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-rw-r--r-- | gfx/skia/skia/include/private/SkTemplates.h | 455 |
1 files changed, 455 insertions, 0 deletions
diff --git a/gfx/skia/skia/include/private/SkTemplates.h b/gfx/skia/skia/include/private/SkTemplates.h new file mode 100644 index 0000000000..94b335cda1 --- /dev/null +++ b/gfx/skia/skia/include/private/SkTemplates.h @@ -0,0 +1,455 @@ +/* + * Copyright 2006 The Android Open Source Project + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#ifndef SkTemplates_DEFINED +#define SkTemplates_DEFINED + +#include "include/core/SkTypes.h" +#include "include/private/SkMalloc.h" +#include "include/private/SkTLogic.h" + +#include <string.h> +#include <array> +#include <cstddef> +#include <memory> +#include <new> +#include <utility> + +/** \file SkTemplates.h + + This file contains light-weight template classes for type-safe and exception-safe + resource management. +*/ + +/** + * Marks a local variable as known to be unused (to avoid warnings). + * Note that this does *not* prevent the local variable from being optimized away. + */ +template<typename T> inline void sk_ignore_unused_variable(const T&) { } + +/** + * Returns a pointer to a D which comes immediately after S[count]. + */ +template <typename D, typename S> static D* SkTAfter(S* ptr, size_t count = 1) { + return reinterpret_cast<D*>(ptr + count); +} + +/** + * Returns a pointer to a D which comes byteOffset bytes after S. + */ +template <typename D, typename S> static D* SkTAddOffset(S* ptr, size_t byteOffset) { + // The intermediate char* has the same cv-ness as D as this produces better error messages. + // This relies on the fact that reinterpret_cast can add constness, but cannot remove it. + return reinterpret_cast<D*>(reinterpret_cast<sknonstd::same_cv_t<char, D>*>(ptr) + byteOffset); +} + +// TODO: when C++17 the language is available, use template <auto P> +template <typename T, T* P> struct SkFunctionWrapper { + template <typename... Args> + auto operator()(Args&&... args) const -> decltype(P(std::forward<Args>(args)...)) { + return P(std::forward<Args>(args)...); + } +}; + +/** \class SkAutoTCallVProc + + Call a function when this goes out of scope. The template uses two + parameters, the object, and a function that is to be called in the destructor. + If release() is called, the object reference is set to null. If the object + reference is null when the destructor is called, we do not call the + function. +*/ +template <typename T, void (*P)(T*)> class SkAutoTCallVProc + : public std::unique_ptr<T, SkFunctionWrapper<skstd::remove_pointer_t<decltype(P)>, P>> { +public: + SkAutoTCallVProc(T* obj) + : std::unique_ptr<T, SkFunctionWrapper<skstd::remove_pointer_t<decltype(P)>, P>>(obj) {} + + operator T*() const { return this->get(); } +}; + +/** Allocate an array of T elements, and free the array in the destructor + */ +template <typename T> class SkAutoTArray { +public: + SkAutoTArray() {} + /** Allocate count number of T elements + */ + explicit SkAutoTArray(int count) { + SkASSERT(count >= 0); + if (count) { + fArray.reset(new T[count]); + } + SkDEBUGCODE(fCount = count;) + } + + SkAutoTArray(SkAutoTArray&& other) : fArray(std::move(other.fArray)) { + SkDEBUGCODE(fCount = other.fCount; other.fCount = 0;) + } + SkAutoTArray& operator=(SkAutoTArray&& other) { + if (this != &other) { + fArray = std::move(other.fArray); + SkDEBUGCODE(fCount = other.fCount; other.fCount = 0;) + } + return *this; + } + + /** Reallocates given a new count. Reallocation occurs even if new count equals old count. + */ + void reset(int count) { *this = SkAutoTArray(count); } + + /** Return the array of T elements. Will be NULL if count == 0 + */ + T* get() const { return fArray.get(); } + + /** Return the nth element in the array + */ + T& operator[](int index) const { + SkASSERT((unsigned)index < (unsigned)fCount); + return fArray[index]; + } + +private: + std::unique_ptr<T[]> fArray; + SkDEBUGCODE(int fCount = 0;) +}; + +/** Wraps SkAutoTArray, with room for kCountRequested elements preallocated. + */ +template <int kCountRequested, typename T> class SkAutoSTArray { +public: + SkAutoSTArray(SkAutoSTArray&&) = delete; + SkAutoSTArray(const SkAutoSTArray&) = delete; + SkAutoSTArray& operator=(SkAutoSTArray&&) = delete; + SkAutoSTArray& operator=(const SkAutoSTArray&) = delete; + + /** Initialize with no objects */ + SkAutoSTArray() { + fArray = nullptr; + fCount = 0; + } + + /** Allocate count number of T elements + */ + SkAutoSTArray(int count) { + fArray = nullptr; + fCount = 0; + this->reset(count); + } + + ~SkAutoSTArray() { + this->reset(0); + } + + /** Destroys previous objects in the array and default constructs count number of objects */ + void reset(int count) { + T* start = fArray; + T* iter = start + fCount; + while (iter > start) { + (--iter)->~T(); + } + + SkASSERT(count >= 0); + if (fCount != count) { + if (fCount > kCount) { + // 'fArray' was allocated last time so free it now + SkASSERT((T*) fStorage != fArray); + sk_free(fArray); + } + + if (count > kCount) { + fArray = (T*) sk_malloc_throw(count, sizeof(T)); + } else if (count > 0) { + fArray = (T*) fStorage; + } else { + fArray = nullptr; + } + + fCount = count; + } + + iter = fArray; + T* stop = fArray + count; + while (iter < stop) { + new (iter++) T; + } + } + + /** Return the number of T elements in the array + */ + int count() const { return fCount; } + + /** Return the array of T elements. Will be NULL if count == 0 + */ + T* get() const { return fArray; } + + T* begin() { return fArray; } + + const T* begin() const { return fArray; } + + T* end() { return fArray + fCount; } + + const T* end() const { return fArray + fCount; } + + /** Return the nth element in the array + */ + T& operator[](int index) const { + SkASSERT(index < fCount); + return fArray[index]; + } + +private: +#if defined(SK_BUILD_FOR_GOOGLE3) + // Stack frame size is limited for SK_BUILD_FOR_GOOGLE3. 4k is less than the actual max, but some functions + // have multiple large stack allocations. + static const int kMaxBytes = 4 * 1024; + static const int kCount = kCountRequested * sizeof(T) > kMaxBytes + ? kMaxBytes / sizeof(T) + : kCountRequested; +#else + static const int kCount = kCountRequested; +#endif + + int fCount; + T* fArray; + // since we come right after fArray, fStorage should be properly aligned + char fStorage[kCount * sizeof(T)]; +}; + +/** Manages an array of T elements, freeing the array in the destructor. + * Does NOT call any constructors/destructors on T (T must be POD). + */ +template <typename T> class SkAutoTMalloc { +public: + /** Takes ownership of the ptr. The ptr must be a value which can be passed to sk_free. */ + explicit SkAutoTMalloc(T* ptr = nullptr) : fPtr(ptr) {} + + /** Allocates space for 'count' Ts. */ + explicit SkAutoTMalloc(size_t count) + : fPtr(count ? (T*)sk_malloc_throw(count, sizeof(T)) : nullptr) {} + + SkAutoTMalloc(SkAutoTMalloc&&) = default; + SkAutoTMalloc& operator=(SkAutoTMalloc&&) = default; + + /** Resize the memory area pointed to by the current ptr preserving contents. */ + void realloc(size_t count) { + fPtr.reset(count ? (T*)sk_realloc_throw(fPtr.release(), count * sizeof(T)) : nullptr); + } + + /** Resize the memory area pointed to by the current ptr without preserving contents. */ + T* reset(size_t count = 0) { + fPtr.reset(count ? (T*)sk_malloc_throw(count, sizeof(T)) : nullptr); + return this->get(); + } + + T* get() const { return fPtr.get(); } + + operator T*() { return fPtr.get(); } + + operator const T*() const { return fPtr.get(); } + + T& operator[](int index) { return fPtr.get()[index]; } + + const T& operator[](int index) const { return fPtr.get()[index]; } + + /** + * Transfer ownership of the ptr to the caller, setting the internal + * pointer to NULL. Note that this differs from get(), which also returns + * the pointer, but it does not transfer ownership. + */ + T* release() { return fPtr.release(); } + +private: + std::unique_ptr<T, SkFunctionWrapper<void(void*), sk_free>> fPtr; +}; + +template <size_t kCountRequested, typename T> class SkAutoSTMalloc { +public: + SkAutoSTMalloc() : fPtr(fTStorage) {} + + SkAutoSTMalloc(size_t count) { + if (count > kCount) { + fPtr = (T*)sk_malloc_throw(count, sizeof(T)); + } else if (count) { + fPtr = fTStorage; + } else { + fPtr = nullptr; + } + } + + SkAutoSTMalloc(SkAutoSTMalloc&&) = delete; + SkAutoSTMalloc(const SkAutoSTMalloc&) = delete; + SkAutoSTMalloc& operator=(SkAutoSTMalloc&&) = delete; + SkAutoSTMalloc& operator=(const SkAutoSTMalloc&) = delete; + + ~SkAutoSTMalloc() { + if (fPtr != fTStorage) { + sk_free(fPtr); + } + } + + // doesn't preserve contents + T* reset(size_t count) { + if (fPtr != fTStorage) { + sk_free(fPtr); + } + if (count > kCount) { + fPtr = (T*)sk_malloc_throw(count, sizeof(T)); + } else if (count) { + fPtr = fTStorage; + } else { + fPtr = nullptr; + } + return fPtr; + } + + T* get() const { return fPtr; } + + operator T*() { + return fPtr; + } + + operator const T*() const { + return fPtr; + } + + T& operator[](int index) { + return fPtr[index]; + } + + const T& operator[](int index) const { + return fPtr[index]; + } + + // Reallocs the array, can be used to shrink the allocation. Makes no attempt to be intelligent + void realloc(size_t count) { + if (count > kCount) { + if (fPtr == fTStorage) { + fPtr = (T*)sk_malloc_throw(count, sizeof(T)); + memcpy(fPtr, fTStorage, kCount * sizeof(T)); + } else { + fPtr = (T*)sk_realloc_throw(fPtr, count, sizeof(T)); + } + } else if (count) { + if (fPtr != fTStorage) { + fPtr = (T*)sk_realloc_throw(fPtr, count, sizeof(T)); + } + } else { + this->reset(0); + } + } + +private: + // Since we use uint32_t storage, we might be able to get more elements for free. + static const size_t kCountWithPadding = SkAlign4(kCountRequested*sizeof(T)) / sizeof(T); +#if defined(SK_BUILD_FOR_GOOGLE3) + // Stack frame size is limited for SK_BUILD_FOR_GOOGLE3. 4k is less than the actual max, but some functions + // have multiple large stack allocations. + static const size_t kMaxBytes = 4 * 1024; + static const size_t kCount = kCountRequested * sizeof(T) > kMaxBytes + ? kMaxBytes / sizeof(T) + : kCountWithPadding; +#else + static const size_t kCount = kCountWithPadding; +#endif + + T* fPtr; + union { + uint32_t fStorage32[SkAlign4(kCount*sizeof(T)) >> 2]; + T fTStorage[1]; // do NOT want to invoke T::T() + }; +}; + +////////////////////////////////////////////////////////////////////////////////////////////////// + +/** + * Pass the object and the storage that was offered during SkInPlaceNewCheck, and this will + * safely destroy (and free if it was dynamically allocated) the object. + */ +template <typename T> void SkInPlaceDeleteCheck(T* obj, void* storage) { + if (storage == obj) { + obj->~T(); + } else { + delete obj; + } +} + +/** + * Allocates T, using storage if it is large enough, and allocating on the heap (via new) if + * storage is not large enough. + * + * obj = SkInPlaceNewCheck<Type>(storage, size); + * ... + * SkInPlaceDeleteCheck(obj, storage); + */ +template<typename T, typename... Args> +T* SkInPlaceNewCheck(void* storage, size_t size, Args&&... args) { + return (sizeof(T) <= size) ? new (storage) T(std::forward<Args>(args)...) + : new T(std::forward<Args>(args)...); +} +/** + * Reserves memory that is aligned on double and pointer boundaries. + * Hopefully this is sufficient for all practical purposes. + */ +template <size_t N> class SkAlignedSStorage { +public: + SkAlignedSStorage() {} + SkAlignedSStorage(SkAlignedSStorage&&) = delete; + SkAlignedSStorage(const SkAlignedSStorage&) = delete; + SkAlignedSStorage& operator=(SkAlignedSStorage&&) = delete; + SkAlignedSStorage& operator=(const SkAlignedSStorage&) = delete; + + size_t size() const { return N; } + void* get() { return fData; } + const void* get() const { return fData; } + +private: + union { + void* fPtr; + double fDouble; + char fData[N]; + }; +}; + +/** + * Reserves memory that is aligned on double and pointer boundaries. + * Hopefully this is sufficient for all practical purposes. Otherwise, + * we have to do some arcane trickery to determine alignment of non-POD + * types. Lifetime of the memory is the lifetime of the object. + */ +template <int N, typename T> class SkAlignedSTStorage { +public: + SkAlignedSTStorage() {} + SkAlignedSTStorage(SkAlignedSTStorage&&) = delete; + SkAlignedSTStorage(const SkAlignedSTStorage&) = delete; + SkAlignedSTStorage& operator=(SkAlignedSTStorage&&) = delete; + SkAlignedSTStorage& operator=(const SkAlignedSTStorage&) = delete; + + /** + * Returns void* because this object does not initialize the + * memory. Use placement new for types that require a cons. + */ + void* get() { return fStorage.get(); } + const void* get() const { return fStorage.get(); } +private: + SkAlignedSStorage<sizeof(T)*N> fStorage; +}; + +using SkAutoFree = std::unique_ptr<void, SkFunctionWrapper<void(void*), sk_free>>; + +template<typename C, std::size_t... Is> +constexpr auto SkMakeArrayFromIndexSequence(C c, skstd::index_sequence<Is...>) +-> std::array<skstd::result_of_t<C(std::size_t)>, sizeof...(Is)> { + return {{ c(Is)... }}; +} + +template<size_t N, typename C> constexpr auto SkMakeArray(C c) +-> std::array<skstd::result_of_t<C(std::size_t)>, N> { + return SkMakeArrayFromIndexSequence(c, skstd::make_index_sequence<N>{}); +} + +#endif |