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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_RUNTIME_BASE_ARRAY_REF_H_
#define ART_RUNTIME_BASE_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 {
public:
using value_type = T;
using reference = T&;
using const_reference = const T&;
using pointer = T*;
using const_pointer = const T*;
using iterator = T*;
using const_iterator = const T*;
using reverse_iterator = std::reverse_iterator<iterator>;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
using difference_type = ptrdiff_t;
using size_type = size_t;
// Constructors.
constexpr ArrayRef()
: array_(nullptr), size_(0u) {
}
template <size_t size>
explicit constexpr ArrayRef(T (&array)[size])
: array_(array), size_(size) {
}
template <typename U,
size_t size,
typename = typename std::enable_if<std::is_same<T, const U>::value>::type>
explicit constexpr ArrayRef(U (&array)[size])
: array_(array), size_(size) {
}
constexpr ArrayRef(T* array_in, size_t size_in)
: array_(array_in), size_(size_in) {
}
template <typename Vector,
typename = typename std::enable_if<
std::is_same<typename Vector::value_type, value_type>::value>::type>
explicit ArrayRef(Vector& v)
: array_(v.data()), size_(v.size()) {
}
template <typename Vector,
typename = typename std::enable_if<
std::is_same<
typename std::add_const<typename Vector::value_type>::type,
value_type>::value>::type>
explicit ArrayRef(const Vector& v)
: array_(v.data()), size_(v.size()) {
}
ArrayRef(const ArrayRef&) = default;
// 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(!empty());
return array_[0];
}
const_reference front() const {
DCHECK(!empty());
return array_[0];
}
reference back() {
DCHECK(!empty());
return array_[size_ - 1u];
}
const_reference back() const {
DCHECK(!empty());
return array_[size_ - 1u];
}
value_type* data() { return array_; }
const value_type* data() const { return array_; }
ArrayRef SubArray(size_type pos) {
return SubArray(pos, size() - pos);
}
ArrayRef<const T> SubArray(size_type pos) const {
return SubArray(pos, size() - pos);
}
ArrayRef SubArray(size_type pos, size_type length) {
DCHECK_LE(pos, size());
DCHECK_LE(length, size() - pos);
return ArrayRef(data() + pos, length);
}
ArrayRef<const T> SubArray(size_type pos, size_type length) const {
DCHECK_LE(pos, size());
DCHECK_LE(length, size() - pos);
return ArrayRef<const T>(data() + pos, length);
}
private:
T* array_;
size_t size_;
};
template <typename T>
bool operator==(const ArrayRef<T>& lhs, const ArrayRef<T>& rhs) {
return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin());
}
template <typename T>
bool operator!=(const ArrayRef<T>& lhs, const ArrayRef<T>& rhs) {
return !(lhs == rhs);
}
} // namespace art
#endif // ART_RUNTIME_BASE_ARRAY_REF_H_
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