X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/4c38b19e2650ca8b79b0d72a9995605ca12d9875..3b1977eab5b3ad1dd97c225518d694b3ec43a151:/NEWS diff --git a/NEWS b/NEWS index e3510938..a2c0b029 100644 --- a/NEWS +++ b/NEWS @@ -3,7 +3,7 @@ Bison News * Changes in version 2.5 (????-??-??): -** Named References Support +** Named references: Historically, Yacc and Bison have supported positional references ($n, $$) to allow access to symbol values from inside of semantic @@ -28,13 +28,13 @@ Bison News These features are experimental in this version. More user feedback will help to stabilize them. -** IELR(1) and Canonical LR(1) Support +** IELR(1) and canonical LR(1): IELR(1) is a minimal LR(1) parser table generation algorithm. That is, given any context-free grammar, IELR(1) generates parser tables with the full language recognition power of canonical LR(1) but with - nearly the same number of parser states as LALR(1). This reduction in - parser states is often an order of magnitude. More importantly, + nearly the same number of parser states as LALR(1). This reduction + in parser states is often an order of magnitude. More importantly, because canonical LR(1)'s extra parser states may contain duplicate conflicts in the case of non-LR(1) grammars, the number of conflicts for IELR(1) is often an order of magnitude less as well. This can @@ -98,15 +98,15 @@ Bison News LAC is an experimental feature. More user feedback will help to stabilize it. -** Unrecognized %code qualifiers are now an error not a warning. +** Unrecognized %code qualifiers are now errors not warnings. -** %define improvements. +** %define improvements: -*** Unrecognized variables are now an error not a warning. +*** Unrecognized variables are now errors not warnings. *** Multiple invocations for any variable is now an error not a warning. -*** Can now be invoked via the command line. +*** Can now be invoked via the command line: Each of these command-line options @@ -125,7 +125,7 @@ Bison News quietly override %define, but -D and --define do not. For further details, see the section "Bison Options" in the Bison manual. -*** Variables renamed. +*** Variables renamed: The following %define variables @@ -140,7 +140,7 @@ Bison News The old names are now deprecated but will be maintained indefinitely for backward compatibility. -*** Values no longer need to be quoted in grammar file. +*** Values no longer need to be quoted in grammar file: If a %define value is an identifier, it no longer needs to be placed within quotations marks. For example, @@ -151,15 +151,15 @@ Bison News %define api.push-pull push -** Symbol names. +** Grammar symbol names can now contain dashes: Consistently with directives (such as %error-verbose) and variables - (e.g. push-pull), symbol names may include dashes in any position, - similarly to periods and underscores. This is GNU extension over - POSIX Yacc whose use is reported by -Wyacc, and rejected in Yacc - mode (--yacc). + (e.g. push-pull), grammar symbol names may include dashes in any + position, similarly to periods and underscores. This is GNU + extension over POSIX Yacc whose use is reported by -Wyacc, and + rejected in Yacc mode (--yacc). -** YYFAIL now produces warnings and Java parsers no longer implement it. +** YYFAIL now produces warnings and Java parsers no longer implement it: YYFAIL has existed for many years as an undocumented feature of deterministic parsers in C generated by Bison. More recently, it was @@ -170,7 +170,7 @@ Bison News discussion of how to suppress C preprocessor warnings about YYFAIL being unused, see the Bison 2.4.2 NEWS entry. -** Temporary hack for adding a semicolon to the user action. +** Temporary hack for adding a semicolon to the user action: Previously, Bison appended a semicolon to every user action for reductions when the output language defaulted to C (specifically, when @@ -191,7 +191,7 @@ Bison News about a missing semicolon where it did not before. Future releases of Bison will cease to append semicolons entirely. -** Character literals not of length one. +** Character literals not of length one: Previously, Bison quietly converted all character literals to length one. For example, without warning, Bison interpreted the operators in @@ -202,7 +202,7 @@ Bison News ; Bison now warns when a character literal is not of length one. In - some future release, Bison will report an error instead. + some future release, Bison will start reporting an error instead. ** Verbose syntax error message fixes: @@ -242,14 +242,14 @@ Bison News canonical LR. However, LAC is still experimental and is disabled by default. -** Destructor calls fixed for lookaheads altered in semantic actions. +** Destructor calls fixed for lookaheads altered in semantic actions: Previously for deterministic parsers in C, if a user semantic action altered yychar, the parser in some cases used the old yychar value to determine which destructor to call for the lookahead upon a syntax error or upon parser return. This bug has been fixed. -** C++ parsers use YYRHSLOC +** C++ parsers use YYRHSLOC: Similarly to the C parsers, the C++ parsers now define the YYRHSLOC macro and use it in the default YYLLOC_DEFAULT. You are encouraged @@ -284,7 +284,7 @@ Bison News } \ while (false) -** YYLLOC_DEFAULT in C++ +** YYLLOC_DEFAULT in C++: The default implementation of YYLLOC_DEFAULT used to be issued in the header file. It is now output in the implementation file, after