TODO: YYPRINT.

[bison.git] / NEWS

diff --git a/NEWS b/NEWS
index 68fb66f030d184d335063be628bef2b7ff2a481f..8a5fc93d4bae61876ecb78eafab2f2499e7adc31 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -1,21 +1,133 @@
 Bison News
 ----------
 
 Bison News
 ----------
 

-Changes in version 2.3a+ (????-??-??):
+Changes in version ?.? (????-??-??):
+
+* Java skeleton improvements:
+
+  The constants for token names were moved to the Lexer interface.
+  Also, it is possible to add code to the parser's constructors using
+  "%code init" and "%define init_throws".
+
+Changes in version 2.4 (2008-11-02):
+
+* %language is an experimental feature.
+
+  We first introduced this feature in test release 2.3b as a cleaner
+  alternative to %skeleton.  Since then, we have discussed the possibility of
+  modifying its effect on Bison's output file names.  Thus, in this release,
+  we consider %language to be an experimental feature that will likely evolve
+  in future releases.
+
+* Forward compatibility with GNU M4 has been improved.
+
+* Several bugs in the C++ skeleton and the experimental Java skeleton have been
+  fixed.
+
+Changes in version 2.3b (2008-05-27):
+
+* The quotes around NAME that used to be required in the following directive
+  are now deprecated:
+
+    %define NAME "VALUE"
+
+* The directive `%pure-parser' is now deprecated in favor of:
+
+    %define api.pure
+
+  which has the same effect except that Bison is more careful to warn about
+  unreasonable usage in the latter case.
+
+* Push Parsing
+
+  Bison can now generate an LALR(1) parser in C with a push interface.  That
+  is, instead of invoking `yyparse', which pulls tokens from `yylex', you can
+  push one token at a time to the parser using `yypush_parse', which will
+  return to the caller after processing each token.  By default, the push
+  interface is disabled.  Either of the following directives will enable it:
+
+    %define api.push_pull "push" // Just push; does not require yylex.
+    %define api.push_pull "both" // Push and pull; requires yylex.
+
+  See the new section `A Push Parser' in the Bison manual for details.
+
+  The current push parsing interface is experimental and may evolve.  More user
+  feedback will help to stabilize it.

 
 * The -g and --graph options now output graphs in Graphviz DOT format,
 
 * The -g and --graph options now output graphs in Graphviz DOT format,

-  not VCG format.
+  not VCG format.  Like --graph, -g now also takes an optional FILE argument
+  and thus cannot be bundled with other short options.
+
+* Java
+
+  Bison can now generate an LALR(1) parser in Java.  The skeleton is
+  `data/lalr1.java'.  Consider using the new %language directive instead of
+  %skeleton to select it.
+
+  See the new section `Java Parsers' in the Bison manual for details.

 
 

-* An experimental directive %language specifies the language of the
-  generated parser, which can be C (the default) or C++.  This
-  directive affects the skeleton used, and the names of the generated
-  files if the grammar file's name ends in ".y".
+  The current Java interface is experimental and may evolve.  More user
+  feedback will help to stabilize it.
+
+* %language
+
+  This new directive specifies the programming language of the generated
+  parser, which can be C (the default), C++, or Java.  Besides the skeleton
+  that Bison uses, the directive affects the names of the generated files if
+  the grammar file's name ends in ".y".
+
+* XML Automaton Report
+
+  Bison can now generate an XML report of the LALR(1) automaton using the new
+  `--xml' option.  The current XML schema is experimental and may evolve.  More
+  user feedback will help to stabilize it.

 
 * The grammar file may now specify the name of the parser header file using
   %defines.  For example:
 
     %defines "parser.h"
 
 
 * The grammar file may now specify the name of the parser header file using
   %defines.  For example:
 
     %defines "parser.h"
 

+* When reporting useless rules, useless nonterminals, and unused terminals,
+  Bison now employs the terms "useless in grammar" instead of "useless",
+  "useless in parser" instead of "never reduced", and "unused in grammar"
+  instead of "unused".
+
+* Unreachable State Removal
+
+  Previously, Bison sometimes generated parser tables containing unreachable
+  states.  A state can become unreachable during conflict resolution if Bison
+  disables a shift action leading to it from a predecessor state.  Bison now:
+
+    1. Removes unreachable states.
+
+    2. Does not report any conflicts that appeared in unreachable states.
+       WARNING: As a result, you may need to update %expect and %expect-rr
+       directives in existing grammar files.
+
+    3. For any rule used only in such states, Bison now reports the rule as
+       "useless in parser due to conflicts".
+
+  This feature can be disabled with the following directive:
+
+    %define lr.keep_unreachable_states
+
+  See the %define entry in the `Bison Declaration Summary' in the Bison manual
+  for further discussion.
+
+* Lookahead Set Correction in the `.output' Report
+
+  When instructed to generate a `.output' file including lookahead sets
+  (using `--report=lookahead', for example), Bison now prints each reduction's
+  lookahead set only next to the associated state's one item that (1) is
+  associated with the same rule as the reduction and (2) has its dot at the end
+  of its RHS.  Previously, Bison also erroneously printed the lookahead set
+  next to all of the state's other items associated with the same rule.  This
+  bug affected only the `.output' file and not the generated parser source
+  code.
+
+* --report-file=FILE is a new option to override the default `.output' file
+  name.
+

 * The `=' that used to be required in the following directives is now
   deprecated:
 
 * The `=' that used to be required in the following directives is now
   deprecated:
 


@@ -23,12 +135,9 @@ Changes in version 2.3a+ (????-??-??):
     %name-prefix "c_"
     %output "parser.c"
 
     %name-prefix "c_"
     %output "parser.c"
 

-* The quotes around NAME that used to be required in the following directive
-  are now deprecated:
-
-    %define NAME "VALUE"
+* An Alternative to `%{...%}' -- `%code QUALIFIER {CODE}'

 
 

-* Bison 2.3a provided a new set of directives as a more flexible alternative to
+  Bison 2.3a provided a new set of directives as a more flexible alternative to

   the traditional Yacc prologue blocks.  Those have now been consolidated into
   a single %code directive with an optional qualifier field, which identifies
   the purpose of the code and thus the location(s) where Bison should generate
   the traditional Yacc prologue blocks.  Those have now been consolidated into
   a single %code directive with an optional qualifier field, which identifies
   the purpose of the code and thus the location(s) where Bison should generate


@@ -39,8 +148,8 @@ Changes in version 2.3a+ (????-??-??):
     3. `%code provides {CODE}' replaces `%end-header    {CODE}'
     4. `%code top      {CODE}' replaces `%before-header {CODE}'
 
     3. `%code provides {CODE}' replaces `%end-header    {CODE}'
     4. `%code top      {CODE}' replaces `%before-header {CODE}'
 

-  See the %code entries in `Appendix A Bison Symbols' in the Bison manual for a
-  summary of the new functionality.  See the new section `Prologue
+  See the %code entries in section `Bison Declaration Summary' in the Bison
+  manual for a summary of the new functionality.  See the new section `Prologue

   Alternatives' for a detailed discussion including the advantages of %code
   over the traditional Yacc prologues.
 
   Alternatives' for a detailed discussion including the advantages of %code
   over the traditional Yacc prologues.
 


@@ -64,10 +173,12 @@ Changes in version 2.3a+ (????-??-??):
   sometimes prove to be false alarms in existing grammars employing the Yacc
   constructs $0 or $-N (where N is some positive integer).
 
   sometimes prove to be false alarms in existing grammars employing the Yacc
   constructs $0 or $-N (where N is some positive integer).
 

-  To enable these warnings, specify the flag `--warnings=midrule-values' or
+  To enable these warnings, specify the option `--warnings=midrule-values' or

   `-W', which is a synonym for `--warnings=all'.
 
   `-W', which is a synonym for `--warnings=all'.
 

-* Bison now recognizes two separate kinds of default %destructor's and
+* Default %destructor or %printer with `<*>' or `<>'
+
+  Bison now recognizes two separate kinds of default %destructor's and

   %printer's:
 
     1. Place `<*>' in a %destructor/%printer symbol list to define a default
   %printer's:
 
     1. Place `<*>' in a %destructor/%printer symbol list to define a default


@@ -90,10 +201,14 @@ Changes in version 2.3a+ (????-??-??):
   See the section `Freeing Discarded Symbols' in the Bison manual for further
   details.
 
   See the section `Freeing Discarded Symbols' in the Bison manual for further
   details.
 

-Changes in version 2.3a, 2006-09-13:
+* %left, %right, and %nonassoc can now declare token numbers.  This is required
+  by POSIX.  However, see the end of section `Operator Precedence' in the Bison
+  manual for a caveat concerning the treatment of literal strings.
+
+* The nonfunctional --no-parser, -n, and %no-parser options have been
+  completely removed from Bison.

 
 

-* Bison now supports generating Java parsers.  Grammars written for
-  the Java language should include the `%language "Java"' directive.
+Changes in version 2.3a, 2006-09-13:

 
 * Instead of %union, you can define and use your own union type
   YYSTYPE if your grammar contains at least one <type> tag.
 
 * Instead of %union, you can define and use your own union type
   YYSTYPE if your grammar contains at least one <type> tag.


@@ -917,21 +1032,19 @@ End:
 -----
 
 Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
 -----
 
 Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,

-2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.

 
 This file is part of Bison, the GNU Compiler Compiler.
 
 
 This file is part of Bison, the GNU Compiler Compiler.
 

-Bison is free software; you can redistribute it and/or modify
+This program is free software: you can redistribute it and/or modify

 it under the terms of the GNU General Public License as published by
 it under the terms of the GNU General Public License as published by

-the Free Software Foundation; either version 2, or (at your option)
-any later version.
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.

 
 

-Bison is distributed in the hope that it will be useful,
+This program is distributed in the hope that it will be useful,

 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License

-along with autoconf; see the file COPYING.  If not, write to
-the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
-Boston, MA 02110-1301, USA.
+along with this program.  If not, see <http://www.gnu.org/licenses/>.