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/*
* Copyright 2018 Google
*
* 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 FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_IMMUTABLE_SORTED_MAP_ITERATOR_H_
#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_IMMUTABLE_SORTED_MAP_ITERATOR_H_
#include <utility>
#include "Firestore/core/src/firebase/firestore/immutable/array_sorted_map.h"
#include "Firestore/core/src/firebase/firestore/immutable/tree_sorted_map.h"
namespace firebase {
namespace firestore {
namespace immutable {
namespace impl {
template <typename V, typename ArrayIter, typename TreeIter>
class SortedMapIterator {
public:
using iterator_category = std::forward_iterator_tag;
using value_type = V;
using pointer = const value_type*;
using reference = const value_type&;
using difference_type = std::ptrdiff_t;
public:
// Default constructor to conform to the requirements of ForwardIterator
SortedMapIterator() : tag_{Tag::Array}, array_iter_{} {
}
explicit SortedMapIterator(ArrayIter&& delegate)
: tag_{Tag::Array}, array_iter_{std::move(delegate)} {
}
explicit SortedMapIterator(TreeIter&& delegate)
: tag_{Tag::Tree}, tree_iter_{std::move(delegate)} {
}
SortedMapIterator(const SortedMapIterator& other) : tag_(other.tag_) {
switch (tag_) {
case Tag::Array:
new (&array_iter_) ArrayIter{other.array_iter_};
break;
case Tag::Tree:
new (&tree_iter_) TreeIter{other.tree_iter_};
break;
}
}
SortedMapIterator(SortedMapIterator&& other) : tag_(other.tag_) {
switch (tag_) {
case Tag::Array:
new (&array_iter_) ArrayIter{std::move(other.array_iter_)};
break;
case Tag::Tree:
new (&tree_iter_) TreeIter{std::move(other.tree_iter_)};
break;
}
}
~SortedMapIterator() {
switch (tag_) {
case Tag::Array:
array_iter_.~ArrayIter();
break;
case Tag::Tree:
tree_iter_.~TreeIter();
break;
}
}
SortedMapIterator& operator=(const SortedMapIterator& other) {
if (tag_ == other.tag_) {
switch (tag_) {
case Tag::Array:
array_iter_ = other.array_iter_;
break;
case Tag::Tree:
tree_iter_ = other.tree_iter_;
break;
}
} else {
this->~SortedMapIterator();
new (this) SortedMapIterator(other);
}
return *this;
}
SortedMapIterator& operator=(SortedMapIterator&& other) {
if (tag_ == other.tag_) {
switch (tag_) {
case Tag::Array:
array_iter_ = std::move(other.array_iter_);
break;
case Tag::Tree:
tree_iter_ = std::move(other.tree_iter_);
break;
}
} else {
this->~SortedMapIterator();
new (this) SortedMapIterator(std::move(other));
}
return *this;
}
pointer get() const {
switch (tag_) {
case Tag::Array:
// std::array::iterator is not guaranteed to be a bare pointer but will
// be a RandomAccessIterator which does have operator*().
return &*array_iter_;
case Tag::Tree:
return tree_iter_.get();
}
UNREACHABLE();
}
reference operator*() const {
return *get();
}
pointer operator->() const {
return get();
}
SortedMapIterator& operator++() {
switch (tag_) {
case Tag::Array:
++array_iter_;
break;
case Tag::Tree:
++tree_iter_;
break;
}
return *this;
}
SortedMapIterator operator++(int /*unused*/) {
SortedMapIterator result = *this;
++*this;
return result;
}
friend bool operator==(const SortedMapIterator& a,
const SortedMapIterator& b) {
if (a.tag_ != b.tag_) {
return false;
}
switch (a.tag_) {
case Tag::Array:
return a.array_iter_ == b.array_iter_;
case Tag::Tree:
return a.tree_iter_ == b.tree_iter_;
}
UNREACHABLE();
}
bool operator!=(const SortedMapIterator& b) const {
return !(*this == b);
}
private:
enum class Tag {
Array,
Tree,
};
Tag tag_;
union {
ArrayIter array_iter_;
TreeIter tree_iter_;
};
};
} // namespace impl
} // namespace immutable
} // namespace firestore
} // namespace firebase
#endif // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_IMMUTABLE_SORTED_MAP_ITERATOR_H_
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