re2: fix bitstate for empty char classes
Fixes issue 52.
R=rsc
CC=re2-dev
https://codereview.appspot.com/50370043
diff --git a/re2/compile.cc b/re2/compile.cc
index 9cddb71..0eb38e7 100644
--- a/re2/compile.cc
+++ b/re2/compile.cc
@@ -374,6 +374,8 @@
// Given a fragment for a, returns a fragment for a? or a?? (if nongreedy)
Frag Compiler::Quest(Frag a, bool nongreedy) {
+ if (IsNoMatch(a))
+ return Nop();
int id = AllocInst(1);
if (id < 0)
return NoMatch();
@@ -446,6 +448,8 @@
// Given a fragment a, returns a fragment with capturing parens around a.
Frag Compiler::Capture(Frag a, int n) {
+ if (IsNoMatch(a))
+ return NoMatch();
int id = AllocInst(2);
if (id < 0)
return NoMatch();
