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1 // Copyright 2006-2008 the V8 project authors. All rights reserved. | 1 // Copyright 2006-2008 the V8 project authors. All rights reserved. |
2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
4 // met: | 4 // met: |
5 // | 5 // |
6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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3017 bool is_valid_; | 3017 bool is_valid_; |
3018 }; | 3018 }; |
3019 | 3019 |
3020 | 3020 |
3021 // The characteristics of a string are stored in its map. Retrieving these | 3021 // The characteristics of a string are stored in its map. Retrieving these |
3022 // few bits of information is moderately expensive, involving two memory | 3022 // few bits of information is moderately expensive, involving two memory |
3023 // loads where the second is dependent on the first. To improve efficiency | 3023 // loads where the second is dependent on the first. To improve efficiency |
3024 // the shape of the string is given its own class so that it can be retrieved | 3024 // the shape of the string is given its own class so that it can be retrieved |
3025 // once and used for several string operations. A StringShape is small enough | 3025 // once and used for several string operations. A StringShape is small enough |
3026 // to be passed by value and is immutable, but be aware that flattening a | 3026 // to be passed by value and is immutable, but be aware that flattening a |
3027 // string can potentially alter its shape. | 3027 // string can potentially alter its shape. Also be aware that a GC caused by |
| 3028 // something else can alter the shape of a string due to ConsString |
| 3029 // shortcutting. |
3028 // | 3030 // |
3029 // Most of the methods designed to interrogate a string as to its exact nature | 3031 // Most of the methods designed to interrogate a string as to its exact nature |
3030 // have been made into methods on StringShape in order to encourage the use of | 3032 // have been made into methods on StringShape in order to encourage the use of |
3031 // StringShape. The String class has both a length() and a length(StringShape) | 3033 // StringShape. The String class has both a length() and a length(StringShape) |
3032 // operation. The former is simpler to type, but the latter is faster if you | 3034 // operation. The former is simpler to type, but the latter is faster if you |
3033 // need the StringShape for some other operation immediately before or after. | 3035 // need the StringShape for some other operation immediately before or after. |
3034 class StringShape BASE_EMBEDDED { | 3036 class StringShape BASE_EMBEDDED { |
3035 public: | 3037 public: |
3036 inline explicit StringShape(String* s); | 3038 inline explicit StringShape(String* s); |
3037 inline explicit StringShape(Map* s); | 3039 inline explicit StringShape(Map* s); |
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3109 inline void TryFlatten(StringShape shape); | 3111 inline void TryFlatten(StringShape shape); |
3110 | 3112 |
3111 Vector<const char> ToAsciiVector(); | 3113 Vector<const char> ToAsciiVector(); |
3112 Vector<const uc16> ToUC16Vector(); | 3114 Vector<const uc16> ToUC16Vector(); |
3113 | 3115 |
3114 // Mark the string as an undetectable object. It only applies to | 3116 // Mark the string as an undetectable object. It only applies to |
3115 // ascii and two byte string types. | 3117 // ascii and two byte string types. |
3116 bool MarkAsUndetectable(); | 3118 bool MarkAsUndetectable(); |
3117 | 3119 |
3118 // Slice the string and return a substring. | 3120 // Slice the string and return a substring. |
3119 Object* Slice(StringShape shape, int from, int to); | 3121 Object* Slice(int from, int to); |
3120 | 3122 |
3121 // String equality operations. | 3123 // String equality operations. |
3122 inline bool Equals(String* other); | 3124 inline bool Equals(String* other); |
3123 bool IsEqualTo(Vector<const char> str); | 3125 bool IsEqualTo(Vector<const char> str); |
3124 | 3126 |
3125 // Return a UTF8 representation of the string. The string is null | 3127 // Return a UTF8 representation of the string. The string is null |
3126 // terminated but may optionally contain nulls. Length is returned | 3128 // terminated but may optionally contain nulls. Length is returned |
3127 // in length_output if length_output is not a null pointer The string | 3129 // in length_output if length_output is not a null pointer The string |
3128 // should be nearly flat, otherwise the performance of this method may | 3130 // should be nearly flat, otherwise the performance of this method may |
3129 // be very slow (quadratic in the length). Setting robustness_flag to | 3131 // be very slow (quadratic in the length). Setting robustness_flag to |
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3464 inline String* buffer(); | 3466 inline String* buffer(); |
3465 inline void set_buffer(String* buffer); | 3467 inline void set_buffer(String* buffer); |
3466 | 3468 |
3467 // The start index of the slice. | 3469 // The start index of the slice. |
3468 inline int start(); | 3470 inline int start(); |
3469 inline void set_start(int start); | 3471 inline void set_start(int start); |
3470 | 3472 |
3471 // Dispatched behavior. | 3473 // Dispatched behavior. |
3472 uint16_t SlicedStringGet(int index); | 3474 uint16_t SlicedStringGet(int index); |
3473 | 3475 |
3474 // Flatten any ConsString hiding behind this SlicedString. | |
3475 Object* SlicedStringFlatten(); | |
3476 | |
3477 // Casting. | 3476 // Casting. |
3478 static inline SlicedString* cast(Object* obj); | 3477 static inline SlicedString* cast(Object* obj); |
3479 | 3478 |
3480 // Garbage collection support. | 3479 // Garbage collection support. |
3481 void SlicedStringIterateBody(ObjectVisitor* v); | 3480 void SlicedStringIterateBody(ObjectVisitor* v); |
3482 | 3481 |
3483 // Layout description | 3482 // Layout description |
3484 static const int kBufferOffset = String::kSize; | 3483 static const int kBufferOffset = String::kSize; |
3485 static const int kStartOffset = kBufferOffset + kPointerSize; | 3484 static const int kStartOffset = kBufferOffset + kPointerSize; |
3486 static const int kSize = kStartOffset + kIntSize; | 3485 static const int kSize = kStartOffset + kIntSize; |
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4166 } else { | 4165 } else { |
4167 value &= ~(1 << bit_position); | 4166 value &= ~(1 << bit_position); |
4168 } | 4167 } |
4169 return value; | 4168 return value; |
4170 } | 4169 } |
4171 }; | 4170 }; |
4172 | 4171 |
4173 } } // namespace v8::internal | 4172 } } // namespace v8::internal |
4174 | 4173 |
4175 #endif // V8_OBJECTS_H_ | 4174 #endif // V8_OBJECTS_H_ |
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