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| <font size="6" face="Verdana, Arial, Helvetica, sans-serif"><b>Tuples</b></font> |
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| <p> |
| Tuples are the most basic infrastructure that the framework builds with. This sub-library provides a mechanism to bundle objects of arbitrary types in a single structure. Tuples hold heterogeneous types up to a predefined maximum.</p> |
| <p> |
| Only the most basic functionality needed are provided. This is a straight-forward and extremely lean and mean library. Unlike other recursive list-like tuple implementations, this tuple library implementation uses simple structs similar to std::pair with specialization for 0 to N tuple elements, where N is a predefined constant. There are only 4 tuple operations to learn:</p> |
| <p> |
| 1) Construction</p> |
| <p> |
| Here are examples on how to construct tuples:</p> |
| <code><pre> |
| <span class=keyword>typedef </span><span class=identifier>tuple</span><span class=special><</span><span class=keyword>int</span><span class=special>, </span><span class=keyword>char</span><span class=special>> </span><span class=identifier>t1_t</span><span class=special>; |
| </span><span class=keyword>typedef </span><span class=identifier>tuple</span><span class=special><</span><span class=keyword>int</span><span class=special>, </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span><span class=special>, </span><span class=keyword>double</span><span class=special>> </span><span class=identifier>t2_t</span><span class=special>; |
| |
| // </span><span class=keyword>this </span><span class=identifier>tuple </span><span class=identifier>has </span><span class=identifier>an </span><span class=keyword>int </span><span class=keyword>and </span><span class=keyword>char </span><span class=identifier>members |
| </span><span class=identifier>t1_t </span><span class=identifier>t1</span><span class=special>(</span><span class=number>3</span><span class=special>, </span><span class=literal>'c'</span><span class=special>); |
| |
| // </span><span class=keyword>this </span><span class=identifier>tuple </span><span class=identifier>has </span><span class=identifier>an </span><span class=keyword>int</span><span class=special>, </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string </span><span class=keyword>and </span><span class=keyword>double </span><span class=identifier>members |
| </span><span class=identifier>t2_t </span><span class=identifier>t2</span><span class=special>(</span><span class=number>3</span><span class=special>, </span><span class=string>"hello"</span><span class=special>, </span><span class=number>3.14</span><span class=special>); |
| </span></pre></code> |
| <p> |
| 2) Member access</p> |
| <p> |
| A member in a tuple can be accessed using the tuple's operator by specifying the Nth tuple_index. Here are some examples:</p> |
| <code><pre> |
| <span class=identifier>tuple_index</span><span class=special><</span><span class=number>0</span><span class=special>> </span><span class=identifier>ix0</span><span class=special>; // </span><span class=number>0</span><span class=identifier>th </span><span class=identifier>index </span><span class=special>== </span><span class=number>1</span><span class=identifier>st </span><span class=identifier>item |
| </span><span class=identifier>tuple_index</span><span class=special><</span><span class=number>1</span><span class=special>> </span><span class=identifier>ix1</span><span class=special>; // </span><span class=number>1</span><span class=identifier>st </span><span class=identifier>index </span><span class=special>== </span><span class=number>2</span><span class=identifier>nd </span><span class=identifier>item |
| </span><span class=identifier>tuple_index</span><span class=special><</span><span class=number>2</span><span class=special>> </span><span class=identifier>ix2</span><span class=special>; // </span><span class=number>2</span><span class=identifier>nd </span><span class=identifier>index </span><span class=special>== </span><span class=number>3</span><span class=identifier>rd </span><span class=identifier>item |
| |
| </span><span class=comment>// Note zero based indexing. 0 = 1st item, 1 = 2nd item |
| |
| </span><span class=identifier>t1</span><span class=special>[</span><span class=identifier>ix0</span><span class=special>] = </span><span class=number>33</span><span class=special>; // </span><span class=identifier>sets </span><span class=identifier>the </span><span class=keyword>int </span><span class=identifier>member </span><span class=identifier>of </span><span class=identifier>the </span><span class=identifier>tuple </span><span class=identifier>t1 |
| </span><span class=identifier>t2</span><span class=special>[</span><span class=identifier>ix2</span><span class=special>] = </span><span class=number>6e6</span><span class=special>; // </span><span class=identifier>sets </span><span class=identifier>the </span><span class=keyword>double </span><span class=identifier>member </span><span class=identifier>of </span><span class=identifier>the </span><span class=identifier>tuple </span><span class=identifier>t2 |
| </span><span class=identifier>t1</span><span class=special>[</span><span class=identifier>ix1</span><span class=special>] = </span><span class=literal>'a'</span><span class=special>; // </span><span class=identifier>sets </span><span class=identifier>the </span><span class=keyword>char </span><span class=identifier>member </span><span class=identifier>of </span><span class=identifier>the </span><span class=identifier>tuple </span><span class=identifier>t1 |
| </span></pre></code> |
| <p> |
| Access to out of bound indexes returns a nil_t value.</p> |
| <p> |
| 3) Member type inquiry</p> |
| <p> |
| The type of an individual member can be queried. Example:</p> |
| <code><pre> |
| <span class=identifier>tuple_element</span><span class=special><</span><span class=number>1</span><span class=special>, </span><span class=identifier>t2_t</span><span class=special>>::</span><span class=identifier>type |
| </span></pre></code> |
| <p> |
| Refers to the type of the second member (again note zero based indexing, hence 0 = 1st item, 1 = 2nd item) of the tuple.</p> |
| <p> |
| Access to out of bound indexes returns a nil_t type.</p> |
| <p> |
| 4) Tuple length</p> |
| <p> |
| The number of elements in a tuple can be queried. Example:</p> |
| <code><pre> |
| <span class=keyword>int </span><span class=identifier>n </span><span class=special>= </span><span class=identifier>t1</span><span class=special>.</span><span class=identifier>length</span><span class=special>; |
| </span></pre></code> |
| <p> |
| gets the number of elements in tuple t1.</p> |
| <p> |
| length is a static constant. Thus, TupleT::length also works. Example:</p> |
| <code><pre> |
| <span class=keyword>int </span><span class=identifier>n </span><span class=special>= </span><span class=identifier>t1_t</span><span class=special>::</span><span class=identifier>length</span><span class=special>; |
| </span></pre></code> |
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| <p class="copyright">Copyright © 2001-2002 Joel de Guzman<br> |
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| <font size="2">Use, modification and distribution is subject to the Boost Software |
| License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
| http://www.boost.org/LICENSE_1_0.txt) </font> </p> |
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