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unordered_set_of Reference

Header "boost/bimap/unordered_set_of.hpp" synopsis
Header "boost/bimap/unordered_multiset_of.hpp" synopsis
Collection type specifiers unordered_set_of and unordered_multiset_of
unordered_[multi]set_of Views
Complexity signature
Instantiation types
Nested types
Constructors, copy and assignment
Modifiers
Lookup
at(), info_at() and operator[] - set_of only
Hash policy
Serialization
namespace boost {
namespace bimaps {


template
<
    class KeyType,
    class HashFunctor   = hash< KeyType >,
    class EqualKey      = std::equal_to< KeyType >
>
struct unordered_set_of;


template
<
    class HashFunctor   = hash< _relation >,
    class EqualKey      = std::equal_to< _relation >
>
struct unordered_set_of_relation;


} // namespace bimap
} // namespace boost
namespace boost {
namespace bimaps {


template
<
    class KeyType,
    class HashFunctor   = hash< KeyType >,
    class EqualKey      = std::equal_to< KeyType >
>
struct unordered_multiset_of;


template
<
    class HashFunctor   = hash< _relation >,
    class EqualKey      = std::equal_to< _relation >
>
struct unordered_multiset_of_relation;


} // namespace bimap
} // namespace boost

These collection types specifiers allow for set views without and with allowance of duplicate elements, respectively. The syntax of set_of and multiset_of coincide, thus we describe them in a grouped manner.

An unordered_[multi]set_of set view is a tr1::unordered[multi]set signature compatible interface to the underlying heap of elements contained in a bimap.

The interface and semantics of unordered_[multi]set_of views are modeled according to the proposal for unordered associative containers given in the C++ Standard Library Technical Report, also known as TR1. An unordered_[multi]set_of view is particularized according to a given Hash function object which returns hash values for the keys and a binary predicate Pred acting as an equivalence relation on values of Key.

There are two variants: unordered_set_of, which do not allow duplicate elements (with respect to its associated comparison predicate) and unordered_multiset_of, which accept those duplicates. The interface of these two variants is the same to a great extent, so they are documented together with their differences explicitly noted when they exist.

If you look the bimap by a side, you will use a map view and if you looked it as a whole you will be using a set view.

Except where noted, unordered_[multi]set_of views (both unique and non-unique) are models of Unordered Associative Container. Validity of iterators and references to elements is preserved in all cases. Occasionally, the exception safety guarantees provided are actually stronger than required by the extension draft. We only provide descriptions of those types and operations that are either not present in the concepts modeled or do not exactly conform to the requirements for unordered associative containers.

namespace boost {
namespace bimap {
namespace views {

template< -implementation defined parameter list- >
class -implementation defined view name-
{
    public:

    // types

    typedef -unspecified- key_type;
    typedef -unspecified- value_type;
    typedef -unspecified- key_compare;
    typedef -unspecified- value_compare;
    typedef -unspecified- hasher;
    typedef -unspecified- key_equal;
    typedef -unspecified- allocator_type;
    typedef -unspecified- reference;
    typedef -unspecified- const_reference;
    typedef -unspecified- iterator;
    typedef -unspecified- const_iterator;
    typedef -unspecified- size_type;
    typedef -unspecified- difference_type;
    typedef -unspecified- pointer;
    typedef -unspecified- const_pointer;
    typedef -unspecified- local_iterator;
    typedef -unspecified- const_local_iterator;

    typedef -unspecified- info_type;

    // construct/destroy/copy:

    this_type & operator=(const this_type & x);

    allocator_type get_allocator() const;

    // size and capacity

    bool      empty() const;
    size_type size() const;
    size_type max_size() const;

    // iterators

    iterator       begin();
    const_iterator begin() const;
    iterator       end();
    const_iterator end() const;

    // modifiers

    std::pair< iterator, bool > insert(const value_type & x);

    iterator insert(iterator position, const value_type & x);

    template< class InputIterator >
    void insert(InputIterator first, InputIterator last);

    iterator erase(iterator position);

    template< class CompatibleKey >
    size_type erase(const CompatibleKey & x);

    iterator erase(iterator first, iterator last);

    bool replace(iterator position, const value_type & x);

    // Only in map views
    // {

      template< class CompatibleKey >
      bool replace_key(iterator position, const CompatibleKey & x);

      template< class CompatibleData >
      bool replace_data(iterator position, const CompatibleData & x);

      template< class KeyModifier >
      bool modify_key(iterator position, KeyModifier mod);

      template< class DataModifier >
      bool modify_data(iterator position, DataModifier mod);

    // }


    void clear();

    // observers

    key_from_value key_extractor() const;
    hasher         hash_function() const;
    key_equal      key_eq() const;

    // lookup

    template< class CompatibleKey >
    iterator find(const CompatibleKey & x);

    template< class CompatibleKey >
    const_iterator find(const CompatibleKey & x) const;

    template< class CompatibleKey >
    size_type count(const CompatibleKey & x) const;

    template< class CompatibleKey >
    std::pair<iterator,iterator>
        equal_range(const CompatibleKey & x);

    template< class CompatibleKey >
    std::pair<const_iterator,const_iterator>
        equal_range(const CompatibleKey & x) const;

    // bucket interface

    size_type bucket_count() const;
    size_type max_bucket_count() const;
    size_type bucket_size(size_type n) const;
    size_type bucket(const key_type & k) const;

    local_iterator       begin(size_type n);
    const_local_iterator begin(size_type n) const;
    local_iterator       end(size_type n);
    const_local_iterator end(size_type n) const;

    // hash policy

    float load_factor() const;
    float max_load_factor() const;
    void  max_load_factor(float z);
    void  rehash(size_type n);

    // Only in maps views
    // {

    typedef -unspecified- data_type;

      // Only in for `unordered_set_of` collection type
      // {

      template<class CompatibleKey>
      const data_type & at(const CompatibleKey & k) const;

        // Only if the other collection type is mutable
        // {

        template<class CompatibleKey>
        data_type & operator[](const CompatibleKey & k);

        template<class CompatibleKey>
        data_type & at(const CompatibleKey & k);

        // }

        // Only if info_hook is used
        // {

        template< class CompatibleKey >
        info_type & info_at(const CompatibleKey & k);

        template< class CompatibleKey >
        const info_type & info_at(const CompatibleKey & k) const;

      // }

    // }

};

} // namespace views
} // namespace bimap
} // namespace boost

In the case of a bimap< unordered_{multi}set_of<Left>, ... >

In the set view:

typedef signature-compatible with relation<       Left, ... > key_type;
typedef signature-compatible with relation< const Left, ... > value_type;

In the left map view:

typedef  Left  key_type;
typedef  ...   data_type;

typedef signature-compatible with std::pair< const Left, ... > value_type;

In the right map view:

typedef  ...  key_type;
typedef  Left data_type;

typedef signature-compatible with std::pair< ... ,const Left > value_type;

Here and in the descriptions of operations of unordered_[multi]set_of views, we adopt the scheme outlined in the complexity signature section. The complexity signature of unordered_[multi]set_of view is:

  • copying: c(n) = n * log(n),
  • insertion: average case i(n) = 1 (constant), worst case i(n) = n,
  • hinted insertion: average case h(n) = 1 (constant), worst case h(n) = n,
  • deletion: average case d(n) = 1 (constant), worst case d(n) = n,
  • replacement:
    • if the new element key is equivalent to the original, r(n) = 1 (constant),
    • otherwise, average case r(n) = 1 (constant), worst case r(n) = n,
  • modifying: average case m(n) = 1 (constant), worst case m(n) = n.

unordered_[multi]set_of views are instantiated internally to bimap specified by means of the collection type specifiers and the bimap itself. Instantiations are dependent on the following types:

  • Value from bimap,
  • Allocator from bimap,
  • Hash from the collection type specifier,
  • Pred from the collection type specifier.

Hash is a Unary Function taking a single argument of type key_type and returning a value of type std::size_t in the range [0, std::numeric_limits<std::size_t>::max()). Pred is a Binary Predicate inducing an equivalence relation on elements of key_type. It is required that the Hash object return the same value for keys equivalent under Pred.

iterator
const_iterator
local_iterator
const_local_iterator

These types are models of Forward Iterator.

As explained in the concepts section, views do not have public constructors or destructors. Assignment, on the other hand, is provided. Upon construction, max_load_factor() is 1.0.

this_type & operator=(const this_type & x);
  • Effects: a = b; where a and b are the bimap objects to which *this and x belong, respectively.
  • Returns: *this.
std::pair<iterator,bool> insert(const value_type & x);
  • Effects: Inserts x into the bimap to which the view belongs if
    • the view is non-unique OR no other element with equivalent key exists,
    • AND insertion is allowed by all other views of the bimap.
  • Returns: The return value is a pair p. p.second is true if and only if insertion took place. On successful insertion, p.first points to the element inserted; otherwise, p.first points to an element that caused the insertion to be banned. Note that more than one element can be causing insertion not to be allowed.
  • Complexity: O(I(n)).
  • Exception safety: Strong.
iterator insert(iterator position, const value_type & x);
  • Requires: position is a valid iterator of the view.
  • Effects: position is used as a hint to improve the efficiency of the operation. Inserts x into the bimap to which the view belongs if
    • the view is non-unique OR no other element with equivalent key exists,
    • AND insertion is allowed by all other views of the bimap.
  • Returns: On successful insertion, an iterator to the newly inserted element. Otherwise, an iterator to an element that caused the insertion to be banned. Note that more than one element can be causing insertion not to be allowed.
  • Complexity: O(H(n)).
  • Exception safety: Strong.
template< class InputIterator>
void insert(InputIterator first, InputIterator last);
  • Requires: InputIterator is a model of Input Iterator over elements of type value_type. first and last are not iterators into any views of the bimap to which this view belongs. last is reachable from first.
  • Effects: iterator hint = end(); while(first != last) hint = insert(hint, *first++);
  • Complexity: O(m*H(n+m)), where m is the number of elements in [first, last).
  • Exception safety: Basic.
iterator erase(iterator position);
  • Requires: position is a valid dereferenceable iterator of the view.
  • Effects: Deletes the element pointed to by position.
  • Returns: An iterator pointing to the element immediately following the one that was deleted, or end() if no such element exists.
  • Complexity: O(D(n)).
  • Exception safety: nothrow.
template< class CompatibleKey >
size_type erase(const CompatibleKey & x);
  • Effects: Deletes the elements with key equivalent to x.
  • Returns: Number of elements deleted.
  • Complexity: Average case, O(1 + m*D(n)), worst case O(n + m*D(n)), where m is the number of elements deleted.
  • Exception safety: Basic.
iterator erase(iterator first, iterator last);
  • Requires: [first,last) is a valid range of the view.
  • Effects: Deletes the elements in [first,last).
  • Returns: last.
  • Complexity: O(m*D(n)), where m is the number of elements in [first,last).
  • Exception safety: nothrow.
bool replace(iterator position, const value_type & x);
  • Requires: position is a valid dereferenceable iterator of the view.
  • Effects: Assigns the value x to the element pointed to by position into the bimap to which the view belongs if, for the value x
    • the view is non-unique OR no other element with equivalent key exists (except possibly *position),
    • AND replacing is allowed by all other views of the bimap.
  • Postconditions: Validity of position is preserved in all cases.
  • Returns: true if the replacement took place, false otherwise.
  • Complexity: O(R(n)).
  • Exception safety: Strong. If an exception is thrown by some user-provided operation the bimap to which the view belongs remains in its original state.
template< class CompatibleKey >
bool replace_key(iterator position, const CompatibleKey & x);
  • Requires: position is a valid dereferenceable iterator of the set view. CompatibleKey can be assigned to key_type.
  • Effects: Assigns the value x to e.first, where e is the element pointed to by position into the bimap to which the set view belongs if,
    • the map view is non-unique OR no other element with equivalent key exists (except possibly *position),
    • AND replacing is allowed by all other views of the bimap.
  • Postconditions: Validity of position is preserved in all cases.
  • Returns: true if the replacement took place, false otherwise.
  • Complexity: O(R(n)).
  • Exception safety: Strong. If an exception is thrown by some user-provided operation, the bimap to which the set view belongs remains in its original state.
template< class CompatibleData >
bool replace_data(iterator position, const CompatibleData & x);
  • Requires: position is a valid dereferenceable iterator of the set view. CompatibleKey can be assigned to data_type.
  • Effects: Assigns the value x to e.second, where e is the element pointed to by position into the bimap to which the set view belongs if,
    • the map view is non-unique OR no other element with equivalent key exists (except possibly *position),
    • AND replacing is allowed by all other views of the bimap.
  • Postconditions: Validity of position is preserved in all cases.
  • Returns: true if the replacement took place, false otherwise.
  • Complexity: O(R(n)).
  • Exception safety: Strong. If an exception is thrown by some user-provided operation, the bimap to which the set view belongs remains in its original state.
template< class KeyModifier >
bool modify_key(iterator position, KeyModifier mod);
  • Requires: KeyModifier is a model of Unary Function accepting arguments of type: key_type&; position is a valid dereferenceable iterator of the view.
  • Effects: Calls mod(e.first) where e is the element pointed to by position and rearranges *position into all the views of the bimap. If the rearrangement fails, the element is erased. Rearrangement is successful if
    • the map view is non-unique OR no other element with equivalent key exists,
    • AND rearrangement is allowed by all other views of the bimap.
  • Postconditions: Validity of position is preserved if the operation succeeds.
  • Returns: true if the operation succeeded, false otherwise.
  • Complexity: O(M(n)).
  • Exception safety: Basic. If an exception is thrown by some user-provided operation (except possibly mod), then the element pointed to by position is erased.
  • Note: Only provided for map views.
template< class DataModifier >
bool modify_data(iterator position, DataModifier mod);
  • Requires: DataModifier is a model of Unary Function accepting arguments of type: data_type&; position is a valid dereferenceable iterator of the view.
  • Effects: Calls mod(e.second) where e is the element pointed to by position and rearranges *position into all the views of the bimap. If the rearrangement fails, the element is erased. Rearrangement is successful if
    • the oppositte map view is non-unique OR no other element with equivalent key in that view exists,
    • AND rearrangement is allowed by all other views of the bimap.
  • Postconditions: Validity of position is preserved if the operation succeeds.
  • Returns: true if the operation succeeded, false otherwise.
  • Complexity: O(M(n)).
  • Exception safety: Basic. If an exception is thrown by some user-provided operation (except possibly mod), then the element pointed to by position is erased.
  • Note: Only provided for map views.

unordered_[multi]set_of views provide the full lookup functionality required by unordered associative containers, namely find, count, and equal_range. Additionally, these member functions are templatized to allow for non-standard arguments, so extending the types of search operations allowed. The kind of arguments permissible when invoking the lookup member functions is defined by the following concept.

A type CompatibleKey is said to be a compatible key of (Hash, Pred) if (CompatibleKey, Hash, Pred) is a compatible extension of (Hash, Pred). This implies that Hash and Pred accept arguments of type CompatibleKey, which usually means they have several overloads of their corresponding operator() member functions.

template< class CompatibleKey >
iterator find(const CompatibleKey & x);

template< class CompatibleKey >
const_iterator find(const CompatibleKey & x) const;
  • Effects: Returns a pointer to an element whose key is equivalent to x, or end() if such an element does not exist.
  • Complexity: Average case O(1) (constant), worst case O(n).
template< class CompatibleKey >
size_type count(const CompatibleKey & x) const;
  • Effects: Returns the number of elements with key equivalent to x.
  • Complexity: Average case O(count(x)), worst case O(n).
template< class CompatibleKey >
std::pair<iterator,iterator>
    equal_range(const CompatibleKey & x);

template< class CompatibleKey >
std::pair<const_iterator,const_iterator>
    equal_range(const CompatibleKey & x) const;
  • Effects: Returns a range containing all elements with keys equivalent to x (and only those).
  • Complexity: Average case O(count(x)), worst case O(n).
template< class CompatibleKey >
const data_type & at(const CompatibleKey & k) const;
  • Requires: CompatibleKey is a compatible key of key_compare.
  • Effects: Returns the data_type reference that is associated with k, or throws std::out_of_range if such key does not exist.
  • Complexity: Average case O(1) (constant), worst case O(n).
  • Note: Only provided when unordered_set_of is used.

The symmetry of bimap imposes some constraints on operator[] and the non constant version of at() that are not found in std::maps. Tey are only provided if the other collection type is mutable (list_of, vector_of and unconstrained_set_of).

template< class CompatibleKey >
data_type & operator[](const CompatibleKey & k);
  • Requires: CompatibleKey is a compatible key of key_compare.
  • Effects: return insert(value_type(k,data_type()))->second;
  • Complexity: If the insertion is performed O(I(n)), else: Average case O(1) (constant), worst case O(n).
  • Note: Only provided when unordered_set_of is used and the other collection type is mutable.
template< class CompatibleKey >
data_type & at(const CompatibleKey & k);
  • Requires: CompatibleKey is a compatible key of key_compare.
  • Effects: Returns the data_type reference that is associated with k, or throws std::out_of_range if such key does not exist.
  • Complexity: Average case O(1) (constant), worst case O(n).
  • Note: Only provided when unordered_set_of is used and the other collection type is mutable.
template< class CompatibleKey >
info_type & info_at(const CompatibleKey & k);

template< class CompatibleKey >
const info_type & info_at(const CompatibleKey & k) const;
  • Requires: CompatibleKey is a compatible key of key_compare.
  • Effects: Returns the info_type reference that is associated with k, or throws std::out_of_range if such key does not exist.
  • Complexity: Average case O(1) (constant), worst case O(n).
  • Note: Only provided when unordered_set_of and info_hook are used
void rehash(size_type n);
  • Effects: Increases if necessary the number of internal buckets so that size()/bucket_count() does not exceed the maximum load factor, and bucket_count()>=n.
  • Postconditions: Validity of iterators and references to the elements contained is preserved.
  • Complexity: Average case O(size()), worst case O(size(n)2).
  • Exception safety: Strong.

Views cannot be serialized on their own, but only as part of the bimap into which they are embedded. In describing the additional preconditions and guarantees associated to unordered_[multi]set_of views with respect to serialization of their embedding containers, we use the concepts defined in the bimap serialization section.

  • Requires: No additional requirements to those imposed by the container.
  • Requires: Additionally to the general requirements, key_eq() must be serialization-compatible with m.get<i>().key_eq(), where i is the position of the unordered_[multi]set_of view in the container.
  • Postconditions: On successful loading, the range [begin(), end()) contains restored copies of every element in [m.get<i>().begin(), m.get<i>().end()), though not necessarily in the same order.
  • Requires: it is a valid iterator of the view. The associated bimap has been previously saved.
  • Postconditions: On successful loading, if it was dereferenceable then *it' is the restored copy of *it, otherwise it' == end().
  • Note: It is allowed that it be a const_iterator and the restored it' an iterator, or viceversa.
  • Requires: it is a valid local iterator of the view. The associated bimap has been previously saved.
  • Postconditions: On successful loading, if it was dereferenceable then *it' is the restored copy of *it; if it was m.get<i>().end(n) for some n, then it' == m'.get<i>().end(n) (where b is the original bimap, b' its restored copy and i is the ordinal of the index.)
  • Note: It is allowed that it be a const_local_iterator and the restored it' a local_iterator, or viceversa.

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