[Boost-commit] svn:boost r65120 - trunk/boost/preprocessor/seq

Subject: [Boost-commit] svn:boost r65120 - trunk/boost/preprocessor/seq
From: steven_at_[hidden]
Date: 2010-08-29 22:26:03

Author: steven_watanabe
Date: 2010-08-29 22:26:02 EDT (Sun, 29 Aug 2010)
New Revision: 65120
URL: http://svn.boost.org/trac/boost/changeset/65120

Log:
Avoid evaluating BOOST_PP_SEQ_HEAD when it isn't needed.  Fixes #4465.
Text files modified: 
   trunk/boost/preprocessor/seq/cat.hpp |     9 +++++----                               
   1 files changed, 5 insertions(+), 4 deletions(-)

Modified: trunk/boost/preprocessor/seq/cat.hpp
==============================================================================
--- trunk/boost/preprocessor/seq/cat.hpp	(original)
+++ trunk/boost/preprocessor/seq/cat.hpp	2010-08-29 22:26:02 EDT (Sun, 29 Aug 2010)
@@ -26,7 +26,7 @@
     BOOST_PP_IF( \
         BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq)), \
         BOOST_PP_SEQ_CAT_I, \
-        BOOST_PP_SEQ_HEAD(seq) BOOST_PP_TUPLE_EAT_1 \
+        BOOST_PP_SEQ_HEAD \
     )(seq) \
     /**/
 # define BOOST_PP_SEQ_CAT_I(seq) BOOST_PP_SEQ_FOLD_LEFT(BOOST_PP_SEQ_CAT_O, BOOST_PP_SEQ_HEAD(seq), BOOST_PP_SEQ_TAIL(seq))
@@ -39,10 +39,11 @@
 # define BOOST_PP_SEQ_CAT_S(s, seq) \
     BOOST_PP_IF( \
         BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq)), \
-        BOOST_PP_SEQ_CAT_S_I, \
-        BOOST_PP_SEQ_HEAD(seq) BOOST_PP_TUPLE_EAT_2 \
+        BOOST_PP_SEQ_CAT_S_I_A, \
+        BOOST_PP_SEQ_CAT_S_I_B \
     )(s, seq) \
     /**/
-# define BOOST_PP_SEQ_CAT_S_I(s, seq) BOOST_PP_SEQ_FOLD_LEFT_ ## s(BOOST_PP_SEQ_CAT_O, BOOST_PP_SEQ_HEAD(seq), BOOST_PP_SEQ_TAIL(seq))
+# define BOOST_PP_SEQ_CAT_S_I_A(s, seq) BOOST_PP_SEQ_FOLD_LEFT_ ## s(BOOST_PP_SEQ_CAT_O, BOOST_PP_SEQ_HEAD(seq), BOOST_PP_SEQ_TAIL(seq))
+# define BOOST_PP_SEQ_CAT_S_I_B(s, seq) BOOST_PP_SEQ_HEAD(seq)
 #
 # endif