runtime/PropertyOffset.h

   1 /*
   2  * Copyright (C) 2012 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef PropertyOffset_h
  27 #define PropertyOffset_h
  28
  29 #include <wtf/Platform.h>
  30 #include <wtf/StdLibExtras.h>
  31
  32 namespace JSC {
  33
  34 typedef int PropertyOffset;
  35
  36 static const PropertyOffset invalidOffset = -1;
  37 static const PropertyOffset firstOutOfLineOffset = 100;
  38
  39 // Declare all of the functions because they tend to do forward calls.
  40 inline void checkOffset(PropertyOffset);
  41 inline void checkOffset(PropertyOffset, int inlineCapacity);
  42 inline void validateOffset(PropertyOffset);
  43 inline void validateOffset(PropertyOffset, int inlineCapacity);
  44 inline bool isValidOffset(PropertyOffset);
  45 inline bool isInlineOffset(PropertyOffset);
  46 inline bool isOutOfLineOffset(PropertyOffset);
  47 inline size_t offsetInInlineStorage(PropertyOffset);
  48 inline size_t offsetInOutOfLineStorage(PropertyOffset);
  49 inline size_t offsetInRespectiveStorage(PropertyOffset);
  50 inline size_t numberOfOutOfLineSlotsForLastOffset(PropertyOffset);
  51 inline size_t numberOfSlotsForLastOffset(PropertyOffset, int inlineCapacity);
  52
  53 inline void checkOffset(PropertyOffset offset)
  54 {
  55     UNUSED_PARAM(offset);
  56     ASSERT(offset >= invalidOffset);
  57 }
  58
  59 inline void checkOffset(PropertyOffset offset, int inlineCapacity)
  60 {
  61     UNUSED_PARAM(offset);
  62     UNUSED_PARAM(inlineCapacity);
  63     ASSERT(offset >= invalidOffset);
  64     ASSERT(offset == invalidOffset
  65         || offset < inlineCapacity
  66         || isOutOfLineOffset(offset));
  67 }
  68
  69 inline void validateOffset(PropertyOffset offset)
  70 {
  71     checkOffset(offset);
  72     ASSERT(isValidOffset(offset));
  73 }
  74
  75 inline void validateOffset(PropertyOffset offset, int inlineCapacity)
  76 {
  77     checkOffset(offset, inlineCapacity);
  78     ASSERT(isValidOffset(offset));
  79 }
  80
  81 inline bool isValidOffset(PropertyOffset offset)
  82 {
  83     checkOffset(offset);
  84     return offset != invalidOffset;
  85 }
  86
  87 inline bool isInlineOffset(PropertyOffset offset)
  88 {
  89     checkOffset(offset);
  90     return offset < firstOutOfLineOffset;
  91 }
  92
  93 inline bool isOutOfLineOffset(PropertyOffset offset)
  94 {
  95     checkOffset(offset);
  96     return !isInlineOffset(offset);
  97 }
  98
  99 inline size_t offsetInInlineStorage(PropertyOffset offset)
 100 {
 101     validateOffset(offset);
 102     ASSERT(isInlineOffset(offset));
 103     return offset;
 104 }
 105
 106 inline size_t offsetInOutOfLineStorage(PropertyOffset offset)
 107 {
 108     validateOffset(offset);
 109     ASSERT(isOutOfLineOffset(offset));
 110     return -static_cast<ptrdiff_t>(offset - firstOutOfLineOffset) - 1;
 111 }
 112
 113 inline size_t offsetInRespectiveStorage(PropertyOffset offset)
 114 {
 115     if (isInlineOffset(offset))
 116         return offsetInInlineStorage(offset);
 117     return offsetInOutOfLineStorage(offset);
 118 }
 119
 120 inline size_t numberOfOutOfLineSlotsForLastOffset(PropertyOffset offset)
 121 {
 122     checkOffset(offset);
 123     if (offset < firstOutOfLineOffset)
 124         return 0;
 125     return offset - firstOutOfLineOffset + 1;
 126 }
 127
 128 inline size_t numberOfSlotsForLastOffset(PropertyOffset offset, int inlineCapacity)
 129 {
 130     checkOffset(offset, inlineCapacity);
 131     if (offset < inlineCapacity)
 132         return offset + 1;
 133     return inlineCapacity + numberOfOutOfLineSlotsForLastOffset(offset);
 134 }
 135
 136 inline PropertyOffset offsetForPropertyNumber(int propertyNumber, int inlineCapacity)
 137 {
 138     PropertyOffset offset = propertyNumber;
 139     if (offset >= inlineCapacity) {
 140         offset += firstOutOfLineOffset;
 141         offset -= inlineCapacity;
 142     }
 143     return offset;
 144 }
 145
 146 } // namespace JSC
 147
 148 #endif // PropertyOffset_h