Maintain the invariant that the pattern string in an atom regexp is always ...

src/jsregexp.cc

Index: src/jsregexp.cc
===================================================================
--- src/jsregexp.cc	(revision 5888)
+++ src/jsregexp.cc	(working copy)
@@ -33,6 +33,7 @@
 #include "factory.h"
 #include "jsregexp.h"
 #include "platform.h"
+#include "string-search.h"
 #include "runtime.h"
 #include "top.h"
 #include "compilation-cache.h"
@@ -120,7 +121,7 @@
     re->set_data(*cached);
     return re;
   }
-  FlattenString(pattern);
+  pattern = FlattenGetString(pattern);
   CompilationZoneScope zone_scope(DELETE_ON_EXIT);
   PostponeInterruptsScope postpone;
   RegExpCompileData parse_result;
@@ -205,23 +206,61 @@
   RegExpImpl::SetCapture(array, 1, to);
 }
 
+  /* template <typename SubjectChar>, typename PatternChar>
+static int ReStringMatch(Vector<const SubjectChar> sub_vector,
+                         Vector<const PatternChar> pat_vector,
+                         int start_index) {
 
+  int pattern_length = pat_vector.length();
+  if (pattern_length == 0) return start_index;
+
+  int subject_length = sub_vector.length();
+  if (start_index + pattern_length > subject_length) return -1;
+  return SearchString(sub_vector, pat_vector, start_index);
+}
+  */
 Handle<Object> RegExpImpl::AtomExec(Handle<JSRegExp> re,
                                     Handle<String> subject,
                                     int index,
                                     Handle<JSArray> last_match_info) {
-  Handle<String> needle(String::cast(re->DataAt(JSRegExp::kAtomPatternIndex)));
+  ASSERT(0 <= index);
+  ASSERT(index <= subject->length());
 
-  uint32_t start_index = index;
+  if (!subject->IsFlat()) FlattenString(subject);
+  AssertNoAllocation no_heap_allocation;  // ensure vectors stay valid
+  // Extract flattened substrings of cons strings before determining asciiness.
+  String* seq_sub = *subject;
+  if (seq_sub->IsConsString()) seq_sub = ConsString::cast(seq_sub)->first();
 
-  int value = Runtime::StringMatch(subject, needle, start_index);
-  if (value == -1) return Factory::null_value();
+  String* needle = String::cast(re->DataAt(JSRegExp::kAtomPatternIndex));
+  int needle_len = needle->length();
+
+  if (needle_len != 0) {
+    if (index + needle_len > subject->length()) return Factory::null_value();
+    // dispatch on type of strings
+    index = (needle->IsAsciiRepresentation()
+             ? (seq_sub->IsAsciiRepresentation()
+                ? SearchString(seq_sub->ToAsciiVector(),
+                               needle->ToAsciiVector(),
+                               index)
+                : SearchString(seq_sub->ToUC16Vector(),
+                               needle->ToAsciiVector(),
+                               index))
+             : (seq_sub->IsAsciiRepresentation()
+                ? SearchString(seq_sub->ToAsciiVector(),
+                               needle->ToUC16Vector(),
+                               index)
+                : SearchString(seq_sub->ToUC16Vector(),
+                               needle->ToUC16Vector(),
+                               index)));
+    if (index == -1) return Factory::null_value();
+  }
   ASSERT(last_match_info->HasFastElements());
 
   {
     NoHandleAllocation no_handles;
     FixedArray* array = FixedArray::cast(last_match_info->elements());
-    SetAtomLastCapture(array, *subject, value, value + needle->length());
+    SetAtomLastCapture(array, *subject, index, index + needle_len);
   }
   return last_match_info;
 }
@@ -364,7 +403,7 @@
     AssertNoAllocation no_gc;
     String* sequential_string = *subject;
     if (subject->IsConsString()) {
-      sequential_string =  ConsString::cast(*subject)->first();
+      sequential_string = ConsString::cast(*subject)->first();
     }
     is_ascii = sequential_string->IsAsciiRepresentation();
   }