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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;
}
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
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