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<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Class template hashtable</title> <link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../../intrusive/reference.html#header.boost.intrusive.hashtable_hpp" title="Header <boost/intrusive/hashtable.hpp>"> <link rel="prev" href="derivation_value_traits.html" title="Struct template derivation_value_traits"> <link rel="next" href="make_hashtable.html" title="Struct template make_hashtable"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> <td align="center"><a href="../../../../index.html">Home</a></td> <td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="derivation_value_traits.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../intrusive/reference.html#header.boost.intrusive.hashtable_hpp"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="make_hashtable.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="refentry"> <a name="boost.intrusive.hashtable"></a><div class="titlepage"></div> <div class="refnamediv"> <h2>Class template hashtable</h2> boost::intrusive::hashtable </div> <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis">// In header: <<a class="link" href="../../intrusive/reference.html#header.boost.intrusive.hashtable_hpp" title="Header <boost/intrusive/hashtable.hpp>">boost/intrusive/hashtable.hpp</a>> template<typename T, class... Options> class <a class="link" href="hashtable.html" title="Class template hashtable">hashtable</a> : private hashtable_data_t< SizeType, BoolFlags &hashtable_data_bool_flags_mask, VoidOrKeyHash, VoidOrKeyEqual, ValueTraits, BucketTraits > { public: // types typedef ValueTraits <a name="boost.intrusive.hashtable.value_traits"></a>value_traits; typedef value_traits::pointer <a name="boost.intrusive.hashtable.pointer"></a>pointer; typedef value_traits::const_pointer <a name="boost.intrusive.hashtable.const_pointer"></a>const_pointer; typedef value_traits::value_type <a name="boost.intrusive.hashtable.value_type"></a>value_type; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< pointer >::reference <a name="boost.intrusive.hashtable.reference"></a>reference; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< const_pointer >::reference <a name="boost.intrusive.hashtable.const_reference"></a>const_reference; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< pointer >::difference_type <a name="boost.intrusive.hashtable.difference_type"></a>difference_type; typedef SizeType <a name="boost.intrusive.hashtable.size_type"></a>size_type; typedef value_type <a name="boost.intrusive.hashtable.key_type"></a>key_type; typedef data_type::value_equal <a name="boost.intrusive.hashtable.key_equal"></a>key_equal; typedef data_type::value_equal <a name="boost.intrusive.hashtable.value_equal"></a>value_equal; typedef data_type::hasher <a name="boost.intrusive.hashtable.hasher"></a>hasher; typedef unspecified <a name="boost.intrusive.hashtable.bucket_type"></a>bucket_type; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< pointer >::template rebind_pointer< bucket_type >::type <a name="boost.intrusive.hashtable.bucket_ptr"></a>bucket_ptr; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< pointer >::template rebind_pointer< const bucket_type >::type <a name="boost.intrusive.hashtable.const_bucket_ptr"></a>const_bucket_ptr; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< bucket_ptr >::reference <a name="boost.intrusive.hashtable.bucket_reference"></a>bucket_reference; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< bucket_ptr >::reference <a name="boost.intrusive.hashtable.const_bucket_reference"></a>const_bucket_reference; typedef slist::iterator <a name="boost.intrusive.hashtable.siterator"></a>siterator; typedef slist::const_iterator <a name="boost.intrusive.hashtable.const_siterator"></a>const_siterator; typedef hashtable_iterator< bucket_plus_vtraits_t, false > <a name="boost.intrusive.hashtable.iterator"></a>iterator; typedef hashtable_iterator< bucket_plus_vtraits_t, true > <a name="boost.intrusive.hashtable.const_iterator"></a>const_iterator; typedef value_traits::node_traits <a name="boost.intrusive.hashtable.node_traits"></a>node_traits; typedef node_traits::node <a name="boost.intrusive.hashtable.node"></a>node; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< pointer >::template rebind_pointer< node >::type <a name="boost.intrusive.hashtable.node_ptr"></a>node_ptr; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< pointer >::template rebind_pointer< const node >::type <a name="boost.intrusive.hashtable.const_node_ptr"></a>const_node_ptr; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< node_ptr >::reference <a name="boost.intrusive.hashtable.node_reference"></a>node_reference; typedef <a class="link" href="pointer_traits.html" title="Struct template pointer_traits">pointer_traits</a>< const_node_ptr >::reference <a name="boost.intrusive.hashtable.const_node_reference"></a>const_node_reference; typedef slist::node_algorithms <a name="boost.intrusive.hashtable.node_algorithms"></a>node_algorithms; typedef unspecified <a name="boost.intrusive.hashtable.insert_commit_data"></a>insert_commit_data; typedef unspecified <a name="boost.intrusive.hashtable.local_iterator"></a>local_iterator; typedef unspecified <a name="boost.intrusive.hashtable.const_local_iterator"></a>const_local_iterator; // <a class="link" href="hashtable.html#boost.intrusive.hashtableconstruct-copy-destruct">construct/copy/destruct</a> explicit <a class="link" href="hashtable.html#idp63190320-bb">hashtable</a>(const <a class="link" href="bucket_traits.html" title="Struct template bucket_traits">bucket_traits</a> &, const hasher & = hasher(), const key_equal & = key_equal(), const value_traits & = value_traits()); <a class="link" href="hashtable.html#idp63200384-bb">hashtable</a>(<a class="link" href="hashtable.html" title="Class template hashtable">hashtable</a> &&); <a class="link" href="hashtable.html" title="Class template hashtable">hashtable</a> & <a class="link" href="hashtable.html#idp63202624-bb">operator=</a>(<a class="link" href="hashtable.html" title="Class template hashtable">hashtable</a> &&); <a class="link" href="hashtable.html#idp63205440-bb">~hashtable</a>(); // <a class="link" href="hashtable.html#idp62802864-bb">public member functions</a> iterator <a class="link" href="hashtable.html#idp62803424-bb">begin</a>(); const_iterator <a class="link" href="hashtable.html#idp62808496-bb">begin</a>() const; const_iterator <a class="link" href="hashtable.html#idp62813856-bb">cbegin</a>() const; iterator <a class="link" href="hashtable.html#idp62819216-bb">end</a>(); const_iterator <a class="link" href="hashtable.html#idp62823504-bb">end</a>() const; const_iterator <a class="link" href="hashtable.html#idp62828064-bb">cend</a>() const; hasher <a class="link" href="hashtable.html#idp62832624-bb">hash_function</a>() const; key_equal <a class="link" href="hashtable.html#idp62837200-bb">key_eq</a>() const; bool <a class="link" href="hashtable.html#idp62841792-bb">empty</a>() const; size_type <a class="link" href="hashtable.html#idp62846480-bb">size</a>() const; void <a class="link" href="hashtable.html#idp62851824-bb">swap</a>(<a class="link" href="hashtable.html" title="Class template hashtable">hashtable</a> &); template<typename Cloner, typename Disposer> void <a class="link" href="hashtable.html#idp62857408-bb">clone_from</a>(const <a class="link" href="hashtable.html" title="Class template hashtable">hashtable</a> &, Cloner, Disposer); iterator <a class="link" href="hashtable.html#idp62867632-bb">insert_equal</a>(reference); template<typename Iterator> void <a class="link" href="hashtable.html#idp62875344-bb">insert_equal</a>(Iterator, Iterator); std::pair< iterator, bool > <a class="link" href="hashtable.html#idp62883088-bb">insert_unique</a>(reference); template<typename Iterator> void <a class="link" href="hashtable.html#idp62891008-bb">insert_unique</a>(Iterator, Iterator); template<typename KeyType, typename KeyHasher, typename KeyValueEqual> std::pair< iterator, bool > <a class="link" href="hashtable.html#idp62898752-bb">insert_unique_check</a>(const KeyType &, KeyHasher, KeyValueEqual, insert_commit_data &); iterator <a class="link" href="hashtable.html#idp62913536-bb">insert_unique_commit</a>(reference, const insert_commit_data &); void <a class="link" href="hashtable.html#idp62923328-bb">erase</a>(const_iterator); void <a class="link" href="hashtable.html#idp62928512-bb">erase</a>(const_iterator, const_iterator); size_type <a class="link" href="hashtable.html#idp62934432-bb">erase</a>(const_reference); template<typename KeyType, typename KeyHasher, typename KeyValueEqual> size_type <a class="link" href="hashtable.html#idp62940592-bb">erase</a>(const KeyType &, KeyHasher, KeyValueEqual); template<typename Disposer> void <a class="link" href="hashtable.html#idp62951552-bb">erase_and_dispose</a>(const_iterator, Disposer); template<typename Disposer> void <a class="link" href="hashtable.html#idp62959168-bb">erase_and_dispose</a>(const_iterator, const_iterator, Disposer); template<typename Disposer> size_type <a class="link" href="hashtable.html#idp62967504-bb">erase_and_dispose</a>(const_reference, Disposer); template<typename KeyType, typename KeyHasher, typename KeyValueEqual, typename Disposer> size_type <a class="link" href="hashtable.html#idp62976144-bb">erase_and_dispose</a>(const KeyType &, KeyHasher, KeyValueEqual, Disposer); void <a class="link" href="hashtable.html#idp62987792-bb">clear</a>(); template<typename Disposer> void <a class="link" href="hashtable.html#idp62992384-bb">clear_and_dispose</a>(Disposer); size_type <a class="link" href="hashtable.html#idp62999376-bb">count</a>(const_reference) const; template<typename KeyType, typename KeyHasher, typename KeyValueEqual> size_type <a class="link" href="hashtable.html#idp63003984-bb">count</a>(const KeyType &, const KeyHasher &, const KeyValueEqual &) const; iterator <a class="link" href="hashtable.html#idp63013360-bb">find</a>(const_reference); template<typename KeyType, typename KeyHasher, typename KeyValueEqual> iterator <a class="link" href="hashtable.html#idp63017728-bb">find</a>(const KeyType &, KeyHasher, KeyValueEqual); const_iterator <a class="link" href="hashtable.html#idp63027920-bb">find</a>(const_reference) const; template<typename KeyType, typename KeyHasher, typename KeyValueEqual> const_iterator <a class="link" href="hashtable.html#idp63032576-bb">find</a>(const KeyType &, KeyHasher, KeyValueEqual) const; std::pair< iterator, iterator > <a class="link" href="hashtable.html#idp63043040-bb">equal_range</a>(const_reference); template<typename KeyType, typename KeyHasher, typename KeyValueEqual> std::pair< iterator, iterator > <a class="link" href="hashtable.html#idp63047488-bb">equal_range</a>(const KeyType &, KeyHasher, KeyValueEqual); std::pair< const_iterator, const_iterator > <a class="link" href="hashtable.html#idp63057728-bb">equal_range</a>(const_reference) const; template<typename KeyType, typename KeyHasher, typename KeyValueEqual> std::pair< const_iterator, const_iterator > <a class="link" href="hashtable.html#idp63062464-bb">equal_range</a>(const KeyType &, KeyHasher, KeyValueEqual) const; iterator <a class="link" href="hashtable.html#idp63072992-bb">iterator_to</a>(reference); const_iterator <a class="link" href="hashtable.html#idp63079680-bb">iterator_to</a>(const_reference) const; local_iterator <a class="link" href="hashtable.html#idp63086640-bb">local_iterator_to</a>(reference); const_local_iterator <a class="link" href="hashtable.html#idp63093296-bb">local_iterator_to</a>(const_reference) const; size_type <a class="link" href="hashtable.html#idp63100240-bb">bucket_count</a>() const; size_type <a class="link" href="hashtable.html#idp63104096-bb">bucket_size</a>(size_type) const; size_type <a class="link" href="hashtable.html#idp63109488-bb">bucket</a>(const key_type &) const; template<typename KeyType, typename KeyHasher> size_type <a class="link" href="hashtable.html#idp63114992-bb">bucket</a>(const KeyType &, const KeyHasher &) const; bucket_ptr <a class="link" href="hashtable.html#idp63123584-bb">bucket_pointer</a>() const; local_iterator <a class="link" href="hashtable.html#idp63127456-bb">begin</a>(size_type); const_local_iterator <a class="link" href="hashtable.html#idp63133552-bb">begin</a>(size_type) const; const_local_iterator <a class="link" href="hashtable.html#idp63139920-bb">cbegin</a>(size_type) const; local_iterator <a class="link" href="hashtable.html#idp63146288-bb">end</a>(size_type); const_local_iterator <a class="link" href="hashtable.html#idp63152368-bb">end</a>(size_type) const; const_local_iterator <a class="link" href="hashtable.html#idp63158736-bb">cend</a>(size_type) const; void <a class="link" href="hashtable.html#idp63165104-bb">rehash</a>(const <a class="link" href="bucket_traits.html" title="Struct template bucket_traits">bucket_traits</a> &); bool <a class="link" href="hashtable.html#idp63172400-bb">incremental_rehash</a>(bool = true); bool <a class="link" href="hashtable.html#idp63178656-bb">incremental_rehash</a>(const <a class="link" href="bucket_traits.html" title="Struct template bucket_traits">bucket_traits</a> &); size_type <a class="link" href="hashtable.html#idp63185520-bb">split_count</a>() const; // <a class="link" href="hashtable.html#idp63210016-bb">public static functions</a> static local_iterator <a class="link" href="hashtable.html#idp63210576-bb">s_local_iterator_to</a>(reference); static const_local_iterator <a class="link" href="hashtable.html#idp63218832-bb">s_local_iterator_to</a>(const_reference); static size_type <a class="link" href="hashtable.html#idp63227104-bb">suggested_upper_bucket_count</a>(size_type); static size_type <a class="link" href="hashtable.html#idp63231888-bb">suggested_lower_bucket_count</a>(size_type); // public data members static const bool stateful_value_traits; static const bool store_hash; static const bool unique_keys; static const bool constant_time_size; static const bool cache_begin; static const bool compare_hash; static const bool incremental; static const bool power_2_buckets; static const bool optimize_multikey; };</pre></div> <div class="refsect1"> <a name="idp283342448"></a><h2>Description</h2> The class template hashtable is an intrusive hash table container, that is used to construct intrusive <a class="link" href="unordered_set.html" title="Class template unordered_set">unordered_set</a> and <a class="link" href="unordered_multiset.html" title="Class template unordered_multiset">unordered_multiset</a> containers. The no-throw guarantee holds only, if the VoidOrKeyEqual object and Hasher don't throw. hashtable is a semi-intrusive container: each object to be stored in the container must contain a proper hook, but the container also needs additional auxiliary memory to work: hashtable needs a pointer to an array of type <code class="computeroutput">bucket_type</code> to be passed in the constructor. This bucket array must have at least the same lifetime as the container. This makes the use of hashtable more complicated than purely intrusive containers. <code class="computeroutput">bucket_type</code> is default-constructible, copyable and assignable The template parameter <code class="computeroutput">T</code> is the type to be managed by the container. The user can specify additional options and if no options are provided default options are used. The container supports the following options: <code class="computeroutput">base_hook<>/member_hook<>/value_traits<></code>, <code class="computeroutput">constant_time_size<></code>, <code class="computeroutput">size_type<></code>, <code class="computeroutput">hash<></code> and <code class="computeroutput">equal<></code> <code class="computeroutput">bucket_traits<></code>, power_2_buckets<>, cache_begin<> and incremental<>. hashtable only provides forward iterators but it provides 4 iterator types: iterator and const_iterator to navigate through the whole container and local_iterator and const_local_iterator to navigate through the values stored in a single bucket. Local iterators are faster and smaller. It's not recommended to use non constant-time size hashtables because several key functions, like "empty()", become non-constant time functions. Non constant_time size hashtables are mainly provided to support auto-unlink hooks. hashtables, does not make automatic rehashings nor offers functions related to a load factor. Rehashing can be explicitly requested and the user must provide a new bucket array that will be used from that moment. Since no automatic rehashing is done, iterators are never invalidated when inserting or erasing elements. Iterators are only invalidated when rehashing. <div c