* doc/bison.texinfo (Initial Action Decl): New.

ChangeLog

@@ -1,3 +1,7 @@
+2004-09-20  Akim Demaille  <akim@epita.fr>
+
+	* doc/bison.texinfo (Initial Action Decl): New.
+
 2004-09-20  Akim Demaille  <akim@epita.fr>
 
 	* data/yacc.c (YY_LOCATION_PRINT): Use YYLTYPE_IS_TRIVIAL as a

NEWS

@@ -3,6 +3,10 @@ Bison News
 
 Changes in version 1.875e:
 
+* New directive: %initial-action.
+  This directive allows the user to run arbitrary code (including
+  initializing @$) from yyparse before parsing starts.
+
 * The option `--report=lookahead' was changed to `--report=look-ahead'.
   The old spelling still works, but is not documented and will be removed.
 

doc/bison.texinfo

@@ -228,6 +228,7 @@ Bison Declarations
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.
 * Type Decl::         Declaring the choice of type for a nonterminal symbol.
+* Initial Action Decl::  Code run before parsing starts.
 * Destructor Decl::   Declaring how symbols are freed.
 * Expect Decl::       Suppressing warnings about parsing conflicts.
 * Start Decl::        Specifying the start symbol.
@@ -3520,6 +3521,7 @@ Grammars}).
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.
 * Type Decl::         Declaring the choice of type for a nonterminal symbol.
+* Initial Action Decl::  Code run before parsing starts.
 * Destructor Decl::   Declaring how symbols are freed.
 * Expect Decl::       Suppressing warnings about parsing conflicts.
 * Start Decl::        Specifying the start symbol.
@@ -3729,6 +3731,22 @@ use the same @code{<@var{type}>} construction in a declaration for the
 terminal symbol.  All kinds of token declarations allow
 @code{<@var{type}>}.
 
+@node Initial Action Decl
+@subsection Performing Actions before Parsing
+@findex %initial-action
+
+Sometimes your parser needs to perform some initializations before
+parsing.  The @code{%initial-action} directive allows for such arbitrary
+code.
+
+@deffn {Directive} %initial-action @{ @var{code} @}
+@findex %initial-action
+Declare that the @var{code} must be invoked before parsing each time
+@code{yyparse} is called.  The @var{code} may use @code{@@$} to
+designate the initial location, and the @code{%parse-param}.
+@end deffn
+
+
 @node Destructor Decl
 @subsection Freeing Discarded Symbols
 @cindex freeing discarded symbols
@@ -7144,6 +7162,10 @@ time to resolve reduce/reduce conflicts.  @xref{GLR Parsers, ,Writing
 @acronym{GLR} Parsers}.
 @end deffn
 
+@deffn {Directive} %initial-action
+Run user code before parsing.  @xref{Initial Action Decl, , Performing Actions before Parsing}.
+@end deffn
+
 @deffn {Directive} %error-verbose
 Bison declaration to request verbose, specific error message strings
 when @code{yyerror} is called.