// bslstl_unorderedmultimap_cpp03.h                                   -*-C++-*-

// Automatically generated file.  **DO NOT EDIT**

#ifndef INCLUDED_BSLSTL_UNORDEREDMULTIMAP_CPP03
#define INCLUDED_BSLSTL_UNORDEREDMULTIMAP_CPP03

//@PURPOSE: Provide C++03 implementation for bslstl_unorderedmultimap.h
//
//@CLASSES: See bslstl_unorderedmultimap.h for list of classes
//
//@SEE_ALSO: bslstl_unorderedmultimap
//
//@DESCRIPTION:  This component is the C++03 translation of a C++11 component,
// generated by the 'sim_cpp11_features.pl' program.  If the original header
// contains any specially delimited regions of C++11 code, then this generated
// file contains the C++03 equivalent, i.e., with variadic templates expanded
// and rvalue-references replaced by 'bslmf::MovableRef' objects.  The header
// code in this file is designed to be '#include'd into the original header
// when compiling with a C++03 compiler.  If there are no specially delimited
// regions of C++11 code, then this header contains no code and is not
// '#include'd in the original header.
//
// Generated on Thu Mar 12 11:46:48 2026
// Command line: sim_cpp11_features.pl bslstl_unorderedmultimap.h

#ifdef COMPILING_BSLSTL_UNORDEREDMULTIMAP_H

namespace bsl {

/// This class template implements a value-semantic container type holding a
/// collection of (possibly equivalent) keys (of the template parameter type
/// `KEY`), each mapped to their associated values (of another template
/// parameter type `VALUE`).
///
/// This class:
/// * supports a complete set of *value-semantic* operations
///   - except for BDEX serialization
/// * is *exception-neutral* (agnostic except for the `at` method)
/// * is *alias-safe*
/// * is `const` *thread-safe*
/// For terminology see {`bsldoc_glossary`}.
template <class KEY,
          class VALUE,
          class HASH      = bsl::hash<KEY>,
          class EQUAL     = bsl::equal_to<KEY>,
          class ALLOCATOR = bsl::allocator<bsl::pair<const KEY, VALUE> > >
class unordered_multimap {

  private:
    // PRIVATE TYPES

    /// This `typedef` is an alias for the allocator traits type associated
    /// with this container.
    typedef bsl::allocator_traits<ALLOCATOR>                 AllocatorTraits;

    /// This `typedef` is an alias for the type of key-value pair objects
    /// maintained by this unordered multimap.
    typedef pair<const KEY, VALUE>                           ValueType;

    /// This `typedef` is an alias for the policy used internally by this
    /// container to extract the `KEY` value from the values maintained by
    /// this unordered multimap.
    typedef ::BloombergLP::bslstl::UnorderedMapKeyConfiguration<const KEY,
                                                                ValueType>
                                                             ListConfiguration;

    /// This `typedef` is an alias for the template instantiation of the
    /// underlying `bslstl::HashTable` used to implement this unordered
    /// multimap.
    typedef ::BloombergLP::bslstl::HashTable<ListConfiguration,
                                             HASH,
                                             EQUAL,
                                             ALLOCATOR>      Impl;

    /// This `typedef` is an alias for the type of links maintained by the
    /// linked list of elements held by the underlying `bslstl::HashTable`.
    typedef ::BloombergLP::bslalg::BidirectionalLink         HashTableLink;

    /// This `typedef` is a convenient alias for the utility associated with
    /// movable references.
    typedef BloombergLP::bslmf::MovableRefUtil               MoveUtil;

    // FRIENDS
    template <class KEY2,
              class VALUE2,
              class HASH2,
              class EQUAL2,
              class ALLOCATOR2>
    friend bool operator==(
           const unordered_multimap<KEY2, VALUE2, HASH2, EQUAL2, ALLOCATOR2>&,
           const unordered_multimap<KEY2, VALUE2, HASH2, EQUAL2, ALLOCATOR2>&);

  public:
    // PUBLIC TYPES
    typedef KEY                                        key_type;
    typedef VALUE                                      mapped_type;
    typedef bsl::pair<const KEY, VALUE>                value_type;
    typedef HASH                                       hasher;
    typedef EQUAL                                      key_equal;
    typedef ALLOCATOR                                  allocator_type;

    typedef value_type&                                reference;
    typedef const value_type&                          const_reference;

    typedef typename AllocatorTraits::size_type        size_type;
    typedef typename AllocatorTraits::difference_type  difference_type;
    typedef typename AllocatorTraits::pointer          pointer;
    typedef typename AllocatorTraits::const_pointer    const_pointer;

    typedef ::BloombergLP::bslstl::HashTableIterator<
                         value_type, difference_type>  iterator;

    typedef ::BloombergLP::bslstl::HashTableIterator<
                   const value_type, difference_type>  const_iterator;

    typedef ::BloombergLP::bslstl::HashTableBucketIterator<
                         value_type, difference_type>  local_iterator;

    typedef ::BloombergLP::bslstl::HashTableBucketIterator<
                   const value_type, difference_type>  const_local_iterator;

  private:
    // DATA
    Impl d_impl;

  public:
    // CREATORS

    /// Create an empty unordered multimap.  Optionally specify an
    /// `initialNumBuckets` indicating the minimum initial size of the array
    /// of buckets of this container.  If `initialNumBuckets` is not
    /// supplied, a single empty bucket is used.  Optionally specify a
    /// `hashFunction` used to generate the hash values for the keys
    /// contained in this unordered multimap.  If `hashFunction` is not
    /// supplied, a default-constructed object of the (template parameter)
    /// type `HASH` is used.  Optionally specify a key-equivalence functor
    /// `keyEqual` used to verify that two keys are equivalent.  If
    /// `keyEqual` is not supplied, a default-constructed object of the
    /// (template parameter) type `EQUAL` is used.  Optionally specify a
    /// `basicAllocator` used to supply memory.  If `basicAllocator` is not
    /// supplied, a default-constructed object of the (template parameter)
    /// type `ALLOCATOR` is used.  If the type `ALLOCATOR` is
    /// `bsl::allocator` (the default), then `basicAllocator`, if supplied,
    /// shall be convertible to `bslma::Allocator *`.  If the type
    /// `ALLOCATOR` is `bsl::allocator` and `basicAllocator` is not
    /// supplied, the currently installed default allocator is used.
    unordered_multimap();
    explicit unordered_multimap(size_type        initialNumBuckets,
                                const HASH&      hashFunction = HASH(),
                                const EQUAL&     keyEqual = EQUAL(),
                                const ALLOCATOR& basicAllocator = ALLOCATOR());
    unordered_multimap(size_type        initialNumBuckets,
                       const HASH&      hashFunction,
                       const ALLOCATOR& basicAllocator);
    unordered_multimap(size_type        initialNumBuckets,
                       const ALLOCATOR& basicAllocator);
    explicit unordered_multimap(const ALLOCATOR& basicAllocator);

    /// Create an unordered multimap having the same value as the specified
    /// `original` object.  Use a copy of `original.hash_function()` to
    /// generate hash values for the keys contained in this unordered
    /// multimap.  Use a copy of `original.key_eq()` to verify that two keys
    /// are equivalent.  Use the allocator returned by
    /// `bsl::allocator_traits<ALLOCATOR>::
    /// select_on_container_copy_construction(original.get_allocator())` to
    /// allocate memory.  This method requires that the (template parameter)
    /// types `KEY` and `VALUE` both be `copy-insertable` into this
    /// unordered multimap (see {Requirements on `KEY` and `VALUE`}).
    unordered_multimap(const unordered_multimap& original);

    /// Create an unordered multimap having the same value as the specified
    /// `original` object by moving (in constant time) the contents of
    /// `original` to the new unordered multimap.  Use a copy of
    /// `original.hash_function()` to generate hash values for the keys
    /// contained in this unordered multimap.  Use a copy of
    /// `original.key_eq()` to verify that two keys are equivalent.  The
    /// allocator associated with `original` is propagated for use in the
    /// newly-created unordered multimap.  `original` is left in a valid but
    /// unspecified state.
    unordered_multimap(
                  BloombergLP::bslmf::MovableRef<unordered_multimap> original);

    /// Create an unordered multimap having the same value as the specified
    /// `original` object that uses the specified `basicAllocator` to supply
    /// memory.  Use a copy of `original.hash_function()` to generate hash
    /// values for the keys contained in this unordered multimap.  Use a
    /// copy of `original.key_eq()` to verify that two keys are equivalent.
    /// This method requires that the (template parameter) types `KEY` and
    /// `VALUE` both be `copy-insertable` into this unordered multimap (see
    /// {Requirements on `KEY` and `VALUE`}).  Note that a
    /// `bslma::Allocator *` can be supplied for `basicAllocator` if the
    /// (template parameter) type `ALLOCATOR` is `bsl::allocator` (the
    /// default).
    unordered_multimap(
                const unordered_multimap&                      original,
                const typename type_identity<ALLOCATOR>::type& basicAllocator);

    /// Create an unordered multimap having the same value as the specified
    /// `original` object that uses the specified `basicAllocator` to supply
    /// memory.  The contents of `original` are moved (in constant time) to
    /// the new unordered multimap if `basicAllocator ==
    /// original.get_allocator()`, and are move-inserted (in linear time)
    /// using `basicAllocator` otherwise.  `original` is left in a valid but
    /// unspecified state.  Use a copy of `original.hash_function()` to
    /// generate hash values for the keys contained in this unordered
    /// multimap.  Use a copy of `original.key_eq()` to verify that two keys
    /// are equivalent.  This method requires that the (template parameter)
    /// types `KEY` and `VALUE` both be `move-insertable` into this
    /// unordered multimap (see {Requirements on `KEY` and `VALUE`}).  Note
    /// that a `bslma::Allocator *` can be supplied for `basicAllocator` if
    /// the (template parameter) type `ALLOCATOR` is `bsl::allocator` (the
    /// default).
    unordered_multimap(
            BloombergLP::bslmf::MovableRef<unordered_multimap> original,
            const typename type_identity<ALLOCATOR>::type&     basicAllocator);

    /// Create an unordered multimap, and insert each `value_type` object in
    /// the sequence starting at the specified `first` element, and ending
    /// immediately before the specified `last` element.  Optionally specify
    /// an `initialNumBuckets` indicating the minimum initial size of the
    /// array of buckets of this container.  If `initialNumBuckets` is not
    /// supplied, a single empty bucket is used if `first` and `last` denote
    /// an empty range, and an unspecified number of buckets is used
    /// otherwise.  Optionally specify a `hashFunction` used to generate
    /// hash values for the keys contained in this unordered multimap.  If
    /// `hashFunction` is not supplied, a default-constructed object of
    /// (template parameter) type `HASH` is used.  Optionally specify a
    /// key-equivalence functor `keyEqual` used to verify that two keys are
    /// equivalent.  If `keyEqual` is not supplied, a default-constructed
    /// object of (template parameter) type `EQUAL` is used.  Optionally
    /// specify a `basicAllocator` used to supply memory.  If
    /// `basicAllocator` is not supplied, a default-constructed object of
    /// the (template parameter) type `ALLOCATOR` is used.  If the type
    /// `ALLOCATOR` is `bsl::allocator` and `basicAllocator` is not
    /// supplied, the currently installed default allocator is used to
    /// supply memory.  The (template parameter) type `INPUT_ITERATOR` shall
    /// meet the requirements of an input iterator defined in the C++11
    /// standard [24.2.3] providing access to values of a type convertible
    /// to `value_type`, and `value_type` must be `emplace-constructible`
    /// from `*i` into this unordered multimap, where `i` is a
    /// dereferenceable iterator in the range `[first .. last)` (see
    /// {Requirements on `KEY` and `VALUE`}).  The behavior is undefined
    /// unless `first` and `last` refer to a sequence of valid values where
    /// `first` is at a position at or before `last`.  Note that a
    /// `bslma::Allocator *` can be supplied for `basicAllocator` if the
    /// type `ALLOCATOR` is `bsl::allocator` (the default).
    template <class INPUT_ITERATOR>
    unordered_multimap(INPUT_ITERATOR   first,
                       INPUT_ITERATOR   last,
                       size_type        initialNumBuckets = 0,
                       const HASH&      hashFunction = HASH(),
                       const EQUAL&     keyEqual = EQUAL(),
                       const ALLOCATOR& basicAllocator = ALLOCATOR());
    template <class INPUT_ITERATOR>
    unordered_multimap(INPUT_ITERATOR   first,
                       INPUT_ITERATOR   last,
                       size_type        initialNumBuckets,
                       const HASH&      hashFunction,
                       const ALLOCATOR& basicAllocator);
    template <class INPUT_ITERATOR>
    unordered_multimap(INPUT_ITERATOR   first,
                       INPUT_ITERATOR   last,
                       size_type        initialNumBuckets,
                       const ALLOCATOR& basicAllocator);
    template <class INPUT_ITERATOR>
    unordered_multimap(INPUT_ITERATOR   first,
                       INPUT_ITERATOR   last,
                       const ALLOCATOR& basicAllocator);

#if defined(BSLS_COMPILERFEATURES_SUPPORT_GENERALIZED_INITIALIZERS)
# ifdef BSLS_COMPILERFEATURES_SUPPORT_CTAD
    template <
    class = bsl::enable_if_t<std::is_invocable_v<HASH, const KEY &>>,
    class = bsl::enable_if_t<
                         std::is_invocable_v<EQUAL, const KEY &, const KEY &>>,
    class = bsl::enable_if_t< bsl::IsStdAllocator_v<ALLOCATOR>>
    >
# endif
    unordered_multimap(
               std::initializer_list<value_type> values,
               size_type                         initialNumBuckets = 0,
               const HASH&                       hashFunction = HASH(),
               const EQUAL&                      keyEqual = EQUAL(),
               const ALLOCATOR&                  basicAllocator = ALLOCATOR());
# ifdef BSLS_COMPILERFEATURES_SUPPORT_CTAD
    template <
    class = bsl::enable_if_t<std::is_invocable_v<HASH, const KEY &>>,
    class = bsl::enable_if_t< bsl::IsStdAllocator_v<ALLOCATOR>>
    >
# endif
    unordered_multimap(std::initializer_list<value_type> values,
                       size_type                         initialNumBuckets,
                       const HASH&                       hashFunction,
                       const ALLOCATOR&                  basicAllocator);
# ifdef BSLS_COMPILERFEATURES_SUPPORT_CTAD
    template <
    class = bsl::enable_if_t< bsl::IsStdAllocator_v<ALLOCATOR>>
    >
# endif
    unordered_multimap(std::initializer_list<value_type> values,
                       size_type                         initialNumBuckets,
                       const ALLOCATOR&                  basicAllocator);
# ifdef BSLS_COMPILERFEATURES_SUPPORT_CTAD
    /// Create an unordered multimap and insert each `value_type` object in
    /// the specified `values` initializer list.  Optionally specify an
    /// `initialNumBuckets` indicating the minimum initial size of the array
    /// of buckets of this container.  If `initialNumBuckets` is not
    /// supplied, a single empty bucket is used if `values` is empty, and an
    /// unspecified number of buckets is used otherwise.  Optionally specify
    /// a `hashFunction` used to generate the hash values for the keys
    /// contained in this unordered multimap.  If `hashFunction` is not
    /// supplied, a default-constructed object of the (template parameter)
    /// type `HASH` is used.  Optionally specify a key-equivalence functor
    /// `keyEqual` used to verify that two keys are equivalent.  If
    /// `keyEqual` is not supplied, a default-constructed object of the
    /// (template parameter) type `EQUAL` is used.  Optionally specify a
    /// `basicAllocator` used to supply memory.  If `basicAllocator` is not
    /// supplied, a default-constructed object of the (template parameter)
    /// type `ALLOCATOR` is used.  If the type `ALLOCATOR` is
    /// `bsl::allocator` and `basicAllocator` is not supplied, the currently
    /// installed default allocator is used to supply memory.  This method
    /// requires that the (template parameter) types `KEY` and `VALUE` both
    /// be `copy-insertable` into this unordered multimap (see {Requirements
    /// on `KEY` and `VALUE`}).  Note that a `bslma::Allocator *` can be
    /// supplied for `basicAllocator` if the type `ALLOCATOR` is
    /// `bsl::allocator` (the default).
    template <
    class = bsl::enable_if_t< bsl::IsStdAllocator_v<ALLOCATOR>>
    >
# endif
    unordered_multimap(std::initializer_list<value_type> values,
                       const ALLOCATOR&                  basicAllocator);
#endif

    /// Create an unordered multimap, and insert each `value_type` object in
    /// the specified `range`.  Optionally specify an `initialNumBuckets`
    /// indicating the initial size of the array of buckets of this
    /// container.  If `initialNumBuckets` is not supplied, an
    /// implementation-defined value is used.  Optionally specify a
    /// `hashFunction` used to generate the hash values for each key value
    /// contained in this unordered multimap.  If `hashFunction` is not
    /// supplied, a default-constructed object of the (template parameter)
    /// type `HASH` is used.  Optionally specify a key-equality functor
    /// `keyEqual` used to determine whether two keys have the same value.
    /// If `keyEqual` is not supplied, a default-constructed object of the
    /// (template parameter) type `EQUAL` is used.  Optionally specify a
    /// `basicAllocator` used to supply memory.  If `basicAllocator` is not
    /// supplied, a default-constructed object of the (template parameter)
    /// type `ALLOCATOR` is used.  If the type `ALLOCATOR` is
    /// `bsl::allocator` (the default), then `basicAllocator`, if supplied,
    /// shall be convertible to `bslma::Allocator *`.  If the type
    /// `ALLOCATOR` is `bsl::allocator` and `basicAllocator` is not
    /// supplied, the currently installed default allocator is used.  This
    /// operation has `O[N]` complexity, where `N` is the number of elements
    /// in `range`.  Note that `RANGE` must meet the requirements of an
    /// input range and the values from `range` must have a type matching or
    /// convertible to `value_type`.
    template <class RANGE>
    BSLSTL_UNORDEREDMULTIMAP_REQUIRES_CONTAINER_COMPATIBLE_RANGE(RANGE,
                                                                 value_type)
    unordered_multimap(
         bsl::from_range_t                        ,
         BSLS_COMPILERFEATURES_FORWARD_REF(RANGE) range,
         size_type                                initialNumBuckets = 0,
         const HASH&                              hashFunction = HASH(),
         const EQUAL&                             keyEqual = EQUAL(),
         const ALLOCATOR&                         basicAllocator = ALLOCATOR())
    : d_impl(hashFunction,
             keyEqual,
             initialNumBuckets,
             1.0f,
             basicAllocator)
    {
        // Defined inline to avoid `clang` and Windows errors.
#if defined(BSLS_LIBRARYFEATURES_HAS_CPP20_CONCEPTS) \
 && defined(BSLS_LIBRARYFEATURES_HAS_CPP20_RANGES)
        if constexpr (ranges::sized_range<RANGE>) {
            constructFromRange(bsl::ranges::begin(range),
                               bsl::ranges::end  (range),
                               bsl::ranges::size (range));
        } else // ...
#endif
        {
            constructFromRange(bsl::ranges::begin(range),
                               bsl::ranges::end  (range));
        }
    }

    template <class RANGE>
    BSLSTL_UNORDEREDMULTIMAP_REQUIRES_CONTAINER_COMPATIBLE_RANGE(RANGE,
                                                                 value_type)
    unordered_multimap(bsl::from_range_t                        ,
                    BSLS_COMPILERFEATURES_FORWARD_REF(RANGE) range,
                    size_type                                initialNumBuckets,
                    const HASH&                              hashFunction,
                    const ALLOCATOR&                         basicAllocator)
    : d_impl(hashFunction, EQUAL(), initialNumBuckets, 1.0f, basicAllocator)
    {
        // Defined inline to avoid `clang` error.

        unordered_multimap other(bsl::from_range,
                                 range,
                                 initialNumBuckets,
                                 hashFunction,
                                 EQUAL(),
                                 basicAllocator);
        this->swap(other);
    }

    template <class RANGE>
    BSLSTL_UNORDEREDMULTIMAP_REQUIRES_CONTAINER_COMPATIBLE_RANGE(RANGE,
                                                                 value_type)
    unordered_multimap(bsl::from_range_t                        ,
                    BSLS_COMPILERFEATURES_FORWARD_REF(RANGE) range,
                    size_type                                initialNumBuckets,
                    const ALLOCATOR&                         basicAllocator)
    : d_impl(HASH(), EQUAL(), initialNumBuckets, 1.0f, basicAllocator)
    {
        // Defined inline to avoid `clang` error.

        unordered_multimap other(bsl::from_range,
                                 range,
                                 initialNumBuckets,
                                 HASH(),
                                 EQUAL(),
                                 basicAllocator);
        this->swap(other);
    }

    template <class RANGE>
    BSLSTL_UNORDEREDMULTIMAP_REQUIRES_CONTAINER_COMPATIBLE_RANGE(RANGE,
                                                                 value_type)
    unordered_multimap(bsl::from_range_t                        ,
                       BSLS_COMPILERFEATURES_FORWARD_REF(RANGE) range,
                       const ALLOCATOR&                         basicAllocator)
    : d_impl(HASH(), EQUAL(), 0, 1.0f, basicAllocator)
    {
        // Defined inline to avoid `clang` error.

        unordered_multimap other(bsl::from_range,
                                 range,
                                 0,
                                 HASH(),
                                 EQUAL(),
                                 basicAllocator);
        this->swap(other);
    }

    /// Destroy this object.
    ~unordered_multimap();

    // MANIPULATORS

    /// Assign to this object the value, hash function, and key-equivalence
    /// comparator of the specified `rhs` object, propagate to this object
    /// the allocator of `rhs` if the `ALLOCATOR` type has trait
    /// `propagate_on_container_copy_assignment`, and return a reference
    /// providing modifiable access to this object.  If an exception is
    /// thrown, `*this` is left in a valid but unspecified state.  This
    /// method requires that the (template parameter) types `KEY` and
    /// `VALUE` both be `copy-assignable` and `copy-insertable` into this
    /// unordered multimap (see {Requirements on `KEY` and `VALUE`}).
    unordered_multimap& operator=(const unordered_multimap& rhs);

    /// Assign to this object the value, hash function, and key-equivalence
    /// comparator of the specified `rhs` object, propagate to this object
    /// the allocator of `rhs` if the `ALLOCATOR` type has trait
    /// `propagate_on_container_move_assignment`, and return a reference
    /// providing modifiable access to this object.  The contents of `rhs`
    /// are moved (in constant time) to this unordered multimap if
    /// `get_allocator() == rhs.get_allocator()` (after accounting for the
    /// aforementioned trait); otherwise, all elements in this unordered
    /// multimap are either destroyed or move-assigned to, and each
    /// additional element in `rhs` is move-inserted into this unordered
    /// multimap.  `rhs` is left in a valid but unspecified state, and if an
    /// exception is thrown, `*this` is left in a valid but unspecified
    /// state.  This method requires that the (template parameter) types
    /// `KEY` and `VALUE` both be `move-assignable` and `move-insertable`
    /// into this unordered multimap (see {Requirements on `KEY` and
    /// `VALUE`}).
    unordered_multimap&
    operator=(BloombergLP::bslmf::MovableRef<unordered_multimap> rhs)
        BSLS_KEYWORD_NOEXCEPT_SPECIFICATION(
                                AllocatorTraits::is_always_equal::value &&
                                std::is_nothrow_move_assignable<HASH>::value &&
                                std::is_nothrow_move_assignable<EQUAL>::value);

#if defined(BSLS_COMPILERFEATURES_SUPPORT_GENERALIZED_INITIALIZERS)
    /// Assign to this object the value resulting from first clearing this
    /// unordered multimap and then inserting each `value_type` object in
    /// the specified `values` initializer list, and return a reference
    /// providing modifiable access to this object.  This method requires
    /// that the (template parameter) types `KEY` and `VALUE` both be
    /// `copy-insertable` into this unordered multimap (see {Requirements on
    /// `KEY` and `VALUE`}).
    unordered_multimap& operator=(std::initializer_list<value_type> values);
#endif

    /// Return an iterator providing modifiable access to the first
    /// `value_type` object (in the sequence of `value_type` objects)
    /// maintained by this unordered multimap, or the `end` iterator if this
    /// unordered multimap is empty.
    iterator begin() BSLS_KEYWORD_NOEXCEPT;

    /// Return an iterator providing modifiable access to the past-the-end
    /// position in the sequence of `value_type` objects maintained by this
    /// unordered multimap.
    iterator end() BSLS_KEYWORD_NOEXCEPT;

    /// Return a local iterator providing modifiable access to the first
    /// `value_type` object in the sequence of `value_type` objects of the
    /// bucket having the specified `index` in the array of buckets
    /// maintained by this unordered multimap, or the `end(index)` iterator
    /// if the indexed bucket is empty.  The behavior is undefined unless
    /// `index < bucket_count()`.
    local_iterator begin(size_type index);

    /// Return a local iterator providing modifiable access to the
    /// past-the-end position in the sequence of `value_type` objects of the
    /// bucket having the specified `index` in the array of buckets
    /// maintained by this unordered multimap.  The behavior is undefined
    /// unless `index < bucket_count()`.
    local_iterator end(size_type index);

    /// Remove all entries from this unordered multimap.  Note that this
    /// object will be empty after this call, but allocated memory may be
    /// retained for future use.
    void clear() BSLS_KEYWORD_NOEXCEPT;

    /// Return a pair of iterators providing modifiable access to the
    /// sequence of `value_type` objects in this unordered multimap with a
    /// key equivalent to the specified `key`, where the first iterator is
    /// positioned at the start of the sequence, and the second is
    /// positioned one past the end of the sequence.  If this unordered
    /// multimap contains no `value_type` objects with a key equivalent to
    /// `key`, then the two returned iterators will have the same value.
    /// The behavior is undefined unless `key` is equivalent to the key of
    /// the elements of at most one equivalent-key group in this unordered
    /// multimap.
    template <class LOOKUP_KEY>
    typename enable_if<
           BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
        && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value,
                      pair<iterator, iterator> >::type
    equal_range(const LOOKUP_KEY& key)
        {
            // Note: implemented inline due to Sun CC compilation error.
            typedef bsl::pair<iterator, iterator> ResultType;
            HashTableLink *first;
            HashTableLink *last;
            d_impl.findRange(&first, &last, key);
            return ResultType(iterator(first), iterator(last));
        }

    /// Return a pair of iterators providing modifiable access to the
    /// sequence of `value_type` objects in this unordered multimap with a
    /// key equivalent to the specified `key`, where the first iterator is
    /// positioned at the start of the sequence, and the second is
    /// positioned one past the end of the sequence.  If this unordered
    /// multimap contains no `value_type` objects with a key equivalent to
    /// `key`, then the two returned iterators will have the same value.
    pair<iterator, iterator> equal_range(const key_type& key);

    /// Remove from this unordered multimap all `value_type` objects with a
    /// key equivalent to the specified `key`, if such exist, and return the
    /// number of objects erased; otherwise, if there are no `value_type`
    /// objects with a key equivalent to `key`, return 0 with no other
    /// effect.  This method invalidates only iterators and references to
    /// the removed element and previously saved values of the `end()`
    /// iterator, and preserves the relative order of the elements not
    /// removed.
    size_type erase(const key_type& key);
    template <class t_KEY>
    typename enable_if<
        BloombergLP::bslmf::IsTransparentPredicate<HASH, t_KEY>::value &&
        BloombergLP::bslmf::IsTransparentPredicate<EQUAL,t_KEY>::value &&
        !is_convertible<BSLS_COMPILERFEATURES_FORWARD_REF(t_KEY),
                        iterator>::value &&
        !is_convertible<BSLS_COMPILERFEATURES_FORWARD_REF(t_KEY),
                        const_iterator>::value,
    size_type>::type erase(BSLS_COMPILERFEATURES_FORWARD_REF(t_KEY) key)
    {
        // Implemented inline due to Sun CC compilation error.
        size_type count = 0;
        // Our implementation always finds the first element
        iterator it = this->find(key);
        if (it != end()) {
            do {
                it = erase(it);
                count++;
            } while (it != end() && key_eq()(it->first, key));
        }
        return count;
    }

    /// Remove from this unordered multimap the `value_type` object at the
    /// specified `position`, and return an iterator referring to the
    /// element immediately following the removed element, or to the
    /// past-the-end position if the removed element was the last element in
    /// the sequence of elements maintained by this unordered multimap.
    /// This method invalidates only iterators and references to the removed
    /// element and previously saved values of the `end()` iterator, and
    /// preserves the relative order of the elements not removed.  The
    /// behavior is undefined unless `position` refers to a `value_type`
    /// object in this unordered multimap.
    iterator erase(const_iterator position);
    iterator erase(iterator position);

    /// Remove from this unordered multimap the `value_type` objects
    /// starting at the specified `first` position up to, but not including,
    /// the specified `last` position, and return `last`.  This method
    /// invalidates only iterators and references to the removed element and
    /// previously saved values of the `end()` iterator, and preserves the
    /// relative order of the elements not removed.  The behavior is
    /// undefined unless `first` and `last` either refer to elements in this
    /// unordered multimap or are the `end` iterator, and the `first`
    /// position is at or before the `last` position in the sequence
    /// provided by this container.
    iterator erase(const_iterator first, const_iterator last);

    /// Return an iterator providing modifiable access to the first
    /// `value_type` object in the sequence of all the `value_type` objects
    /// of this unordered multimap with a key equivalent to the specified
    /// `key`, if such entries exist, and the past-the-end (`end`) iterator
    /// otherwise.  The behavior is undefined unless `key` is equivalent to
    /// the key of the elements of at most one equivalent-key group in this
    /// unordered multimap.
    template <class LOOKUP_KEY>
    typename enable_if<
           BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
        && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value,
                      iterator>::type
    find(const LOOKUP_KEY& key)
        {
            // Note: implemented inline due to Sun CC compilation error.
            return iterator(d_impl.find(key));
        }

    /// Return an iterator providing modifiable access to the first
    /// `value_type` object in the sequence of all the `value_type` objects
    /// of this unordered multimap with a key equivalent to the specified
    /// `key`, if such entries exist, and the past-the-end (`end`) iterator
    /// otherwise.
    iterator find(const key_type& key);

    /// Insert the specified `value` into this unordered multimap, and
    /// return an iterator referring to the newly inserted `value_type`
    /// object.  This method requires that the (template parameter) types
    /// `KEY` and `VALUE` both be `copy-insertable` into this unordered
    /// multimap (see {Requirements on `KEY` and `VALUE`}).
    iterator insert(const value_type& value);

#if defined(BSLS_PLATFORM_CMP_SUN) && BSLS_PLATFORM_CMP_VERSION < 0x5130
    template <class ALT_VALUE_TYPE>
    iterator
#elif !defined(BSLS_COMPILERFEATURES_SUPPORT_TRAITS_HEADER)
    template <class ALT_VALUE_TYPE>
    typename enable_if<is_convertible<ALT_VALUE_TYPE, value_type>::value,
                       iterator>::type
#else
    /// Insert into this unordered multimap a `value_type` object created
    /// from the specified `value`, and return an iterator referring to the
    /// newly inserted `value_type` object.  This method requires that the
    /// (template parameter) types `KEY` and `VALUE` both be
    /// `move-insertable` into this unordered multimap (see {Requirements on
    /// `KEY` and `VALUE`}), and the `value_type` be constructible from the
    /// (template parameter) `ALT_VALUE_TYPE`.
    template <class ALT_VALUE_TYPE>
    typename enable_if<std::is_constructible<value_type,
                                             ALT_VALUE_TYPE&&>::value,
                       iterator>::type
#endif
    insert(BSLS_COMPILERFEATURES_FORWARD_REF(ALT_VALUE_TYPE) value)
    {
        // Note that some compilers fail when this method is defined
        // out-of-line.

        return emplace(BSLS_COMPILERFEATURES_FORWARD(ALT_VALUE_TYPE, value));
    }

    /// Insert the specified `value` into this unordered multimap (in
    /// constant time if the specified `hint` refers to an element in this
    /// container with a key equivalent to the key of `value`), and return
    /// an iterator referring to the newly inserted `value_type` object.  If
    /// `hint` does not refer to an element in this container with a key
    /// equivalent to the key of `value`, this operation has worst case
    /// `O[N]` and average case constant-time complexity, where `N` is the
    /// size of this unordered multimap.  This method requires that the
    /// (template parameter) types `KEY` and `VALUE` both be
    /// `copy-insertable` into this unordered multimap (see {Requirements on
    /// `KEY` and `VALUE`}).  The behavior is undefined unless `hint` is an
    /// iterator in the range `[begin() .. end()]` (both endpoints
    /// included).
    iterator insert(const_iterator hint, const value_type& value);

#if defined(BSLS_PLATFORM_CMP_SUN) && BSLS_PLATFORM_CMP_VERSION < 0x5130
    template <class ALT_VALUE_TYPE>
    iterator
#elif !defined(BSLS_COMPILERFEATURES_SUPPORT_TRAITS_HEADER)
    template <class ALT_VALUE_TYPE>
    typename enable_if<is_convertible<ALT_VALUE_TYPE, value_type>::value,
                       iterator>::type
#else
    /// Insert into this unordered multimap a `value_type` object created
    /// from the specified `value` (in constant time if the specified `hint`
    /// refers to an element in this container with a key equivalent to the
    /// key of `value`), and return an iterator referring to the newly
    /// inserted `value_type` object.  If `hint` does not refer to an
    /// element in this container with a key equivalent to the key of
    /// `value`, this operation has worst case `O[N]` and average case
    /// constant-time complexity, where `N` is the size of this unordered
    /// multimap.  This method requires that the (template parameter) types
    /// `KEY` and `VALUE` both be `move-insertable` into this unordered
    /// multimap (see {Requirements on `KEY` and `VALUE`}), and the
    /// `value_type` be constructible from the (template parameter)
    /// `ALT_VALUE_TYPE`.  The behavior is undefined unless `hint` is an
    /// iterator in the range `[begin() .. end()]` (both endpoints
    /// included).
    template <class ALT_VALUE_TYPE>
    typename enable_if<std::is_constructible<value_type,
                                             ALT_VALUE_TYPE&&>::value,
                       iterator>::type
#endif
    insert(const_iterator                                    hint,
           BSLS_COMPILERFEATURES_FORWARD_REF(ALT_VALUE_TYPE) value)
    {
        // Note that some compilers fail when this method is defined
        // out-of-line.

        return emplace_hint(hint,
                        BSLS_COMPILERFEATURES_FORWARD(ALT_VALUE_TYPE, value));
    }

    /// Insert into this unordered multimap the value of each `value_type`
    /// object in the range starting at the specified `first` iterator and
    /// ending immediately before the specified `last` iterator.  The
    /// (template parameter) type `INPUT_ITERATOR` shall meet the
    /// requirements of an input iterator defined in the C++11 standard
    /// [24.2.3] providing access to values of a type convertible to
    /// `value_type`, and `value_type` must be `emplace-constructible` from
    /// `*i` into this unordered multimap, where `i` is a dereferenceable
    /// iterator in the range `[first .. last)` (see {Requirements on `KEY`
    /// and `VALUE`}).  The behavior is undefined unless `first` and `last`
    /// refer to a sequence of valid values where `first` is at a position
    /// at or before `last`.
    template <class INPUT_ITERATOR>
    void insert(INPUT_ITERATOR first, INPUT_ITERATOR last);

    /// Insert into this unordered multimap the value of each `value_type`
    /// object in the specified `range`.  Note that `RANGE` must meet the
    /// requirements of an input range and the values from `range` must have
    /// a type matching or convertible to `value_type`.
    template <class RANGE>
    BSLSTL_UNORDEREDMULTIMAP_REQUIRES_CONTAINER_COMPATIBLE_RANGE(RANGE,
                                                                 value_type)
    void insert_range(BSLS_COMPILERFEATURES_FORWARD_REF(RANGE) range)
    {
        // Defined inline to avoid `clang` and Windows errors.
#if defined(BSLS_LIBRARYFEATURES_HAS_CPP20_CONCEPTS) \
 && defined(BSLS_LIBRARYFEATURES_HAS_CPP20_RANGES)
        if constexpr (ranges::sized_range<RANGE>) {
            insertFromRange(bsl::ranges::begin(range),
                            bsl::ranges::end  (range),
                            bsl::ranges::size (range));
        } else // ...
#endif
        {
            insertFromRange(bsl::ranges::begin(range),
                            bsl::ranges::end  (range));
        }
    }

#if defined(BSLS_COMPILERFEATURES_SUPPORT_GENERALIZED_INITIALIZERS)
    /// Insert into this unordered multimap the value of each `value_type`
    /// object in the specified `values` initializer list.  This method
    /// requires that the (template parameter) types `KEY` and `VALUE` both
    /// be `copy-insertable` into this unordered multimap (see {Requirements
    /// on `KEY` and `VALUE`}).
    void insert(std::initializer_list<value_type> values);
#endif

#if BSLS_COMPILERFEATURES_SIMULATE_VARIADIC_TEMPLATES
// {{{ BEGIN GENERATED CODE
// Command line: sim_cpp11_features.pl bslstl_unorderedmultimap.h
#ifndef BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT
#define BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT 2
#endif
#ifndef BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A
#define BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT
#endif

#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 0
    iterator emplace();
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 0

#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 1
    template <class Args_1>
    iterator emplace(BSLS_COMPILERFEATURES_FORWARD_REF(Args_1) args_1);
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 1

#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 2
    template <class Args_1,
              class Args_2>
    iterator emplace(BSLS_COMPILERFEATURES_FORWARD_REF(Args_1) args_1,
                     BSLS_COMPILERFEATURES_FORWARD_REF(Args_2) args_2);
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 2


#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 0
    iterator emplace_hint(const_iterator hint);
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 0

#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 1
    template <class Args_1>
    iterator emplace_hint(const_iterator hint,
                             BSLS_COMPILERFEATURES_FORWARD_REF(Args_1) args_1);
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 1

#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 2
    template <class Args_1,
              class Args_2>
    iterator emplace_hint(const_iterator hint,
                             BSLS_COMPILERFEATURES_FORWARD_REF(Args_1) args_1,
                             BSLS_COMPILERFEATURES_FORWARD_REF(Args_2) args_2);
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_A >= 2

#else
// The generated code below is a workaround for the absence of perfect
// forwarding in some compilers.

    template <class... Args>
    iterator emplace(BSLS_COMPILERFEATURES_FORWARD_REF(Args)... args);

    template <class... Args>
    iterator emplace_hint(const_iterator hint,
                              BSLS_COMPILERFEATURES_FORWARD_REF(Args)... args);

// }}} END GENERATED CODE
#endif

    /// Set the maximum load factor of this container to the specified
    /// `newLoadFactor`.
    void max_load_factor(float newLoadFactor);

    /// Change the size of the array of buckets maintained by this container
    /// to the specified `numBuckets`, and redistribute all the contained
    /// elements into the new sequence of buckets, according to their hash
    /// values.  Note that this operation has no effect if rehashing the
    /// elements into `numBuckets` would cause this unordered multimap to
    /// exceed its `max_load_factor`.
    void rehash(size_type numBuckets);

    /// Increase the number of buckets of this unordered multimap to a
    /// quantity such that the ratio between the specified `numElements` and
    /// the new number of buckets does not exceed `max_load_factor`.  Note
    /// that this guarantees that, after the reserve, elements can be
    /// inserted to grow the container to `size() == numElements` without
    /// rehashing.  Also note that memory allocations may still occur when
    /// growing the container to `size() == numElements`.  Also note that
    /// this operation has no effect if `numElements <= size()`.
    void reserve(size_type numElements);

    // Exchange the value, hasher, key-equality functor, and
    // `max_load_factor` of this object with those of the specified `other`
    // object; also exchange the allocator of this object with that of
    // `other` if the (template parameter) type `ALLOCATOR` has the
    // `propagate_on_container_swap` trait, and do not modify either
    // allocator otherwise.  This method provides the no-throw
    // exception-safety guarantee if and only if both the (template
    // parameter) types `HASH` and `EQUAL` provide no-throw swap
    // operations; if an exception is thrown, both objects are left in
    // valid but unspecified states.  This operation guarantees `O[1]`
    // complexity.  The behavior is undefined unless either this object was
    // created with the same allocator as `other` or `ALLOCATOR` has the
    // `propagate_on_container_swap` trait.
    void swap(unordered_multimap& other) BSLS_KEYWORD_NOEXCEPT_SPECIFICATION(
                                     AllocatorTraits::is_always_equal::value &&
                                     bsl::is_nothrow_swappable<HASH>::value &&
                                     bsl::is_nothrow_swappable<EQUAL>::value);

    // ACCESSORS

    /// Return (a copy of) the allocator used for memory allocation by this
    /// unordered multimap.
    allocator_type get_allocator() const BSLS_KEYWORD_NOEXCEPT;

    const_iterator  begin() const BSLS_KEYWORD_NOEXCEPT;

    /// Return an iterator providing non-modifiable access to the first
    /// `value_type` object in the sequence of `value_type` objects
    /// maintained by this unordered multimap, or the `end` iterator if this
    /// unordered multimap is empty.
    const_iterator cbegin() const BSLS_KEYWORD_NOEXCEPT;

    const_iterator  end() const BSLS_KEYWORD_NOEXCEPT;

    /// Return an iterator providing non-modifiable access to the
    /// past-the-end position in the sequence of `value_type` objects
    /// maintained by this unordered multimap.
    const_iterator cend() const BSLS_KEYWORD_NOEXCEPT;

    /// Return `true` if this unordered map contains an element whose key is
    /// equivalent to the specified `key`.
    bool contains(const key_type &key) const;

    /// Return `true` if this unordered map contains an element whose key is
    /// equivalent to the specified `key`.
    template <class LOOKUP_KEY>
    typename enable_if<
        BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value &&
            BloombergLP::bslmf::IsTransparentPredicate<EQUAL,
                                                       LOOKUP_KEY>::value,
        bool>::type
    contains(const LOOKUP_KEY& key) const
    {
        // Note: implemented inline due to Sun CC compilation error
        return find(key) != end();
    }

    /// Return `true` if this unordered multimap contains no elements, and
    /// `false` otherwise.
    bool empty() const BSLS_KEYWORD_NOEXCEPT;

    /// Return the number of elements in this unordered multimap.
    size_type size() const BSLS_KEYWORD_NOEXCEPT;

    /// Return a theoretical upper bound on the largest number of elements
    /// that this unordered multimap could possibly hold.  Note that there
    /// is no guarantee that the unordered multimap can successfully grow to
    /// the returned size, or even close to that size without running out of
    /// resources.
    size_type max_size() const BSLS_KEYWORD_NOEXCEPT;

    /// Return (a copy of) the key-equivalence binary functor that returns
    /// `true` if the value of two `key_type` objects are equivalent, and
    /// `false` otherwise.
    EQUAL key_eq() const;

    /// Return (a copy of) the hash unary functor used by this unordered
    /// multimap to generate a hash value (of type `size_type`) for a
    /// `key_type` object.
    HASH hash_function() const;

    /// Return an iterator providing modifiable access to the first
    /// `value_type` object in this unordered multimap whose key is
    /// equivalent to the specified `key`, if such an entry exists, and the
    /// past-the-end (`end`) iterator otherwise.  The behavior is undefined
    /// unless `key` is equivalent to the key of the elements of at most one
    /// equivalent-key group in this unordered multimap.
    template <class LOOKUP_KEY>
    typename enable_if<
           BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
        && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value,
                      const_iterator>::type
    find(const LOOKUP_KEY& key) const
        {
            // Note: implemented inline due to Sun CC compilation error.
            return const_iterator(d_impl.find(key));
        }

    /// Return an iterator providing non-modifiable access to the first
    /// `value_type` object in the sequence of `value_type` objects of this
    /// unordered multimap with a key equivalent to the specified `key`, if
    /// such entries exist, and the past-the-end (`end`) iterator otherwise.
    const_iterator find(const key_type& key) const;

    /// Return the number of `value_type` objects in this unordered multimap
    /// with a key equivalent to the specified `key`.  The behavior is
    /// undefined unless `key` is equivalent to the key of the elements of
    /// at most one equivalent-key group in this unordered multimap.
    template <class LOOKUP_KEY>
    typename enable_if<
           BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
        && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value,
                      size_type>::type
    count(const LOOKUP_KEY& key) const
        {
            // Note: implemented inline due to Sun CC compilation error.
            typedef ::BloombergLP::bslalg::BidirectionalNode<value_type> BNode;

            size_type result = 0;
            for (HashTableLink *cursor = d_impl.find(key);
                 cursor;
                 ++result, cursor = cursor->nextLink())
            {
                BNode *cursorNode = static_cast<BNode *>(cursor);
                if (!this->key_eq()(
                         key,
                         ListConfiguration::extractKey(cursorNode->value()))) {

                    break;
                }
            }
            return result;
        }

    /// Return the number of `value_type` objects in this unordered multimap
    /// with a key equivalent to the specified `key`.
    size_type count(const key_type& key) const;

    /// Return a pair of iterators providing non-modifiable access to the
    /// sequence of `value_type` objects in this unordered multimap with a
    /// key equivalent to the specified `key`, where the first iterator is
    /// positioned at the start of the sequence, and the second is
    /// positioned one past the end of the sequence.  If this unordered
    /// multimap contains no `value_type` objects with a key equivalent to
    /// `key`, then the two returned iterators will have the same value.
    /// The behavior is undefined unless `key` is equivalent to the key of
    /// the elements of at most one equivalent-key group in this unordered
    /// multimap.
    template <class LOOKUP_KEY>
    typename enable_if<
           BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
        && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value,
                      pair<const_iterator, const_iterator> >::type
    equal_range(const LOOKUP_KEY& key) const
        {
            // Note: implemented inline due to Sun CC compilation error.
            typedef bsl::pair<const_iterator, const_iterator> ResultType;
            HashTableLink *first;
            HashTableLink *last;
            d_impl.findRange(&first, &last, key);
            return ResultType(const_iterator(first), const_iterator(last));
        }

    /// Return a pair of iterators providing non-modifiable access to the
    /// sequence of `value_type` objects in this unordered multimap with a
    /// key equivalent to the specified `key`, where the first iterator is
    /// positioned at the start of the sequence, and the second is
    /// positioned one past the end of the sequence.  If this unordered
    /// multimap contains no `value_type` objects with a key equivalent to
    /// `key`, then the two returned iterators will have the same value.
    pair<const_iterator, const_iterator> equal_range(
                                                    const key_type& key) const;

    const_local_iterator  begin(size_type index) const;

    /// Return a local iterator providing non-modifiable access to the first
    /// `value_type` object (in the sequence of `value_type` objects) of the
    /// bucket having the specified `index` in the array of buckets
    /// maintained by this unordered multimap, or the `end(index)` iterator
    /// if the indexed bucket is empty.  The behavior is undefined unless
    /// `index < bucket_count()`.
    const_local_iterator cbegin(size_type index) const;

    const_local_iterator  end(size_type index) const;

    /// Return a local iterator providing non-modifiable access to the
    /// past-the-end position (in the sequence of `value_type` objects) of
    /// the bucket having the specified `index` in the array of buckets
    /// maintained by this unordered multimap.  The behavior is undefined
    /// unless `index < bucket_count()`.
    const_local_iterator cend(size_type index) const;

    /// Return the index of the bucket, in the array of buckets of this
    /// container, where a value with a key equivalent to the specified
    /// `key` would be inserted.
    size_type bucket(const key_type& key) const;

    /// Return the index of the bucket, in the array of buckets maintained
    /// by this unordered map, where values having a key equivalent to the
    /// specified `key` would be inserted.
    ///
    /// Note: implemented inline due to Sun CC compilation error.
    template <class LOOKUP_KEY>
    typename enable_if<
           BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
        && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value,
                      size_type>::type
    bucket(const LOOKUP_KEY& key) const
    {
        return d_impl.bucketIndexForKey(key);
    }

    /// Return the number of buckets in the array of buckets maintained by
    /// this unordered multimap.
    size_type bucket_count() const BSLS_KEYWORD_NOEXCEPT;

    /// Return a theoretical upper bound on the largest number of buckets
    /// that this container could possibly manage.  Note that there is no
    /// guarantee that the unordered multimap can successfully grow to the
    /// returned size, or even close to that size without running out of
    /// resources.
    size_type max_bucket_count() const BSLS_KEYWORD_NOEXCEPT;

    /// Return the number of elements contained in the bucket at the
    /// specified `index` in the array of buckets maintained by this
    /// container.  The behavior is undefined unless
    /// `index < bucket_count()`.
    size_type bucket_size(size_type index) const;

    /// Return the current ratio between the `size` of this container and
    /// the number of buckets.  The load factor is a measure of how full the
    /// container is, and a higher load factor typically leads to an
    /// increased number of collisions, thus resulting in a loss of
    /// performance.
    float load_factor() const BSLS_KEYWORD_NOEXCEPT;

    /// Return the maximum load factor allowed for this container.  Note
    /// that if an insert operation would cause the load factor to exceed
    /// the `max_load_factor`, that same insert operation will increase the
    /// number of buckets and rehash the elements of the container into
    /// those buckets (see `rehash`).
    float max_load_factor() const BSLS_KEYWORD_NOEXCEPT;

  private:
    // PRIVATE MANIPULATORS

    /// Create an empty unordered multimap, and insert each `value_type`
    /// object in the range starting at the specified `first` iterator and
    /// ending immediately before the specified `last` sentinel.  Optionally
    /// specify the initial `numElements` size of the unordered multimap.
    /// Note: this method is intended for internal use only.
    template <class INPUT_ITERATOR, class SENTINEL>
    void constructFromRange(INPUT_ITERATOR first, SENTINEL last);

#if defined(BSLS_LIBRARYFEATURES_HAS_CPP20_CONCEPTS) \
 && defined(BSLS_LIBRARYFEATURES_HAS_CPP20_RANGES)
    template <class INPUT_ITERATOR, class SENTINEL>
    void constructFromRange(INPUT_ITERATOR first,
                            SENTINEL       last,
                            size_t         numElements);
#endif

    /// Insert into this unordered multimap the value of each `value_type`
    /// object in the range starting at the specified `first` iterator and
    /// ending immediately before the specified `last` sentinel.  Optionally
    /// specify the initial `numElements` size of the range.  Note: this
    /// method is intended for internal use only.
    template <class INPUT_ITERATOR, class SENTINEL>
    void insertFromRange(INPUT_ITERATOR first, SENTINEL last);

#if defined(BSLS_LIBRARYFEATURES_HAS_CPP20_CONCEPTS) \
 && defined(BSLS_LIBRARYFEATURES_HAS_CPP20_RANGES)
    template <class INPUT_ITERATOR, class SENTINEL>
    void insertFromRange(INPUT_ITERATOR first,
                         SENTINEL       last,
                         size_t         numElements);
#endif
};

#ifdef BSLS_COMPILERFEATURES_SUPPORT_CTAD
// CLASS TEMPLATE DEDUCTION GUIDES

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the iterators supplied to the constructor of `unordered_multimap`.
/// Deduce the template parameters `HASH`, `EQUAL` and `ALLOCATOR` from the
/// other parameters passed to the constructor of `unordered_multimap`.
///  This deduction guide does not participate unless the supplied allocator
/// meets the requirements of a standard allocator.
template <
    class INPUT_ITERATOR,
    class KEY = BloombergLP::bslstl::IteratorUtil::IterKey_t<INPUT_ITERATOR>,
    class VALUE =
               BloombergLP::bslstl::IteratorUtil::IterMapped_t<INPUT_ITERATOR>,
    class HASH = bsl::hash<KEY>,
    class EQUAL = bsl::equal_to<KEY>,
    class ALLOCATOR = bsl::allocator<pair<const KEY, VALUE>>,
    class = bsl::enable_if_t<std::is_invocable_v<HASH, const KEY &>>,
    class = bsl::enable_if_t<
                         std::is_invocable_v<EQUAL, const KEY &, const KEY &>>,
    class = bsl::enable_if_t<bsl::IsStdAllocator_v<ALLOCATOR>>
    >
unordered_multimap(INPUT_ITERATOR,
                   INPUT_ITERATOR,
                   typename bsl::allocator_traits<ALLOCATOR>::size_type = 0,
                   HASH = HASH(),
                   EQUAL = EQUAL(),
                   ALLOCATOR = ALLOCATOR())
-> unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the iterators supplied to the constructor of `unordered_multimap`.
/// Deduce the template parameters `HASH` and "EQUAL' from the other
/// parameters passed to the constructor of `unordered_multimap`.  This
/// deduction guide does not participate unless the supplied allocator is
/// convertible to `bsl::allocator<bsl::pair<const KEY, VALUE>>`.
template <
    class INPUT_ITERATOR,
    class HASH,
    class EQUAL,
    class ALLOC,
    class KEY = BloombergLP::bslstl::IteratorUtil::IterKey_t<INPUT_ITERATOR>,
    class VALUE =
               BloombergLP::bslstl::IteratorUtil::IterMapped_t<INPUT_ITERATOR>,
    class DEFAULT_ALLOCATOR = bsl::allocator<pair<const KEY, VALUE>>,
    class = bsl::enable_if_t<bsl::is_convertible_v<ALLOC *, DEFAULT_ALLOCATOR>>
    >
unordered_multimap(
    INPUT_ITERATOR,
    INPUT_ITERATOR,
    typename bsl::allocator_traits<DEFAULT_ALLOCATOR>::size_type,
    HASH,
    EQUAL,
    ALLOC *)
-> unordered_multimap<KEY, VALUE, HASH, EQUAL>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the iterators supplied to the constructor of `unordered_multimap`.
/// Deduce the template parameters `HASH` and `ALLOCATOR` from the other
/// parameters passed to the constructor of `unordered_multimap`.  This
/// deduction guide does not participate unless the supplied hash is
/// invokable with a `KEY`, and the supplied allocator meets the
/// requirements of a standard allocator.
template <
    class INPUT_ITERATOR,
    class HASH,
    class ALLOCATOR,
    class KEY = BloombergLP::bslstl::IteratorUtil::IterKey_t<INPUT_ITERATOR>,
    class VALUE =
               BloombergLP::bslstl::IteratorUtil::IterMapped_t<INPUT_ITERATOR>,
    class = bsl::enable_if_t<std::is_invocable_v<HASH, const KEY &>>,
    class = bsl::enable_if_t<bsl::IsStdAllocator_v<ALLOCATOR>>
    >
unordered_multimap(INPUT_ITERATOR,
                   INPUT_ITERATOR,
                   typename bsl::allocator_traits<ALLOCATOR>::size_type,
                   HASH,
                   ALLOCATOR)
-> unordered_multimap<KEY, VALUE, HASH, bsl::equal_to<KEY>, ALLOCATOR>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the iterators supplied to the constructor of `unordered_multimap`.
/// Deduce the template parameter `HASH` from the other parameters passed to
/// the constructor of `unordered_multimap`.  This deduction guide does not
/// participate unless the supplied allocator is convertible to
/// `bsl::allocator<bsl::pair<const KEY, VALUE>>`.
template <
    class INPUT_ITERATOR,
    class HASH,
    class ALLOC,
    class KEY = BloombergLP::bslstl::IteratorUtil::IterKey_t<INPUT_ITERATOR>,
    class VALUE =
               BloombergLP::bslstl::IteratorUtil::IterMapped_t<INPUT_ITERATOR>,
    class DEFAULT_ALLOCATOR = bsl::allocator<bsl::pair<const KEY, VALUE>>,
    class = bsl::enable_if_t<bsl::is_convertible_v<ALLOC *, DEFAULT_ALLOCATOR>>
    >
unordered_multimap(
    INPUT_ITERATOR,
    INPUT_ITERATOR,
    typename bsl::allocator_traits<DEFAULT_ALLOCATOR>::size_type,
    HASH,
    ALLOC *)
-> unordered_multimap<KEY, VALUE, HASH>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the iterators supplied to the constructor of `unordered_multimap`.
/// This deduction guide does not participate unless the supplied allocator
/// meets the requirements of a standard allocator.
template <
    class INPUT_ITERATOR,
    class ALLOCATOR,
    class KEY = BloombergLP::bslstl::IteratorUtil::IterKey_t<INPUT_ITERATOR>,
    class VALUE =
               BloombergLP::bslstl::IteratorUtil::IterMapped_t<INPUT_ITERATOR>,
    class = bsl::enable_if_t<bsl::IsStdAllocator_v<ALLOCATOR>>
    >
unordered_multimap(INPUT_ITERATOR,
              INPUT_ITERATOR,
              typename bsl::allocator_traits<ALLOCATOR>::size_type,
              ALLOCATOR)
-> unordered_multimap<KEY,
                      VALUE,
                      bsl::hash<KEY>,
                      bsl::equal_to<KEY>,
                      ALLOCATOR>;

/// of the iterators supplied to the constructor of `unordered_multimap`.
/// Deduce the template parameter `ALLOCATOR` from the other parameter
/// passed to the constructor of `unordered_multimap`.  This deduction guide
/// does not participate unless the supplied allocator meets the
/// requirements of a standard allocator.
template <
    class INPUT_ITERATOR,
    class ALLOC,
    class KEY = BloombergLP::bslstl::IteratorUtil::IterKey_t<INPUT_ITERATOR>,
    class VALUE =
               BloombergLP::bslstl::IteratorUtil::IterMapped_t<INPUT_ITERATOR>,
    class DEFAULT_ALLOCATOR = bsl::allocator<bsl::pair<const KEY, VALUE>>,
    class = bsl::enable_if_t<bsl::is_convertible_v<ALLOC *, DEFAULT_ALLOCATOR>>
    >
unordered_multimap(
    INPUT_ITERATOR,
    INPUT_ITERATOR,
    typename bsl::allocator_traits<DEFAULT_ALLOCATOR>::size_type,
    ALLOC *)
-> unordered_multimap<KEY, VALUE>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the iterators supplied to the constructor of `unordered_multimap`.
/// Deduce the template parameter `ALLOCATOR` from the other parameter
/// passed to the constructor of `unordered_multimap`.  This deduction guide
/// does not participate unless the supplied allocator meets the
/// requirements of a standard allocator.
template <
    class INPUT_ITERATOR,
    class ALLOCATOR,
    class KEY = BloombergLP::bslstl::IteratorUtil::IterKey_t<INPUT_ITERATOR>,
    class VALUE =
               BloombergLP::bslstl::IteratorUtil::IterMapped_t<INPUT_ITERATOR>,
    class = bsl::enable_if_t<bsl::IsStdAllocator_v<ALLOCATOR>>
    >
unordered_multimap(INPUT_ITERATOR, INPUT_ITERATOR, ALLOCATOR)
-> unordered_multimap<KEY,
                      VALUE,
                      bsl::hash<KEY>,
                      bsl::equal_to<KEY>,
                      ALLOCATOR>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the iterators supplied to the constructor of `unordered_multimap`.
/// This deduction guide does not participate unless the supplied allocator
/// is convertible to `bsl::allocator<bsl::pair<const KEY, VALUE>>`.
template <
    class INPUT_ITERATOR,
    class ALLOC,
    class KEY = BloombergLP::bslstl::IteratorUtil::IterKey_t<INPUT_ITERATOR>,
    class VALUE =
               BloombergLP::bslstl::IteratorUtil::IterMapped_t<INPUT_ITERATOR>,
    class DEFAULT_ALLOCATOR = bsl::allocator<bsl::pair<const KEY, VALUE>>,
    class = bsl::enable_if_t<bsl::is_convertible_v<ALLOC *, DEFAULT_ALLOCATOR>>
    >
unordered_multimap(INPUT_ITERATOR, INPUT_ITERATOR, ALLOC *)
-> unordered_multimap<KEY, VALUE>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the initializer_list supplied to the constructor of
/// `unordered_multimap`.  Deduce the template parameters `HASH`, `EQUAL`
/// and `ALLOCATOR` from the other parameters supplied to the constructor of
/// `unordered_multimap`.  This deduction guide does not participate unless:
/// (1) the supplied `HASH` is invokable with a `KEY`, (2) the supplied
/// `EQUAL` is invokable with two `KEY`s, and (3) the supplied allocator
/// meets the requirements of a standard allocator.
template <
    class KEY,
    class VALUE,
    class HASH = bsl::hash<KEY>,
    class EQUAL = bsl::equal_to<KEY>,
    class ALLOCATOR = bsl::allocator<bsl::pair<const KEY, VALUE>>,
    class = bsl::enable_if_t<std::is_invocable_v<HASH, const KEY &>>,
    class = bsl::enable_if_t<
                         std::is_invocable_v<EQUAL, const KEY &, const KEY &>>,
    class = bsl::enable_if_t<bsl::IsStdAllocator_v<ALLOCATOR>>
    >
unordered_multimap(std::initializer_list<bsl::pair<const KEY, VALUE>>,
                   typename bsl::allocator_traits<ALLOCATOR>::size_type = 0,
                   HASH      = HASH(),
                   EQUAL     = EQUAL(),
                   ALLOCATOR = ALLOCATOR())
-> unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the initializer_list supplied to the constructor of
/// `unordered_multimap`.  Deduce the template parameters `HASH`, `EQUAL`
/// and `ALLOCATOR` from the other parameters supplied to the constructor of
/// `unordered_multimap`. This deduction guide does not participate unless
/// the supplied allocator is convertible to
/// `bsl::allocator<bsl::pair<const KEY, VALUE>>`.
template <
    class KEY,
    class VALUE,
    class HASH,
    class EQUAL,
    class ALLOC,
    class DEFAULT_ALLOCATOR = bsl::allocator<bsl::pair<const KEY, VALUE>>,
    class = bsl::enable_if_t<bsl::is_convertible_v<ALLOC *, DEFAULT_ALLOCATOR>>
    >
unordered_multimap(
    std::initializer_list<bsl::pair<const KEY, VALUE>>,
    typename bsl::allocator_traits<DEFAULT_ALLOCATOR>::size_type,
    HASH,
    EQUAL,
    ALLOC *)
-> unordered_multimap<KEY, VALUE, HASH, EQUAL>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the initializer_list supplied to the constructor of
/// `unordered_multimap`.  Deduce the template parameters `HASH` and
/// `ALLOCATOR` from the other parameters supplied to the constructor of
/// `unordered_multimap`.  This deduction guide does not participate unless
/// the supplied `HASH` is invokable with a `KEY`, and the supplied
/// allocator meets the requirements of a standard allocator.
template <
    class KEY,
    class VALUE,
    class HASH,
    class ALLOCATOR,
    class = bsl::enable_if_t<std::is_invocable_v<HASH, const KEY &>>,
    class = bsl::enable_if_t<bsl::IsStdAllocator_v<ALLOCATOR>>
    >
unordered_multimap(std::initializer_list<bsl::pair<const KEY, VALUE>>,
                   typename bsl::allocator_traits<ALLOCATOR>::size_type,
                   HASH,
                   ALLOCATOR)
-> unordered_multimap<KEY, VALUE, HASH, bsl::equal_to<KEY>, ALLOCATOR>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the initializer_list supplied to the constructor of
/// `unordered_multimap`.  Deduce the template parameter `HASH` from the
/// other parameters supplied to the constructor of `unordered_multimap`.
/// This deduction guide does not participate unless the supplied allocator
/// is convertible to `bsl::allocator<bsl::pair<const KEY, VALUE>>`.
template <
    class KEY,
    class VALUE,
    class HASH,
    class ALLOC,
    class DEFAULT_ALLOCATOR = bsl::allocator<bsl::pair<const KEY, VALUE>>,
    class = bsl::enable_if_t<bsl::is_convertible_v<ALLOC *, DEFAULT_ALLOCATOR>>
    >
unordered_multimap(
    std::initializer_list<bsl::pair<const KEY, VALUE>>,
    typename bsl::allocator_traits<DEFAULT_ALLOCATOR>::size_type,
    HASH,
    ALLOC *)
-> unordered_multimap<KEY, VALUE, HASH>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the initializer_list supplied to the constructor of
/// `unordered_multimap`.  This deduction guide does not participate unless
/// the supplied allocator meets the requirements of a standard allocator.
template <
    class KEY,
    class VALUE,
    class ALLOCATOR,
    class = bsl::enable_if_t<bsl::IsStdAllocator_v<ALLOCATOR>>
    >
unordered_multimap(std::initializer_list<bsl::pair<const KEY, VALUE>>,
                   typename bsl::allocator_traits<ALLOCATOR>::size_type,
                   ALLOCATOR)
-> unordered_multimap<KEY,
                      VALUE,
                      bsl::hash<KEY>,
                      bsl::equal_to<KEY>,
                      ALLOCATOR>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the initializer_list supplied to the constructor of
/// `unordered_multimap`.  This deduction guide does not participate unless
/// the supplied allocator is convertible to
/// `bsl::allocator<bsl::pair<const KEY, VALUE>>`.
template <
    class KEY,
    class VALUE,
    class ALLOC,
    class DEFAULT_ALLOCATOR = bsl::allocator<bsl::pair<const KEY, VALUE>>,
    class = bsl::enable_if_t<bsl::is_convertible_v<ALLOC *, DEFAULT_ALLOCATOR>>
    >
unordered_multimap(
    std::initializer_list<bsl::pair<const KEY, VALUE>>,
    typename bsl::allocator_traits<DEFAULT_ALLOCATOR>::size_type,
    ALLOC *)
-> unordered_multimap<KEY, VALUE>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the initializer_list supplied to the constructor of
/// `unordered_multimap`.  Deduce the template parameter `ALLOCATOR` from
/// the other parameters supplied to the constructor of
/// `unordered_multimap`.  This deduction guide does not participate unless
/// the supplied allocator meets the requirements of a standard allocator.
template <
    class KEY,
    class VALUE,
    class ALLOCATOR,
    class = bsl::enable_if_t<bsl::IsStdAllocator_v<ALLOCATOR>>
    >
unordered_multimap(std::initializer_list<bsl::pair<const KEY, VALUE>>,
                   ALLOCATOR)
-> unordered_multimap<KEY,
                      VALUE,
                      bsl::hash<KEY>,
                      bsl::equal_to<KEY>,
                      ALLOCATOR>;

/// Deduce the template parameters `KEY` and `VALUE` from the `value_type`
/// of the initializer_list supplied to the constructor of
/// `unordered_multimap`.  This deduction guide does not participate unless
/// the supplied allocator is convertible to
/// `bsl::allocator<bsl::pair<const KEY, VALUE>>`.
template <
    class KEY,
    class VALUE,
    class ALLOC,
    class DEFAULT_ALLOCATOR = bsl::allocator<bsl::pair<const KEY, VALUE>>,
    class = bsl::enable_if_t<bsl::is_convertible_v<ALLOC *, DEFAULT_ALLOCATOR>>
    >
unordered_multimap(std::initializer_list<bsl::pair<const KEY, VALUE>>, ALLOC *)
-> unordered_multimap<KEY, VALUE>;
#endif

// FREE OPERATORS

/// Return `true` if the specified `lhs` and `rhs` objects have the same
/// value, and `false` otherwise.  Two `unordered_multimap` objects have the
/// same value if they have the same number of key-value pairs, and each
/// key-value pair that is contained in one of the objects is also contained
/// in the other object.  This method requires that the (template parameter)
/// types `KEY` and `VALUE` both be `equality-comparable` (see {Requirements
/// on `KEY` and `VALUE`}).
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
bool operator==(
            const unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& lhs,
            const unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& rhs);

#ifndef BSLS_COMPILERFEATURES_SUPPORT_THREE_WAY_COMPARISON
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
bool operator!=(
            const unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& lhs,
            const unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& rhs);
    // Return 'true' if the specified 'lhs' and 'rhs' objects do not have the
    // same value, and 'false' otherwise.  Two 'unordered_multimap' objects do
    // not have the same value if they do not have the same number of key-value
    // pairs, or some key-value pair that is contained in one of the objects is
    // not also contained in the other object.  This method requires that the
    // (template parameter) types 'KEY' and 'VALUE' both be
    // 'equality-comparable' (see {Requirements on 'KEY' and 'VALUE'}).
#endif

// FREE FUNCTIONS

/// Erase all the elements in the specified unordered_multimap `m` that satisfy
/// the specified predicate `predicate`.  Return the number of elements
/// erased.
template <class KEY,
          class VALUE,
          class HASH,
          class EQUAL,
          class ALLOCATOR,
          class PREDICATE>
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::size_type
erase_if(unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>&    m,
                                                          PREDICATE predicate);

/// Exchange the value, hasher, key-equality functor, and `max_load_factor`
/// of the specified `a` object with those of the specified `b` object; also
/// exchange the allocator of `a` with that of `b` if the (template
/// parameter) type `ALLOCATOR` has the `propagate_on_container_swap` trait,
/// and do not modify either allocator otherwise.  This function provides
/// the no-throw exception-safety guarantee if and only if both the
/// (template parameter) types `HASH` and `EQUAL` provide no-throw swap
/// operations; if an exception is thrown, both objects are left in valid
/// but unspecified states.  This operation guarantees `O[1]` complexity.
/// The behavior is undefined unless either `a` was created with the same
/// allocator as `b` or `ALLOCATOR` has the `propagate_on_container_swap`
/// trait.
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
void swap(unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& a,
          unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& b)
                                    BSLS_KEYWORD_NOEXCEPT_SPECIFICATION(false);

// ============================================================================
//                  TEMPLATE AND INLINE FUNCTION DEFINITIONS
// ============================================================================

                        //-------------------------
                        // class unordered_multimap
                        //-------------------------

// PRIVATE MANIPULATORS

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class INPUT_ITERATOR, class SENTINEL>
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::
                                       constructFromRange(INPUT_ITERATOR first,
                                                          SENTINEL       last)
{
    BSLS_ASSERT_SAFE(this->empty());

    const difference_type maxInsertions =
              ::BloombergLP::bslstl::IteratorUtil::insertDistance(first, last);
    if (0 < maxInsertions) {
        this->reserve(maxInsertions);
    }
    else {
        BSLS_ASSERT_SAFE(0 == maxInsertions);
    }

    while (first != last) {
        d_impl.emplace(*first);
        ++first;
    }
}

#if defined(BSLS_LIBRARYFEATURES_HAS_CPP20_CONCEPTS) \
 && defined(BSLS_LIBRARYFEATURES_HAS_CPP20_RANGES)
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class INPUT_ITERATOR, class SENTINEL>
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::
                                 constructFromRange(INPUT_ITERATOR first,
                                                    SENTINEL       last,
                                                    size_t         numElements)
{
    BSLS_ASSERT_SAFE(this->empty());

    if (0 < numElements) {
        this->reserve(numElements);
    }

    while (first != last) {
        d_impl.emplace(*first);
        ++first;
    }
}
#endif

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class INPUT_ITERATOR, class SENTINEL>
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::
                                          insertFromRange(INPUT_ITERATOR first,
                                                          SENTINEL       last)
{
    const difference_type maxInsertions =
              ::BloombergLP::bslstl::IteratorUtil::insertDistance(first, last);
    if (0 < maxInsertions) {
        this->reserve(this->size() + maxInsertions);
    }
    else {
        BSLS_ASSERT_SAFE(0 == maxInsertions);
    }

    while (first != last) {
        d_impl.emplace(*first);
        ++first;
    }
}

#if defined(BSLS_LIBRARYFEATURES_HAS_CPP20_CONCEPTS) \
 && defined(BSLS_LIBRARYFEATURES_HAS_CPP20_RANGES)
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class INPUT_ITERATOR, class SENTINEL>
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::
                                    insertFromRange(INPUT_ITERATOR first,
                                                    SENTINEL       last,
                                                    size_t         numElements)
{
    if (0 < numElements) {
        this->reserve(this->size() + numElements);
    }

    while (first != last) {
        d_impl.emplace(*first);
        ++first;
    }
}
#endif

// CREATORS
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap()
: d_impl(HASH(), EQUAL(), 0, 1.0f, ALLOCATOR())
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                                            size_type        initialNumBuckets,
                                            const HASH&      hashFunction,
                                            const EQUAL&     keyEqual,
                                            const ALLOCATOR& basicAllocator)
: d_impl(hashFunction, keyEqual, initialNumBuckets, 1.0f, basicAllocator)
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                                            size_type        initialNumBuckets,
                                            const HASH&      hashFunction,
                                            const ALLOCATOR& basicAllocator)
: d_impl(hashFunction, EQUAL(), initialNumBuckets, 1.0f, basicAllocator)
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                                            size_type        initialNumBuckets,
                                            const ALLOCATOR& basicAllocator)
: d_impl(HASH(), EQUAL(), initialNumBuckets, 1.0f, basicAllocator)
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                                               const ALLOCATOR& basicAllocator)
: d_impl(basicAllocator)
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                                            const unordered_multimap& original)
: d_impl(original.d_impl,
         AllocatorTraits::select_on_container_copy_construction(
                                                     original.get_allocator()))
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                   BloombergLP::bslmf::MovableRef<unordered_multimap> original)
: d_impl(MoveUtil::move(MoveUtil::access(original).d_impl))
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                 const unordered_multimap&                      original,
                 const typename type_identity<ALLOCATOR>::type& basicAllocator)
: d_impl(original.d_impl, basicAllocator)
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
             BloombergLP::bslmf::MovableRef<unordered_multimap> original,
             const typename type_identity<ALLOCATOR>::type&     basicAllocator)
: d_impl(MoveUtil::move(MoveUtil::access(original).d_impl), basicAllocator)
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class INPUT_ITERATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                                            INPUT_ITERATOR   first,
                                            INPUT_ITERATOR   last,
                                            size_type        initialNumBuckets,
                                            const HASH&      hashFunction,
                                            const EQUAL&     keyEqual,
                                            const ALLOCATOR& basicAllocator)
: d_impl(hashFunction, keyEqual, initialNumBuckets, 1.0f, basicAllocator)
{
    constructFromRange(first, last);
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class INPUT_ITERATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                                            INPUT_ITERATOR   first,
                                            INPUT_ITERATOR   last,
                                            size_type        initialNumBuckets,
                                            const HASH&      hashFunction,
                                            const ALLOCATOR& basicAllocator)
: d_impl(hashFunction, EQUAL(), initialNumBuckets, 1.0f, basicAllocator)
{
    this->insert(first, last);
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class INPUT_ITERATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                                            INPUT_ITERATOR   first,
                                            INPUT_ITERATOR   last,
                                            size_type        initialNumBuckets,
                                            const ALLOCATOR& basicAllocator)
: d_impl(HASH(), EQUAL(), initialNumBuckets, 1.0f, basicAllocator)
{
    this->insert(first, last);
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class INPUT_ITERATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                                               INPUT_ITERATOR   first,
                                               INPUT_ITERATOR   last,
                                               const ALLOCATOR& basicAllocator)
: d_impl(HASH(), EQUAL(), 0, 1.0f, basicAllocator)
{
    this->insert(first, last);
}

#if defined(BSLS_COMPILERFEATURES_SUPPORT_GENERALIZED_INITIALIZERS)
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
# ifdef BSLS_COMPILERFEATURES_SUPPORT_CTAD
template <class, class, class>
# endif
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                           std::initializer_list<value_type> values,
                           size_type                         initialNumBuckets,
                           const HASH&                       hashFunction,
                           const EQUAL&                      keyEqual,
                           const ALLOCATOR&                  basicAllocator)
: unordered_multimap(values.begin(),
                     values.end(),
                     initialNumBuckets,
                     hashFunction,
                     keyEqual,
                     basicAllocator)
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
# ifdef BSLS_COMPILERFEATURES_SUPPORT_CTAD
template <class, class>
# endif
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                           std::initializer_list<value_type> values,
                           size_type                         initialNumBuckets,
                           const HASH&                       hashFunction,
                           const ALLOCATOR&                  basicAllocator)
: unordered_multimap(values.begin(),
                     values.end(),
                     initialNumBuckets,
                     hashFunction,
                     EQUAL(),
                     basicAllocator)
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
# ifdef BSLS_COMPILERFEATURES_SUPPORT_CTAD
template <class>
# endif
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                          std::initializer_list<value_type> values,
                          size_type                         initialNumBuckets,
                          const ALLOCATOR&                  basicAllocator)
: unordered_multimap(values.begin(),
                     values.end(),
                     initialNumBuckets,
                     HASH(),
                     EQUAL(),
                     basicAllocator)
{
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
# ifdef BSLS_COMPILERFEATURES_SUPPORT_CTAD
template <class>
# endif
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::unordered_multimap(
                          std::initializer_list<value_type> values,
                          const ALLOCATOR&                  basicAllocator)
: unordered_multimap(values.begin(),
                     values.end(),
                     0,
                     HASH(),
                     EQUAL(),
                     basicAllocator)
{
}
#endif  // defined(BSLS_COMPILERFEATURES_SUPPORT_GENERALIZED_INITIALIZERS)

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::~unordered_multimap()
{
    // All memory management is handled by the base 'd_impl' member.
}

// MANIPULATORS
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>&
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::operator=(
                                                 const unordered_multimap& rhs)
{
    // Note that we have delegated responsibility for correct handling of
    // allocator propagation to the 'HashTable' implementation.

    d_impl = rhs.d_impl;

    return *this;
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>&
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::operator=(
                        BloombergLP::bslmf::MovableRef<unordered_multimap> rhs)
    BSLS_KEYWORD_NOEXCEPT_SPECIFICATION(
                                AllocatorTraits::is_always_equal::value &&
                                std::is_nothrow_move_assignable<HASH>::value &&
                                std::is_nothrow_move_assignable<EQUAL>::value)
{
    // Note that we have delegated responsibility for correct handling of
    // allocator propagation to the 'HashTable' implementation.

    unordered_multimap& lvalue = rhs;

    d_impl = MoveUtil::move(lvalue.d_impl);

    return *this;
}

#if defined(BSLS_COMPILERFEATURES_SUPPORT_GENERALIZED_INITIALIZERS)
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>&
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::operator=(
                                      std::initializer_list<value_type> values)
{
    unordered_multimap tmp(values.begin(), values.end(), d_impl.allocator());

    d_impl.swap(tmp.d_impl);

    return *this;
}
#endif

#if BSLS_COMPILERFEATURES_SIMULATE_VARIADIC_TEMPLATES
// {{{ BEGIN GENERATED CODE
// Command line: sim_cpp11_features.pl bslstl_unorderedmultimap.h
#ifndef BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT
#define BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT 2
#endif
#ifndef BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B
#define BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT
#endif
#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 0
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::emplace(
                               )
{
    return iterator(d_impl.emplace(
                                ));

}
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 0

#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 1
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class Args_1>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::emplace(
                              BSLS_COMPILERFEATURES_FORWARD_REF(Args_1) args_1)
{
    return iterator(d_impl.emplace(
                               BSLS_COMPILERFEATURES_FORWARD(Args_1, args_1)));

}
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 1

#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 2
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class Args_1,
          class Args_2>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::emplace(
                              BSLS_COMPILERFEATURES_FORWARD_REF(Args_1) args_1,
                              BSLS_COMPILERFEATURES_FORWARD_REF(Args_2) args_2)
{
    return iterator(d_impl.emplace(
                               BSLS_COMPILERFEATURES_FORWARD(Args_1, args_1),
                               BSLS_COMPILERFEATURES_FORWARD(Args_2, args_2)));

}
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 2


#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 0
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::emplace_hint(
                                                           const_iterator hint)
{
    return iterator(d_impl.emplaceWithHint(hint.node()));
}
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 0

#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 1
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class Args_1>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::emplace_hint(
                                                           const_iterator hint,
                              BSLS_COMPILERFEATURES_FORWARD_REF(Args_1) args_1)
{
    return iterator(d_impl.emplaceWithHint(hint.node(),
                               BSLS_COMPILERFEATURES_FORWARD(Args_1, args_1)));
}
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 1

#if BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 2
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class Args_1,
          class Args_2>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::emplace_hint(
                                                           const_iterator hint,
                              BSLS_COMPILERFEATURES_FORWARD_REF(Args_1) args_1,
                              BSLS_COMPILERFEATURES_FORWARD_REF(Args_2) args_2)
{
    return iterator(d_impl.emplaceWithHint(hint.node(),
                               BSLS_COMPILERFEATURES_FORWARD(Args_1, args_1),
                               BSLS_COMPILERFEATURES_FORWARD(Args_2, args_2)));
}
#endif  // BSLSTL_UNORDEREDMULTIMAP_VARIADIC_LIMIT_B >= 2

#else
// The generated code below is a workaround for the absence of perfect
// forwarding in some compilers.
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class... Args>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::emplace(
                               BSLS_COMPILERFEATURES_FORWARD_REF(Args)... args)
{
    return iterator(d_impl.emplace(
                                BSLS_COMPILERFEATURES_FORWARD(Args, args)...));

}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class... Args>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::emplace_hint(
                                                           const_iterator hint,
                               BSLS_COMPILERFEATURES_FORWARD_REF(Args)... args)
{
    return iterator(d_impl.emplaceWithHint(hint.node(),
                                BSLS_COMPILERFEATURES_FORWARD(Args, args)...));
}
// }}} END GENERATED CODE
#endif

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::begin()
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return iterator(d_impl.elementListRoot());
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::end()
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return iterator();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::local_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::begin(size_type index)
{
    BSLS_ASSERT_SAFE(index < this->bucket_count());

    return local_iterator(&d_impl.bucketAtIndex(index));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::local_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::end(size_type index)
{
    BSLS_ASSERT_SAFE(index < this->bucket_count());

    return local_iterator(0, &d_impl.bucketAtIndex(index));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::clear()
                                                          BSLS_KEYWORD_NOEXCEPT
{
    d_impl.removeAll();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
bool unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::contains(
                                                     const key_type& key) const
{
    return find(key) != end();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::find(
                                                           const key_type& key)
{
    return iterator(d_impl.find(key));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
bsl::pair<
     typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator,
     typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator>
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::equal_range(
                                                           const key_type& key)
{
    HashTableLink *first;
    HashTableLink *last;
    d_impl.findRange(&first, &last, key);
    return bsl::pair<iterator, iterator>(iterator(first), iterator(last));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::erase(
                                                       const_iterator position)
{
    BSLS_ASSERT(position != this->end());

    return iterator(d_impl.remove(position.node()));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::erase(
                                                             iterator position)
{
    return erase(const_iterator(position));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::size_type
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::erase(
                                                           const key_type& key)
{   // As an alternative implementation, the table could return an extracted
    // "slice" list from the underlying table, and now need merely:
    //   iterate each node, destroying the associated value
    //   reclaim each node (potentially returning to a node-pool)

    typedef ::BloombergLP::bslalg::BidirectionalNode<value_type> BNode;

    if (HashTableLink *target = d_impl.find(key)) {
        target = d_impl.remove(target);
        size_type result = 1;
        while (target &&
               this->key_eq()(key, ListConfiguration::extractKey(
                                    static_cast<BNode *>(target)->value()))) {
            target = d_impl.remove(target);
            ++result;
        }
        return result;                                                // RETURN
    }

    return 0;
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::erase(
                                                          const_iterator first,
                                                          const_iterator last)
{
#if defined BDE_BUILD_TARGET_SAFE_2
    if (first != last) {
        iterator it        = this->begin();
        const iterator end = this->end();
        for (; it != first; ++it) {
            BSLS_ASSERT(last != it);
            BSLS_ASSERT(end  != it);
        }
        for (; it != last; ++it) {
            BSLS_ASSERT(end  != it);
        }
    }
#endif

    while (first != last) {
        first = this->erase(first);
    }

    return iterator(first.node());          // convert from const_iterator
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::insert(
                                                       const value_type& value)
{
    return iterator(d_impl.insert(value));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::insert(
                                                       const_iterator    hint,
                                                       const value_type& value)
{
    return iterator(d_impl.insert(value, hint.node()));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
template <class INPUT_ITERATOR>
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::insert(
                                                          INPUT_ITERATOR first,
                                                          INPUT_ITERATOR last)
{
    insertFromRange(first, last);
}

#if defined(BSLS_COMPILERFEATURES_SUPPORT_GENERALIZED_INITIALIZERS)
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::insert(
                                      std::initializer_list<value_type> values)
{
    insert(values.begin(), values.end());
}
#endif

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::max_load_factor(
                                                           float newLoadFactor)
{
    d_impl.setMaxLoadFactor(newLoadFactor);
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::rehash(
                                                          size_type numBuckets)
{
    d_impl.rehashForNumBuckets(numBuckets);
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::reserve(
                                                         size_type numElements)
{
    d_impl.reserveForNumElements(numElements);
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
void unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::swap(
                                                     unordered_multimap& other)
    BSLS_KEYWORD_NOEXCEPT_SPECIFICATION(
                                     AllocatorTraits::is_always_equal::value &&
                                     bsl::is_nothrow_swappable<HASH>::value &&
                                     bsl::is_nothrow_swappable<EQUAL>::value)
{
    d_impl.swap(other.d_impl);
}

// ACCESSORS
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
ALLOCATOR
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::get_allocator() const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return d_impl.allocator();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::const_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::begin() const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return const_iterator(d_impl.elementListRoot());
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::const_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::end() const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return const_iterator();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::const_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::cbegin() const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return const_iterator(d_impl.elementListRoot());
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::const_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::cend() const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return const_iterator();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::
                                                           const_local_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::begin(
                                                         size_type index) const
{
    BSLS_ASSERT_SAFE(index < this->bucket_count());

    return const_local_iterator(&d_impl.bucketAtIndex(index));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::const_local_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::end(
                                                         size_type index) const
{
    BSLS_ASSERT_SAFE(index < this->bucket_count());

    return const_local_iterator(0, &d_impl.bucketAtIndex(index));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::const_local_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::cbegin(
                                                         size_type index) const
{
    BSLS_ASSERT_SAFE(index < this->bucket_count());

    return const_local_iterator(&d_impl.bucketAtIndex(index));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::
                                                           const_local_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::cend(
                                                         size_type index) const
{
    BSLS_ASSERT_SAFE(index < this->bucket_count());

    return const_local_iterator(0, &d_impl.bucketAtIndex(index));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::size_type
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::bucket(
                                                     const key_type& key) const
{
    return d_impl.bucketIndexForKey(key);
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::size_type
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::bucket_count() const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return d_impl.numBuckets();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::size_type
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::bucket_size(
                                                         size_type index) const
{
    BSLS_ASSERT_SAFE(index < this->bucket_count());

    return d_impl.countElementsInBucket(index);
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>:: size_type
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::count(
                                                     const key_type& key) const
{
    typedef ::BloombergLP::bslalg::BidirectionalNode<value_type> BNode;

    size_type result = 0;
    for (HashTableLink *cursor = d_impl.find(key);
         cursor;
         ++result, cursor = cursor->nextLink())
    {
        BNode *cursorNode = static_cast<BNode *>(cursor);
        if (!this->key_eq()(key,
                         ListConfiguration::extractKey(cursorNode->value()))) {

            break;
        }
    }
    return  result;
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::const_iterator
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::find(
                                                     const key_type& key) const
{
    return const_iterator(d_impl.find(key));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
bool unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::empty() const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return 0 == d_impl.size();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::size_type
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::size() const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return d_impl.size();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::size_type
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::max_size() const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return AllocatorTraits::max_size(get_allocator());
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::hasher
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::hash_function() const
{
    return d_impl.hasher();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::key_equal
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::key_eq() const
{
    return d_impl.comparator();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
bsl::pair<typename unordered_multimap<KEY,
                                      VALUE,
                                      HASH,
                                      EQUAL,
                                      ALLOCATOR>::const_iterator,
          typename unordered_multimap<KEY,
                                      VALUE,
                                      HASH,
                                      EQUAL,
                                      ALLOCATOR>::const_iterator>
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::equal_range(
                                                     const key_type& key) const
{
    HashTableLink *first;
    HashTableLink *last;
    d_impl.findRange(&first, &last, key);
    return bsl::pair<const_iterator, const_iterator>(const_iterator(first),
                                                     const_iterator(last));
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
typename unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::size_type
unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>:: max_bucket_count()
                                                                          const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return d_impl.maxNumBuckets();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
float unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::load_factor()
                                                                          const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return d_impl.loadFactor();
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
float unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::max_load_factor()
                                                                          const
                                                          BSLS_KEYWORD_NOEXCEPT
{
    return d_impl.maxLoadFactor();
}

}  // close namespace bsl

// FREE OPERATORS
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
bool bsl::operator==(
        const bsl::unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& lhs,
        const bsl::unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& rhs)
{
    return lhs.d_impl == rhs.d_impl;
}

#ifndef BSLS_COMPILERFEATURES_SUPPORT_THREE_WAY_COMPARISON
template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
bool bsl::operator!=(
        const bsl::unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& lhs,
        const bsl::unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& rhs)
{
    return !(lhs == rhs);
}
#endif

// FREE FUNCTIONS
template <class KEY,
          class VALUE,
          class HASH,
          class EQUAL,
          class ALLOCATOR,
          class PREDICATE>
inline
typename bsl::unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>::size_type
bsl::erase_if(unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& m,
                                                           PREDICATE predicate)
{
    return BloombergLP::bslstl::AlgorithmUtil::containerEraseIf(m, predicate);
}

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
inline
void bsl::swap(bsl::unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& a,
               bsl::unordered_multimap<KEY, VALUE, HASH, EQUAL, ALLOCATOR>& b)
                                     BSLS_KEYWORD_NOEXCEPT_SPECIFICATION(false)
{
    a.swap(b);
}

// ============================================================================
//                                TYPE TRAITS
// ============================================================================

// Type traits for STL *unordered* *associative* containers:
//: o An unordered associative container defines STL iterators.
//: o An unordered associative container is bitwise movable if both functors
//:   and the allocator are bitwise movable.
//: o An unordered associative container uses 'bslma' allocators if the
//:   (template parameter) type 'ALLOCATOR' is convertible from
//:   'bslma::Allocator*'.

namespace BloombergLP {

namespace bslalg {

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
struct HasStlIterators<bsl::unordered_multimap<KEY,
                                               VALUE,
                                               HASH,
                                               EQUAL,
                                               ALLOCATOR> >
: bsl::true_type
{};

}  // close namespace bslalg

namespace bslma {

template <class KEY, class VALUE, class HASH, class EQUAL, class ALLOCATOR>
struct UsesBslmaAllocator<bsl::unordered_multimap<KEY,
                                                  VALUE,
                                                  HASH,
                                                  EQUAL,
                                                  ALLOCATOR> >
: bsl::is_convertible<Allocator*, ALLOCATOR>::type
{};

}  // close namespace bslma

namespace bslmf {

template <class KEY, class MAPPED, class HASH, class EQUAL, class ALLOCATOR>
struct IsBitwiseMoveable<
    bsl::unordered_multimap<KEY, MAPPED, HASH, EQUAL, ALLOCATOR> >
    : ::BloombergLP::bslmf::IsBitwiseMoveable<BloombergLP::bslstl::HashTable<
          ::BloombergLP::bslstl::
              UnorderedMapKeyConfiguration<KEY, bsl::pair<const KEY, MAPPED> >,
          HASH,
          EQUAL,
          ALLOCATOR> >::type
{};

}
}  // close enterprise namespace

#else // if ! defined(DEFINED_BSLSTL_UNORDEREDMULTIMAP_H)
# error Not valid except when included from bslstl_unorderedmultimap.h
#endif // ! defined(COMPILING_BSLSTL_UNORDEREDMULTIMAP_H)

#endif // ! defined(INCLUDED_BSLSTL_UNORDEREDMULTIMAP_CPP03)

// ----------------------------------------------------------------------------
// Copyright 2013 Bloomberg Finance L.P.
//
// 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.
// ----------------------------- END-OF-FILE ----------------------------------
