preprocessor/doc/reference/repeat_8hpp.html

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<hr><h1>repeat.hpp File Reference</h1><table border=0 cellpadding=0 cellspacing=0>
<tr><td colspan=2><br><h2>Defines</h2></td></tr>
<tr><td nowrap align=right valign=top>#define&nbsp;</td><td valign=bottom><a class="el" href="repeat_8hpp.html#a0">BOOST_PP_REPEAT</a>(N, M, P)</td></tr>
<tr><td>&nbsp;</td><td><font size=-1><em>Repeats the macro M(I,P) for I = 0 to N-1.</em> <a href="#a0">More...</a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top>#define&nbsp;</td><td valign=bottom><a class="el" href="repeat_8hpp.html#a1">BOOST_PREPROCESSOR_REPEAT</a>(N, M, P)</td></tr>
<tr><td>&nbsp;</td><td><font size=-1><em>Obsolete. Use <a class="el" href="repeat_8hpp.html#a0">BOOST_PP_REPEAT</a>().</em> <a href="#a1">More...</a><em></em></font><br><br></td></tr>
</table>
<hr><a name="_details"></a><h2>Detailed Description</h2>
 <a href="../../../../boost/preprocessor/repeat.hpp">Click here to see the header.</a>
<p>
<hr><h2>Define Documentation</h2>
<a name="a0" doxytag="repeat.hpp::BOOST_PP_REPEAT"></a><p>
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          <td class="md" nowrap valign="top"> #define BOOST_PP_REPEAT</td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top">N,         <tr>
          <td></td>
          <td></td>
          <td class="md" nowrap>M,         <tr>
          <td></td>
          <td></td>
          <td class="md" nowrap>P&nbsp;</td>
          <td class="mdname1" valign="top" nowrap>&nbsp;          </td>
          <td class="md" valign="top">)&nbsp;</td>
          <td class="md" nowrap>
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      &nbsp;
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<p>
Repeats the macro M(I,P) for I = 0 to N-1.
<p>
In other words, expands to the sequence:
<p>
<pre><div class="fragment"><pre>
  M(0,P) M(1,P) ... M(N-1,P)
</pre></div></pre>
<p>
See BOOST_PP_LIMIT_MAG.
<p>
<h3>2D and 3D repetition</h3>

<p>
2D and 3D repetition are supported with the <a class="el" href="repeat__2nd_8hpp.html#a0">BOOST_PP_REPEAT_2ND</a>() and <a class="el" href="repeat__3rd_8hpp.html#a0">BOOST_PP_REPEAT_3RD</a>() macros. For example,
<p>
<pre><div class="fragment"><pre>
  // A generalized macro for generating 2D arrays
  #define ARRAY_2D(W,H,M,P)\
    BOOST_PP_REPEAT_2ND\
    ( H\
    , ARRAY_2D_ROW\
    , (W,H,M,P)\
    )
  #define ARRAY_2D_ROW(Y,WHMP)\
    BOOST_PP_EXPAND\
    ( BOOST_PP_REPEAT\
      ( BOOST_PP_TUPLE_ELEM(4,0,WHMP)\
      , ARRAY_2D_ELEM\
      , (Y,BOOST_PP_TUPLE4_ENUM WHMP)\
      )\
    )
  #define BOOST_PP_TUPLE4_ENUM(A,B,C,D) A,B,C,D
  #define ARRAY_2D_ELEM(X,YWHMP)\
    BOOST_PP_TUPLE_ELEM(5,3,YWHMP)\
    BOOST_PP_EXPAND\
    ( ( X\
      , BOOST_PP_TUPLE_ELEM(5,0,YWHMP)\
      , BOOST_PP_TUPLE_ELEM(5,1,YWHMP)\
      , BOOST_PP_TUPLE_ELEM(5,2,YWHMP)\
      , BOOST_PP_TUPLE_ELEM(5,4,YWHMP)\
      )\
    )

  // Here we use the above macro to generate something
  #define ELEM(X,Y,W,H,E) BOOST_PP_COMMA_IF(BOOST_PP_OR(X,Y)) E##_##X##_##Y

  ARRAY_2D(3,4,ELEM,elem)
</pre></div></pre>
<p>
expands to:
<p>
<pre><div class="fragment"><pre>
  elem_0_0, elem_1_0, elem_2_0,
  elem_0_1, elem_1_1, elem_2_1,
  elem_0_2, elem_1_2, elem_2_2,
  elem_0_3, elem_1_3, elem_2_3
</pre></div></pre>
<p>
Since recursive expansion of macros is not allowed by the C++ preprocessor, replacing the BOOST_PP_REPEAT_2ND above with BOOST_PP_REPEAT, would not produce the above expansion.
<p>
See <a class="el" href="for_8hpp.html#a0">BOOST_PP_FOR</a>().     </td>
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<a name="a1" doxytag="repeat.hpp::BOOST_PREPROCESSOR_REPEAT"></a><p>
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          <td class="md" nowrap valign="top"> #define BOOST_PREPROCESSOR_REPEAT</td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top">N,         <tr>
          <td></td>
          <td></td>
          <td class="md" nowrap>M,         <tr>
          <td></td>
          <td></td>
          <td class="md" nowrap>P&nbsp;</td>
          <td class="mdname1" valign="top" nowrap>&nbsp;          </td>
          <td class="md" valign="top">)&nbsp;</td>
          <td class="md" nowrap>
      </table>
    </td>
  </tr>
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    <td>
      &nbsp;
    </td>
    <td>

<p>
Obsolete. Use <a class="el" href="repeat_8hpp.html#a0">BOOST_PP_REPEAT</a>().
<p>
    </td>
  </tr>
</table>
<hr>
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