PxStrideIterator.h

// 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 with the distribution.
//  * Neither the name of NVIDIA CORPORATION nor the names of its
//    contributors may be used to endorse or promote products derived
//    from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Copyright (c) 2008-2022 NVIDIA Corporation. All rights reserved.
// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.
 
#ifndef PX_STRIDE_ITERATOR_H
#define PX_STRIDE_ITERATOR_H
 
#include "foundation/Px.h"
#include "foundation/PxAssert.h"
 
#if !PX_DOXYGEN
namespace physx
{
#endif
 
template <typename T>
class PxStrideIterator
{
 
#if !PX_DOXYGEN
    template <typename X>
    struct StripConst
    {
        typedef X Type;
    };
 
    template <typename X>
    struct StripConst<const X>
    {
        typedef X Type;
    };
#endif
 
  public:
    explicit PX_INLINE PxStrideIterator(T* ptr = NULL, PxU32 stride = sizeof(T)) : mPtr(ptr), mStride(stride)
    {
        PX_ASSERT(mStride == 0 || sizeof(T) <= mStride);
    }
 
    PX_INLINE PxStrideIterator(const PxStrideIterator<typename StripConst<T>::Type>& strideIterator)
    : mPtr(strideIterator.ptr()), mStride(strideIterator.stride())
    {
        PX_ASSERT(mStride == 0 || sizeof(T) <= mStride);
    }
 
    PX_INLINE T* ptr() const
    {
        return mPtr;
    }
 
    PX_INLINE PxU32 stride() const
    {
        return mStride;
    }
 
    PX_INLINE T& operator*() const
    {
        return *mPtr;
    }
 
    PX_INLINE T* operator->() const
    {
        return mPtr;
    }
 
    PX_INLINE T& operator[](unsigned int i) const
    {
        return *byteAdd(mPtr, i * stride());
    }
 
    PX_INLINE PxStrideIterator& operator++()
    {
        mPtr = byteAdd(mPtr, stride());
        return *this;
    }
 
    PX_INLINE PxStrideIterator operator++(int)
    {
        PxStrideIterator tmp = *this;
        mPtr = byteAdd(mPtr, stride());
        return tmp;
    }
 
    PX_INLINE PxStrideIterator& operator--()
    {
        mPtr = byteSub(mPtr, stride());
        return *this;
    }
 
    PX_INLINE PxStrideIterator operator--(int)
    {
        PxStrideIterator tmp = *this;
        mPtr = byteSub(mPtr, stride());
        return tmp;
    }
 
    PX_INLINE PxStrideIterator operator+(unsigned int i) const
    {
        return PxStrideIterator(byteAdd(mPtr, i * stride()), stride());
    }
 
    PX_INLINE PxStrideIterator operator-(unsigned int i) const
    {
        return PxStrideIterator(byteSub(mPtr, i * stride()), stride());
    }
 
    PX_INLINE PxStrideIterator& operator+=(unsigned int i)
    {
        mPtr = byteAdd(mPtr, i * stride());
        return *this;
    }
 
    PX_INLINE PxStrideIterator& operator-=(unsigned int i)
    {
        mPtr = byteSub(mPtr, i * stride());
        return *this;
    }
 
    PX_INLINE int operator-(const PxStrideIterator& other) const
    {
        PX_ASSERT(isCompatible(other));
        int byteDiff = static_cast<int>(reinterpret_cast<const PxU8*>(mPtr) - reinterpret_cast<const PxU8*>(other.mPtr));
        return byteDiff / static_cast<int>(stride());
    }
 
    PX_INLINE bool operator==(const PxStrideIterator& other) const
    {
        PX_ASSERT(isCompatible(other));
        return mPtr == other.mPtr;
    }
 
    PX_INLINE bool operator!=(const PxStrideIterator& other) const
    {
        PX_ASSERT(isCompatible(other));
        return mPtr != other.mPtr;
    }
 
    PX_INLINE bool operator<(const PxStrideIterator& other) const
    {
        PX_ASSERT(isCompatible(other));
        return mPtr < other.mPtr;
    }
 
    PX_INLINE bool operator>(const PxStrideIterator& other) const
    {
        PX_ASSERT(isCompatible(other));
        return mPtr > other.mPtr;
    }
 
    PX_INLINE bool operator<=(const PxStrideIterator& other) const
    {
        PX_ASSERT(isCompatible(other));
        return mPtr <= other.mPtr;
    }
 
    PX_INLINE bool operator>=(const PxStrideIterator& other) const
    {
        PX_ASSERT(isCompatible(other));
        return mPtr >= other.mPtr;
    }
 
  private:
    PX_INLINE static T* byteAdd(T* ptr, PxU32 bytes)
    {
        return const_cast<T*>(reinterpret_cast<const T*>(reinterpret_cast<const PxU8*>(ptr) + bytes));
    }
 
    PX_INLINE static T* byteSub(T* ptr, PxU32 bytes)
    {
        return const_cast<T*>(reinterpret_cast<const T*>(reinterpret_cast<const PxU8*>(ptr) - bytes));
    }
 
    PX_INLINE bool isCompatible(const PxStrideIterator& other) const
    {
        int byteDiff = static_cast<int>(reinterpret_cast<const PxU8*>(mPtr) - reinterpret_cast<const PxU8*>(other.mPtr));
        return (stride() == other.stride()) && (abs(byteDiff) % stride() == 0);
    }
 
    T* mPtr;
    PxU32 mStride;
};
 
template <typename T>
PX_INLINE PxStrideIterator<T> operator+(int i, PxStrideIterator<T> it)
{
    it += i;
    return it;
}
 
template <typename T>
PX_INLINE PxStrideIterator<T> PxMakeIterator(T* ptr, PxU32 stride = sizeof(T))
{
    return PxStrideIterator<T>(ptr, stride);
}
 
template <typename T>
PX_INLINE PxStrideIterator<const T> PxMakeIterator(const T* ptr, PxU32 stride = sizeof(T))
{
    return PxStrideIterator<const T>(ptr, stride);
}
 
#if !PX_DOXYGEN
} // namespace physx
#endif
 
#endif