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bison 2.0 主要可以用来做语法分析用的

* Reports
  In addition to --verbose, bison supports --report=THINGS, which
  produces additional information:
  - itemset
    complete the core item sets with their closure
  - lookahead [changed to `look-ahead' in 1.875e and later]
    explicitly associate look-ahead tokens to items
  - solved
    describe shift/reduce conflicts solving.
    Bison used to systematically output this information on top of
    the report.  Solved conflicts are now attached to their states.

* Type clashes
  Previous versions don't complain when there is a type clash on
  the default action if the rule has a mid-rule action, such as in:

      %type <foo> bar
      %%
      bar: '0' {} '0';

  This is fixed.

* GNU M4 is now required when using Bison.

Changes in version 1.35, 2002-03-25:

* C Skeleton
  Some projects use Bison's C parser with C++ compilers, and define
  YYSTYPE as a class.  The recent adjustment of C parsers for data
  alignment and 64 bit architectures made this impossible.

  Because for the time being no real solution for C++ parser
  generation exists, kludges were implemented in the parser to
  maintain this use.  In the future, when Bison has C++ parsers, this
  kludge will be disabled.

  This kludge also addresses some C++ problems when the stack was
  extended.

Changes in version 1.34, 2002-03-12:

* File name clashes are detected
  $ bison foo.y -d -o foo.x
  fatal error: header and parser would both be named `foo.x'

* A missing `;' at the end of a rule triggers a warning
  In accordance with POSIX, and in agreement with other
  Yacc implementations, Bison will mandate this semicolon in the near
  future.  This eases the implementation of a Bison parser of Bison
  grammars by making this grammar LALR(1) instead of LR(2).  To
  facilitate the transition, this release introduces a warning.

* Revert the C++ namespace changes introduced in 1.31, as they caused too
  many portability hassles.

* DJGPP support added.

* Fix test suite portability problems.

Changes in version 1.33, 2002-02-07:

* Fix C++ issues
  Groff could not be compiled for the definition of size_t was lacking
  under some conditions.

* Catch invalid @n
  As is done with $n.

Changes in version 1.32, 2002-01-23:

* Fix Yacc output file names

* Portability fixes

* Italian, Dutch translations

Changes in version 1.31, 2002-01-14:

* Many Bug Fixes

* GNU Gettext and %expect
  GNU Gettext asserts 10 s/r conflicts, but there are 7.  Now that
  Bison dies on incorrect %expectations, we fear there will be
  too many bug reports for Gettext, so _for the time being_, %expect
  does not trigger an error when the input file is named `plural.y'.

* Use of alloca in parsers
  If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use
  malloc exclusively.  Since 1.29, but was not NEWS'ed.

  alloca is used only when compiled with GCC, to avoid portability
  problems as on AIX.

* When the generated parser lacks debugging code, YYDEBUG is now 0
  (as POSIX requires) instead of being undefined.

* User Actions
  Bison has always permitted actions such as { $$ = $1 }: it adds the
  ending semicolon.  Now if in Yacc compatibility mode, the semicolon
  is no longer output: one has to write { $$ = $1; }.

* Better C++ compliance
  The output parsers try to respect C++ namespaces.
  [This turned out to be a failed experiment, and it was reverted later.]

* Reduced Grammars
  Fixed bugs when reporting useless nonterminals.

* 64 bit hosts
  The parsers work properly on 64 bit hosts.

* Error messages
  Some calls to strerror resulted in scrambled or missing error messages.

* %expect
  When the number of shift/reduce conflicts is correct, don't issue
  any warning.

* The verbose report includes the rule line numbers.

* Rule line numbers are fixed in traces.

* Swedish translation

* Parse errors
  Verbose parse error messages from the parsers are better looking.
  Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'(''
     Now: parse error: unexpected '/', expecting "number" or '-' or '('

* Fixed parser memory leaks.
  When the generated parser was using malloc to extend its stacks, the
  previous allocations were not freed.

* Fixed verbose output file.
  Some newlines were missing.
  Some conflicts in state descriptions were missing.

* Fixed conflict report.
  Option -v was needed to get the result.

* %expect
  Was not used.
  Mismatches are errors, not warnings.

* Fixed incorrect processing of some invalid input.

* Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H.

* Fixed some typos in the documentation.

* %token MY_EOF 0 is supported.
  Before, MY_EOF was silently renumbered as 257.

* doc/refcard.tex is updated.

* %output, %file-prefix, %name-prefix.
  New.

* --output
  New, aliasing `--output-file'.

Changes in version 1.30, 2001-10-26:

* `--defines' and `--graph' have now an optional argument which is the
  output file name. `-d' and `-g' do not change; they do not take any
  argument.

* `%source_extension' and `%header_extension' are removed, failed
  experiment.

* Portability fixes.

Changes in version 1.29, 2001-09-07:

* The output file does not define const, as this caused problems when used
  with common autoconfiguration schemes.  If you still use ancient compilers
  that lack const, compile with the equivalent of the C compiler option
  `-Dconst='.  autoconf's AC_C_CONST macro provides one way to do this.

* Added `-g' and `--graph'.

* The Bison manual is now distributed under the terms of the GNU FDL.

* The input and the output files has automatically a similar extension.

* Russian translation added.

* NLS support updated; should hopefully be less troublesome.

* Added the old Bison reference card.

* Added `--locations' and `%locations'.

* Added `-S' and `--skeleton'.

* `%raw', `-r', `--raw' is disabled.

* Special characters are escaped when output.  This solves the problems
  of the #line lines with path names including backslashes.

* New directives.
  `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose',
  `%debug', `%source_extension' and `%header_extension'.

* @$
  Automatic location tracking.

Changes in version 1.28, 1999-07-06:

* Should compile better now with K&R compilers.

* Added NLS.

* Fixed a problem with escaping the double quote character.

* There is now a FAQ.

Changes in version 1.27:

* The make rule which prevented bison.simple from being created on
  some systems has been fixed.

Changes in version 1.26:

* Bison now uses automake.

* New mailing lists: <[e-mail]> and <[e-mail]>.

* Token numbers now start at 257 as previously documented, not 258.

* Bison honors the TMPDIR environment variable.

* A couple of buffer overruns have been fixed.

* Problems when closing files should now be reported.

* Generated parsers should now work even on operating systems which do
  not provide alloca().

Changes in version 1.25, 1995-10-16:

* Errors in the input grammar are not fatal; Bison keeps reading
the grammar file, and reports all the errors found in it.

* Tokens can now be specified as multiple-character strings: for
example, you could use "<=" for a token which looks like <=, instead
of chosing a name like LESSEQ.

* The %token_table declaration says to write a table of tokens (names
and numbers) into the parser file.  The yylex function can use this
table to recognize multiple-character string tokens, or for other
purposes.

* The %no_lines declaration says not to generate any #line preprocessor
directives in the parser file.

* The %raw declaration says to use internal Bison token numbers, not
Yacc-compatible token numbers, when token names are defined as macros.

* The --no-parser option produces the parser tables without including
the parser engine; a project can now use its own parser engine.
The actions go into a separate file called NAME.act, in the form of
a switch statement body.

Changes in version 1.23:

The user can define YYPARSE_PARAM as the name of an argument to be
passed into yyparse.  The argument should have type void *.  It should
actually point to an object.  Grammar actions can access the variable
by casting it to the proper pointer type.

Line numbers in output file corrected.

Changes in version 1.22:

--help option added.

Changes in version 1.20:

Output file does not redefine const for C++.

Local Variables:
mode: outline
End:

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