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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0.1 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Boost.MultiIndex Documentation - Random access indices reference</title> <link rel="stylesheet" href="../style.css" type="text/css"> <link rel="start" href="../index.html"> <link rel="prev" href="seq_indices.html"> <link rel="up" href="index.html"> <link rel="next" href="key_extraction.html"> </head> <body> <h1><img src="../../../../boost.png" alt="boost.png (6897 bytes)" align= "middle" width="277" height="86">Boost.MultiIndex Random access indices reference</h1> <div class="prev_link"><a href="seq_indices.html"><img src="../prev.gif" alt="sequenced indices" border="0"> Sequenced indices </a></div> <div class="up_link"><a href="index.html"><img src="../up.gif" alt="Boost.MultiIndex reference" border="0"> Boost.MultiIndex reference </a></div> <div class="next_link"><a href="key_extraction.html"><img src="../next.gif" alt="key extraction" border="0"> Key extraction </a></div> <hr> <h2>Contents</h2> <ul> <li><a href="#rnd_index_fwd_synopsis">Header <code>"boost/multi_index/random_access_index_fwd.hpp"</code> synopsis</a></li> <li><a href="#synopsis">Header <code>"boost/multi_index/random_access_index.hpp"</code> synopsis</a> <ul> <li><a href="#random_access"><code>random_access</code> index specifier</a></li> <li><a href="#rnd_indices">Random access indices</a> <ul> <li><a href="#complexity_signature">Complexity signature</a></li> <li><a href="#instantiation_types">Instantiation types</a></li> <li><a href="#constructors">Constructors, copy and assignment</a></li> <li><a href="#iterators">Iterators</a></li> <li><a href="#capacity">Capacity operations</a></li> <li><a href="#modifiers">Modifiers</a></li> <li><a href="#list_operations">List operations</a></li> <li><a href="#rearrange_operations">Rearrange operations</a></li> <li><a href="#serialization">Serialization</a></li> </ul> </li> </ul> </li> </ul> <h2> <a name="rnd_index_fwd_synopsis">Header <a href="../../../../boost/multi_index/random_access_index_fwd.hpp"> <code>"boost/multi_index/random_access_index_fwd.hpp"</code></a> synopsis</a></h2> <blockquote><pre> namespace boost{ namespace multi_index{ // random_access index specifier template<typename TagList=tag<> > struct random_access; // indices namespace detail{ template<implementation defined> class index class name implementation defined; } // namespace boost::multi_index::detail } // namespace boost::multi_index } // namespace boost </pre></blockquote> <code>random_access_index_fwd.hpp</code> provides forward declarations for the <a href="#random_access"><code>random_access</code></a> index specifier and its associated <a href="#rnd_indices">random access index</a> class. <h2> <a name="synopsis">Header <a href="../../../../boost/multi_index/random_access_index.hpp"> <code>"boost/multi_index/random_access_index.hpp"</code></a> synopsis</a></h2> <blockquote><pre> #include <initializer_list> namespace boost{ namespace multi_index{ // random_access index specifier template<typename TagList=tag<> > struct random_access; // indices namespace detail{ template<implementation defined> class index class name implementation defined; // index comparison: // OP is any of ==,<,!=,>,>=,<= template<arg set 1,arg set 2> bool operator OP( const index class name<arg set 1>& x,const index class name<arg set 2>& y); // index specialized algorithms: template<implementation defined> void swap(index class name& x,index class name& y); } // namespace boost::multi_index::detail } // namespace boost::multi_index } // namespace boost </pre></blockquote> <h3><a name="random_access"> <code>random_access</code> index specifier </a></h3> This index specifier allows for insertion of a <a href="#rnd_indices">random access index</a>. <blockquote><pre> template<typename TagList=tag<> > struct random_access; </pre></blockquote> If provided, <code>TagList</code> must be an instantiation of <a href="indices.html#tag"><code>tag</code></a>. <h3><a name="rnd_indices">Random access indices</a></h3> Random access indices are free-order sequences with constant time positional access and random access iterators. Elements in a random access index are by default sorted according to their order of insertion: this means that new elements inserted through a different index of the <code>multi_index_container</code> are appended to the end of the random access index; additionally, facilities are provided for further rearrangement of the elements. The public interface of random access indices includes that of <a href="seq_indices.html">sequenced indices</a>, with differences in the complexity of the operations, plus extra operations for positional access (<code>operator[]</code> and <code>at()</code>) and for capacity handling. Validity of iterators and references to elements is preserved in all operations, regardless of the capacity status. Except where noted or if the corresponding interface does not exist, random access indices verify the same container requirements as <code>std::vector</code> plus the requirements for <code>std::list</code> specific list operations at [list.ops]. Some of the most important differences with respect to <code>std::vector</code> are: <ul> <li>Random access indices do not provide memory contiguity, and hence do not have <code>data</code> member functions. </li> <li>The complexity of some operations, notably insertion and deletion, differ from those of <code>std::vector</code>. </li> <li>Unlike as in <code>std::vector</code>, insertions into a random access index may fail due to clashings with other indices. This alters the semantics of the operations provided with respect to their analogues in <code>std::vector</code>. </li> <li>Elements in a randon access index are not mutable, and can only be changed by means of <a href="#replace"><code>replace</code></a> and <a href="#modify"><code>modify</code></a> member functions. </li> <li><code>push_front</code> and <code>pop_front</code> are provided for compatibility with sequenced indices, even though they take linear time to execute. </li></ul> <blockquote><pre> namespace boost{ namespace multi_index{ namespace detail{ template<implementation defined: dependent on types Value, Allocator, TagList> class name is implementation defined { public: // types: typedef Value value_type; typedef boost::tuples::null_type ctor_args; typedef TagList tag_list; typedef Allocator allocator_type; typedef typename allocator_type::reference reference; typedef typename allocator_type::const_reference const_reference; typedef implementation defined iterator; typedef implementation defined const_iterator; typedef std::size_t size_type; typedef std::ptrdiff_t difference_type; typedef typename allocator_type::pointer pointer; typedef typename allocator_type::const_pointer const_pointer; typedef equivalent to std::reverse_iterator<iterator> reverse_iterator; typedef equivalent to std::reverse_iterator<const_iterator> const_reverse_iterator; // construct/copy/destroy: index class name& operator=(const index class name& x); index class name& operator=(std::initializer_list<value_type> list); template <class InputIterator> void assign(InputIterator first,InputIterator last); void assign(std::initializer_list<value_type> list) void assign(size_type n,const value_type& value); allocator_type get_allocator()const noexcept; // iterators: iterator begin()noexcept; const_iterator begin()const noexcept; iterator end()noexcept; const_iterator end()const noexcept; reverse_iterator rbegin()noexcept; const_reverse_iterator rbegin()const noexcept; reverse_iterator rend()noexcept; const_reverse_iterator rend()const noexcept; const_iterator cbegin()const noexcept; const_iterator cend()const noexcept; const_reverse_iterator crbegin()const noexcept; const_reverse_iterator crend()const noexcept; iterator iterator_to(const value_type& x); const_iterator iterator_to(const value_type& x)const; // capacity: bool empty()const noexcept; size_type size()const noexcept; size_type max_size()const noexcept; size_type capacity()const noexcept; void reserve(size_type m); void shrink_to_fit(); void resize(size_type n); void resize(size_type n,const value_type& x); // access: const_reference operator[](size_type n)const; const_reference at(size_type n)const; const_reference front()const; const_reference back()const; // modifiers: template<typename... Args> std::pair<iterator,bool> emplace_front(Args&&... args); std::pair<iterator,bool> push_front(const value_type& x); std::pair<iterator,bool> push_front(value_type&& x); void pop_front(); template<typename... Args> std::pair<iterator,bool> emplace_back(Args&&... args); std::pair<iterator,bool> push_back(const value_type& x); std::pair<iterator,bool> push_back(value_type&& x); void pop_back(); template<typename... Args> std::pair<iterator,bool> emplace(iterator position,Args&&... args); std::pair<iterator,bool> insert(iterator position,const value_type& x); std::pair<iterator,bool> insert(iterator position,value_type&& x); void insert(iterator position,size_type m,const value_type& x); template<typename InputIterator> void insert(iterator position,InputIterator first,InputIterator last); void insert(iterator position,std::initializer_list<value_type> list); iterator erase(iterator position); iterator erase(iterator first,iterator last); bool replace(iterator position,const value_type& x); bool replace(iterator position,value_type&& x); template<typename Modifier> bool modify(iterator position,Modifier mod); template<typename Modifier,typename Rollback> bool modify(iterator position,Modifier mod,Rollback back); void swap(index class name& x); void clear()noexcept; // list operations: void splice(iterator position,index class name& x); void splice(iterator position,index class name& x,iterator i); void splice( iterator position,index class name& x,iterator first,iterator last); void remove(const value_type& value); template<typename Predicate> void remove_if(Predicate pred); void unique(); template <class BinaryPredicate> void unique(BinaryPredicate binary_pred); void merge(index class name& x); template <typename Compare> void merge(index class name& x,Compare comp); void sort(); template <typename Compare> void sort(Compare comp); void reverse()noexcept; // rearrange operations: void relocate(iterator position,iterator i); void relocate(iterator position,iterator first,iterator last); template<typename InputIterator> void rearrange(InputIterator first); } // index comparison: template<arg set 1,arg set 2> bool operator==( const index class name<arg set 1>& x, const index class name<arg set 2>& y) { return x.size()==y.size()&&std::equal(x.begin(),x.end(),y.begin()); } template<arg set 1,arg set 2> bool operator<( const index class name<arg set 1>& x, const index class name<arg set 2>& y) { return std::lexicographical_compare(x.begin(),x.end(),y.begin(),y.end()); } template<arg set 1,arg set 2> bool operator!=( const index class name<arg set 1>& x, const index class name<arg set 2>& y) { return !(x==y); } template<arg set 1,arg set 2> bool operator>( const index class name<arg set 1>& x ,const index class name<arg set 2>& y) { return y<x; } template<arg set 1,arg set 2> bool operator>=( const index class name<arg set 1>& x, const index class name<arg set 2>& y) { return !(x<y); } template<arg set 1,arg set 2> bool operator<=( const index class name<arg set 1>& x, const index class name<arg set 2>& y) { return !(x>y); } // index specialized algorithms: template<implementation defined> void swap(index class name& x,index class name& y); } // namespace boost::multi_index::detail } // namespace boost::multi_index } // namespace boost </pre></blockquote> <h4><a name="complexity_signature">Complexity signature</a></h4> Here and in the descriptions of operations of random access indices, we adopt the scheme outlined in the <a href="indices.html#complexity_signature">complexity signature section</a>. The complexity signature of random access indices is: <ul> <li>copying: <code>c(n)=n*log(n)</code>,</li> <li>insertion: <code>i(n)=1</code> (amortized constant),</li> <li>hinted insertion: <code>h(n)=1</code> (amortized constant),</li> <li>deletion: <code>d(n)=m</code>, where <code>m</code> is the distance from the deleted element to the end of the sequence,</li> <li>replacement: <code>r(n)=1</code> (constant),</li> <li>modifying: <code>m(n)=1</code> (constant).</li> </ul> The following expressions are also used as a convenience for writing down some of the complexity formulas: <blockquote> <code>shl(a,b)</code> = <code>a+b</code> if a is nonzero, <code>0</code> otherwise. <code>rel(a,b,c)</code> = if <code>a<b</code>, <code>c-a</code>, else <code>a-b</code>, </blockquote> (<code>shl</code> and <code>rel</code> stand for shift left and relocate, respectively.) <h4><a name="instantiation_types">Instantiation types</a></h4> Random access indices are instantiated internally to <code>multi_index_container</code> and specified by means of <a href="indices.html#indexed_by"> <code>indexed_by</code></a> with the <a href="#random_access"><code>random_access</code></a> index specifier. Instantiations are dependent on the following types: <ul> <li><code>Value</code> from <code>multi_index_container</code>,</li> <li><code>Allocator</code> from <code>multi_index_container</code>,</li> <li><code>TagList</code> from the index specifier (if provided, otherwise <code>tag<></code> is assumed).</li> </ul> <code>TagList</code> must be an instantiation of <a href="indices.html#tag"><code>tag</code></a>. <h4><a name="constructors">Constructors, copy and assignment</a></h4> As explained in the <a href="indices.html#index_concepts">index concepts section</a>, indices do not have public constructors or destructors. Assignment, on the other hand, is provided. <code>index class name& operator=(const index class name& x);</code> <blockquote> Effects: <blockquote><pre> a=b; </pre></blockquote> where <code>a</code> and <code>b</code> are the <code>multi_index_container</code> objects to which <code>*this</code> and <code>x</code> belong, respectively. Returns: <code>*this</code>. </blockquote> <code>index class name& operator=(std::initializer_list<value_type> list);</code> <blockquote> Effects: <blockquote><pre> a=list; </pre></blockquote> where <code>a</code> is the <code>multi_index_container</code> object to which <code>*this</code> belongs. Returns: <code>*this</code>. </blockquote> <code>template <class InputIterator> void assign(InputIterator first,InputIterator last);</code> <blockquote> Effects: <blockquote><pre> clear(); insert(end(),first,last); </pre></blockquote> </blockquote> <code>void assign(std::initializer_list<value_type> list);</code> <blockquote> Effects: <blockquote><pre> assign(list.begin(),list.end()); </pre></blockquote> </blockquote> <code>void assign(size_type n,const value_type& value);</code> <blockquote> Effects: <blockquote><pre> clear(); for(size_type i=0;i<n;++n)push_back(v); </pre></blockquote> </blockquote> <h4><a name="iterators">Iterators</a></h4> <code>iterator       iterator_to(const value_type& x); const_iterator iterator_to(const value_type& x)const;</code> <blockquote> Requires: <code>x</code> is a reference to an element of the container. Returns: An iterator to <code>x</code>. Complexity: Constant. Exception safety: <code>nothrow</code>. </blockquote> <h4><a name="capacity">Capacity operations</a></h4> <a name="capacity_memfun"><code>size_type capacity()const noexcept;</code></a> <blockquote> Returns: The total number of elements <code>c</code> such that, when <code>size()<c</code>, back insertions happen in constant time (the general case as described by <a href="#complexity_signature"><code>i(n)</code></a> is amortized constant time.) Note:<