| Brian Silverman | f27e085 | 2018-08-04 23:56:45 -0700 | [diff] [blame^] | 1 | <html> |
| 2 | <head> |
| 3 | <title>BOOST_PP_ENUM_z</title> |
| 4 | <link rel="stylesheet" type="text/css" href="../styles.css"> |
| 5 | </head> |
| 6 | <body> |
| 7 | <div style="margin-left: 0px;"> |
| 8 | The <b>BOOST_PP_ENUM_<i>z</i></b> macro represents a reentry into the <b>BOOST_PP_ENUM</b> repetition construct. |
| 9 | </div> |
| 10 | <h4>Usage</h4> |
| 11 | <div class="code"> |
| 12 | <b>BOOST_PP_ENUM_</b> ## <i>z</i>(<i>count</i>, <i>macro</i>, <i>data</i>) |
| 13 | </div> |
| 14 | <h4>Arguments</h4> |
| 15 | <dl> |
| 16 | <dt>z</dt> |
| 17 | <dd> |
| 18 | The next available <b>BOOST_PP_REPEAT</b> dimension. |
| 19 | </dd> |
| 20 | <dt>count</dt> |
| 21 | <dd> |
| 22 | The number of repetitious calls to <i>macro</i>. |
| 23 | Valid values range from <i>0</i> to <b>BOOST_PP_LIMIT_REPEAT</b>. |
| 24 | </dd> |
| 25 | <dt>macro</dt> |
| 26 | <dd> |
| 27 | A ternary operation of the form <i>macro</i>(<i>z</i>, <i>n</i>, <i>data</i>). |
| 28 | This macro is expanded by <b>BOOST_PP_ENUM</b> with the next available repetition depth, |
| 29 | the current repetition number, and the auxiliary <i>data</i> argument. |
| 30 | </dd> |
| 31 | <dt>data</dt> |
| 32 | <dd> |
| 33 | Auxiliary data passed to <i>macro</i>. |
| 34 | </dd> |
| 35 | </dl> |
| 36 | <h4>Remarks</h4> |
| 37 | <div> |
| 38 | This macro expands to the sequence: |
| 39 | <div> |
| 40 | <i>macro</i>(<i>z</i>, <i>0</i>, <i>data</i>), <i>macro</i>(<i>z</i>, <i>1</i>, <i>data</i>), ... <i>macro</i>(<i>z</i>, <i>count</i> - <i>1</i>, <i>data</i>) |
| 41 | </div> |
| 42 | </div> |
| 43 | <div> |
| 44 | At certain times, it may be necessary to perform the concatenation with <b>BOOST_PP_CAT</b> rather than the preprocessor token-pasting operator. |
| 45 | This happens when the <i>z</i> value is a macro invocation itself. |
| 46 | It needs a delay to allow it to expand. |
| 47 | The syntax in such a scenario becomes: |
| 48 | <div> |
| 49 | <b>BOOST_PP_CAT</b>(<b>BOOST_PP_ENUM_</b>, <i>z</i>)(<i>count</i>, <i>macro</i>, <i>data</i>) |
| 50 | </div> |
| 51 | </div> |
| 52 | <h4>See Also</h4> |
| 53 | <ul> |
| 54 | <li><a href="cat.html">BOOST_PP_CAT</a></li> |
| 55 | <li><a href="enum.html">BOOST_PP_ENUM</a></li> |
| 56 | <li><a href="limit_repeat.html">BOOST_PP_LIMIT_REPEAT</a></li> |
| 57 | </ul> |
| 58 | <h4>Requirements</h4> |
| 59 | <div> |
| 60 | <b>Header:</b> <a href="../headers/repetition/enum.html"><boost/preprocessor/repetition/enum.hpp></a> |
| 61 | </div> |
| 62 | <h4>Sample Code</h4> |
| 63 | <div><pre> |
| 64 | #include <<a href="../headers/arithmetic/inc.html">boost/preprocessor/arithmetic/inc.hpp</a>> |
| 65 | #include <<a href="../headers/repetition/enum.html">boost/preprocessor/repetition/enum.hpp</a>> |
| 66 | |
| 67 | #define TEXT(z, n, text) text |
| 68 | |
| 69 | #define TTP(z, n, _) \ |
| 70 | template< \ |
| 71 | <a href="enum_z.html">BOOST_PP_ENUM_</a> ## z(<a href="inc.html">BOOST_PP_INC</a>(n), TEXT, class) \ |
| 72 | > \ |
| 73 | class T ## n \ |
| 74 | /**/ |
| 75 | |
| 76 | <a href="enum.html">BOOST_PP_ENUM</a>(3, TTP, nil) |
| 77 | /* |
| 78 | expands to... |
| 79 | template<class> class T0, |
| 80 | template<class, class> class T1, |
| 81 | template<class, class, class> class T2 |
| 82 | */ |
| 83 | </pre></div> |
| 84 | <hr size="1"> |
| 85 | <div style="margin-left: 0px;"> |
| 86 | <i>© Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i> |
| 87 | </br><i>© Copyright Paul Mensonides 2002</i> |
| 88 | </div> |
| 89 | <div style="margin-left: 0px;"> |
| 90 | <p><small>Distributed under the Boost Software License, Version 1.0. (See |
| 91 | accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or |
| 92 | copy at <a href= |
| 93 | "http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p> |
| 94 | </div> |
| 95 | </body> |
| 96 | </html> |