Fix impure push parser compile error reported by Bob Rossi at

[bison.git] / doc / bison.texinfo

diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index 9d0da773eb75ebef0bc91b66f03ade79f5beddf0..d513b5558826ccca1a797bcd44ab5651cf101db9 100644 (file)
--- a/doc/bison.texinfo
+++ b/doc/bison.texinfo
@@ -34,7 +34,8 @@ This manual is for @acronym{GNU} Bison (version @value{VERSION},
 @value{UPDATED}), the @acronym{GNU} parser generator.
 
 Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1995, 1998,
-1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software
+Foundation, Inc.
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document
@@ -45,10 +46,10 @@ being ``A @acronym{GNU} Manual,'' and with the Back-Cover Texts as in
 (a) below.  A copy of the license is included in the section entitled
 ``@acronym{GNU} Free Documentation License.''
 
-(a) The @acronym{FSF}'s Back-Cover Text is: ``You have freedom to copy
-and modify this @acronym{GNU} Manual, like @acronym{GNU} software.
-Copies published by the Free Software Foundation raise funds for
-@acronym{GNU} development.''
+(a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
+modify this @acronym{GNU} manual.  Buying copies from the @acronym{FSF}
+supports it in developing @acronym{GNU} and promoting software
+freedom.''
 @end quotation
 @end copying
 
@@ -4022,7 +4023,7 @@ associativity and precedence.  @xref{Precedence Decl, ,Operator
 Precedence}.
 
 You can explicitly specify the numeric code for a token type by appending
-a decimal or hexadecimal integer value in the field immediately
+a nonnegative decimal or hexadecimal integer value in the field immediately
 following the token name:
 
 @example
@@ -4075,6 +4076,16 @@ Once you equate the literal string and the token name, you can use them
 interchangeably in further declarations or the grammar rules.  The
 @code{yylex} function can use the token name or the literal string to
 obtain the token type code number (@pxref{Calling Convention}).
+Syntax error messages passed to @code{yyerror} from the parser will reference
+the literal string instead of the token name.
+
+The token numbered as 0 corresponds to end of file; the following line
+allows for nicer error messages referring to ``end of file'' instead
+of ``$end'':
+
+@example
+%token END 0 "end of file"
+@end example
 
 @node Precedence Decl
 @subsection Operator Precedence
@@ -4088,7 +4099,7 @@ once.  These are called @dfn{precedence declarations}.
 @xref{Precedence, ,Operator Precedence}, for general information on
 operator precedence.
 
-The syntax of a precedence declaration is the same as that of
+The syntax of a precedence declaration is nearly the same as that of
 @code{%token}: either
 
 @example
@@ -4126,6 +4137,18 @@ When two tokens declared in different precedence declarations associate,
 the one declared later has the higher precedence and is grouped first.
 @end itemize
 
+For backward compatibility, there is a confusing difference between the
+argument lists of @code{%token} and precedence declarations.
+Only a @code{%token} can associate a literal string with a token type name.
+A precedence declaration always interprets a literal string as a reference to a
+separate token.
+For example:
+
+@example
+%left  OR "<="         // Does not declare an alias.
+%left  OR 134 "<=" 135 // Declares 134 for OR and 135 for "<=".
+@end example
+
 @node Union Decl
 @subsection The Collection of Value Types
 @cindex declaring value types
@@ -5316,7 +5339,9 @@ This function is available if either the @code{%define api.push_pull "push"} or
 
 @deftypefun yypstate *yypstate_new (void)
 The fuction will return a valid parser instance if there was memory available
-or NULL if no memory was available.
+or 0 if no memory was available.
+In impure mode, it will also return 0 if a parser instance is currently
+allocated.
 @end deftypefun
 
 @node Parser Delete Function
@@ -7197,14 +7222,14 @@ State 11 conflicts: 4 shift/reduce
 The next section reports useless tokens, nonterminal and rules.  Useless
 nonterminals and rules are removed in order to produce a smaller parser,
 but useless tokens are preserved, since they might be used by the
-scanner (note the difference between ``useless'' and ``not used''
+scanner (note the difference between ``useless'' and ``unused''
 below):
 
 @example
-Useless nonterminals:
+Nonterminals useless in grammar:
    useless
 
-Terminals which are not used:
+Terminals unused in grammar:
    STR
 
 Rules useless in grammar: