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1 | <HTML> |
| 2 | <!-- | |
| 3 | Copyright (c) Jeremy Siek, Lie-Quan Lee, and Andrew Lumsdaine 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>Vector Property Map</Title> | |
| 11 | <BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" | |
| 12 | ALINK="#ff0000"> | |
| 13 | <IMG SRC="../../../boost.png" | |
| 14 | ALT="C++ Boost" width="277" height="86"> | |
| 15 | ||
| 16 | <BR Clear> | |
| 17 | ||
| 18 | ||
| 19 | <H2><A NAME="sec:vector-property-map"></A> | |
| 20 | </h2> | |
| 21 | <PRE> | |
| 22 | template<typename T, typename IndexMap = identity_property_map> | |
| 23 | class vector_property_map; | |
| 24 | </PRE> | |
| 25 | ||
| 26 | <P> | |
| 27 | This property map is used to efficiently store properties for a variable | |
| 28 | number of elements. It's somewhere between <a | |
| 29 | href="associative_property_map.html">associative_property_map</a> and | |
| 30 | <a href="iterator_property_map.html">iterator_property_map</a>. The latter | |
| 31 | is very fast, but requires that the number of stored elements is known | |
| 32 | when creating property map. The former does not have this requirement, but | |
| 33 | is slower, and requires stored elements to be comparable. | |
| 34 | ||
| 35 | <p> | |
| 36 | The <tt>vector_property_map</tt> uses mapping from key to indices, | |
| 37 | and allows to add new elements. It accoplishes this by storing values | |
| 38 | in a vector, which is resized on demand. | |
| 39 | ||
| 40 | <p> | |
| 41 | Note that <tt>vector_property_map</tt> does not provide reference/pointer | |
| 42 | stability for stored values. | |
| 43 | ||
| 44 | <h3>Example</h3> | |
| 45 | ||
| 46 | <a href="../example/example3.cpp">example3.cpp</a>: | |
| 47 | ||
| 48 | <p> | |
| 49 | <pre> | |
| 50 | #include <boost/property_map/vector_property_map.hpp> | |
| 51 | #include <string> | |
| 52 | #include <iostream> | |
| 53 | ||
| 54 | int main() | |
| 55 | { | |
| 56 | boost::vector_property_map<std::string> m; | |
| 57 | ||
| 58 | // Assign string to '4'. | |
| 59 | m[4] = "e"; | |
| 60 | std::cout << "'" << m[4] << "'\n"; | |
| 61 | ||
| 62 | // Grab string from '10'. Since none is associated, | |
| 63 | // "" will be returned. | |
| 64 | std::cout << "'" << m[10] << "'\n"; | |
| 65 | } | |
| 66 | </pre> | |
| 67 | ||
| 68 | <H3>Where Defined</H3> | |
| 69 | ||
| 70 | <P> | |
| 71 | <a href="../../../boost/property_map/vector_property_map.hpp"><TT>boost/property_map/vector_property_map.hpp</TT></a> | |
| 72 | ||
| 73 | <p> | |
| 74 | <H3>Model Of</H3> | |
| 75 | ||
| 76 | <a href="./LvaluePropertyMap.html">Lvalue Property Map</a> | |
| 77 | ||
| 78 | <P> | |
| 79 | ||
| 80 | <H3>Template Parameters</H3> | |
| 81 | ||
| 82 | <P> | |
| 83 | ||
| 84 | <TABLE border> | |
| 85 | <TR> | |
| 86 | <th>Parameter</th><th>Description</th><th>Default</th> | |
| 87 | </tr> | |
| 88 | ||
| 89 | ||
| 90 | <TR> | |
| 91 | <TD><TT>T</TT></TD> | |
| 92 | <TD>The type of property value. Must be both <a | |
| 93 | href="http://www.sgi.com/tech/stl/Assignable.html">Assignable</a> | |
| 94 | and <a | |
| 95 | href="http://www.sgi.com/tech/stl/DefaultConstructible.html">DefaultConstructible</a>. | |
| 96 | </TD> | |
| 97 | <TD> </td> | |
| 98 | </tr> | |
| 99 | ||
| 100 | <TR> | |
| 101 | <TD><TT>IndexMap</TT></TD> <TD>Must be a model of <a | |
| 102 | href="./ReadablePropertyMap.html">Readable Property Map</a> | |
| 103 | and the value type must be convertible to | |
| 104 | <tt>std::vector<T>::size_type</tt>.</TD> | |
| 105 | <TD><a href="identity_property_map.html">identity_property_map</a></TD> | |
| 106 | </TR> | |
| 107 | ||
| 108 | </TABLE> | |
| 109 | <P> | |
| 110 | ||
| 111 | <H3>Members</H3> | |
| 112 | ||
| 113 | <P> | |
| 114 | In addition to the methods and functions required by <a | |
| 115 | href="./LvaluePropertyMap.html">Lvalue Property Map</a>, this | |
| 116 | class has the following members. | |
| 117 | ||
| 118 | <hr> | |
| 119 | ||
| 120 | <pre> | |
| 121 | vector_property_map(const IndexMap& index = IndexMap()) | |
| 122 | </pre> | |
| 123 | Constructor which takes an index map. | |
| 124 | ||
| 125 | <hr> | |
| 126 | ||
| 127 | <pre> | |
| 128 | vector_property_map(unsigned initial_size, const IndexMap& index = IndexMap()) | |
| 129 | </pre> | |
| 130 | This constructor version allows to specify maximum index of element | |
| 131 | that will be stored. Correct number will improve performance, but semantic | |
| 132 | is always the same. | |
| 133 | ||
| 134 | <hr> | |
| 135 | ||
| 136 | <pre> | |
| 137 | vector_property_map(const vector_property_map&) | |
| 138 | </pre> | |
| 139 | Copy constructor. The copy will share the same data and changes | |
| 140 | made to it will affect original property map. | |
| 141 | ||
| 142 | <hr> | |
| 143 | ||
| 144 | <pre> | |
| 145 | vector_property_map& operator=(const vector_property_map&) | |
| 146 | </pre> | |
| 147 | Assignment operator. The semantic is the same as for copy constructor. | |
| 148 | ||
| 149 | <hr> | |
| 150 | ||
| 151 | <pre> | |
| 152 | reference operator[](const key_type& v) const | |
| 153 | </pre> | |
| 154 | The operator bracket for property access. | |
| 155 | ||
| 156 | <hr> | |
| 157 | ||
| 158 | <pre> | |
| 159 | std::vector<T>::iterator storage_begin() | |
| 160 | std::vector<T>::iterator storage_end() | |
| 161 | std::vector<T>::const_iterator storage_begin() | |
| 162 | std::vector<T>::const_iterator storage_end() | |
| 163 | </pre> | |
| 164 | ||
| 165 | <p>This group of methods gives access to begin and end iterators of the | |
| 166 | underlying vector.</p> | |
| 167 | ||
| 168 | <p><b>Rationale:</b> The methods are handy, for example, when it's needed to | |
| 169 | specify a single value for all elements in a freshly created property map. The | |
| 170 | methods are not called simply "begin" and "end" since | |
| 171 | conceptually, <tt>vector_property_map</tt> is unbounded map, and has no end | |
| 172 | iterator. The direct access to the underlying method is not provided, since | |
| 173 | it would decrease encapsulation and make future performance tuning dangerous. | |
| 174 | ||
| 175 | <p><b>Acknolegements:</b> Matthias Troyer suggested adding those functions. | |
| 176 | ||
| 177 | <hr> | |
| 178 | ||
| 179 | <pre> | |
| 180 | void reserve(unsigned size) | |
| 181 | </pre> | |
| 182 | Reserve the space for storing elements with maximum index of 'size'. Unless | |
| 183 | element with greater index is accesses, all accesses will be take O(1) time. | |
| 184 | ||
| 185 | ||
| 186 | <hr> | |
| 187 | ||
| 188 | <h3>Non-Member functions</h3> | |
| 189 | ||
| 190 | <hr> | |
| 191 | ||
| 192 | <pre> | |
| 193 | template<typename T, typename IndexMap> | |
| 194 | vector_property_map<T, IndexMap> | |
| 195 | make_vector_property_map(IndexMap index) | |
| 196 | { | |
| 197 | return vector_property_map<T, IndexMap>(index); | |
| 198 | } | |
| 199 | </pre> | |
| 200 | A function for conveniently creating a vector property map. | |
| 201 | ||
| 202 | <br> | |
| 203 | <HR> | |
| 204 | <TABLE> | |
| 205 | <TR valign=top> | |
| 206 | <TD nowrap>Copyright © 2002</TD><TD> | |
| 207 | <a HREF="http://www.boost.org/people/jeremy_siek.htm">Jeremy Siek</a>, | |
| 208 | Indiana University (<A | |
| 209 | HREF="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</A>)<br> | |
| 210 | <A HREF="http://www.boost.org/people/liequan_lee.htm">Lie-Quan Lee</A>, Indiana University (<A HREF="mailto:llee1@osl.iu.edu">llee1@osl.iu.edu</A>)<br> | |
| 211 | <A HREF="http://www.osl.iu.edu/~lums">Andrew Lumsdaine</A>, | |
| 212 | Indiana University (<A | |
| 213 | HREF="mailto:lums@osl.iu.edu">lums@osl.iu.edu</A>) | |
| 214 | </TD></TR> | |
| 215 | <tr> | |
| 216 | <td nowrap>Copyright © 2003</td><td>Vladimir Prus</td> | |
| 217 | </tr> | |
| 218 | </TABLE> | |
| 219 | ||
| 220 | </BODY> | |
| 221 | </HTML> |