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1 /* | 1 /* |
2 * Copyright (C) 2011 Apple Inc. All rights reserved. | 2 * Copyright (C) 2011 Apple Inc. All rights reserved. |
3 * | 3 * |
4 * Redistribution and use in source and binary forms, with or without | 4 * Redistribution and use in source and binary forms, with or without |
5 * modification, are permitted provided that the following conditions | 5 * modification, are permitted provided that the following conditions |
6 * are met: | 6 * are met: |
7 * 1. Redistributions of source code must retain the above copyright | 7 * 1. Redistributions of source code must retain the above copyright |
8 * notice, this list of conditions and the following disclaimer. | 8 * notice, this list of conditions and the following disclaimer. |
9 * 2. Redistributions in binary form must reproduce the above copyright | 9 * 2. Redistributions in binary form must reproduce the above copyright |
10 * notice, this list of conditions and the following disclaimer in the | 10 * notice, this list of conditions and the following disclaimer in the |
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30 #include "wtf/Assertions.h" | 30 #include "wtf/Assertions.h" |
31 #include "wtf/StdLibExtras.h" | 31 #include "wtf/StdLibExtras.h" |
32 #include "wtf/WTFExport.h" | 32 #include "wtf/WTFExport.h" |
33 | 33 |
34 namespace WTF { | 34 namespace WTF { |
35 | 35 |
36 class PrintStream; | 36 class PrintStream; |
37 | 37 |
38 // This is a space-efficient, resizeable bitvector class. In the common case it | 38 // This is a space-efficient, resizeable bitvector class. In the common case it |
39 // occupies one word, but if necessary, it will inflate this one word to point | 39 // occupies one word, but if necessary, it will inflate this one word to point |
40 // to a single chunk of out-of-line allocated storage to store an arbitrary numb
er | 40 // to a single chunk of out-of-line allocated storage to store an arbitrary |
41 // of bits. | 41 // number of bits. |
42 // | 42 // |
43 // - The bitvector remembers the bound of how many bits can be stored, but this | 43 // - The bitvector remembers the bound of how many bits can be stored, but this |
44 // may be slightly greater (by as much as some platform-specific constant) | 44 // may be slightly greater (by as much as some platform-specific constant) |
45 // than the last argument passed to ensureSize(). | 45 // than the last argument passed to ensureSize(). |
46 // | 46 // |
47 // - The bitvector can resize itself automatically (set, clear, get) or can be u
sed | 47 // - The bitvector can resize itself automatically (set, clear, get) or can be |
48 // in a manual mode, which is faster (quickSet, quickClear, quickGet, ensureSi
ze). | 48 // used in a manual mode, which is faster (quickSet, quickClear, quickGet, |
| 49 // ensureSize). |
49 // | 50 // |
50 // - Accesses ASSERT that you are within bounds. | 51 // - Accesses ASSERT that you are within bounds. |
51 // | 52 // |
52 // - Bits are automatically initialized to zero. | 53 // - Bits are automatically initialized to zero. |
53 // | 54 // |
54 // On the other hand, this BitVector class may not be the fastest around, since | 55 // On the other hand, this BitVector class may not be the fastest around, since |
55 // it does conditionals on every get/set/clear. But it is great if you need to | 56 // it does conditionals on every get/set/clear. But it is great if you need to |
56 // juggle a lot of variable-length BitVectors and you're worried about wasting | 57 // juggle a lot of variable-length BitVectors and you're worried about wasting |
57 // space. | 58 // space. |
58 | 59 |
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217 } | 218 } |
218 | 219 |
219 uintptr_t m_bitsOrPointer; | 220 uintptr_t m_bitsOrPointer; |
220 }; | 221 }; |
221 | 222 |
222 } // namespace WTF | 223 } // namespace WTF |
223 | 224 |
224 using WTF::BitVector; | 225 using WTF::BitVector; |
225 | 226 |
226 #endif // BitVector_h | 227 #endif // BitVector_h |
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