diff options
| -rw-r--r-- | ChangeLog | 12 | ||||
| -rw-r--r-- | parser.y | 4 |
2 files changed, 14 insertions, 2 deletions
@@ -1,3 +1,15 @@ +2010-01-06 Kaz Kylheku <kkylheku@gmail.com> + + Some fine tuning in regex grammar. + + * parser.y (regex): Empty regex handled by + allowing regex to generate empty, rather than + a special case production for '/' '/'. Thus + empty subexpressions are possible. + (regbranch, regterm): Complement is handled + in regbranch, so that it has lower precedence + than aggregation. + 2010-01-05 Kaz Kylheku <kkylheku@gmail.com> Implemented the regular expression ~ and & operators. @@ -449,7 +449,6 @@ expr : IDENT { $$ = intern(string_own($1), nil); } ; regex : '/' regexpr '/' { $$ = $2; } - | '/' '/' { $$ = nil; } | '/' error { $$ = nil; yybadtoken(yychar, lit("regex")); } ; @@ -459,10 +458,12 @@ regexpr : regbranch { $$ = $1; } $3, nao), nao); } | regexpr '&' regexpr { $$ = list(list(and_s, $1, $3, nao), nao); } + | /* empty */ { $$ = nil; } ; regbranch : regterm { $$ = cons($1, nil); } | regterm regbranch { $$ = cons($1, $2); } + | '~' regbranch { $$ = cons(cons(compl_s, $2), nil); } ; regterm : '[' regclass ']' { $$ = cons(set_s, $2); } @@ -474,7 +475,6 @@ regterm : '[' regclass ']' { $$ = cons(set_s, $2); } | regterm '*' { $$ = list(zeroplus_s, $1, nao); } | regterm '+' { $$ = list(oneplus_s, $1, nao); } | regterm '?' { $$ = list(optional_s, $1, nao); } - | '~' regterm { $$ = list(compl_s, $2, nao); } | REGCHAR { $$ = chr($1); } | '(' regexpr ')' { $$ = cons(compound_s, $2); } | '(' error { $$ = nil; |