runtime/GenericOffset.h

   1 /*
   2  * Copyright (C) 2015 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 GenericOffset_h
  27 #define GenericOffset_h
  28
  29 #include <limits.h>
  30 #include <wtf/Assertions.h>
  31
  32 namespace JSC {
  33
  34 // A mixin for creating the various kinds of variable offsets that our engine supports.
  35 template<typename T>
  36 class GenericOffset {
  37 public:
  38     static const unsigned invalidOffset = UINT_MAX;
  39
  40     GenericOffset()
  41         : m_offset(invalidOffset)
  42     {
  43     }
  44
  45     explicit GenericOffset(unsigned offset)
  46         : m_offset(offset)
  47     {
  48     }
  49
  50     bool operator!() const { return m_offset == invalidOffset; }
  51
  52     unsigned offsetUnchecked() const
  53     {
  54         return m_offset;
  55     }
  56
  57     unsigned offset() const
  58     {
  59         ASSERT(m_offset != invalidOffset);
  60         return m_offset;
  61     }
  62
  63     bool operator==(const T& other) const
  64     {
  65         return m_offset == other.offsetUnchecked();
  66     }
  67     bool operator!=(const T& other) const
  68     {
  69         return m_offset != other.offsetUnchecked();
  70     }
  71     bool operator<(const T& other) const
  72     {
  73         return m_offset < other.offsetUnchecked();
  74     }
  75     bool operator>(const T& other) const
  76     {
  77         return m_offset > other.offsetUnchecked();
  78     }
  79     bool operator<=(const T& other) const
  80     {
  81         return m_offset <= other.offsetUnchecked();
  82     }
  83     bool operator>=(const T& other) const
  84     {
  85         return m_offset >= other.offsetUnchecked();
  86     }
  87
  88     T operator+(int value) const
  89     {
  90         return T(offset() + value);
  91     }
  92     T operator-(int value) const
  93     {
  94         return T(offset() - value);
  95     }
  96     T& operator+=(int value)
  97     {
  98         return *this = *this + value;
  99     }
 100     T& operator-=(int value)
 101     {
 102         return *this = *this - value;
 103     }
 104
 105 private:
 106     unsigned m_offset;
 107 };
 108
 109 } // namespace JSC
 110
 111 #endif // GenericOffset_h
 112