CSE2410 Fall 2014 Bounce

#include "hashmap.h"

#include "list.h"

class UnicodeCache {

// ---------------------------------------------------------------------

// DuplicateFinder discovers duplicate symbols.

class DuplicateFinder {

 public:

  explicit DuplicateFinder(UnicodeCache* constants)

      : unicode_constants_(constants),

        backing_store_(16),

        map_(&Match) { }

  int AddAsciiSymbol(Vector<const char> key, int value);

  int AddUtf16Symbol(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 AddAsciiSymbol.

  // 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 char> key, int value);

 private:

  int AddSymbol(Vector<const byte> key, bool is_ascii, 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 ASCII),

  // followed by the bytes of the key.

  byte* BackupKey(Vector<const byte> key, bool is_ascii);

  // Compare two encoded keys (both pointing into the backing store)

  // for having the same base-127 encoded lengths and ASCII-ness,

  // 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 byte> key, bool is_ascii);

  // Checks whether a string containing a JS number is its canonical

  // form.

  static bool IsNumberCanonical(Vector<const char> 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_;

  HashMap map_;

  // Buffer used for string->number->canonical string conversions.

  char number_buffer_[kBufferSize];

};