[Feature #13712] String#start_with? supports regexp

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60234 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 77 insertions, 0 deletions

diff --git a/re.c b/re.c
index c1c29aea37..a78672b6bb 100644
--- a/re.c
+++ b/re.c
@@ -1580,6 +1580,83 @@ rb_reg_search(VALUE re, VALUE str, long pos, int reverse)
     return rb_reg_search0(re, str, pos, reverse, 1);
 }
 
+bool
+rb_reg_start_with_p(VALUE re, VALUE str)
+{
+    long result;
+    VALUE match;
+    struct re_registers regi, *regs = &regi;
+    regex_t *reg;
+    int tmpreg;
+    onig_errmsg_buffer err = "";
+
+    reg = rb_reg_prepare_re0(re, str, err);
+    tmpreg = reg != RREGEXP_PTR(re);
+    if (!tmpreg) RREGEXP(re)->usecnt++;
+
+    match = rb_backref_get();
+    if (!NIL_P(match)) {
+	if (FL_TEST(match, MATCH_BUSY)) {
+	    match = Qnil;
+	}
+	else {
+	    regs = RMATCH_REGS(match);
+	}
+    }
+    if (NIL_P(match)) {
+	MEMZERO(regs, struct re_registers, 1);
+    }
+    result = onig_match(reg,
+	    (UChar*)(RSTRING_PTR(str)),
+	    ((UChar*)(RSTRING_PTR(str)) + RSTRING_LEN(str)),
+	    (UChar*)(RSTRING_PTR(str)),
+	    regs, ONIG_OPTION_NONE);
+    if (!tmpreg) RREGEXP(re)->usecnt--;
+    if (tmpreg) {
+	if (RREGEXP(re)->usecnt) {
+	    onig_free(reg);
+	}
+	else {
+	    onig_free(RREGEXP_PTR(re));
+	    RREGEXP_PTR(re) = reg;
+	}
+    }
+    if (result < 0) {
+	if (regs == &regi)
+	    onig_region_free(regs, 0);
+	if (result == ONIG_MISMATCH) {
+	    rb_backref_set(Qnil);
+	    return false;
+	}
+	else {
+	    onig_error_code_to_str((UChar*)err, (int)result);
+	    rb_reg_raise(RREGEXP_SRC_PTR(re), RREGEXP_SRC_LEN(re), err, re);
+	}
+    }
+
+    if (NIL_P(match)) {
+	int err;
+	match = match_alloc(rb_cMatch);
+	err = rb_reg_region_copy(RMATCH_REGS(match), regs);
+	onig_region_free(regs, 0);
+	if (err) rb_memerror();
+    }
+    else {
+	FL_UNSET(match, FL_TAINT);
+    }
+
+    RMATCH(match)->str = rb_str_new4(str);
+    OBJ_INFECT(match, str);
+
+    RMATCH(match)->regexp = re;
+    RMATCH(match)->rmatch->char_offset_updated = 0;
+    rb_backref_set(match);
+
+    OBJ_INFECT(match, re);
+
+    return true;
+}
+
 VALUE
 rb_reg_nth_defined(int nth, VALUE match)
 {