re2: add CapturingGroupNames
Export from Google source tree.
R=rsc
CC=re2-dev
http://codereview.appspot.com/3981051
diff --git a/re2/regexp.cc b/re2/regexp.cc
index 6ecf834..d8d3cda 100644
--- a/re2/regexp.cc
+++ b/re2/regexp.cc
@@ -559,6 +559,46 @@
return w.TakeMap();
}
+// Walker class to build map from capture group indices to their names.
+class CaptureNamesWalker : public Regexp::Walker<Ignored> {
+ public:
+ CaptureNamesWalker() : map_(NULL) {}
+ ~CaptureNamesWalker() { delete map_; }
+
+ map<int, string>* TakeMap() {
+ map<int, string>* m = map_;
+ map_ = NULL;
+ return m;
+ }
+
+ Ignored PreVisit(Regexp* re, Ignored ignored, bool* stop) {
+ if (re->op() == kRegexpCapture && re->name() != NULL) {
+ // Allocate map once we find a name.
+ if (map_ == NULL)
+ map_ = new map<int, string>;
+
+ (*map_)[re->cap()] = *re->name();
+ }
+ return ignored;
+ }
+
+ virtual Ignored ShortVisit(Regexp* re, Ignored ignored) {
+ // Should never be called: we use Walk not WalkExponential.
+ LOG(DFATAL) << "CaptureNamesWalker::ShortVisit called";
+ return ignored;
+ }
+
+ private:
+ map<int, string>* map_;
+ DISALLOW_EVIL_CONSTRUCTORS(CaptureNamesWalker);
+};
+
+map<int, string>* Regexp::CaptureNames() {
+ CaptureNamesWalker w;
+ w.Walk(this, 0);
+ return w.TakeMap();
+}
+
// 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
