Separate DuplicateFinder from Scanner.

src/parsing/duplicate-finder.h

+// Copyright 2011 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_PARSING_DUPLICATE_FINDER_H_
+#define V8_PARSING_DUPLICATE_FINDER_H_
+
+#include "src/base/hashmap.h"
+#include "src/collector.h"
+
+namespace v8 {
+namespace internal {
+
+class UnicodeCache;
+
+// DuplicateFinder discovers duplicate symbols.
+class DuplicateFinder {
+ public:
+  explicit DuplicateFinder(UnicodeCache* constants)
+      : unicode_constants_(constants), backing_store_(16), map_(&Match) {}
+
+  int AddOneByteSymbol(Vector<const uint8_t> key, int value);
+  int AddTwoByteSymbol(Vector<const uint16_t> key, int value);
+  // Add a a number literal by converting it (if necessary)
+  // to the string that ToString(ToNumber(literal)) would generate.
+  // and then adding that string with AddOneByteSymbol.
+  // This string is the actual value used as key in an object literal,
+  // and the one that must be different from the other keys.
+  int AddNumber(Vector<const uint8_t> key, int value);
+
+ private:
+  int AddSymbol(Vector<const uint8_t> key, bool is_one_byte, int value);
+  // Backs up the key and its length in the backing store.
+  // The backup is stored with a base 127 encoding of the
+  // length (plus a bit saying whether the string is one byte),
+  // followed by the bytes of the key.
+  uint8_t* BackupKey(Vector<const uint8_t> key, bool is_one_byte);
+
+  // Compare two encoded keys (both pointing into the backing store)
+  // for having the same base-127 encoded lengths and representation.
+  // and then having the same 'length' bytes following.
+  static bool Match(void* first, void* second);
+  // Creates a hash from a sequence of bytes.
+  static uint32_t Hash(Vector<const uint8_t> key, bool is_one_byte);
+  // Checks whether a string containing a JS number is its canonical
+  // form.
+  static bool IsNumberCanonical(Vector<const uint8_t> key);
+
+  // Size of buffer. Sufficient for using it to call DoubleToCString in
+  // from conversions.h.
+  static const int kBufferSize = 100;
+
+  UnicodeCache* unicode_constants_;
+  // Backing store used to store strings used as hashmap keys.
+  SequenceCollector<unsigned char> backing_store_;
+  base::HashMap map_;
+  // Buffer used for string->number->canonical string conversions.
+  char number_buffer_[kBufferSize];
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_PARSING_DUPLICATE_FINDER_H_