From ac3052223465ce654457fec17b34f27de1706e57 Mon Sep 17 00:00:00 2001 From: Gil Date: Wed, 31 Jan 2018 14:28:20 -0800 Subject: Start on ArraySortedMap in C++ (#721) * Implement ArraySortedMap.remove * Implement ArraySortedMap.insert * Ensure ArraySortedMap.insert avoids copying on duplicates * Port more ArraySortedMapTests --- .../firebase/firestore/immutable/CMakeLists.txt | 21 ++ .../firestore/immutable/array_sorted_map.cc | 30 ++ .../firestore/immutable/array_sorted_map.h | 318 +++++++++++++++++++++ .../src/firebase/firestore/immutable/map_entry.h | 62 ++++ 4 files changed, 431 insertions(+) create mode 100644 Firestore/core/src/firebase/firestore/immutable/CMakeLists.txt create mode 100644 Firestore/core/src/firebase/firestore/immutable/array_sorted_map.cc create mode 100644 Firestore/core/src/firebase/firestore/immutable/array_sorted_map.h create mode 100644 Firestore/core/src/firebase/firestore/immutable/map_entry.h (limited to 'Firestore/core/src/firebase/firestore/immutable') diff --git a/Firestore/core/src/firebase/firestore/immutable/CMakeLists.txt b/Firestore/core/src/firebase/firestore/immutable/CMakeLists.txt new file mode 100644 index 0000000..e8a95cd --- /dev/null +++ b/Firestore/core/src/firebase/firestore/immutable/CMakeLists.txt @@ -0,0 +1,21 @@ +# 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. + +cc_library( + firebase_firestore_immutable + SOURCES + array_sorted_map.cc + array_sorted_map.h + map_entry.h +) diff --git a/Firestore/core/src/firebase/firestore/immutable/array_sorted_map.cc b/Firestore/core/src/firebase/firestore/immutable/array_sorted_map.cc new file mode 100644 index 0000000..48e7553 --- /dev/null +++ b/Firestore/core/src/firebase/firestore/immutable/array_sorted_map.cc @@ -0,0 +1,30 @@ +/* + * 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. + */ + +#include "Firestore/core/src/firebase/firestore/immutable/array_sorted_map.h" + +namespace firebase { +namespace firestore { +namespace immutable { +namespace impl { + +// Define external storage for constants: +constexpr ArraySortedMapBase::size_type ArraySortedMapBase::kFixedSize; + +} // namespace impl +} // namespace immutable +} // namespace firestore +} // namespace firebase diff --git a/Firestore/core/src/firebase/firestore/immutable/array_sorted_map.h b/Firestore/core/src/firebase/firestore/immutable/array_sorted_map.h new file mode 100644 index 0000000..d0210a8 --- /dev/null +++ b/Firestore/core/src/firebase/firestore/immutable/array_sorted_map.h @@ -0,0 +1,318 @@ +/* + * 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_ARRAY_SORTED_MAP_H_ +#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_IMMUTABLE_ARRAY_SORTED_MAP_H_ + +#include +#include +#include +#include +#include +#include + +#include "Firestore/core/src/firebase/firestore/immutable/map_entry.h" + +namespace firebase { +namespace firestore { +namespace immutable { + +namespace impl { + +/** + * A base class for implementing ArraySortedMap, containing types and constants + * that don't depend upon the template parameters to the main class. + * + * Note that this exists as a base class rather than as just a namespace in + * order to make it possible for users of ArraySortedMap to avoid needing to + * declare storage for each instantiation of the template. + */ +class ArraySortedMapBase { + public: + /** + * The type of size() methods on immutable collections. Note that this is not + * size_t specifically to save space in the TreeSortedMap implementation. + */ + using size_type = uint32_t; + + /** + * The maximum size of an ArraySortedMap. + * + * This is the size threshold where we use a tree backed sorted map instead of + * an array backed sorted map. This is a more or less arbitrary chosen value, + * that was chosen to be large enough to fit most of object kind of Firebase + * data, but small enough to not notice degradation in performance for + * inserting and lookups. Feel free to empirically determine this constant, + * but don't expect much gain in real world performance. + */ + // TODO(wilhuff): actually use this for switching implementations. + static constexpr size_type kFixedSize = 25; +}; + +/** + * A bounded-size array that allocates its contents directly in itself. This + * saves a heap allocation when compared with std::vector (though std::vector + * can resize itself while FixedArray cannot). + * + * Unlike std::array, FixedArray keeps track of its size and grows up to the + * fixed_size limit. Inserting more elements than fixed_size will trigger an + * assertion failure. + * + * ArraySortedMap does not actually contain its array: it contains a shared_ptr + * to a FixedArray. + * + * @tparam T The type of an element in the array. + * @tparam fixed_size the fixed size to use in creating the FixedArray. + */ +template +class FixedArray { + public: + using size_type = ArraySortedMapBase::size_type; + using array_type = std::array; + using iterator = typename array_type::iterator; + using const_iterator = typename array_type::const_iterator; + + FixedArray() { + } + + template + FixedArray(SourceIterator src_begin, SourceIterator src_end) { + append(src_begin, src_end); + } + + /** + * Appends to this array, copying from the given src_begin up to but not + * including the src_end. + */ + template + void append(SourceIterator src_begin, SourceIterator src_end) { + size_type appending = static_cast(src_end - src_begin); + size_type new_size = size_ + appending; + assert(new_size <= fixed_size); + + std::copy(src_begin, src_end, end()); + size_ = new_size; + } + + /** + * Appends a single value to the array. + */ + void append(T&& value) { + size_type new_size = size_ + 1; + assert(new_size <= fixed_size); + + *end() = std::move(value); + size_ = new_size; + } + + const_iterator begin() const { + return contents_.begin(); + } + + const_iterator end() const { + return begin() + size_; + } + + size_type size() const { + return size_; + } + + private: + iterator begin() { + return contents_.begin(); + } + + iterator end() { + return begin() + size_; + } + + array_type contents_; + size_type size_ = 0; +}; + +} // namespace impl + +/** + * ArraySortedMap is a value type containing a map. It is immutable, but has + * methods to efficiently create new maps that are mutations of it. + */ +template > +class ArraySortedMap : public impl::ArraySortedMapBase { + public: + using key_comparator_type = KeyComparator; + + /** + * The type of the entries stored in the map. + */ + using value_type = std::pair; + + /** + * The type of the fixed-size array containing entries of value_type. + */ + using array_type = impl::FixedArray; + using const_iterator = typename array_type::const_iterator; + + using array_pointer = std::shared_ptr; + + /** + * Creates an empty ArraySortedMap. + */ + explicit ArraySortedMap(const C& comparator = C()) + : array_(EmptyArray()), key_comparator_(comparator) { + } + + /** + * Creates an ArraySortedMap containing the given entries. + */ + ArraySortedMap(std::initializer_list entries, + const C& comparator = C()) + : array_(std::make_shared(entries.begin(), entries.end())), + key_comparator_(comparator) { + } + + /** + * Creates a new map identical to this one, but with a key-value pair added or + * updated. + * + * @param key The key to insert/update. + * @param value The value to associate with the key. + * @return A new dictionary with the added/updated value. + */ + ArraySortedMap insert(const K& key, const V& value) const { + const_iterator current_end = end(); + const_iterator pos = LowerBound(key); + bool replacing_entry = false; + + if (pos != current_end) { + // LowerBound found an entry where pos->first >= pair.first. Reversing the + // argument order here tests pair.first < pos->first. + replacing_entry = !key_comparator_(key, *pos); + if (replacing_entry && value == pos->second) { + return *this; + } + } + + // Copy the segment before the found position. If not found, this is + // everything. + auto copy = std::make_shared(begin(), pos); + + // Copy the value to be inserted. + copy->append(value_type(key, value)); + + if (replacing_entry) { + // Skip the thing at pos because it compares the same as the pair above. + copy->append(pos + 1, current_end); + } else { + copy->append(pos, current_end); + } + return wrap(copy); + } + + /** + * Creates a new map identical to this one, but with a key removed from it. + * + * @param key The key to remove. + * @return A new dictionary without that value. + */ + ArraySortedMap erase(const K& key) const { + const_iterator current_end = end(); + const_iterator pos = find(key); + if (pos == current_end) { + return *this; + } else if (size() <= 1) { + // If the key was found and it's the last entry, removing it would make + // the result empty. + return wrap(EmptyArray()); + } else { + auto copy = std::make_shared(begin(), pos); + copy->append(pos + 1, current_end); + return wrap(copy); + } + } + + /** + * Finds a value in the map. + * + * @param key The key to look up. + * @return An iterator pointing to the entry containing the key, or end() if + * not found. + */ + const_iterator find(const K& key) const { + const_iterator not_found = end(); + const_iterator lower_bound = LowerBound(key); + if (lower_bound != not_found && !key_comparator_(key, *lower_bound)) { + return lower_bound; + } else { + return not_found; + } + } + + // TODO(wilhuff): indexof + + /** Returns true if the map contains no elements. */ + bool empty() const { + return size() == 0; + } + + /** Returns the number of items in this map. */ + size_type size() const { + return array_->size(); + } + + /** + * Returns an iterator pointing to the first entry in the map. If there are + * no entries in the map, begin() == end(). + */ + const_iterator begin() const { + return array_->begin(); + } + + /** + * Returns an iterator pointing past the last entry in the map. + */ + const_iterator end() const { + return array_->end(); + } + + private: + static array_pointer EmptyArray() { + static const array_pointer kEmptyArray = + std::make_shared(); + return kEmptyArray; + } + + ArraySortedMap(const array_pointer& array, + const key_comparator_type& key_comparator) noexcept + : array_(array), key_comparator_(key_comparator) { + } + + ArraySortedMap wrap(const array_pointer& array) const noexcept { + return ArraySortedMap(array, key_comparator_); + } + + const_iterator LowerBound(const K& key) const { + return std::lower_bound(begin(), end(), key, key_comparator_); + } + + array_pointer array_; + key_comparator_type key_comparator_; +}; + +} // namespace immutable +} // namespace firestore +} // namespace firebase + +#endif // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_IMMUTABLE_ARRAY_SORTED_MAP_H_ diff --git a/Firestore/core/src/firebase/firestore/immutable/map_entry.h b/Firestore/core/src/firebase/firestore/immutable/map_entry.h new file mode 100644 index 0000000..2130b5b --- /dev/null +++ b/Firestore/core/src/firebase/firestore/immutable/map_entry.h @@ -0,0 +1,62 @@ +/* + * 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_MAP_ENTRY_H_ +#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_IMMUTABLE_MAP_ENTRY_H_ + +#include +#include + +namespace firebase { +namespace firestore { +namespace immutable { + +/** + * Compares two keys out of a map entry. + * + * @tparam K The type of the first value in the pair. + * @tparam V The type of the second value in the pair. + * @tparam C The comparator for use for values of type K + */ +template > +struct KeyComparator { + typedef std::pair pair_type; + + explicit KeyComparator(const C& comparator = C()) + : key_comparator_(comparator) { + } + + bool operator()(const K& lhs, const pair_type& rhs) const noexcept { + return key_comparator_(lhs, rhs.first); + } + + bool operator()(const pair_type& lhs, const K& rhs) const noexcept { + return key_comparator_(lhs.first, rhs); + } + + bool operator()(const pair_type& lhs, const pair_type& rhs) const noexcept { + return key_comparator_(lhs.first, rhs.first); + } + + private: + C key_comparator_; +}; + +} // namespace immutable +} // namespace firestore +} // namespace firebase + +#endif // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_IMMUTABLE_MAP_ENTRY_H_ -- cgit v1.2.3