Adding SearchableList for implementing a list with fast search capability.

src/list-inl.h

Index: src/list-inl.h
===================================================================
--- src/list-inl.h	(revision 6372)
+++ src/list-inl.h	(working copy)
@@ -201,6 +201,65 @@
 }
 
 
+template<typename T, class P>
+void SearchableList<T, P>::Add(const T& element) {
+  is_sorted_ = false;
+  List<T, P>::Add(element);
+}
+
+
+template<typename T, class P>
+void SearchableList<T, P>::AddAll(const List<T, P>& other) {
+  is_sorted_ = false;
+  List<T, P>::AddAll(other);
+}
+
+
+template<typename T, class P>
+Vector<T> SearchableList<T, P>::AddBlock(T value, int count) {
+  is_sorted_ = false;
+  return List<T, P>::AddBlock(value, count);
+}
+
+
+template<typename T, class P>
+bool SearchableList<T, P>::Contains(const T& elm) {
+  if (is_sorted_) {
+    return ContainsSorted(elm);
+  }
+  return List<T, P>::Contains(elm);
+}
+
+
+template<typename T, class P>
+bool SearchableList<T, P>::Contains(const T& elm, bool ensure_sorted) {
+  if (ensure_sorted) {
+    Sort();  // Will only sort if not already sorted.
+  }
+  return List<T, P>::Contains(elm);
+}
+
+
+template<typename T, class P>
+void SearchableList<T, P>::Sort() {
+  if (!is_sorted_) {
+    List<T, P>::Sort(comparator_);
+    is_sorted_ = true;
+  }
+}
+
+
+template<typename T, class P>
+bool SearchableList<T, P>::ContainsSorted(const T& elm) {
+  typedef int (*RawComparer)(const void*, const void*);
+  return (NULL != bsearch(&elm,
+                          List<T, P>::data(),
+                          List<T, P>::length(),
+                          sizeof(T),
+                          reinterpret_cast<RawComparer>(comparator_)));
+}
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_LIST_INL_H_