LiveEdit: optimize substring comparison

src/liveedit.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 250 matching lines @@
 
 void Comparator::CalculateDifference(Comparator::Input* input,
                                      Comparator::Output* result_writer) {
   Differencer differencer(input);
   differencer.Initialize();
   differencer.FillTable();
   differencer.SaveResult(result_writer);
 }
 
 
-static bool CompareSubstrings(Isolate* isolate, Handle<String> s1, int pos1,
+static bool CompareSubstrings(Handle<String> s1, int pos1,
                               Handle<String> s2, int pos2, int len) {
-  StringInputBuffer& buf1 = *isolate->liveedit_compare_substrings_buf1();
-  StringInputBuffer& buf2 = *isolate->liveedit_compare_substrings_buf2();
-  buf1.Reset(*s1);
-  buf1.Seek(pos1);
-  buf2.Reset(*s2);
-  buf2.Seek(pos2);
   for (int i = 0; i < len; i++) {
-    ASSERT(buf1.has_more() && buf2.has_more());
-    if (buf1.GetNext() != buf2.GetNext()) {
+    if (s1->Get(i + pos1) != s2->Get(i + pos2)) {
       return false;
     }
   }
   return true;
 }
 
 
 // A helper class that writes chunk numbers into JSArray.
 // Each chunk is stored as 3 array elements: (pos1_begin, pos1_end, pos2_end).
 class CompareOutputArrayWriter {
@@ skipping 111 matching lines @@
 
   int GetPosAfterNewLine(int index) {
     return Smi::cast(ends_array_->get(index))->value() + 1;
   }
 };
 
 
 // Represents 2 strings as 2 arrays of lines.
 class LineArrayCompareInput : public Comparator::Input {
  public:
-  LineArrayCompareInput(Isolate* isolate, Handle<String> s1, Handle<String> s2,
+  LineArrayCompareInput(Handle<String> s1, Handle<String> s2,
                         LineEndsWrapper line_ends1, LineEndsWrapper line_ends2)
-      : isolate_(isolate), s1_(s1), s2_(s2), line_ends1_(line_ends1),
+      : s1_(s1), s2_(s2), line_ends1_(line_ends1),
         line_ends2_(line_ends2) {
   }
   int getLength1() {
     return line_ends1_.length();
   }
   int getLength2() {
     return line_ends2_.length();
   }
   bool equals(int index1, int index2) {
     int line_start1 = line_ends1_.GetLineStart(index1);
     int line_start2 = line_ends2_.GetLineStart(index2);
     int line_end1 = line_ends1_.GetLineEnd(index1);
     int line_end2 = line_ends2_.GetLineEnd(index2);
     int len1 = line_end1 - line_start1;
     int len2 = line_end2 - line_start2;
     if (len1 != len2) {
       return false;
     }
-    return CompareSubstrings(isolate_, s1_, line_start1, s2_, line_start2,
+    return CompareSubstrings(s1_, line_start1, s2_, line_start2,
                              len1);
   }
 
  private:
-  Isolate* isolate_;
   Handle<String> s1_;
   Handle<String> s2_;
   LineEndsWrapper line_ends1_;
   LineEndsWrapper line_ends2_;
 };
 
 
 // Stores compare result in JSArray. For each chunk tries to conduct
 // a fine-grained nested diff token-wise.
 class TokenizingLineArrayCompareOutput : public Comparator::Output {
@@ skipping 35 matching lines @@
   CompareOutputArrayWriter array_writer_;
   LineEndsWrapper line_ends1_;
   LineEndsWrapper line_ends2_;
   Handle<String> s1_;
   Handle<String> s2_;
 };
 
 
 Handle<JSArray> LiveEdit::CompareStrings(Handle<String> s1,
                                          Handle<String> s2) {
+  s1 = FlattenGetString(s1);
+  s2 = FlattenGetString(s2);
+
   LineEndsWrapper line_ends1(s1);
   LineEndsWrapper line_ends2(s2);
 
-  LineArrayCompareInput
-      input(Isolate::Current(), s1, s2, line_ends1, line_ends2);
+  LineArrayCompareInput input(s1, s2, line_ends1, line_ends2);
   TokenizingLineArrayCompareOutput output(line_ends1, line_ends2, s1, s2);
 
   Comparator::CalculateDifference(&input, &output);
 
   return output.GetResult();
 }
 
 
 static void CompileScriptForTracker(Isolate* isolate, Handle<Script> script) {
   // TODO(635): support extensions.
@@ skipping 1174 matching lines @@
 
 bool LiveEditFunctionTracker::IsActive() {
   return false;
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 
 } }  // namespace v8::internal