X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/75ad86eebd3f49dff81976eb83036eb7b7793e68..4fc55348e59ab81573d188c8fd529ed9faf81444:/NEWS diff --git a/NEWS b/NEWS index 854023cc..8a5fc93d 100644 --- a/NEWS +++ b/NEWS @@ -1,10 +1,102 @@ Bison News ---------- -Changes in version 2.3a+ (????-??-??): +Changes in version ?.? (????-??-??): -* Previously, Bison sometimes generated parser tables with states that were - unreachable due to conflicts in predecessor states. Bison now: +* 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, + 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. + + 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, 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. @@ -13,20 +105,28 @@ Changes in version 2.3a+ (????-??-??): directives in existing grammar files. 3. For any rule used only in such states, Bison now reports the rule as - "never reduced because of conflicts". + "useless in parser due to conflicts". -* The -g and --graph options now output graphs in Graphviz DOT format, - not VCG format. + This feature can be disabled with the following directive: -* 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". + %define lr.keep_unreachable_states -* The grammar file may now specify the name of the parser header file using - %defines. For example: + See the %define entry in the `Bison Declaration Summary' in the Bison manual + for further discussion. - %defines "parser.h" +* 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: @@ -35,12 +135,9 @@ Changes in version 2.3a+ (????-??-??): %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 @@ -51,8 +148,8 @@ Changes in version 2.3a+ (????-??-??): 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. @@ -76,10 +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). - 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'. -* 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 @@ -102,6 +201,13 @@ Changes in version 2.3a+ (????-??-??): 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 @@ -926,21 +1032,19 @@ End: ----- 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. -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 -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 -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 .