115 lines
3.0 KiB
C++
115 lines
3.0 KiB
C++
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/*
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* Copyright (C) 2013 Max Kellermann <max@duempel.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef CONST_BUFFER_HPP
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#define CONST_BUFFER_HPP
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#include "Compiler.h"
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#include <cstddef>
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#ifndef NDEBUG
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#include <assert.h>
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#endif
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/**
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* A reference to a memory area that is read-only.
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*/
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template<typename T>
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struct ConstBuffer {
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typedef size_t size_type;
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typedef const T *pointer_type;
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typedef pointer_type const_pointer_type;
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typedef pointer_type iterator;
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typedef pointer_type const_iterator;
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pointer_type data;
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size_type size;
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ConstBuffer() = default;
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constexpr ConstBuffer(std::nullptr_t):data(nullptr), size(0) {}
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constexpr ConstBuffer(pointer_type _data, size_type _size)
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:data(_data), size(_size) {}
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constexpr static ConstBuffer Null() {
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return ConstBuffer(nullptr, 0);
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}
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/**
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* Cast a ConstBuffer<void> to a ConstBuffer<T>. A "void"
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* buffer records its size in bytes, and when casting to "T",
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* the assertion below ensures that the size is a multiple of
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* sizeof(T).
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*/
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#ifdef NDEBUG
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constexpr
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#endif
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static ConstBuffer<T> FromVoid(ConstBuffer<void> other) {
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static_assert(sizeof(T) > 0, "Empty base type");
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#ifndef NDEBUG
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assert(other.size % sizeof(T) == 0);
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#endif
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return ConstBuffer<T>(pointer_type(other.data),
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other.size / sizeof(T));
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}
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constexpr ConstBuffer<void> ToVoid() const {
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static_assert(sizeof(T) > 0, "Empty base type");
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return ConstBuffer<void>(data, size * sizeof(T));
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}
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constexpr bool IsNull() const {
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return data == nullptr;
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}
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constexpr bool IsEmpty() const {
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return size == 0;
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}
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constexpr iterator begin() const {
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return data;
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}
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constexpr iterator end() const {
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return data + size;
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}
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constexpr const_iterator cbegin() const {
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return data;
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}
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constexpr const_iterator cend() const {
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return data + size;
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}
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};
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#endif
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