Replace the use CharacterStreams in Heap::AllocateSymbolInternal and String::ComputeHash

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3024 matching lines @@
       int length,
       Object** s);
   MUST_USE_RESULT MaybeObject* LookupTwoByteSymbol(Vector<const uc16> str,
                                                    Object** s);
   MUST_USE_RESULT MaybeObject* LookupString(String* key, Object** s);
 
   // Looks up a symbol that is equal to the given string and returns
   // true if it is found, assigning the symbol to the given output
   // parameter.
   bool LookupSymbolIfExists(String* str, String** symbol);
-  bool LookupTwoCharsSymbolIfExists(uint32_t c1, uint32_t c2, String** symbol);
+  bool LookupTwoCharsSymbolIfExists(uint16_t c1, uint16_t c2, String** symbol);
 
   // Casting.
   static inline SymbolTable* cast(Object* obj);
 
  private:
   MUST_USE_RESULT MaybeObject* LookupKey(HashTableKey* key, Object** s);
 
   template <bool seq_ascii> friend class JsonParser;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(SymbolTable);
@@ skipping 3844 matching lines @@
 
 
 enum AllowNullsFlag {ALLOW_NULLS, DISALLOW_NULLS};
 enum RobustnessFlag {ROBUST_STRING_TRAVERSAL, FAST_STRING_TRAVERSAL};
 
 
 class StringHasher {
  public:
   explicit inline StringHasher(int length, uint32_t seed);
 
-  // Returns true if the hash of this string can be computed without
-  // looking at the contents.
-  inline bool has_trivial_hash();
+  template <typename schar>
+  static inline uint32_t HashSequentialString(const schar* chars,
+                                              int length,
+                                              uint32_t seed);
 
-  // Add a character to the hash and update the array index calculation.
-  inline void AddCharacter(uint32_t c);
-
-  // Adds a character to the hash but does not update the array index
-  // calculation.  This can only be called when it has been verified
-  // that the input is not an array index.
-  inline void AddCharacterNoIndex(uint32_t c);
-
-  // Add a character above 0xffff as a surrogate pair.  These can get into
-  // the hasher through the routines that take a UTF-8 string and make a symbol.
-  void AddSurrogatePair(uc32 c);
-  void AddSurrogatePairNoIndex(uc32 c);
-
-  // Returns the value to store in the hash field of a string with
-  // the given length and contents.
-  uint32_t GetHashField();
-
-  // Returns true if the characters seen so far make up a legal array
-  // index.
-  bool is_array_index() { return is_array_index_; }
+  static uint32_t ComputeHashField(unibrow::CharacterStream* buffer,
+                                   int length,
+                                   uint32_t seed);
 
   // Calculated hash value for a string consisting of 1 to
   // String::kMaxArrayIndexSize digits with no leading zeros (except "0").
   // value is represented decimal value.
   static uint32_t MakeArrayIndexHash(uint32_t value, int length);
 
   // No string is allowed to have a hash of zero.  That value is reserved
   // for internal properties.  If the hash calculation yields zero then we
   // use 27 instead.
   static const int kZeroHash = 27;
 
+  // Reusable parts of the hashing algorithm.
+  INLINE(static uint32_t AddCharacterCore(uint32_t running_hash, uint16_t c));
+  INLINE(static uint32_t GetHashCore(uint32_t running_hash));
+
+ protected:
+  // Returns the value to store in the hash field of a string with
+  // the given length and contents.
+  uint32_t GetHashField();
+  // Returns true if the hash of this string can be computed without
+  // looking at the contents.
+  inline bool has_trivial_hash();
+  // Adds a block of characters to the hash.
+  template<typename Char>
+  inline void AddCharacters(const Char* chars, int len);
+
  private:
-  uint32_t array_index() {
-    ASSERT(is_array_index());
-    return array_index_;
-  }
-
-  inline uint32_t GetHash();
-
-  // Reusable parts of the hashing algorithm.
-  INLINE(static uint32_t AddCharacterCore(uint32_t running_hash, uint32_t c));
-  INLINE(static uint32_t GetHashCore(uint32_t running_hash));
+  // Add a character to the hash.
+  inline void AddCharacter(uint16_t c);
+  // Update index. Returns true if string is still an index.
+  inline bool UpdateIndex(uint16_t c);
 
   int length_;
   uint32_t raw_running_hash_;
   uint32_t array_index_;
   bool is_array_index_;
   bool is_first_char_;
-  friend class TwoCharHashTableKey;
-
-  template <bool seq_ascii> friend class JsonParser;
+  DISALLOW_COPY_AND_ASSIGN(StringHasher);
 };
 
 
-class IncrementalAsciiStringHasher {
- public:
-  explicit inline IncrementalAsciiStringHasher(uint32_t seed, char first_char);
-  inline void AddCharacter(uc32 c);
-  inline uint32_t GetHash();
-
- private:
-  int length_;
-  uint32_t raw_running_hash_;
-  uint32_t array_index_;
-  bool is_array_index_;
-  char first_char_;
-};
-
-
-// Calculates string hash.
-template <typename schar>
-inline uint32_t HashSequentialString(const schar* chars,
-                                     int length,
-                                     uint32_t seed);
-
-
 // The characteristics of a string are stored in its map.  Retrieving these
 // few bits of information is moderately expensive, involving two memory
 // loads where the second is dependent on the first.  To improve efficiency
 // the shape of the string is given its own class so that it can be retrieved
 // once and used for several string operations.  A StringShape is small enough
 // to be passed by value and is immutable, but be aware that flattening a
 // string can potentially alter its shape.  Also be aware that a GC caused by
 // something else can alter the shape of a string due to ConsString
 // shortcutting.  Keeping these restrictions in mind has proven to be error-
 // prone and so we no longer put StringShapes in variables unless there is a
@@ skipping 198 matching lines @@
   // do any heap allocations.  This is useful when printing stack traces.
   SmartArrayPointer<uc16> ToWideCString(
       RobustnessFlag robustness_flag = FAST_STRING_TRAVERSAL);
 
   // Tells whether the hash code has been computed.
   inline bool HasHashCode();
 
   // Returns a hash value used for the property table
   inline uint32_t Hash();
 
-  static uint32_t ComputeHashField(unibrow::CharacterStream* buffer,
-                                   int length,
-                                   uint32_t seed);
-
   static bool ComputeArrayIndex(unibrow::CharacterStream* buffer,
                                 uint32_t* index,
                                 int length);
 
   // Externalization.
   bool MakeExternal(v8::String::ExternalStringResource* resource);
   bool MakeExternal(v8::String::ExternalAsciiStringResource* resource);
 
   // Conversion.
   inline bool AsArrayIndex(uint32_t* index);
@@ skipping 619 matching lines @@
 // not always desirable, however (esp. in debugging situations).
 class StringInputBuffer: public unibrow::InputBuffer<String, String*, 1024> {
  public:
   virtual void Seek(unsigned pos);
   inline StringInputBuffer(): unibrow::InputBuffer<String, String*, 1024>() {}
   explicit inline StringInputBuffer(String* backing):
       unibrow::InputBuffer<String, String*, 1024>(backing) {}
 };
 
 
+// A ConsStringOp that returns null.
+// Useful when the operation to apply on a ConsString
+// requires an expensive data structure.
+struct ConsStringNullOp {
+  static inline String* Operate(String*, unsigned*, int32_t*, unsigned*);
+};
+
+
 // This maintains an off-stack representation of the stack frames required
 // to traverse a ConsString, allowing an entirely iterative and restartable
 // traversal of the entire string
 // Note: this class is not GC-safe.
 class ConsStringIteratorOp {
  public:
-  struct ContinueResponse {
-    String* string_;
-    unsigned offset_;
-    unsigned length_;
-    int32_t type_;
-  };
   inline ConsStringIteratorOp() {}
-  String* Operate(ConsString* cons_string, unsigned* offset_out,
-      int32_t* type_out, unsigned* length_out);
-  inline bool ContinueOperation(ContinueResponse* response);
+  String* Operate(String* string,
+                  unsigned* offset_out,
+                  int32_t* type_out,
+                  unsigned* length_out);
+  inline String* ContinueOperation(int32_t* type_out, unsigned* length_out);
   inline void Reset();
   inline bool HasMore();
 
  private:
   // TODO(dcarney): Templatize this out for different stack sizes.
   static const unsigned kStackSize = 32;
   // Use a mask instead of doing modulo operations for stack wrapping.
   static const unsigned kDepthMask = kStackSize-1;
   STATIC_ASSERT(IS_POWER_OF_TWO(kStackSize));
   static inline unsigned OffsetForDepth(unsigned depth);
 
   inline void PushLeft(ConsString* string);
   inline void PushRight(ConsString* string);
   inline void AdjustMaximumDepth();
   inline void Pop();
   String* NextLeaf(bool* blew_stack, int32_t* type_out, unsigned* length_out);
+  String* Search(unsigned* offset_out,
+                 int32_t* type_out,
+                 unsigned* length_out);
 
   unsigned depth_;
   unsigned maximum_depth_;
   // Stack must always contain only frames for which right traversal
   // has not yet been performed.
   ConsString* frames_[kStackSize];
   unsigned consumed_;
   ConsString* root_;
-  int32_t root_type_;
-  unsigned root_length_;
   DISALLOW_COPY_AND_ASSIGN(ConsStringIteratorOp);
 };
 
 
 // Note: this class is not GC-safe.
 class StringCharacterStream {
  public:
-  inline StringCharacterStream(
-      String* string, unsigned offset, ConsStringIteratorOp* op);
+  inline StringCharacterStream(String* string,
+                               unsigned offset,
+                               ConsStringIteratorOp* op);
   inline uint16_t GetNext();
   inline bool HasMore();
   inline void Reset(String* string, unsigned offset, ConsStringIteratorOp* op);
   inline void VisitOneByteString(const uint8_t* chars, unsigned length);
   inline void VisitTwoByteString(const uint16_t* chars, unsigned length);
 
  private:
   bool is_one_byte_;
   union {
     const uint8_t* buffer8_;
@@ skipping 970 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_