (l, m);
@@ -8950,24 +9278,22 @@ parser's to get the set of defined tokens.
 @comment file: calc++-scanner.ll
 @example
 %@{                                            /* -*- C++ -*- */
-# include <cstdlib>
 # include <cerrno>
 # include <climits>
+# include <cstdlib>
 # include <string>
 # include "calc++-driver.hh"
 # include "calc++-parser.hh"
 
-/* Work around an incompatibility in flex (at least versions
-   2.5.31 through 2.5.33): it generates code that does
-   not conform to C89.  See Debian bug 333231
-   <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=333231>.  */
+// Work around an incompatibility in flex (at least versions
+// 2.5.31 through 2.5.33): it generates code that does
+// not conform to C89.  See Debian bug 333231
+// <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=333231>.
 # undef yywrap
 # define yywrap() 1
 
-/* By default yylex returns an int; we use token_type.
-   The default yyterminate implementation returns 0, which is
-   not of token_type.  */
-#define yyterminate() return TOKEN(END)
+// The location of the current token.
+static yy::location loc;
 %@}
 @end example
 
@@ -8975,7 +9301,7 @@ parser's to get the set of defined tokens.
 Because there is no @code{#include}-like feature we don't need
 @code{yywrap}, we don't need @code{unput} either, and we parse an
 actual file, this is not an interactive session with the user.
-Finally we enable the scanner tracing features.
+Finally, we enable scanner tracing.
 
 @comment file: calc++-scanner.ll
 @example
@@ -8995,8 +9321,8 @@ blank [ \t]
 @noindent
 The following paragraph suffices to track locations accurately.  Each
 time @code{yylex} is invoked, the begin position is moved onto the end
-position.  Then when a pattern is matched, the end position is
-advanced of its width.  In case it matched ends of lines, the end
+position.  Then when a pattern is matched, its width is added to the end
+column.  When matching ends of lines, the end
 cursor is adjusted, and each time blanks are matched, the begin cursor
 is moved onto the end cursor to effectively ignore the blanks
 preceding tokens.  Comments would be treated equally.
@@ -9004,49 +9330,46 @@ preceding tokens.  Comments would be treated equally.
 @comment file: calc++-scanner.ll
 @example
 %@{
-# define YY_USER_ACTION  yylloc->columns (yyleng);
+  // Code run each time a pattern is matched.
+  # define YY_USER_ACTION  loc.columns (yyleng);
 %@}
 %%
 %@{
-  yylloc->step ();
+  // Code run each time yylex is called.
+  loc.step ();
 %@}
-@{blank@}+   yylloc->step ();
-[\n]+      yylloc->lines (yyleng); yylloc->step ();
+@{blank@}+   loc.step ();
+[\n]+      loc.lines (yyleng); loc.step ();
 @end example
 
 @noindent
-The rules are simple.  The driver is used to report errors.  It is
-convenient to use a macro to shorten
-@code{yy::calcxx_parser::token::TOK_@var{Name}} into
-@code{TOKEN(@var{Name})}; note the token prefix, @code{TOK_}.
+The rules are simple.  The driver is used to report errors.
 
 @comment file: calc++-scanner.ll
 @example
-%@{
-# define TOKEN(Name)                          \
-  yy::calcxx_parser::token::TOK_ ## Name
-%@}
-           /* Convert ints to the actual type of tokens.  */
-[-+*/()]   return yy::calcxx_parser::token_type (yytext[0]);
-":="       return TOKEN(ASSIGN);
+"-"      return yy::calcxx_parser::make_MINUS(loc);
+"+"      return yy::calcxx_parser::make_PLUS(loc);
+"*"      return yy::calcxx_parser::make_STAR(loc);
+"/"      return yy::calcxx_parser::make_SLASH(loc);
+"("      return yy::calcxx_parser::make_LPAREN(loc);
+")"      return yy::calcxx_parser::make_RPAREN(loc);
+":="     return yy::calcxx_parser::make_ASSIGN(loc);
+
 @{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);
+    driver.error (loc, "integer is out of range");
+  return yy::calcxx_parser::make_NUMBER(n, loc);
 @}
-@{id@}       @{
-  yylval->sval = new std::string (yytext);
-  return TOKEN(IDENTIFIER);
-@}
-.          driver.error (*yylloc, "invalid character");
+@{id@}       return yy::calcxx_parser::make_IDENTIFIER(yytext, loc);
+.          driver.error (loc, "invalid character");
+<<EOF>>    return yy::calcxx_parser::make_END(loc);
 %%
 @end example
 
 @noindent
-Finally, because the scanner related driver's member function depend
+Finally, because the scanner-related driver's member-functions depend
 on the scanner's data, it is simpler to implement them in this file.
 
 @comment file: calc++-scanner.ll
@@ -9059,7 +9382,7 @@ calcxx_driver::scan_begin ()
     yyin = stdin;
   else if (!(yyin = fopen (file.c_str (), "r")))
     @{
-      error (std::string ("cannot open ") + file);
+      error (std::string ("cannot open ") + file + ": " + strerror(errno));
       exit (1);
     @}
 @}
@@ -9163,7 +9486,7 @@ if needed.  Also, in the future the
 access the token names and codes.
 
 Getting a ``code too large'' error from the Java compiler means the code
-hit the 64KB bytecode per method limination of the Java class file.
+hit the 64KB bytecode per method limitation of the Java class file.
 Try reducing the amount of code in actions and static initializers;
 otherwise, report a bug so that the parser skeleton will be improved.
 
@@ -9226,7 +9549,7 @@ in a file; Bison itself defines a class representing a @dfn{location},
 a range composed of a pair of positions (possibly spanning several
 files).  The location class is an inner class of the parser; the name
 is @code{Location} by default, and may also be renamed using
-@samp{%define location_type "@var{class-name}}.
+@samp{%define location_type "@var{class-name}"}.
 
 The location class treats the position as a completely opaque value.
 By default, the class name is @code{Position}, but this can be changed
@@ -9296,21 +9619,22 @@ which initialize them automatically.
 
 @deftypeop {Constructor} {YYParser} {} YYParser (@var{lex_param}, @dots{}, @var{parse_param}, @dots{})
 Build a new parser object with embedded @code{%code lexer}.  There are
-no parameters, unless @code{%parse-param}s and/or @code{%lex-param}s are
-used.
+no parameters, unless @code{%param}s and/or @code{%parse-param}s and/or
+@code{%lex-param}s are used.
 
 Use @code{%code init} for code added to the start of the constructor
 body. This is especially useful to initialize superclasses. Use
-@samp{%define init_throws} to specify any uncatch exceptions.
+@samp{%define init_throws} to specify any uncaught exceptions.
 @end deftypeop
 
 @deftypeop {Constructor} {YYParser} {} YYParser (Lexer @var{lexer}, @var{parse_param}, @dots{})
 Build a new parser object using the specified scanner.  There are no
-additional parameters unless @code{%parse-param}s are used.
+additional parameters unless @code{%param}s and/or @code{%parse-param}s are
+used.
 
 If the scanner is defined by @code{%code lexer}, this constructor is
 declared @code{protected} and is called automatically with a scanner
-created with the correct @code{%lex-param}s.
+created with the correct @code{%param}s and/or @code{%lex-param}s.
 
 Use @code{%code init} for code added to the start of the constructor
 body. This is especially useful to initialize superclasses. Use
@@ -9325,7 +9649,7 @@ Run the syntactic analysis, and return @code{true} on success,
 @deftypemethod {YYParser} {boolean} getErrorVerbose ()
 @deftypemethodx {YYParser} {void} setErrorVerbose (boolean @var{verbose})
 Get or set the option to produce verbose error messages.  These are only
-available with @samp{%define parse.error "verbose"}, which also turns on
+available with @samp{%define parse.error verbose}, which also turns on
 verbose error messages.
 @end deftypemethod
 
@@ -9396,7 +9720,7 @@ changed using @samp{%define location_type "@var{class-name}".}
 
 @deftypemethod {Lexer} {int} yylex ()
 Return the next token.  Its type is the return value, its semantic
-value and location are saved and returned by the ther methods in the
+value and location are saved and returned by the their methods in the
 interface.
 
 Use @samp{%define lex_throws} to specify any uncaught exceptions.
@@ -9414,7 +9738,7 @@ The return type can be changed using @samp{%define position_type
 @end deftypemethod
 
 @deftypemethod {Lexer} {Object} getLVal ()
-Return the semantical value of the last token that yylex returned.
+Return the semantic value of the last token that yylex returned.
 
 The return type can be changed using @samp{%define stype
 "@var{class-name}".}
@@ -9531,7 +9855,7 @@ corresponds to these C macros.}.
 @item
 Java lacks unions, so @code{%union} has no effect.  Instead, semantic
 values have a common base type: @code{Object} or as specified by
-@samp{%define stype}.  Angle backets on @code{%token}, @code{type},
+@samp{%define stype}.  Angle brackets on @code{%token}, @code{type},
 @code{$@var{n}} and @code{$$} specify subtypes rather than fields of
 an union.  The type of @code{$$}, even with angle brackets, is the base
 type since Java casts are not allow on the left-hand side of assignments.
@@ -9540,7 +9864,7 @@ left-hand side of assignments. See @pxref{Java Semantic Values} and
 @pxref{Java Action Features}.
 
 @item
-The prolog declarations have a different meaning than in C/C++ code.
+The prologue declarations have a different meaning than in C/C++ code.
 @table @asis
 @item @code{%code imports}
 blocks are placed at the beginning of the Java source code.  They may
@@ -10212,6 +10536,7 @@ Precedence}.
 
 @deffn {Directive} %define @var{define-variable}
 @deffnx {Directive} %define @var{define-variable} @var{value}
+@deffnx {Directive} %define @var{define-variable} "@var{value}"
 Define a variable to adjust Bison's behavior.
 @xref{Decl Summary,,%define}.
 @end deffn
@@ -10254,7 +10579,7 @@ token is reset to the token that originally caused the violation.
 @end deffn
 
 @deffn {Directive} %error-verbose
-An obsolete directive standing for @samp{%define parse.error "verbose"}.
+An obsolete directive standing for @samp{%define parse.error verbose}.
 @end deffn
 
 @deffn {Directive} %file-prefix "@var{prefix}"
@@ -10281,8 +10606,8 @@ Bison declaration to assign precedence and left associativity to token(s).
 @xref{Precedence Decl, ,Operator Precedence}.
 @end deffn
 
-@deffn {Directive} %lex-param @{@var{argument-declaration}@}
-Bison declaration to specifying an additional parameter that
+@deffn {Directive} %lex-param @{@var{argument-declaration}@} @dots{}
+Bison declaration to specifying additional arguments that
 @code{yylex} should accept.  @xref{Pure Calling,, Calling Conventions
 for Pure Parsers}.
 @end deffn
@@ -10321,10 +10646,15 @@ Bison declaration to set the name of the parser file.  @xref{Decl
 Summary}.
 @end deffn
 
-@deffn {Directive} %parse-param @{@var{argument-declaration}@}
-Bison declaration to specifying an additional parameter that
-@code{yyparse} should accept.  @xref{Parser Function,, The Parser
-Function @code{yyparse}}.
+@deffn {Directive} %param @{@var{argument-declaration}@} @dots{}
+Bison declaration to specify additional arguments that both
+@code{yylex} and @code{yyparse} should accept.  @xref{Parser Function,, The
+Parser Function @code{yyparse}}.
+@end deffn
+
+@deffn {Directive} %parse-param @{@var{argument-declaration}@} @dots{}
+Bison declaration to specify additional arguments that @code{yyparse}
+should accept.  @xref{Parser Function,, The Parser Function @code{yyparse}}.
 @end deffn
 
 @deffn {Directive} %prec
@@ -10460,7 +10790,7 @@ An obsolete macro used in the @file{yacc.c} skeleton, that you define
 with @code{#define} in the prologue to request verbose, specific error
 message strings when @code{yyerror} is called.  It doesn't matter what
 definition you use for @code{YYERROR_VERBOSE}, just whether you define
-it.  Using @samp{%define parse.error "verbose"} is preferred
+it.  Using @samp{%define parse.error verbose} is preferred
 (@pxref{Error Reporting, ,The Error Reporting Function @code{yyerror}}).
 @end deffn
 
@@ -10813,32 +11143,55 @@ grammatically indivisible.  The piece of text it represents is a token.
 @c fill-column: 76
 @c End:
 
-@c LocalWords: texinfo setfilename settitle setchapternewpage finalout
-@c LocalWords: ifinfo smallbook shorttitlepage titlepage GPL FIXME iftex
-@c LocalWords: akim fn cp syncodeindex vr tp synindex dircategory direntry
-@c LocalWords: ifset vskip pt filll insertcopying sp ISBN Etienne Suvasa
-@c LocalWords: ifnottex yyparse detailmenu GLR RPN Calc var Decls Rpcalc
-@c LocalWords: rpcalc Lexer Expr ltcalc mfcalc yylex
-@c LocalWords: yyerror pxref LR yylval cindex dfn LALR samp gpl BNF xref
-@c LocalWords: const int paren ifnotinfo AC noindent emph expr stmt findex
-@c LocalWords: glr YYSTYPE TYPENAME prog dprec printf decl init stmtMerge
-@c LocalWords: pre STDC GNUC endif yy YY alloca lf stddef stdlib YYDEBUG
-@c LocalWords: NUM exp subsubsection kbd Ctrl ctype EOF getchar isdigit
-@c LocalWords: ungetc stdin scanf sc calc ulator ls lm cc NEG prec yyerrok
-@c LocalWords: longjmp fprintf stderr yylloc YYLTYPE cos ln
-@c LocalWords: smallexample symrec val tptr FNCT fnctptr func struct sym
-@c LocalWords: fnct putsym getsym fname arith fncts atan ptr malloc sizeof
-@c LocalWords: strlen strcpy fctn strcmp isalpha symbuf realloc isalnum
-@c LocalWords: ptypes itype YYPRINT trigraphs yytname expseq vindex dtype
-@c LocalWords: Rhs YYRHSLOC LE nonassoc op deffn typeless yynerrs
-@c LocalWords: yychar yydebug msg YYNTOKENS YYNNTS YYNRULES YYNSTATES
-@c LocalWords: cparse clex deftypefun NE defmac YYACCEPT YYABORT param
-@c LocalWords: strncmp intval tindex lvalp locp llocp typealt YYBACKUP
-@c LocalWords: YYEMPTY YYEOF YYRECOVERING yyclearin GE def UMINUS maybeword
-@c LocalWords: Johnstone Shamsa Sadaf Hussain Tomita TR uref YYMAXDEPTH
-@c LocalWords: YYINITDEPTH stmnts ref stmnt initdcl maybeasm notype
-@c LocalWords: hexflag STR exdent itemset asis DYYDEBUG YYFPRINTF args
-@c LocalWords: infile ypp yxx outfile itemx tex leaderfill
-@c LocalWords: hbox hss hfill tt ly yyin fopen fclose ofirst gcc ll
-@c LocalWords: nbar yytext fst snd osplit ntwo strdup AST
-@c LocalWords: YYSTACK DVI fdl printindex IELR
+@c LocalWords: texinfo setfilename settitle setchapternewpage finalout texi FSF
+@c LocalWords: ifinfo smallbook shorttitlepage titlepage GPL FIXME iftex FSF's
+@c LocalWords: akim fn cp syncodeindex vr tp synindex dircategory direntry Naur
+@c LocalWords: ifset vskip pt filll insertcopying sp ISBN Etienne Suvasa Multi
+@c LocalWords: ifnottex yyparse detailmenu GLR RPN Calc var Decls Rpcalc multi
+@c LocalWords: rpcalc Lexer Expr ltcalc mfcalc yylex defaultprec Donnelly Gotos
+@c LocalWords: yyerror pxref LR yylval cindex dfn LALR samp gpl BNF xref yypush
+@c LocalWords: const int paren ifnotinfo AC noindent emph expr stmt findex lr
+@c LocalWords: glr YYSTYPE TYPENAME prog dprec printf decl init stmtMerge POSIX
+@c LocalWords: pre STDC GNUC endif yy YY alloca lf stddef stdlib YYDEBUG yypull
+@c LocalWords: NUM exp subsubsection kbd Ctrl ctype EOF getchar isdigit nonfree
+@c LocalWords: ungetc stdin scanf sc calc ulator ls lm cc NEG prec yyerrok rr
+@c LocalWords: longjmp fprintf stderr yylloc YYLTYPE cos ln Stallman Destructor
+@c LocalWords: smallexample symrec val tptr FNCT fnctptr func struct sym enum
+@c LocalWords: fnct putsym getsym fname arith fncts atan ptr malloc sizeof Lex
+@c LocalWords: strlen strcpy fctn strcmp isalpha symbuf realloc isalnum DOTDOT
+@c LocalWords: ptypes itype YYPRINT trigraphs yytname expseq vindex dtype Unary
+@c LocalWords: Rhs YYRHSLOC LE nonassoc op deffn typeless yynerrs nonterminal
+@c LocalWords: yychar yydebug msg YYNTOKENS YYNNTS YYNRULES YYNSTATES reentrant
+@c LocalWords: cparse clex deftypefun NE defmac YYACCEPT YYABORT param yypstate
+@c LocalWords: strncmp intval tindex lvalp locp llocp typealt YYBACKUP subrange
+@c LocalWords: YYEMPTY YYEOF YYRECOVERING yyclearin GE def UMINUS maybeword loc
+@c LocalWords: Johnstone Shamsa Sadaf Hussain Tomita TR uref YYMAXDEPTH inline
+@c LocalWords: YYINITDEPTH stmnts ref stmnt initdcl maybeasm notype Lookahead
+@c LocalWords: hexflag STR exdent itemset asis DYYDEBUG YYFPRINTF args Autoconf
+@c LocalWords: infile ypp yxx outfile itemx tex leaderfill Troubleshouting sqrt
+@c LocalWords: hbox hss hfill tt ly yyin fopen fclose ofirst gcc ll lookahead
+@c LocalWords: nbar yytext fst snd osplit ntwo strdup AST Troublereporting th
+@c LocalWords: YYSTACK DVI fdl printindex IELR nondeterministic nonterminals ps
+@c LocalWords: subexpressions declarator nondeferred config libintl postfix
+@c LocalWords: preprocessor nonpositive unary nonnumeric typedef extern rhs
+@c LocalWords: yytokentype filename destructor multicharacter nonnull EBCDIC
+@c LocalWords: lvalue nonnegative XNUM CHR chr TAGLESS tagless stdout api TOK
+@c LocalWords: destructors Reentrancy nonreentrant subgrammar nonassociative
+@c LocalWords: deffnx namespace xml goto lalr ielr runtime lex yacc yyps env
+@c LocalWords: yystate variadic Unshift NLS gettext po UTF Automake LOCALEDIR
+@c LocalWords: YYENABLE bindtextdomain Makefile DEFS CPPFLAGS DBISON DeRemer
+@c LocalWords: autoreconf Pennello multisets nondeterminism Generalised baz
+@c LocalWords: redeclare automata Dparse localedir datadir XSLT midrule Wno
+@c LocalWords: makefiles Graphviz multitable headitem hh basename Doxygen fno
+@c LocalWords: doxygen ival sval deftypemethod deallocate pos deftypemethodx
+@c LocalWords: Ctor defcv defcvx arg accessors arithmetics CPP ifndef CALCXX
+@c LocalWords: lexer's calcxx bool LPAREN RPAREN deallocation cerrno climits
+@c LocalWords: cstdlib Debian undef yywrap unput noyywrap nounput zA yyleng
+@c LocalWords: errno strtol ERANGE str strerror iostream argc argv Javadoc
+@c LocalWords: bytecode initializers superclass stype ASTNode autoboxing nls
+@c LocalWords: toString deftypeivar deftypeivarx deftypeop YYParser strictfp
+@c LocalWords: superclasses boolean getErrorVerbose setErrorVerbose deftypecv
+@c LocalWords: getDebugStream setDebugStream getDebugLevel setDebugLevel url
+@c LocalWords: bisonVersion deftypecvx bisonSkeleton getStartPos getEndPos
+@c LocalWords: getLVal defvar YYFAIL deftypefn deftypefnx gotos msgfmt
+@c LocalWords: subdirectory Solaris nonassociativity