Re: [Boost-users] BOOST_PP_ERROR(0x0003, BOOST_PP_REPEAT_OVERFLOW) with multiply nested BOOST_PP_REPEATS

Subject: Re: [Boost-users] BOOST_PP_ERROR(0x0003, BOOST_PP_REPEAT_OVERFLOW) with multiply nested BOOST_PP_REPEATS
From: pfultz2 (pfultz2_at_[hidden])
Date: 2014-09-26 15:38:07

> Am I hitting a nesting depth limit or something else? Is there a way
> around this? Ideally I want to write a decl5 macro and have successfully
> written a decl1, decl2 and decl3 so far 

Ok, the best way seems to generate a sequence of your data:

    #define GEN_SEQS_EACH_INNER(z, n, data) (n)
    #define GEN_SEQS_EACH(s, data, n) BOOST_PP_REPEAT(n,
GEN_SEQS_EACH_INNER, ~)
    #define GEN_SEQS(dims) BOOST_PP_SEQ_TRANSFORM(GEN_SEQS_EACH, ~, dims) 

This would take a sequence of each of the max values and generates a
sequence of
sequences.  So this:

    GEN_SEQS((2)(3))

Expands to:

    ( (0)(1) ) ( (0)(1)(2) )

Then you can use `BOOST_PP_SEQ_FOR_EACH_PRODUCT` to do the cross product of
each
of the sequences concated together:

    #define DECL_EACH(r, product) BOOST_PP_SEQ_CAT((int x)product);
    #define DECL(dims) BOOST_PP_SEQ_FOR_EACH_PRODUCT(DECL_EACH,
GEN_SEQS(dims))

However, you may want underscores place between the number so you can use an
intersperse macro like this:

    #define INTERSPERSE_EACH(r, data, i, elem) BOOST_PP_IF(i, (data)(elem),
(elem))
    #define INTERSPERSE(seq, x) BOOST_PP_SEQ_FOR_EACH_I(INTERSPERSE_EACH, x,
seq)  

    #define DECL_EACH(r, product) BOOST_PP_SEQ_CAT(INTERSPERSE((int
x)product, _));
    #define DECL(dims) BOOST_PP_SEQ_FOR_EACH_PRODUCT(DECL_EACH,
GEN_SEQS(dims))

And then you can call it like this:

    DECL((2)(2)(2)(2)(2)) 

Which will generate this:

    int x_0_0_0_0_0; 
    int x_0_0_0_0_1; 
    int x_0_0_0_1_0; 
    int x_0_0_0_1_1; 
    int x_0_0_1_0_0; 
    int x_0_0_1_0_1; 
    int x_0_0_1_1_0; 
    int x_0_0_1_1_1; 
    int x_0_1_0_0_0; 
    int x_0_1_0_0_1; 
    int x_0_1_0_1_0; 
    int x_0_1_0_1_1; 
    int x_0_1_1_0_0; 
    int x_0_1_1_0_1; 
    int x_0_1_1_1_0; 
    int x_0_1_1_1_1; 
    int x_1_0_0_0_0; 
    int x_1_0_0_0_1; 
    int x_1_0_0_1_0; 
    int x_1_0_0_1_1; 
    int x_1_0_1_0_0; 
    int x_1_0_1_0_1; 
    int x_1_0_1_1_0; 
    int x_1_0_1_1_1; 
    int x_1_1_0_0_0; 
    int x_1_1_0_0_1; 
    int x_1_1_0_1_0; 
    int x_1_1_0_1_1; 
    int x_1_1_1_0_0; 
    int x_1_1_1_0_1; 
    int x_1_1_1_1_0; 
    int x_1_1_1_1_1;

Paul Fultz II

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