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1 | <html> |
2 | <head> | |
3 | <title>BOOST_PP_SEQ_FOLD_LEFT</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_SEQ_FOLD_LEFT</b> macro folds (or accumulates) the elements of | |
9 | a <i>seq</i> left-to-right. | |
10 | </div> | |
11 | <h4> | |
12 | Usage | |
13 | </h4> | |
14 | <div class="code"> | |
15 | <b>BOOST_PP_SEQ_FOLD_LEFT</b>(<i>op</i>, <i>state</i>, <i>seq</i>) | |
16 | </div> | |
17 | <h4> | |
18 | Arguments | |
19 | </h4> | |
20 | <dl> | |
21 | <dt>op</dt> | |
22 | <dd> | |
23 | A ternary operation of the form <i>op</i>(<i>s</i>, <i>state</i>, <i>elem</i>). | |
24 | This macro is called for each element in <i>seq</i>--each time returning a new <i>state</i>. | |
25 | This operation is expanded by <b>BOOST_PP_SEQ_FOLD_LEFT</b> with the next | |
26 | available fold step, the current <i>state</i>, and the current element. | |
27 | </dd> | |
28 | <dt>state</dt> | |
29 | <dd> | |
30 | The initial state of the fold. | |
31 | </dd> | |
32 | <dt>seq</dt> | |
33 | <dd> | |
34 | The <i>seq</i> to be folded. | |
35 | </dd> | |
36 | </dl> | |
37 | <h4> | |
38 | Remarks | |
39 | </h4> | |
40 | <div> | |
41 | For the <i>seq</i>, (<i>0</i>)(<i>1</i>)(<i>2</i>), this macro expands to: | |
42 | <div> | |
43 | <i>op</i>(<i>s</i>, <i>op</i>(<i>s</i>, <i>op</i>(<i>s</i>, <i>state</i>, <i>0</i>), | |
44 | <i>1</i>), <i>2</i>) | |
45 | </div> | |
46 | </div> | |
47 | <div> | |
48 | For maximum efficiency, <b>BOOST_PP_SEQ_FOLD_LEFT</b> can be reentered with <b>BOOST_PP_SEQ_FOLD_LEFT_<i>s</i></b>. | |
49 | </div> | |
50 | <h4> | |
51 | See Also | |
52 | </h4> | |
53 | <ul> | |
54 | <li> | |
55 | <a href="seq_fold_left_s.html">BOOST_PP_SEQ_FOLD_LEFT_<i>s</i></a></li> | |
56 | </ul> | |
57 | <h4> | |
58 | Requirements | |
59 | </h4> | |
60 | <div> | |
61 | <b>Header:</b> <a href="../headers/seq/fold_left.html"><boost/preprocessor/seq/fold_left.hpp></a> | |
62 | </div> | |
63 | <h4> | |
64 | Sample Code | |
65 | </h4> | |
66 | <div> | |
67 | <pre> | |
68 | #include <<a href="../headers/cat.html">boost/preprocessor/cat.hpp</a>> | |
69 | #include <<a href="../headers/seq/fold_left.html">boost/preprocessor/seq/fold_left.hpp</a>> | |
70 | ||
71 | #define SEQ (b)(o)(o)(s)(t) | |
72 | ||
73 | #define OP(s, state, x) <a href="cat.html">BOOST_PP_CAT</a>(state, x) | |
74 | ||
75 | <a href="seq_fold_left.html">BOOST_PP_SEQ_FOLD_LEFT</a>(OP, <a href="seq_head.html">BOOST_PP_SEQ_HEAD</a>(SEQ), <a href="seq_tail.html">BOOST_PP_SEQ_TAIL</a>(SEQ)) // expands to boost | |
76 | </pre> | |
77 | </div> | |
78 | <hr size="1"> | |
79 | <div style="margin-left: 0px;"> | |
80 |