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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_COMPILER_UTILS_ARRAY_REF_H_
#define ART_COMPILER_UTILS_ARRAY_REF_H_
#include <type_traits>
#include <vector>
#include "base/logging.h"
namespace art {
/**
* @brief A container that references an array.
*
* @details The template class ArrayRef provides a container that references
* an external array. This external array must remain alive while the ArrayRef
* object is in use. The external array may be a std::vector<>-backed storage
* or any other contiguous chunk of memory but that memory must remain valid,
* i.e. the std::vector<> must not be resized for example.
*
* Except for copy/assign and insert/erase/capacity functions, the interface
* is essentially the same as std::vector<>. Since we don't want to throw
* exceptions, at() is also excluded.
*/
template <typename T>
class ArrayRef {
private:
struct tag { };
public:
typedef T value_type;
typedef T& reference;
typedef const T& const_reference;
typedef T* pointer;
typedef const T* const_pointer;
typedef T* iterator;
typedef const T* const_iterator;
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
typedef ptrdiff_t difference_type;
typedef size_t size_type;
// Constructors.
constexpr ArrayRef()
: array_(nullptr), size_(0u) {
}
template <size_t size>
constexpr ArrayRef(T (&array)[size])
: array_(array), size_(size) {
}
template <typename U, size_t size>
constexpr ArrayRef(U (&array)[size],
typename std::enable_if<std::is_same<T, const U>::value, tag>::type t = tag())
: array_(array), size_(size) {
}
constexpr ArrayRef(T* array, size_t size)
: array_(array), size_(size) {
}
template <typename U>
constexpr ArrayRef(U* array, size_t size,
typename std::enable_if<std::is_same<T, const U>::value, tag>::type t = tag())
: array_(array), size_(size) {
}
explicit ArrayRef(std::vector<T>& v)
: array_(v.data()), size_(v.size()) {
}
template <typename U>
ArrayRef(const std::vector<U>& v,
typename std::enable_if<std::is_same<T, const U>::value, tag>::tag t = tag())
: array_(v.data()), size_(v.size()) {
}
// Assignment operators.
ArrayRef& operator=(const ArrayRef& other) {
array_ = other.array_;
size_ = other.size_;
return *this;
}
template <typename U>
typename std::enable_if<std::is_same<T, const U>::value, ArrayRef>::type&
operator=(const ArrayRef<U>& other) {
return *this = ArrayRef(other);
}
// Destructor.
~ArrayRef() = default;
// Iterators.
iterator begin() { return array_; }
const_iterator begin() const { return array_; }
const_iterator cbegin() const { return array_; }
iterator end() { return array_ + size_; }
const_iterator end() const { return array_ + size_; }
const_iterator cend() const { return array_ + size_; }
reverse_iterator rbegin() { return reverse_iterator(end()); }
const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
const_reverse_iterator crbegin() const { return const_reverse_iterator(cend()); }
reverse_iterator rend() { return reverse_iterator(begin()); }
const_reverse_iterator rend() const { return const_reverse_iterator(begin()); }
const_reverse_iterator crend() const { return const_reverse_iterator(cbegin()); }
// Size.
size_type size() const { return size_; }
bool empty() const { return size() == 0u; }
// Element access. NOTE: Not providing at().
reference operator[](size_type n) {
DCHECK_LT(n, size_);
return array_[n];
}
const_reference operator[](size_type n) const {
DCHECK_LT(n, size_);
return array_[n];
}
reference front() {
DCHECK_NE(size_, 0u);
return array_[0];
}
const_reference front() const {
DCHECK_NE(size_, 0u);
return array_[0];
}
reference back() {
DCHECK_NE(size_, 0u);
return array_[size_ - 1u];
}
const_reference back() const {
DCHECK_NE(size_, 0u);
return array_[size_ - 1u];
}
value_type* data() { return array_; }
const value_type* data() const { return array_; }
private:
T* array_;
size_t size_;
};
} // namespace art
#endif // ART_COMPILER_UTILS_ARRAY_REF_H_
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