1<HTML> 2<!-- 3 Copyright (c) Jeremy Siek 2000 4 5 Distributed under the Boost Software License, Version 1.0. 6 (See accompanying file LICENSE_1_0.txt or copy at 7 http://www.boost.org/LICENSE_1_0.txt) 8 --> 9<Head> 10<Title>Buffer</Title> 11</HEAD> 12<BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" 13 ALINK="#ff0000"> 14<IMG SRC="../../../boost.png" 15 ALT="C++ Boost" width="277" height="86"> 16 17<BR Clear> 18 19<h3>Buffer Concept</h3> 20 21A Buffer is something in which items can be put and removed. 22The Buffer <i>concept</i> has very few requirements. It does 23not require any particular ordering of how the items are stored or in 24what order they will appear when removed, however, there is typically 25some sort of ordering policy. 26 27<h3>Notation</h3> 28 29<table> 30<tr> <td> <tt>B</tt> </td> <td> is a type that models Buffer. </td></tr> 31<tr> <td> <tt>T</tt> </td> <td> is the value type of <tt>B</tt>. </td></tr> 32<tr> <td> <tt>t</tt> </td> <td> is an object of type <tt>T</tt>. </td></tr> 33</table> 34 35 36<h3>Members</h3> 37 38For a type to model the Buffer concept it must have the following members. 39 40<p> 41 42<table border="1"> 43 44<tr> <td><b>Member</b></td> <td><b>Description</b></td> </tr> 45 46<tr> <td> <tt>value_type</tt> </td> 47 <td> The type of object stored in the Buffer. The value type 48 must be <A href="http://www.boost.org/sgi/stl/Assignable.html">Assignable</a>.</td> 49 </tr> 50 51<tr> <td> <tt>size_type</tt> </td> 52 <td> An unsigned integral type for representing the number of 53 objects in the Buffer.</td> 54 </tr> 55 56<tr> <td> <tt>void push(const T& t)</tt> </td> 57 <td> Inserts <tt>t</tt> into the Buffer. <tt>size()</tt> will be 58 incremented by one.</td> 59 </tr> 60 61<tr> <td> <tt>void pop()</tt> </td> 62 <td> Removes an object from the Buffer. <tt>size()</tt> will be 63 decremented by one. Precondition: <tt>empty()</tt> 64 is <tt>false</tt>. </td> 65 </tr> 66 67<tr> <td> <tt>T& top()</tt> </td> 68 <td> Returns a mutable reference to some object in the Buffer. 69 Precondition: <tt>empty()</tt> is <tt>false</tt>.</td> 70 </tr> 71 72<tr> <td> <tt>const T& top() const</tt> </td> 73 <td> Returns a const reference to some object in the Buffer. 74 Precondition: <tt>empty()</tt> is <tt>false</tt>.</td> 75 </tr> 76 77<tr> <td> <tt>size_type size() const</tt> </td> 78 <td> Returns the number of objects in the Buffer. 79 Invariant: <tt>size() >= 0</tt>. </td> 80 </tr> 81 82<tr> <td> <tt>bool empty() const</tt> </td> 83 <td> Equivalent to <tt>b.size() == 0</tt>.</td> 84 </tr> 85 86</table> 87 88<h3>Complexity Guarantees</h3> 89 90<UL> 91 92<LI> <tt>push()</tt>, <tt>pop()</tt>, and <tt>size()</tt> must be at 93most linear time complexity in the size of the Generalized Queue. 94 95<LI> <tt>top()</tt> and <tt>empty()</tt> must be amortized constant time. 96 97</UL> 98 99<h3>Models</h3> 100 101<UL> 102<LI><a href="http://www.boost.org/sgi/stl/stack.html"><tt>std::stack</tt></a> 103<LI><a href="../../../boost/pending/mutable_queue.hpp"><tt>boost::mutable_queue</tt></a> 104</UL> 105 106<p> 107 108<br> 109<HR> 110<TABLE> 111<TR valign=top> 112<TD nowrap>Copyright © 2000-2001</TD><TD> 113<A HREF="http://www.boost.org/people/jeremy_siek.htm">Jeremy Siek</A>, Indiana University and C++ Library & Compiler Group/SGI (<A HREF="mailto:jsiek@engr.sgi.com">jsiek@engr.sgi.com</A>) 114</TD></TR></TABLE> 115 116</BODY> 117</HTML> 118 119
