feedc0de/boost_preprocessor
1
0
Fork 0
forked from boostorg/preprocessor
Code Pull Requests Activity

Automatic recursion

Browse Source 
[SVN r14100]
This commit is contained in:
Vesa Karvonen
2002-06-07 13:04:18 +00:00
parent a18d5f79fc
commit 9f9048e805
82 changed files with 971 additions and 869 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
include/boost/preprocessor/while.hpp
View File

@ -57,13 +57,21 @@ BOOST_PP_WHILE(PRED,OP,(0,3))
C++ preprocessor.</li>
</ul>
<h3>Automatic recursion?</h3>
<p>BOOST_PP_WHILE() currently does not implement automatic recursion. The reason
for this is that it would lead to very poor performance. The automatic recursion
technique takes O(N) steps just to find out that the Nth recursion should be used.
This would dramatically effect the time complexity of macros using automatic
recursion.</p>
<h3>Note</h3>
<ul>
<li>The value of the D parameter may exceed BOOST_PP_LIMIT_MAG.</li>
<li>Using BOOST_PP_WHILE() is a bit tricky. This is due to the C++
preprocessor limitations. It is recommended to take a look at the
implementations of the various PREPROCESSOR library primitives such as
BOOST_PP_ADD() for additional examples.</li>
implementations of the various PREPROCESSOR library primitives
such as BOOST_PP_ADD() for additional examples.</li>
</ul>
<h3>Example</h3>
@ -334,6 +342,6 @@ BOOST_PP_WHILE(PRED,OP,(0,3))
#define BOOST_PP_WHILE255(P,O,S) BOOST_PP_WHILE_C(P(257,S),256,S)(P,O,O(257,S))
#define BOOST_PP_WHILE256(P,O,S) BOOST_PP_WHILE_C(P(258,S),257,S)(P,O,O(258,S))
#define BOOST_PP_WHILE257(P,O,S) BOOST_PP_WHILE_C(P(259,S),258,S)(P,O,O(259,S))
#define BOOST_PP_WHILE258(P,O,S) RECURSION DEPTH EXCEEDED!
#define BOOST_PP_WHILE259(P,O,S) RECURSION DEPTH EXCEEDED!
#define BOOST_PP_WHILE258(P,O,S) (RECURSION DEPTH EXCEEDED!)
#define BOOST_PP_WHILE259(P,O,S) (RECURSION DEPTH EXCEEDED!)
#endif