146 lines
5.3 KiB
C++
146 lines
5.3 KiB
C++
// Copyright 2010 Google
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef BASE_MAP_UTIL_H_
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#define BASE_MAP_UTIL_H_
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#include <utility>
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#include "base/util.h"
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namespace operations_research {
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// Perform a lookup in a map or hash_map.
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// If the key is present in the map then the value associated with that
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// key is returned, otherwise the value passed as a default is returned.
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template <class Collection>
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const typename Collection::value_type::second_type&
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FindWithDefault(const Collection& collection,
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const typename Collection::value_type::first_type& key,
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const typename Collection::value_type::second_type& value) {
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typename Collection::const_iterator it = collection.find(key);
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if (it == collection.end()) {
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return value;
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}
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return it->second;
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}
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// Perform a lookup in a map or hash_map.
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// If the key is present a const pointer to the associated value is returned,
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// otherwise a NULL pointer is returned.
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template <class Collection>
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const typename Collection::value_type::second_type*
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FindOrNull(const Collection& collection,
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const typename Collection::value_type::first_type& key) {
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typename Collection::const_iterator it = collection.find(key);
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if (it == collection.end()) {
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return 0;
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}
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return &it->second;
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}
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// Perform a lookup in a map or hash_map.
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// Same as above but the returned pointer is not const and can be used to change
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// the stored value.
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template <class Collection>
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typename Collection::value_type::second_type*
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FindOrNull(Collection& collection, // NOLINT
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const typename Collection::value_type::first_type& key) {
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typename Collection::iterator it = collection.find(key);
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if (it == collection.end()) {
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return 0;
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}
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return &it->second;
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}
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// Perform a lookup in a map or hash_map whose values are pointers.
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// If the key is present a const pointer to the associated value is returned,
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// otherwise a NULL pointer is returned.
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// This function does not distinguish between a missing key and a key mapped
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// to a NULL value.
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template <class Collection>
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const typename Collection::value_type::second_type
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FindPtrOrNull(const Collection& collection,
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const typename Collection::value_type::first_type& key) {
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typename Collection::const_iterator it = collection.find(key);
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if (it == collection.end()) {
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return 0;
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}
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return it->second;
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}
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// Change the value associated with a particular key in a map or hash_map.
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// If the key is not present in the map the key and value are inserted,
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// otherwise the value is updated to be a copy of the value provided.
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// True indicates that an insert took place, false indicates an update.
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template <class Collection, class Key, class Value>
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bool InsertOrUpdate(Collection * const collection,
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const Key& key, const Value& value) {
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pair<typename Collection::iterator, bool> ret =
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collection->insert(typename Collection::value_type(key, value));
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if (!ret.second) {
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// update
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ret.first->second = value;
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return false;
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}
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return true;
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}
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// Insert a new key and value into a map or hash_map.
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// If the key is not present in the map the key and value are
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// inserted, otherwise nothing happens. True indicates that an insert
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// took place, false indicates the key was already present.
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template <class Collection, class Key, class Value>
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bool InsertIfNotPresent(Collection * const collection,
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const Key& key, const Value& value) {
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pair<typename Collection::iterator, bool> ret =
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collection->insert(typename Collection::value_type(key, value));
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return ret.second;
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}
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// Perform a lookup in map or hash_map.
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// If the key is present and value is non-NULL then a copy of the value
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// associated with the key is made into *value. Returns whether key was present.
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template <class Collection, class Key, class Value>
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bool FindCopy(const Collection& collection,
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const Key& key,
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Value* const value) {
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typename Collection::const_iterator it = collection.find(key);
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if (it == collection.end()) {
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return false;
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}
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if (value) {
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*value = it->second;
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}
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return true;
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}
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// Test to see if a set, map, hash_set or hash_map contains a particular key.
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// Returns true if the key is in the collection.
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template <class Collection, class Key>
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bool ContainsKey(const Collection& collection, const Key& key) {
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typename Collection::const_iterator it = collection.find(key);
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return it != collection.end();
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}
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template <class Collection>
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const typename Collection::value_type::second_type&
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FindOrDie(const Collection& collection,
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const typename Collection::value_type::first_type& key) {
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typename Collection::const_iterator it = collection.find(key);
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CHECK(it != collection.end()) << "Map key not found: " << key;
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return it->second;
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}
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} // namespace operations_research
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#endif // BASE_MAP_UTIL_H_
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