| 1 | <HTML> |
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| 2 | <!-- |
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| 3 | -- Copyright (c) Jeremy Siek 2000 |
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| 4 | -- |
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| 5 | -- Permission to use, copy, modify, distribute and sell this software |
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| 6 | -- and its documentation for any purpose is hereby granted without fee, |
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| 7 | -- provided that the above copyright notice appears in all copies and |
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| 8 | -- that both that copyright notice and this permission notice appear |
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| 9 | -- in supporting documentation. Silicon Graphics makes no |
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| 10 | -- representations about the suitability of this software for any |
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| 11 | -- purpose. It is provided "as is" without express or implied warranty. |
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| 12 | --> |
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| 13 | <Head> |
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| 14 | <Title>Buffer</Title> |
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| 15 | </HEAD> |
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| 16 | <BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" |
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| 17 | ALINK="#ff0000"> |
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| 18 | <IMG SRC="../../../boost.png" |
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| 19 | ALT="C++ Boost" width="277" height="86"> |
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| 20 | |
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| 21 | <BR Clear> |
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| 22 | |
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| 23 | <h3>Buffer Concept</h3> |
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| 24 | |
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| 25 | A Buffer is something in which items can be put and removed. |
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| 26 | The Buffer <i>concept</i> has very few requirements. It does |
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| 27 | not require any particular ordering of how the items are stored or in |
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| 28 | what order they will appear when removed, however, there is typically |
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| 29 | some sort of ordering policy. |
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| 30 | |
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| 31 | <h3>Notation</h3> |
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| 32 | |
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| 33 | <table> |
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| 34 | <tr> <td> <tt>B</tt> </td> <td> is a type that models Buffer. </td></tr> |
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| 35 | <tr> <td> <tt>T</tt> </td> <td> is the value type of <tt>B</tt>. </td></tr> |
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| 36 | <tr> <td> <tt>t</tt> </td> <td> is an object of type <tt>T</tt>. </td></tr> |
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| 37 | </table> |
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| 38 | |
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| 39 | |
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| 40 | <h3>Members</h3> |
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| 41 | |
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| 42 | For a type to model the Buffer concept it must have the following members. |
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| 43 | |
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| 44 | <p> |
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| 45 | |
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| 46 | <table border="1"> |
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| 47 | |
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| 48 | <tr> <td><b>Member</b></td> <td><b>Description</b></td> </tr> |
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| 49 | |
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| 50 | <tr> <td> <tt>value_type</tt> </td> |
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| 51 | <td> The type of object stored in the Buffer. The value type |
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| 52 | must be <A href="http://www.sgi.com/tech/stl/Assignable.html">Assignable</a>.</td> |
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| 53 | </tr> |
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| 54 | |
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| 55 | <tr> <td> <tt>size_type</tt> </td> |
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| 56 | <td> An unsigned integral type for representing the number of |
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| 57 | objects in the Buffer.</td> |
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| 58 | </tr> |
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| 59 | |
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| 60 | <tr> <td> <tt>void push(const T& t)</tt> </td> |
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| 61 | <td> Inserts <tt>t</tt> into the Buffer. <tt>size()</tt> will be |
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| 62 | incremented by one.</td> |
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| 63 | </tr> |
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| 64 | |
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| 65 | <tr> <td> <tt>void pop()</tt> </td> |
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| 66 | <td> Removes an object from the Buffer. <tt>size()</tt> will be |
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| 67 | decremented by one. Precondition: <tt>empty()</tt> |
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| 68 | is <tt>false</tt>. </td> |
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| 69 | </tr> |
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| 70 | |
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| 71 | <tr> <td> <tt>T& top()</tt> </td> |
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| 72 | <td> Returns a mutable reference to some object in the Buffer. |
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| 73 | Precondition: <tt>empty()</tt> is <tt>false</tt>.</td> |
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| 74 | </tr> |
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| 75 | |
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| 76 | <tr> <td> <tt>const T& top() const</tt> </td> |
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| 77 | <td> Returns a const reference to some object in the Buffer. |
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| 78 | Precondition: <tt>empty()</tt> is <tt>false</tt>.</td> |
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| 79 | </tr> |
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| 80 | |
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| 81 | <tr> <td> <tt>size_type size() const</tt> </td> |
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| 82 | <td> Returns the number of objects in the Buffer. |
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| 83 | Invariant: <tt>size() >= 0</tt>. </td> |
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| 84 | </tr> |
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| 85 | |
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| 86 | <tr> <td> <tt>bool empty() const</tt> </td> |
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| 87 | <td> Equivalent to <tt>b.size() == 0</tt>.</td> |
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| 88 | </tr> |
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| 89 | |
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| 90 | </table> |
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| 91 | |
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| 92 | <h3>Complexity Guarantees</h3> |
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| 93 | |
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| 94 | <UL> |
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| 95 | |
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| 96 | <LI> <tt>push()</tt>, <tt>pop()</tt>, and <tt>size()</tt> must be at |
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| 97 | most linear time complexity in the size of the Generalized Queue. |
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| 98 | |
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| 99 | <LI> <tt>top()</tt> and <tt>empty()</tt> must be amortized constant time. |
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| 100 | |
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| 101 | </UL> |
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| 102 | |
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| 103 | <h3>Models</h3> |
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| 104 | |
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| 105 | <UL> |
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| 106 | <LI><a href="http://www.sgi.com/tech/stl/stack.html"><tt>std::stack</tt></a> |
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| 107 | <LI><a href="../../../boost/pending/mutable_queue.hpp"><tt>boost::mutable_queue</tt></a> |
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| 108 | </UL> |
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| 109 | |
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| 110 | <p> |
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| 111 | |
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| 112 | <br> |
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| 113 | <HR> |
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| 114 | <TABLE> |
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| 115 | <TR valign=top> |
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| 116 | <TD nowrap>Copyright © 2000-2001</TD><TD> |
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| 117 | <A HREF="../../../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>) |
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| 118 | </TD></TR></TABLE> |
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| 119 | |
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| 120 | </BODY> |
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| 121 | </HTML> |
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| 122 | |
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