[Boost-bugs] [Boost C++ Libraries] #4523: fix for #4501

Subject: [Boost-bugs] [Boost C++ Libraries] #4523: fix for #4501
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-08-08 14:24:46

#4523: fix for #4501
----------------------------+-----------------------------------------------
 Reporter:  ookami1@…       |       Owner:  no-maintainer
     Type:  Patches         |      Status:  new          
Milestone:  Boost 1.44.0    |   Component:  preprocessor 
  Version:  Boost 1.44.0    |    Severity:  Problem      
 Keywords:                  |  
----------------------------+-----------------------------------------------
 The following three patches fix issue #4501.
 detail_auto_rec.patch and repetition_for.patch extend the maximum loop
 count in BOOST_PP_FOR from 255 to 256.
 seq_for_each.patch modifies the state of BOOST_PP_SEQ_FOR_EACH in such a
 way that the calculation of the sequence size is done just once now, and
 its cached value is used for loop control instead. This cuts down on the
 evaluation cost especially for long sequences.
 Small sequences benefit from an early-out execution path, in the frequent
 case, when no outer for loop blocks iteration slots.

 I manually enabled configuration flags 0x0004, 0x0010, 0x0020 (MSVC, BCC,
 EDG resp.) to enforce the execution of compiler specific code under GCC,
 and they compiled and executed fine, but that is only a poor replacement
 for the native compilers, of course. The code for MWCC and DMG does not
 conform to C90 or later, so GNU gcc could not be fooled to emulate them.

 cheers

 Wolf Lammen


 complexity:


 BOOST_CONFIG_FLAGS 0x0001 (strict)



 {{{
 boost 1.43.0:                     patched:

   0 elements   345 replacements      67 replacements
   1            388                  105
   2            431                  142
   4            520                  216
   8            710                  364
  16           1138                  660
  32           2186                 1252
  64           5050                 2436
 128          13850                 4804
 255 elements 43441 replacements    9503
 256          failure               9540


 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4523>
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