Refactor Regexp::RequiredPrefix().
Change-Id: Ibb45dde63bde1b71d8237c7fa903b82b7914df2c
Reviewed-on: https://code-review.googlesource.com/c/re2/+/56210
Reviewed-by: Paul Wankadia <junyer@google.com>
diff --git a/re2/regexp.cc b/re2/regexp.cc
index 5732166..ea8b37e 100644
--- a/re2/regexp.cc
+++ b/re2/regexp.cc
@@ -658,78 +658,60 @@
return w.TakeMap();
}
+void ConvertRunesToBytes(bool latin1, Rune* runes, int nrunes,
+ std::string* bytes) {
+ if (latin1) {
+ bytes->resize(nrunes);
+ for (int i = 0; i < nrunes; i++)
+ (*bytes)[i] = static_cast<char>(runes[i]);
+ } else {
+ bytes->resize(nrunes * UTFmax); // worst case
+ char* p = &(*bytes)[0];
+ for (int i = 0; i < nrunes; i++)
+ p += runetochar(p, &runes[i]);
+ bytes->resize(p - &(*bytes)[0]);
+ bytes->shrink_to_fit();
+ }
+}
+
// Determines whether regexp matches must be anchored
// with a fixed string prefix. If so, returns the prefix and
// the regexp that remains after the prefix. The prefix might
// be ASCII case-insensitive.
bool Regexp::RequiredPrefix(std::string* prefix, bool* foldcase,
Regexp** suffix) {
+ prefix->clear();
+ *foldcase = false;
+ *suffix = NULL;
+
// No need for a walker: the regexp must be of the form
// 1. some number of ^ anchors
// 2. a literal char or string
// 3. the rest
- prefix->clear();
- *foldcase = false;
- *suffix = NULL;
if (op_ != kRegexpConcat)
return false;
-
- // Some number of anchors, then a literal or concatenation.
- int i = 0;
Regexp** sub = this->sub();
+ int i = 0;
while (i < nsub_ && sub[i]->op_ == kRegexpBeginText)
i++;
if (i == 0 || i >= nsub_)
return false;
+ if (sub[i]->op_ != kRegexpLiteral &&
+ sub[i]->op_ != kRegexpLiteralString)
+ return false;
- Regexp* re = sub[i];
- switch (re->op_) {
- default:
- return false;
-
- case kRegexpLiteralString:
- // Convert to string in proper encoding.
- if (re->parse_flags() & Latin1) {
- prefix->resize(re->nrunes_);
- for (int j = 0; j < re->nrunes_; j++)
- (*prefix)[j] = static_cast<char>(re->runes_[j]);
- } else {
- // Convert to UTF-8 in place.
- // Assume worst-case space and then trim.
- prefix->resize(re->nrunes_ * UTFmax);
- char *p = &(*prefix)[0];
- for (int j = 0; j < re->nrunes_; j++) {
- Rune r = re->runes_[j];
- if (r < Runeself)
- *p++ = static_cast<char>(r);
- else
- p += runetochar(p, &r);
- }
- prefix->resize(p - &(*prefix)[0]);
- }
- break;
-
- case kRegexpLiteral:
- if ((re->parse_flags() & Latin1) || re->rune_ < Runeself) {
- prefix->append(1, static_cast<char>(re->rune_));
- } else {
- char buf[UTFmax];
- prefix->append(buf, runetochar(buf, &re->rune_));
- }
- break;
- }
+ bool latin1 = (sub[i]->parse_flags() & Latin1) != 0;
+ Rune* runes = sub[i]->op_ == kRegexpLiteral ? &sub[i]->rune_ : sub[i]->runes_;
+ int nrunes = sub[i]->op_ == kRegexpLiteral ? 1 : sub[i]->nrunes_;
+ ConvertRunesToBytes(latin1, runes, nrunes, prefix);
*foldcase = (sub[i]->parse_flags() & FoldCase) != 0;
- i++;
-
- // The rest.
- if (i < nsub_) {
+ if (++i < nsub_) {
for (int j = i; j < nsub_; j++)
sub[j]->Incref();
- re = Concat(sub + i, nsub_ - i, parse_flags());
+ *suffix = Concat(sub + i, nsub_ - i, parse_flags());
} else {
- re = new Regexp(kRegexpEmptyMatch, parse_flags());
+ *suffix = new Regexp(kRegexpEmptyMatch, parse_flags());
}
- *suffix = re;
return true;
}
