Defines | |
| #define | BOOST_PP_FOR(X, C, F, I) |
| Repeats I(R,X) and iterates F(R,X) while C(R,X) is true. More... | |
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Repeats I(R,X) and iterates F(R,X) while C(R,X) is true. In other words, expands to the sequence:
The length of the sequence is determined by C(R,X).
LegendX is the current state of iteration. The state is usually a tuple. C is the condition for iteration. It must expand to a decimal integer literal. F is the iterated macro. Note that if the state is a tuple, then F(R,X) usually expands to a tuple of the same number of elements. I is the state instantiation macro. R is the recursion depth and should only be used as a parameter to other macros implemented using BOOST_PP_FOR() or for invoking BOOST_PP_FOR#R() directly. For each macro implemented using BOOST_PP_FOR(), there is a version of the macro, distinguished by the _R suffix, that accepts an additional recursion depth as the first parameter. This technique is necessary to avoid recursively expanding the same macro again, which is not permitted by the C++ preprocessor.
BOOST_PP_REPEAT() vs BOOST_PP_FOR()BOOST_PP_FOR() is a generalization of BOOST_PP_REPEAT(). This means that BOOST_PP_REPEAT() can be implemented using BOOST_PP_FOR(). Unfortunately, BOOST_PP_FOR() is slower than BOOST_PP_REPEAT(). In addition, BOOST_PP_REPEAT() was introduced earlier, is generally easier to use, and is still quite useful on its own.
2D and 3D repetitionBOOST_PP_FOR() can be used for multidimensional repetition simply by invoking BOOST_PP_FOR#R() directly. |
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