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: DuplicateFinder(UnicodeCache * constants)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::CustomMatcherHashMap 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_ 65