The BOOST_PP_SEQ_FILTER macro filters a seq according to a supplied criterion.

#### Usage

BOOST_PP_SEQ_FILTER(pred, data, seq)

#### Arguments

pred
  A ternary predicate of the form pred(s, data, elem). This predicate is expanded by BOOST_PP_SEQ_FILTER for each element in seq with the next available BOOST_PP_SEQ_FOLD_LEFT fold step, the auxiliary data, and the current element in seq. This macro must return a integral value in the range of 0 to BOOST_PP_LIMIT_MAG. If this predicate expands to non-zero for a certain element, that element is included in the resulting seq.
data
  Auxiliary data passed to pred.
seq
  The seq to be filtered.

#### Remarks

This macro expands pred for each element in seq. It builds a new seq out of each element for which pred returns non-zero.
For maximum efficiency, use BOOST_PP_SEQ_FILTER_S.

#### See Also

- BOOST_PP_LIMIT_MAG
- BOOST_PP_SEQ_FILTER_S

#### Requirements

Header: <boost/preprocessor/seq/filter.hpp>

#### Sample Code

    #include <boost/preprocessor/comparison/less_equal.hpp>
    #include <boost/preprocessor/seq/filter.hpp>

    #define SEQ (1)(3)(2)(5)

    #define PRED(s, data, elem) BOOST_PP_LESS_EQUAL(elem, data)

    BOOST_PP_SEQ_FILTER(PRED, 3, SEQ)
       // expands to (1)(3)(2)