X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/6721294104e47dd932e755d4d5352407859a4663..5b1ff42379edbbf37b135d33aa5fb3c72da2dca1:/NEWS diff --git a/NEWS b/NEWS index b9ce898c..d5851390 100644 --- a/NEWS +++ b/NEWS @@ -3,14 +3,81 @@ Bison News * Changes in version ?.? (????-??-??): -** Java skeleton improvements: +** Additional yylex/yyparse arguments + + The new directive %param declare additional argument to both yylex + and yyparse. The %lex-param, %parse-param, and %param directive + support one or more arguments. Instead of + + %lex-param {arg1_type *arg1} + %lex-param {arg2_type *arg2} + %parse-param {arg1_type *arg1} + %parse-param {arg2_type *arg2} + + one may now declare + + %param {arg1_type *arg1} {arg2_type *arg2} + +** 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". +** Variable api.tokens.prefix + + The variable api.tokens.prefix changes the way tokens are identified in + the generated files. This is especially useful to avoid collisions + with identifiers in the target language. For instance + + %token FILE for ERROR + %define api.tokens.prefix "TOK_" + %% + start: FILE for ERROR; + + will generate the definition of the symbols TOK_FILE, TOK_for, and + TOK_ERROR in the generated sources. In particular, the scanner must + use these prefixed token names, although the grammar itself still + uses the short names (as in the sample rule given above). + +** Variable api.namespace + + The "namespace" variable is renamed "api.namespace". Backward + compatibility is ensured, but upgrading is recommended. + +** Variable parse.error + + The variable error controls the verbosity of error messages. The + use of the %error-verbose directive is deprecated in favor of + %define parse.error "verbose". + * Changes in version 2.5 (????-??-??): +** Named References Support + + Historically, Yacc and Bison have supported positional references + ($n, $$) to allow access to symbol values from inside of semantic + actions code. + + Starting from this version, Bison can also accept named references. + When no ambiguity is possible, original symbol names may be used + as named references: + + if_stmt : 'if' cond_expr 'then' then_stmt ';' + { $if_stmt = mk_if_stmt($cond_expr, $then_stmt); } + + In the more common case, explicit names may be declared: + + stmt[res] : 'if' expr[cond] 'then' stmt[then] 'else' stmt[else] ';' + { $res = mk_if_stmt($cond, $then, $else); } + + Location information is also accessible using @name syntax. When + accessing symbol names containing dots or dashes, explicit bracketing + ($[sym.1]) must be used. + + These features are experimental in this version. More user feedback + will help to stabilize them. + ** IELR(1) and Canonical LR(1) Support IELR(1) is a minimal LR(1) parser table generation algorithm. That @@ -28,9 +95,9 @@ Bison News default. You can specify the type of parser tables in the grammar file with these directives: - %define lr.type "LALR" - %define lr.type "IELR" - %define lr.type "canonical LR" + %define lr.type lalr + %define lr.type ielr + %define lr.type canonical-lr The default reduction optimization in the parser tables can also be adjusted using `%define lr.default-reductions'. See the documentation @@ -41,21 +108,34 @@ Bison News These features are experimental. More user feedback will help to stabilize them. -** %define can now be invoked via the command line. +** Unrecognized %code qualifiers are now an error not a warning. + +** %define improvements. + +*** Unrecognized variables are now an error not a warning. + +*** Multiple invocations for any variable is now an error not a warning. + +*** Can now be invoked via the command line. - Each of these bison command-line options + Each of these command-line options - -D NAME=VALUE - --define=NAME=VALUE + -D NAME[=VALUE] + --define=NAME[=VALUE] + + -F NAME[=VALUE] + --force-define=NAME[=VALUE] is equivalent to this grammar file declaration - %define NAME "VALUE" + %define NAME ["VALUE"] - for any NAME and VALUE. Omitting `=VALUE' on the command line is - equivalent to omitting `"VALUE"' in the declaration. + except that the manner in which Bison processes multiple definitions + for the same NAME differs. Most importantly, -F and --force-define + quietly override %define, but -D and --define do not. For further + details, see the section "Bison Options" in the Bison manual. -** %define variables renamed. +*** Variables renamed. The following %define variables @@ -70,6 +150,25 @@ 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. + + If a %define value is an identifier, it no longer needs to be placed + within quotations marks. For example, + + %define api.push-pull "push" + + can be rewritten as + + %define api.push-pull push + +** Symbol names. + + 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). + ** Temporary hack for adding a semicolon to the user action. Previously, Bison appended a semicolon to every user action for @@ -91,8 +190,61 @@ 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. + + Previously, Bison quietly converted all character literals to length + one. For example, without warning, Bison interpreted the operators in + the following grammar to be the same token: + + exp: exp '++' + | exp '+' exp + ; + + Bison now warns when a character literal is not of length one. In + some future release, Bison will report an error instead. + +** Verbose error messages fixed for nonassociative tokens. + + When %error-verbose is specified, syntax error messages produced by + the generated parser include the unexpected token as well as a list of + expected tokens. Previously, this list erroneously included tokens + that would actually induce a syntax error because conflicts for them + were resolved with %nonassoc. Such tokens are now properly omitted + from the list. + * Changes in version 2.4.2 (????-??-??): +** Detection of GNU M4 1.4.6 or newer during configure is improved. + +** %code is now a permanent feature. + + A traditional Yacc prologue directive is written in the form: + + %{CODE%} + + To provide a more flexible alternative, Bison 2.3b introduced the + %code directive with the following forms for C/C++: + + %code {CODE} + %code requires {CODE} + %code provides {CODE} + %code top {CODE} + + These forms are now considered permanent features of Bison. See the + %code entries in the section "Bison Declaration Summary" in the Bison + manual for a summary of their functionality. See the section + "Prologue Alternatives" for a detailed discussion including the + advantages of %code over the traditional Yacc prologue directive. + + Bison's Java feature as a whole including its current usage of %code + is still considered experimental. + +** Internationalization. + + Fix a regression introduced in Bison 2.4: Under some circumstances, + message translations were not installed although supported by the + host system. + * Changes in version 2.4.1 (2008-12-11): ** In the GLR defines file, unexpanded M4 macros in the yylval and yylloc