Space-Project/dependencies/physx-4.1/include/foundation/PxStrideIterator.h
2021-01-16 17:11:39 +01:00

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//
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// Copyright (c) 2008-2019 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 PXFOUNDATION_PXSTRIDEITERATOR_H
#define PXFOUNDATION_PXSTRIDEITERATOR_H
#include "foundation/Px.h"
#include "foundation/PxSharedAssert.h"
/** \addtogroup foundation
@{
*/
#if !PX_DOXYGEN
namespace physx
{
#endif
/**
\brief Iterator class for iterating over arrays of data that may be interleaved with other data.
This class is used for iterating over arrays of elements that may have a larger element to element
offset, called the stride, than the size of the element itself (non-contiguous).
The template parameter T denotes the type of the element accessed. The stride itself
is stored as a member field so multiple instances of a PxStrideIterator class can have
different strides. This is useful for cases were the stride depends on runtime configuration.
The stride iterator can be used for index based access, e.g.:
\code
PxStrideIterator<PxVec3> strideArray(...);
for (unsigned i = 0; i < 10; ++i)
{
PxVec3& vec = strideArray[i];
...
}
\endcode
or iteration by increment, e.g.:
\code
PxStrideIterator<PxVec3> strideBegin(...);
PxStrideIterator<PxVec3> strideEnd(strideBegin + 10);
for (PxStrideIterator<PxVec3> it = strideBegin; it < strideEnd; ++it)
{
PxVec3& vec = *it;
...
}
\endcode
Two special cases:
- A stride of sizeof(T) represents a regular c array of type T.
- A stride of 0 can be used to describe re-occurrence of the same element multiple times.
*/
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:
/**
\brief Constructor.
Optionally takes a pointer to an element and a stride.
\param[in] ptr pointer to element, defaults to NULL.
\param[in] stride stride for accessing consecutive elements, defaults to the size of one element.
*/
explicit PX_INLINE PxStrideIterator(T* ptr = NULL, PxU32 stride = sizeof(T)) : mPtr(ptr), mStride(stride)
{
PX_SHARED_ASSERT(mStride == 0 || sizeof(T) <= mStride);
}
/**
\brief Copy constructor.
\param[in] strideIterator PxStrideIterator to be copied.
*/
PX_INLINE PxStrideIterator(const PxStrideIterator<typename StripConst<T>::Type>& strideIterator)
: mPtr(strideIterator.ptr()), mStride(strideIterator.stride())
{
PX_SHARED_ASSERT(mStride == 0 || sizeof(T) <= mStride);
}
/**
\brief Get pointer to element.
*/
PX_INLINE T* ptr() const
{
return mPtr;
}
/**
\brief Get stride.
*/
PX_INLINE PxU32 stride() const
{
return mStride;
}
/**
\brief Indirection operator.
*/
PX_INLINE T& operator*() const
{
return *mPtr;
}
/**
\brief Dereferencing operator.
*/
PX_INLINE T* operator->() const
{
return mPtr;
}
/**
\brief Indexing operator.
*/
PX_INLINE T& operator[](unsigned int i) const
{
return *byteAdd(mPtr, i * stride());
}
/**
\brief Pre-increment operator.
*/
PX_INLINE PxStrideIterator& operator++()
{
mPtr = byteAdd(mPtr, stride());
return *this;
}
/**
\brief Post-increment operator.
*/
PX_INLINE PxStrideIterator operator++(int)
{
PxStrideIterator tmp = *this;
mPtr = byteAdd(mPtr, stride());
return tmp;
}
/**
\brief Pre-decrement operator.
*/
PX_INLINE PxStrideIterator& operator--()
{
mPtr = byteSub(mPtr, stride());
return *this;
}
/**
\brief Post-decrement operator.
*/
PX_INLINE PxStrideIterator operator--(int)
{
PxStrideIterator tmp = *this;
mPtr = byteSub(mPtr, stride());
return tmp;
}
/**
\brief Addition operator.
*/
PX_INLINE PxStrideIterator operator+(unsigned int i) const
{
return PxStrideIterator(byteAdd(mPtr, i * stride()), stride());
}
/**
\brief Subtraction operator.
*/
PX_INLINE PxStrideIterator operator-(unsigned int i) const
{
return PxStrideIterator(byteSub(mPtr, i * stride()), stride());
}
/**
\brief Addition compound assignment operator.
*/
PX_INLINE PxStrideIterator& operator+=(unsigned int i)
{
mPtr = byteAdd(mPtr, i * stride());
return *this;
}
/**
\brief Subtraction compound assignment operator.
*/
PX_INLINE PxStrideIterator& operator-=(unsigned int i)
{
mPtr = byteSub(mPtr, i * stride());
return *this;
}
/**
\brief Iterator difference.
*/
PX_INLINE int operator-(const PxStrideIterator& other) const
{
PX_SHARED_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());
}
/**
\brief Equality operator.
*/
PX_INLINE bool operator==(const PxStrideIterator& other) const
{
PX_SHARED_ASSERT(isCompatible(other));
return mPtr == other.mPtr;
}
/**
\brief Inequality operator.
*/
PX_INLINE bool operator!=(const PxStrideIterator& other) const
{
PX_SHARED_ASSERT(isCompatible(other));
return mPtr != other.mPtr;
}
/**
\brief Less than operator.
*/
PX_INLINE bool operator<(const PxStrideIterator& other) const
{
PX_SHARED_ASSERT(isCompatible(other));
return mPtr < other.mPtr;
}
/**
\brief Greater than operator.
*/
PX_INLINE bool operator>(const PxStrideIterator& other) const
{
PX_SHARED_ASSERT(isCompatible(other));
return mPtr > other.mPtr;
}
/**
\brief Less or equal than operator.
*/
PX_INLINE bool operator<=(const PxStrideIterator& other) const
{
PX_SHARED_ASSERT(isCompatible(other));
return mPtr <= other.mPtr;
}
/**
\brief Greater or equal than operator.
*/
PX_INLINE bool operator>=(const PxStrideIterator& other) const
{
PX_SHARED_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;
};
/**
\brief Addition operator.
*/
template <typename T>
PX_INLINE PxStrideIterator<T> operator+(int i, PxStrideIterator<T> it)
{
it += i;
return it;
}
/**
\brief Stride iterator factory function which infers the iterator type.
*/
template <typename T>
PX_INLINE PxStrideIterator<T> PxMakeIterator(T* ptr, PxU32 stride = sizeof(T))
{
return PxStrideIterator<T>(ptr, stride);
}
/**
\brief Stride iterator factory function which infers the iterator type.
*/
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 // PXFOUNDATION_PXSTRIDEITERATOR_H