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Diffstat (limited to 'src/util/ConstBuffer.hxx')
| -rw-r--r-- | src/util/ConstBuffer.hxx | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/src/util/ConstBuffer.hxx b/src/util/ConstBuffer.hxx new file mode 100644 index 000000000..319102126 --- /dev/null +++ b/src/util/ConstBuffer.hxx @@ -0,0 +1,228 @@ +/* + * Copyright (C) 2013-2014 Max Kellermann <max@duempel.org> + * + * 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. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * ``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 + * FOUNDATION 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. + */ + +#ifndef CONST_BUFFER_HPP +#define CONST_BUFFER_HPP + +#include "Compiler.h" + +#include <cstddef> + +#ifndef NDEBUG +#include <assert.h> +#endif + +template<typename T> +struct ConstBuffer; + +template<> +struct ConstBuffer<void> { + typedef size_t size_type; + typedef const void *pointer_type; + typedef pointer_type const_pointer_type; + typedef pointer_type iterator; + typedef pointer_type const_iterator; + + pointer_type data; + size_type size; + + ConstBuffer() = default; + + constexpr ConstBuffer(std::nullptr_t):data(nullptr), size(0) {} + + constexpr ConstBuffer(pointer_type _data, size_type _size) + :data(_data), size(_size) {} + + constexpr static ConstBuffer Null() { + return ConstBuffer(nullptr, 0); + } + + constexpr static ConstBuffer<void> FromVoid(ConstBuffer<void> other) { + return other; + } + + constexpr ConstBuffer<void> ToVoid() const { + return *this; + } + + constexpr bool IsNull() const { + return data == nullptr; + } + + constexpr bool IsEmpty() const { + return size == 0; + } +}; + +/** + * A reference to a memory area that is read-only. + */ +template<typename T> +struct ConstBuffer { + typedef size_t size_type; + typedef const T &reference_type; + typedef reference_type const_reference_type; + typedef const T *pointer_type; + typedef pointer_type const_pointer_type; + typedef pointer_type iterator; + typedef pointer_type const_iterator; + + pointer_type data; + size_type size; + + ConstBuffer() = default; + + constexpr ConstBuffer(std::nullptr_t):data(nullptr), size(0) {} + + constexpr ConstBuffer(pointer_type _data, size_type _size) + :data(_data), size(_size) {} + + constexpr static ConstBuffer Null() { + return ConstBuffer(nullptr, 0); + } + + /** + * Cast a ConstBuffer<void> to a ConstBuffer<T>. A "void" + * buffer records its size in bytes, and when casting to "T", + * the assertion below ensures that the size is a multiple of + * sizeof(T). + */ +#ifdef NDEBUG + constexpr +#endif + static ConstBuffer<T> FromVoid(ConstBuffer<void> other) { + static_assert(sizeof(T) > 0, "Empty base type"); +#ifndef NDEBUG + assert(other.size % sizeof(T) == 0); +#endif + return ConstBuffer<T>(pointer_type(other.data), + other.size / sizeof(T)); + } + + constexpr ConstBuffer<void> ToVoid() const { + static_assert(sizeof(T) > 0, "Empty base type"); + return ConstBuffer<void>(data, size * sizeof(T)); + } + + constexpr bool IsNull() const { + return data == nullptr; + } + + constexpr bool IsEmpty() const { + return size == 0; + } + + constexpr iterator begin() const { + return data; + } + + constexpr iterator end() const { + return data + size; + } + + constexpr const_iterator cbegin() const { + return data; + } + + constexpr const_iterator cend() const { + return data + size; + } + +#ifdef NDEBUG + constexpr +#endif + reference_type operator[](size_type i) const { +#ifndef NDEBUG + assert(i < size); +#endif + + return data[i]; + } + + /** + * Returns a reference to the first element. Buffer must not + * be empty. + */ +#ifdef NDEBUG + constexpr +#endif + reference_type front() const { +#ifndef NDEBUG + assert(!IsEmpty()); +#endif + return data[0]; + } + + /** + * Returns a reference to the last element. Buffer must not + * be empty. + */ +#ifdef NDEBUG + constexpr +#endif + reference_type back() const { +#ifndef NDEBUG + assert(!IsEmpty()); +#endif + return data[size - 1]; + } + + /** + * Remove the first element (by moving the head pointer, does + * not actually modify the buffer). Buffer must not be empty. + */ + void pop_front() { + assert(!IsEmpty()); + + ++data; + --size; + } + + /** + * Remove the last element (by moving the tail pointer, does + * not actually modify the buffer). Buffer must not be empty. + */ + void pop_back() { + assert(!IsEmpty()); + + --size; + } + + /** + * Remove the first element and return a reference to it. + * Buffer must not be empty. + */ + reference_type shift() { + reference_type result = front(); + pop_front(); + return result; + } +}; + +#endif |