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regex: rewrite the repetition parsing code

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The goto logic was hard to follow and modify. This is
in preparation for the BRE \+ and \? support.
This commit is contained in:
Szabolcs Nagy 2015-04-18 17:25:31 +00:00 committed by Rich Felker
parent da4cc13b97
commit 03498ec22a
1 changed files with 29 additions and 30 deletions
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59
src/regex/regcomp.c
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@ -984,41 +984,40 @@ static reg_errcode_t tre_parse(tre_parse_ctx_t *ctx)
/* extension: repetitions are rejected after an empty node
eg. (+), |*, {2}, but assertions are not treated as empty
so ^* or $? are accepted currently. */
switch (*s) {
case '+':
case '?':
if (!ere)
for (;;) {
if (*s!='\\' && *s!='*') {
if (!ere)
break;
if (*s!='+' && *s!='?' && *s!='{')
break;
}
if (*s=='\\' && ere)
break;
/* fallthrough */
case '*':;
int min=0, max=-1;
if (*s == '+')
min = 1;
if (*s == '?')
max = 1;
s++;
ctx->n = tre_ast_new_iter(ctx->mem, ctx->n, min, max, 0);
if (!ctx->n)
return REG_ESPACE;
if (*s=='\\' && s[1]!='{')
break;
if (*s=='\\')
s++;
/* extension: multiple consecutive *+?{,} is unspecified,
but (a+)+ has to be supported so accepting a++ makes
sense, note however that the RE_DUP_MAX limit can be
circumvented: (a{255}){255} uses a lot of memory.. */
goto parse_iter;
case '\\':
if (ere || s[1] != '{')
break;
s++;
goto parse_brace;
case '{':
if (!ere)
break;
parse_brace:
err = parse_dup(ctx, s+1);
if (err != REG_OK)
return err;
s = ctx->s;
goto parse_iter;
if (*s=='{') {
err = parse_dup(ctx, s+1);
if (err != REG_OK)
return err;
s = ctx->s;
} else {
int min=0, max=-1;
if (*s == '+')
min = 1;
if (*s == '?')
max = 1;
s++;
ctx->n = tre_ast_new_iter(ctx->mem, ctx->n, min, max, 0);
if (!ctx->n)
return REG_ESPACE;
}
}
nbranch = tre_ast_new_catenation(ctx->mem, nbranch, ctx->n);