map_util.h

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// Copyright 2010-2021 Google LLC
// 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 OR_TOOLS_BASE_MAP_UTIL_H_
#define OR_TOOLS_BASE_MAP_UTIL_H_

#include <utility>

#include "ortools/base/logging.h"

namespace gtl {
// Perform a lookup in a std::map or std::unordered_map.
// If the key is present in the map then the value associated with that
// key is returned, otherwise the value passed as a default is returned.
//
// Prefer the two-argument form unless you need to specify a custom default
// value (i.e., one that is not equal to a value-initialized instance).
template <class Collection>
const typename Collection::value_type::second_type& FindWithDefault(
    const Collection& collection,
    const typename Collection::value_type::first_type& key,
    const typename Collection::value_type::second_type& value) {
  typename Collection::const_iterator it = collection.find(key);
  if (it == collection.end()) {
    return value;
  }
  return it->second;
}

// Returns a const reference to the value associated with the given key if it
// exists, otherwise returns a const reference to a value-initialized object
// that is never destroyed.
template <class Collection>
const typename Collection::value_type::second_type& FindWithDefault(
    const Collection& collection,
    const typename Collection::value_type::first_type& key) {
  static const typename Collection::value_type::second_type* const
      default_value = new typename Collection::value_type::second_type{};
  typename Collection::const_iterator it = collection.find(key);
  if (it == collection.end()) {
    return *default_value;
  }
  return it->second;
}

// Perform a lookup in a std::map or std::unordered_map.
// If the key is present a const pointer to the associated value is returned,
// otherwise a NULL pointer is returned.
template <class Collection>
const typename Collection::value_type::second_type* FindOrNull(
    const Collection& collection,
    const typename Collection::value_type::first_type& key) {
  typename Collection::const_iterator it = collection.find(key);
  if (it == collection.end()) {
    return 0;
  }
  return &it->second;
}

// Perform a lookup in a std::map or std::unordered_map.
// Same as above but the returned pointer is not const and can be used to change
// the stored value.
template <class Collection>
typename Collection::value_type::second_type* FindOrNull(
    Collection& collection,  // NOLINT
    const typename Collection::value_type::first_type& key) {
  typename Collection::iterator it = collection.find(key);
  if (it == collection.end()) {
    return 0;
  }
  return &it->second;
}

// Perform a lookup in a std::map or std::unordered_map whose values are
// pointers. If the key is present a const pointer to the associated value is
// returned, otherwise a NULL pointer is returned. This function does not
// distinguish between a missing key and a key mapped to a NULL value.
template <class Collection>
const typename Collection::value_type::second_type FindPtrOrNull(
    const Collection& collection,
    const typename Collection::value_type::first_type& key) {
  typename Collection::const_iterator it = collection.find(key);
  if (it == collection.end()) {
    return 0;
  }
  return it->second;
}

// Change the value associated with a particular key in a std::map or
// std::unordered_map. If the key is not present in the map the key and value
// are inserted, otherwise the value is updated to be a copy of the value
// provided. True indicates that an insert took place, false indicates an
// update.
template <class Collection, class Key, class Value>
bool InsertOrUpdate(Collection* const collection, const Key& key,
                    const Value& value) {
  std::pair<typename Collection::iterator, bool> ret =
      collection->insert(typename Collection::value_type(key, value));
  if (!ret.second) {
    // update
    ret.first->second = value;
    return false;
  }
  return true;
}

// Insert a new key into a set.
// If the key is not present in the set the key is
// inserted, otherwise nothing happens. True indicates that an insert
// took place, false indicates the key was already present.
template <class Collection>
bool InsertIfNotPresent(Collection* const collection,
                        const typename Collection::value_type& value) {
  std::pair<typename Collection::iterator, bool> ret =
      collection->insert(value);
  return ret.second;
}

// Insert a new key and value into a std::map or std::unordered_map.
// If the key is not present in the map the key and value are
// inserted, otherwise nothing happens. True indicates that an insert
// took place, false indicates the key was already present.
template <class Collection, class Key, class Value>
bool InsertIfNotPresent(Collection* const collection, const Key& key,
                        const Value& value) {
  std::pair<typename Collection::iterator, bool> ret =
      collection->insert(typename Collection::value_type(key, value));
  return ret.second;
}

// Inserts a new std::pair<key,value> into a std::map or std::unordered_map.
// Insert a new key into a std::set or std::unordered_set.
// Dies if the key is already present.
template <class Collection>
void InsertOrDieNoPrint(Collection* const collection,
                        const typename Collection::value_type& value) {
  CHECK(collection->insert(value).second);
}

// Inserts a new std::pair<key,value> into a std::map or std::unordered_map.
// Insert a new key into a std::set or std::unordered_set.
// Dies if the key is already present.
template <class Collection>
void InsertOrDie(Collection* const collection,
                 const typename Collection::value_type& value) {
  CHECK(collection->insert(value).second) << "duplicate value: " << value;
}

// Inserts a new key/value into a std::map or std::unordered_map.
// Dies if the key is already present.
template <class Collection>
void InsertOrDie(Collection* const collection,
                 const typename Collection::value_type::first_type& key,
                 const typename Collection::value_type::second_type& data) {
  typedef typename Collection::value_type value_type;
  CHECK(collection->insert(value_type(key, data)).second)
      << "duplicate key: " << key;
}

// Inserts a key into a map with the default value or dies. Returns a reference
// to the inserted element.
template <typename Collection>
auto& InsertKeyOrDie(Collection* const collection,
                     const typename Collection::value_type::first_type& key) {
  auto [it, did_insert] = collection->insert(typename Collection::value_type(
      key, typename Collection::value_type::second_type()));
  CHECK(did_insert) << "duplicate key " << key;
  return it->second;
}

// Perform a lookup in std::map or std::unordered_map.
// If the key is present and value is non-NULL then a copy of the value
// associated with the key is made into *value. Returns whether key was present.
template <class Collection, class Key, class Value>
bool FindCopy(const Collection& collection, const Key& key,
              Value* const value) {
  typename Collection::const_iterator it = collection.find(key);
  if (it == collection.end()) {
    return false;
  }
  if (value) {
    *value = it->second;
  }
  return true;
}

// Test to see if a std::set, std::map, std::unordered_set or std::unordered_map
// contains a particular key. Returns true if the key is in the collection.
template <class Collection, class Key>
bool ContainsKey(const Collection& collection, const Key& key) {
  typename Collection::const_iterator it = collection.find(key);
  return it != collection.end();
}

template <class Collection>
const typename Collection::value_type::second_type& FindOrDie(
    const Collection& collection,
    const typename Collection::value_type::first_type& key) {
  typename Collection::const_iterator it = collection.find(key);
  CHECK(it != collection.end()) << "Map key not found: " << key;
  return it->second;
}

// Same as FindOrDie above, but doesn't log the key on failure.
template <class Collection>
const typename Collection::value_type::second_type& FindOrDieNoPrint(
    const Collection& collection,
    const typename Collection::value_type::first_type& key) {
  typename Collection::const_iterator it = collection.find(key);
  CHECK(it != collection.end()) << "Map key not found";
  return it->second;
}

// Same as above, but returns a non-const reference.
template <class Collection>
typename Collection::value_type::second_type& FindOrDieNoPrint(
    Collection& collection,  // NOLINT
    const typename Collection::value_type::first_type& key) {
  typename Collection::iterator it = collection.find(key);
  CHECK(it != collection.end()) << "Map key not found";
  return it->second;
}

// Lookup a key in a std::map or std::unordered_map, insert it if it is not
// present. Returns a reference to the value associated with the key.
template <class Collection>
typename Collection::value_type::second_type& LookupOrInsert(
    Collection* const collection,
    const typename Collection::value_type::first_type& key,
    const typename Collection::value_type::second_type& value) {
  std::pair<typename Collection::iterator, bool> ret =
      collection->insert(typename Collection::value_type(key, value));
  return ret.first->second;
}
}  // namespace gtl
#endif  // OR_TOOLS_BASE_MAP_UTIL_H_