Bison News
----------
-Changes in version 1.49b:
+Changes in version 1.49d:
+
+
+Changes in version 1.49b, 2002-08-12:
* GLR parsing
The declaration
%glr-parser
causes Bison to produce a Generalized LR (GLR) parser, capable of handling
almost any context-free grammar, ambiguous or not. The new declarations
- %dprec and %merge on grammar rules allow parse-time resolution of
+ %dprec and %merge on grammar rules allow parse-time resolution of
ambiguities. Contributed by Paul Hilfinger.
* Output Directory
When not in Yacc compatibility mode, when the output file was not
- specified, runnning `bison foo/bar.y' created `foo/bar.c'. It
+ specified, running `bison foo/bar.y' created `foo/bar.c'. It
now creates `bar.c'.
* Undefined token
The undefined token was systematically mapped to 2 which prevented
- the use of 2 from the user. This is no longer the case.
+ the use of 2 by the user. This is no longer the case.
* Unknown token numbers
- If yylex returned a code out of range, yyparse could die. This is
+ If yylex returned an out of range value, yyparse could die. This is
no longer the case.
* Error token
- According to POSIX, the error token should be numbered as 256.
+ According to POSIX, the error token must be 256.
Bison extends this requirement by making it a preference: *if* the
user specified that one of her tokens is numbered 256, then error
will be mapped onto another number.
+* Verbose error messages
+ They no longer report `..., expecting error or...' for states where
+ error recovery is possible.
+
+* End token
+ Defaults to `$end' instead of `$'.
+
* Error recovery now conforms to documentation and to POSIX
When a Bison-generated parser encounters a syntax error, it now pops
the stack until it finds a state that allows shifting the error
* Traces
Popped tokens and nonterminals are now reported.
-* Large grammars
- Large grammars are now supported (large token numbers, large grammar
- size (= sum of the LHS and RHS lengths), large LALR tables).
+* Larger grammars
+ Larger grammars are now supported (larger token numbers, larger grammar
+ size (= sum of the LHS and RHS lengths), larger LALR tables).
+ Formerly, many of these numbers ran afoul of 16-bit limits;
+ now these limits are 32 bits on most hosts.
* Explicit initial rule
Bison used to play hacks with the initial rule, which the user does
* Useless rules, useless nonterminals
They are now reported, as a warning, with their locations.
+* Rules never reduced
+ Rules that can never be reduced because of conflicts are now
+ reported.
+
* Incorrect `Token not used'
On a grammar such as
* Token end-of-file
The token end of file may be specified by the user, in which case,
the user symbol is used in the reports, the graphs, and the verbose
- error messages instead of `$', which remains being the defaults.
+ error messages instead of `$end', which remains being the default.
For instance
%token YYEOF 0
or
* Semantic parser
This old option, which has been broken for ages, is removed.
-* New translation
+* New translations
+ Brazilian Portuguese, thanks to Alexandre Folle de Menezes.
Croatian, thanks to Denis Lackovic.
* Incorrect token definitions
- When fed with `%token 'a' "A"', Bison used to output `#define 'a' 65'.
+ When given `%token 'a' "A"', Bison used to output `#define 'a' 65'.
* Token definitions as enums
Tokens are output both as the traditional #define's, and, provided
the compiler supports ANSI C or is a C++ compiler, as enums.
- This helps debuggers producing symbols instead of values.
+ This lets debuggers display names instead of integers.
* Reports
In addition to --verbose, bison supports --report=THINGS, which
bar: '0' {} '0';
This is fixed.
+
+* GNU M4 is now required when using Bison.
\f
Changes in version 1.35, 2002-03-25:
projects / bison.git / blobdiff