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:
* 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
+ 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:
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,
- 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
-* 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".
+ 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.
+
+ 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"
-* When reporting useless rules and nonterminals, Bison now employs the term
- "useless in grammar" instead of "useless" and employs the term "useless in
- parser" instead of "never reduced".
+* 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
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
bug affected only the `.output' file and not the generated parser source
code.
-* --report-file=FILE is a new flag to override the default `.output' file name.
+* --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:
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'.
* Default %destructor or %printer with `<*>' or `<>'
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
-----
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-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.
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