bench.pl --bench.

[bison.git] / NEWS

diff --git a/NEWS b/NEWS
index 41eb292ca33b80f02a6f293b2f72fc1f4f0e38dd..dcaa386d92e060bf78bee8d2da57d91976ef929c 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -1,41 +1,151 @@
 Bison News
 ----------
 
 Bison News
 ----------
 

-Changes in version 2.3a+ (????-??-??):
+Changes in version ?.? (????-??-??):
+
+*
+
+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"
 

-* The `=' that used to be required in the following declarations is now
+* 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:
 
     %file-prefix "parser"
     %name-prefix "c_"
     %output "parser.c"
 
   deprecated:
 
     %file-prefix "parser"
     %name-prefix "c_"
     %output "parser.c"
 

-* Bison 2.3a provided a new set of directives as a more flexible alternative to
+* An Alternative to `%{...%}' -- `%code QUALIFIER {CODE}'
+
+  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
   it:
 
   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
   it:
 

-    1. `%code            {CODE}' replaces `%after-header  {CODE}'
-    2. `%code "requires" {CODE}' replaces `%start-header  {CODE}'
-    3. `%code "provides" {CODE}' replaces `%end-header    {CODE}'
-    4. `%code "top"      {CODE}' replaces `%before-header {CODE}'
+    1. `%code          {CODE}' replaces `%after-header  {CODE}'
+    2. `%code requires {CODE}' replaces `%start-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.
 


@@ -59,10 +169,12 @@ 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


@@ -85,6 +197,13 @@ 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.
 

+* %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.
+

 Changes in version 2.3a, 2006-09-13:
 
 * Instead of %union, you can define and use your own union type
 Changes in version 2.3a, 2006-09-13:
 
 * Instead of %union, you can define and use your own union type


@@ -909,21 +1028,19 @@ 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 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/>.