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| 1 // Copyright 2011 the V8 project authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #ifndef V8_PARSING_DUPLICATE_FINDER_H_ |
| 6 #define V8_PARSING_DUPLICATE_FINDER_H_ |
| 7 |
| 8 #include "src/base/hashmap.h" |
| 9 #include "src/collector.h" |
| 10 |
| 11 namespace v8 { |
| 12 namespace internal { |
| 13 |
| 14 class UnicodeCache; |
| 15 |
| 16 // DuplicateFinder discovers duplicate symbols. |
| 17 class DuplicateFinder { |
| 18 public: |
| 19 explicit DuplicateFinder(UnicodeCache* constants) |
| 20 : unicode_constants_(constants), backing_store_(16), map_(&Match) {} |
| 21 |
| 22 int AddOneByteSymbol(Vector<const uint8_t> key, int value); |
| 23 int AddTwoByteSymbol(Vector<const uint16_t> key, int value); |
| 24 // Add a a number literal by converting it (if necessary) |
| 25 // to the string that ToString(ToNumber(literal)) would generate. |
| 26 // and then adding that string with AddOneByteSymbol. |
| 27 // This string is the actual value used as key in an object literal, |
| 28 // and the one that must be different from the other keys. |
| 29 int AddNumber(Vector<const uint8_t> key, int value); |
| 30 |
| 31 private: |
| 32 int AddSymbol(Vector<const uint8_t> key, bool is_one_byte, int value); |
| 33 // Backs up the key and its length in the backing store. |
| 34 // The backup is stored with a base 127 encoding of the |
| 35 // length (plus a bit saying whether the string is one byte), |
| 36 // followed by the bytes of the key. |
| 37 uint8_t* BackupKey(Vector<const uint8_t> key, bool is_one_byte); |
| 38 |
| 39 // Compare two encoded keys (both pointing into the backing store) |
| 40 // for having the same base-127 encoded lengths and representation. |
| 41 // and then having the same 'length' bytes following. |
| 42 static bool Match(void* first, void* second); |
| 43 // Creates a hash from a sequence of bytes. |
| 44 static uint32_t Hash(Vector<const uint8_t> key, bool is_one_byte); |
| 45 // Checks whether a string containing a JS number is its canonical |
| 46 // form. |
| 47 static bool IsNumberCanonical(Vector<const uint8_t> key); |
| 48 |
| 49 // Size of buffer. Sufficient for using it to call DoubleToCString in |
| 50 // from conversions.h. |
| 51 static const int kBufferSize = 100; |
| 52 |
| 53 UnicodeCache* unicode_constants_; |
| 54 // Backing store used to store strings used as hashmap keys. |
| 55 SequenceCollector<unsigned char> backing_store_; |
| 56 base::HashMap map_; |
| 57 // Buffer used for string->number->canonical string conversions. |
| 58 char number_buffer_[kBufferSize]; |
| 59 }; |
| 60 |
| 61 } // namespace internal |
| 62 } // namespace v8 |
| 63 |
| 64 #endif // V8_PARSING_DUPLICATE_FINDER_H_ |
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