// Ceres Solver - A fast non-linear least squares minimizer

// Copyright 2015 Google Inc. All rights reserved.

// http://ceres-solver.org/

//

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// modification, are permitted provided that the following conditions are met:

//

// * Redistributions of source code must retain the above copyright notice,

//   this list of conditions and the following disclaimer.

// * Redistributions in binary form must reproduce the above copyright notice,

//   this list of conditions and the following disclaimer in the documentation

//   and/or other materials provided with the distribution.

// * Neither the name of Google Inc. nor the names of its contributors may be

//   used to endorse or promote products derived from this software without

//   specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

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//

// Author: keir@google.com (Keir Mierle)

//

// Originally by Anton Carver

#ifndef CERES_INTERNAL_MAP_UTIL_H_

#define CERES_INTERNAL_MAP_UTIL_H_

#include <utility>

#include "ceres/internal/port.h"

#include "glog/logging.h"

namespace ceres {

// Perform a lookup in a map or hash_map, assuming that the key exists.

// Crash if it does not.

//

// This is intended as a replacement for operator[] as an rvalue (for reading)

// when the key is guaranteed to exist.

//

// operator[] is discouraged for several reasons:

//  * It has a side-effect of inserting missing keys

//  * It is not thread-safe (even when it is not inserting, it can still

//      choose to resize the underlying storage)

//  * It invalidates iterators (when it chooses to resize)

//  * It default constructs a value object even if it doesn't need to

//

// This version assumes the key is printable, and includes it in the fatal log

// message.

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;

}

// Perform a lookup in a map or hash_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.

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;

}

// Insert a new key and value into a map or hash_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>

bool InsertIfNotPresent(

    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.second;

}

// Perform a lookup in a map or hash_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;

}

// Test to see if a set, map, hash_set or hash_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();

}

// Inserts a new key/value into a map or hash_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;

}

}  // namespace ceres

#endif  // CERES_INTERNAL_MAP_UTIL_H_