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+/*
+ * 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;
+ }
+
+ template<typename U>
+ gcc_pure
+ bool Contains(U &&u) const {
+ for (const auto &i : *this)
+ if (u == i)
+ return true;
+
+ return false;
+ }
+
+ 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() {
+#ifndef NDEBUG
+ assert(!IsEmpty());
+#endif
+
+ ++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() {
+#ifndef NDEBUG
+ assert(!IsEmpty());
+#endif
+
+ --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;
+ }
+
+ void skip_front(size_type n) {
+#ifndef NDEBUG
+ assert(size >= n);
+#endif
+
+ data += n;
+ size -= n;
+ }
+};
+
+#endif