#include <boost/preprocessor/list/fold_left.hpp>

#define BOOST_PP_LIST_FOLD_LEFT(F,P,L)

Iterates F(D,P,X) for each element X of the list L (from the left or the start of the list).

In other words, expands to:

  F
  ( D
  , ... F(D, F(D,P,BOOST_PP_LIST_AT(L,0)), BOOST_PP_LIST_AT(L,1)) ...
  , BOOST_PP_LIST_AT(L,BOOST_PP_DEC(BOOST_PP_LIST_SIZE(L))
  )

For example,

  #define TEST(D,P,X) BOOST_PP_CAT(P,X)
  BOOST_PP_LIST_FOLD_LEFT(TEST,_,BOOST_PP_TUPLE_TO_LIST(3,(A,B,C)))

expands to:

  _ABC

Note

• Folding, or accumulation, is a very general pattern of computation. Most list operations can be implemented in terms of folding.

See

• BOOST_PP_LIST_FOLD_RIGHT()

Uses

• BOOST_PP_WHILE() (see for explanation of the D parameter)

Test

• list_test.cpp

#define BOOST_PP_LIST_FOLD_LEFT_D(D,F,P,L)

Can be used inside BOOST_PP_WHILE().

Revised

© Copyright Housemarque Oy 2002

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