skia2/gpu/include/GrTArray.h

/*
 * Copyright 2010 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */



#ifndef GrTArray_DEFINED
#define GrTArray_DEFINED

#include <new>
#include "GrTypes.h"
#include "GrTemplates.h"

// DATA_TYPE indicates that T has a trivial cons, destructor
// and can be shallow-copied
template <typename T, bool DATA_TYPE = false> class GrTArray {
public:
    GrTArray() {
        fCount = 0;
        fReserveCount = MIN_ALLOC_COUNT;
        fAllocCount = 0;
        fMemArray = NULL;
        fPreAllocMemArray = NULL;
    }

    explicit GrTArray(int reserveCount) {
        GrAssert(reserveCount >= 0);
        fCount = 0;
        fReserveCount = reserveCount > MIN_ALLOC_COUNT ? reserveCount :
                                                         MIN_ALLOC_COUNT;
        fAllocCount = fReserveCount;
        fMemArray = GrMalloc(sizeof(T) * fReserveCount);
        fPreAllocMemArray = NULL;
    }

    template <int N>
    GrTArray(GrAlignedSTStorage<N,T>* storage) {
        GrAssert(N > 0);
        fCount              = 0;
        fReserveCount       = N;
        fAllocCount         = N;
        fMemArray           = storage->get();
        fPreAllocMemArray   = storage->get();
    }

    GrTArray(void* preAllocStorage, int preAllocCount) {
        GrAssert(preAllocCount >= 0);
        // we allow NULL,0 args and revert to the default cons. behavior
        // this makes it possible for a owner-object to use same constructor
        // to get either prealloc or nonprealloc behavior based using same line
        GrAssert((NULL == preAllocStorage) == !preAllocCount);

        fCount              = 0;
        fReserveCount       = preAllocCount > 0 ? preAllocCount :
                                                  MIN_ALLOC_COUNT;
        fAllocCount         = preAllocCount;
        fMemArray           = preAllocStorage;
        fPreAllocMemArray   = preAllocStorage;
    }

    explicit GrTArray(const GrTArray& array) {
        fCount              = array.count();
        fReserveCount       = MIN_ALLOC_COUNT;
        fAllocCount         = GrMax(fReserveCount, fCount);
        fMemArray           = GrMalloc(sizeof(T) * fAllocCount);
        fPreAllocMemArray   = NULL;

        if (DATA_TYPE) {
            memcpy(fMemArray, array.fMemArray, sizeof(T) * fCount);
        } else {
            for (int i = 0; i < fCount; ++i) {
                new (fItemArray + i) T(array[i]);
            }
        }
    }

    GrTArray(const T* array, int count) {
        GrAssert(count >= 0);
        fCount              = count;
        fReserveCount       = MIN_ALLOC_COUNT;
        fAllocCount         = GrMax(fReserveCount, fCount);
        fMemArray           = GrMalloc(sizeof(T) * fAllocCount);
        fPreAllocMemArray   = NULL;
        if (DATA_TYPE) {
            memcpy(fMemArray, array, sizeof(T) * fCount);
        } else {
            for (int i = 0; i < fCount; ++i) {
                new (fItemArray + i) T(array[i]);
            }
        }
    }

    GrTArray(const GrTArray& array,
             void* preAllocStorage, int preAllocCount) {

        GrAssert(preAllocCount >= 0);

        // for same reason as non-copying cons we allow NULL, 0 for prealloc
        GrAssert((NULL == preAllocStorage) == !preAllocCount);

        fCount              = array.count();
        fReserveCount       = preAllocCount > 0 ? preAllocCount :
                                                  MIN_ALLOC_COUNT;
        fPreAllocMemArray   = preAllocStorage;

        if (fReserveCount >= fCount && preAllocCount) {
            fAllocCount = fReserveCount;
            fMemArray = preAllocStorage;
        } else {
            fAllocCount = GrMax(fCount, fReserveCount);
            fMemArray = GrMalloc(fAllocCount * sizeof(T));
        }

        if (DATA_TYPE) {
            memcpy(fMemArray, array.fMemArray, sizeof(T) * fCount);
        } else {
            for (int i = 0; i < fCount; ++i) {
                new (fItemArray + i) T(array[i]);
            }
        }
    }

    GrTArray(const T* array, int count,
             void* preAllocStorage, int preAllocCount) {

        GrAssert(count >= 0);
        GrAssert(preAllocCount >= 0);

        // for same reason as non-copying cons we allow NULL, 0 for prealloc
        GrAssert((NULL == preAllocStorage) == !preAllocCount);

        fCount              = count;
        fReserveCount       = (preAllocCount > 0) ? preAllocCount :
                                                    MIN_ALLOC_COUNT;
        fPreAllocMemArray   = preAllocStorage;

        if (fReserveCount >= fCount && preAllocCount) {
            fAllocCount = fReserveCount;
            fMemArray = preAllocStorage;
        } else {
            fAllocCount = GrMax(fCount, fReserveCount);
            fMemArray = GrMalloc(fAllocCount * sizeof(T));
        }

        if (DATA_TYPE) {
            memcpy(fMemArray, array, sizeof(T) * fCount);
        } else {
            for (int i = 0; i < fCount; ++i) {
                new (fItemArray + i) T(array[i]);
            }
        }
    }

    GrTArray& operator =(const GrTArray& array) {
        for (int i = 0; i < fCount; ++i) {
            fItemArray[i].~T();
        }
        fCount = 0;
        checkRealloc((int)array.count());
        fCount = array.count();
        if (DATA_TYPE) {
            memcpy(fMemArray, array.fMemArray, sizeof(T) * fCount);
        } else {
            for (int i = 0; i < fCount; ++i) {
                new (fItemArray + i) T(array[i]);
            }
        }
        return *this;
    }

    ~GrTArray() {
        for (int i = 0; i < fCount; ++i) {
            fItemArray[i].~T();
        }
        if (fMemArray != fPreAllocMemArray) {
            GrFree(fMemArray);
        }
    }

    void reset() { this->pop_back_n(fCount); }

    int count() const { return fCount; }

    bool empty() const { return !fCount; }

    T& push_back() {
        checkRealloc(1);
        new ((char*)fMemArray+sizeof(T)*fCount) T;
        ++fCount;
        return fItemArray[fCount-1];
    }

    void push_back_n(int n) {
        GrAssert(n >= 0);
        checkRealloc(n);
        for (int i = 0; i < n; ++i) {
            new (fItemArray + fCount + i) T;
        }
        fCount += n;
    }

    void pop_back() {
        GrAssert(fCount > 0);
        --fCount;
        fItemArray[fCount].~T();
        checkRealloc(0);
    }

    void pop_back_n(int n) {
        GrAssert(n >= 0);
        GrAssert(fCount >= n);
        fCount -= n;
        for (int i = 0; i < n; ++i) {
            fItemArray[i].~T();
        }
        checkRealloc(0);
    }

    // pushes or pops from the back to resize
    void resize_back(int newCount) {
        GrAssert(newCount >= 0);

        if (newCount > fCount) {
            push_back_n(newCount - fCount);
        } else if (newCount < fCount) {
            pop_back_n(fCount - newCount);
        }
    }

    T& operator[] (int i) {
        GrAssert(i < fCount);
        GrAssert(i >= 0);
        return fItemArray[i];
    }

    const T& operator[] (int i) const {
        GrAssert(i < fCount);
        GrAssert(i >= 0);
        return fItemArray[i];
    }

    T& front() { GrAssert(fCount > 0); return fItemArray[0];}

    const T& front() const { GrAssert(fCount > 0); return fItemArray[0];}

    T& back() { GrAssert(fCount); return fItemArray[fCount - 1];}

    const T& back() const { GrAssert(fCount > 0); return fItemArray[fCount - 1];}

    T& fromBack(int i) {
        GrAssert(i >= 0);
        GrAssert(i < fCount);
        return fItemArray[fCount - i - 1];
    }

    const T& fromBack(int i) const {
        GrAssert(i >= 0);
        GrAssert(i < fCount);
        return fItemArray[fCount - i - 1];
    }

private:

    static const int MIN_ALLOC_COUNT = 8;

    inline void checkRealloc(int delta) {
        GrAssert(fCount >= 0);
        GrAssert(fAllocCount >= 0);

        GrAssert(-delta <= fCount);

        int newCount = fCount + delta;
        int fNewAllocCount = fAllocCount;

        if (newCount > fAllocCount) {
            fNewAllocCount = GrMax(newCount + ((newCount + 1) >> 1),
                                   fReserveCount);
        } else if (newCount < fAllocCount / 3) {
            fNewAllocCount = GrMax(fAllocCount / 2, fReserveCount);
        }

        if (fNewAllocCount != fAllocCount) {

            fAllocCount = fNewAllocCount;
            char* fNewMemArray;

            if (fAllocCount == fReserveCount && NULL != fPreAllocMemArray) {
                fNewMemArray = (char*) fPreAllocMemArray;
            } else {
                fNewMemArray = (char*) GrMalloc(fAllocCount*sizeof(T));
            }

            if (DATA_TYPE) {
                memcpy(fNewMemArray, fMemArray, fCount * sizeof(T));
            } else {
                for (int i = 0; i < fCount; ++i) {
                    new (fNewMemArray + sizeof(T) * i) T(fItemArray[i]);
                    fItemArray[i].~T();
                }
            }

            if (fMemArray != fPreAllocMemArray) {
                GrFree(fMemArray);
            }
            fMemArray = fNewMemArray;
        }
    }

    int fReserveCount;
    int fCount;
    int fAllocCount;
    void*    fPreAllocMemArray;
    union {
        T*       fItemArray;
        void*    fMemArray;
    };
};

#endif