On 02/09/10 16:12, Hicham Mouline wrote:
-----Original Message----- From: boost-users-bounces@lists.boost.org [mailto:boost-users- bounces@lists.boost.org] On Behalf Of Larry Evans Sent: 09 February 2010 18:11 To: boost-users@lists.boost.org Subject: Re: [Boost-users] generate structs with all combinations of members from a given struct [snip] I'd be interesting in seeing this code when you're done with it. I'd like to try using:
composite_tagged_seq < all_of_aligned , field_I1 , field_I2 ... , field_In
where field_I1...field_In is some subset of S::field1,...field5 and composite_tagged is from composite_tagged_seq.zip in the boost vault:
http://www.boostpro.com/vault/index.php?&directory=Data Structures
Then compare the compile-time and run-time performance. I've no doubt it would be slower than the PP version, but I'm just curious about how much.
The attached shows a test driver using composite_tagged_seq. The composite_tagged_seq used is a bit different than the one in vault. The one used modified layout to handle the case where the type was void. In this case, not project template function for a void member is produced. The fields_subsets_t time contains 32 members, 1 for each subset of 5 fields. However, as shown in the driver, you have to access the field with: field_subset_struct.project<FieldNum>(); The compile time was slow (maybe 10-20 secs) on my machine, but that sounds a lot faster than you PP method. If you think you can use this, I'll upload the code to the sandbox. -regards, Larry BTW, the output is: /home/evansl/prog_dev/boost-svn/ro/trunk/sandbox-local/build/gcc4_4v/sandbox/variadic_templates/libs/mpl/sandbox/composite_tagged~field_subsets~cross_product_pack.exe absent_fields_seq= package< absent_tag, type=1> package< absent_tag, type=2> package< absent_tag, type=3> package< absent_tag, type=4> package< absent_tag, type=5> size<select_fields_seq>::value=32 select_fields_seq= { absent , absent , absent , absent , absent } { absent , absent , absent , absent , ( type= 5) } { absent , absent , absent , ( type= 4) , absent } { absent , absent , absent , ( type= 4) , ( type= 5) } { absent , absent , ( type= 3) , absent , absent } { absent , absent , ( type= 3) , absent , ( type= 5) } { absent , absent , ( type= 3) , ( type= 4) , absent } { absent , absent , ( type= 3) , ( type= 4) , ( type= 5) } { absent , ( type= 2) , absent , absent , absent } { absent , ( type= 2) , absent , absent , ( type= 5) } { absent , ( type= 2) , absent , ( type= 4) , absent } { absent , ( type= 2) , absent , ( type= 4) , ( type= 5) } { absent , ( type= 2) , ( type= 3) , absent , absent } { absent , ( type= 2) , ( type= 3) , absent , ( type= 5) } { absent , ( type= 2) , ( type= 3) , ( type= 4) , absent } { absent , ( type= 2) , ( type= 3) , ( type= 4) , ( type= 5) } { ( type= 1) , absent , absent , absent , absent } { ( type= 1) , absent , absent , absent , ( type= 5) } { ( type= 1) , absent , absent , ( type= 4) , absent } { ( type= 1) , absent , absent , ( type= 4) , ( type= 5) } { ( type= 1) , absent , ( type= 3) , absent , absent } { ( type= 1) , absent , ( type= 3) , absent , ( type= 5) } { ( type= 1) , absent , ( type= 3) , ( type= 4) , absent } { ( type= 1) , absent , ( type= 3) , ( type= 4) , ( type= 5) } { ( type= 1) , ( type= 2) , absent , absent , absent } { ( type= 1) , ( type= 2) , absent , absent , ( type= 5) } { ( type= 1) , ( type= 2) , absent , ( type= 4) , absent } { ( type= 1) , ( type= 2) , absent , ( type= 4) , ( type= 5) } { ( type= 1) , ( type= 2) , ( type= 3) , absent , absent } { ( type= 1) , ( type= 2) , ( type= 3) , absent , ( type= 5) } { ( type= 1) , ( type= 2) , ( type= 3) , ( type= 4) , absent } { ( type= 1) , ( type= 2) , ( type= 3) , ( type= 4) , ( type= 5) } no_f1_v.F_2=field_type=2 no_f1_v.F_3=field_type=3 Compilation finished at Sun Feb 14 13:59:27