[Boost-commit] svn:boost r84999 - trunk/boost/regex/v4

Subject: [Boost-commit] svn:boost r84999 - trunk/boost/regex/v4
From: john_at_[hidden]
Date: 2013-07-10 12:10:44

Author: johnmaddock
Date: 2013-07-10 12:10:44 EDT (Wed, 10 Jul 2013)
New Revision: 84999
URL: http://svn.boost.org/trac/boost/changeset/84999

Log:
Optimise iterator advances for slow (non-random access) iterators.

Text files modified: 
   trunk/boost/regex/v4/perl_matcher_non_recursive.hpp |    24 +++++++++++++++++++++---                
   trunk/boost/regex/v4/perl_matcher_recursive.hpp     |    16 ++++++++++++++--                        
   2 files changed, 35 insertions(+), 5 deletions(-)

Modified: trunk/boost/regex/v4/perl_matcher_non_recursive.hpp
==============================================================================
--- trunk/boost/regex/v4/perl_matcher_non_recursive.hpp	Wed Jul 10 12:08:57 2013	(r84998)
+++ trunk/boost/regex/v4/perl_matcher_non_recursive.hpp	2013-07-10 12:10:44 EDT (Wed, 10 Jul 2013)	(r84999)
@@ -703,7 +703,13 @@
    if(::boost::is_random_access_iterator<BidiIterator>::value)
    {
       BidiIterator end = position;
-      std::advance(end, (std::min)((std::size_t)::boost::re_detail::distance(position, last), desired));
+      // Move end forward by "desired", preferably without using distance or advance if we can
+      // as these can be slow for some iterator types.
+      std::size_t len = (desired == (std::numeric_limits<std::size_t>::max)()) ? 0u : ::boost::re_detail::distance(position, last);
+      if(desired >= len)
+         end = last;
+      else
+         std::advance(end, desired);
       BidiIterator origin(position);
       while((position != end) && (traits_inst.translate(*position, icase) == what))
       {
@@ -771,7 +777,13 @@
    if(::boost::is_random_access_iterator<BidiIterator>::value)
    {
       BidiIterator end = position;
-      std::advance(end, (std::min)((std::size_t)::boost::re_detail::distance(position, last), desired));
+      // Move end forward by "desired", preferably without using distance or advance if we can
+      // as these can be slow for some iterator types.
+      std::size_t len = (desired == (std::numeric_limits<std::size_t>::max)()) ? 0u : ::boost::re_detail::distance(position, last);
+      if(desired >= len)
+         end = last;
+      else
+         std::advance(end, desired);
       BidiIterator origin(position);
       while((position != end) && map[static_cast<unsigned char>(traits_inst.translate(*position, icase))])
       {
@@ -840,7 +852,13 @@
    if(::boost::is_random_access_iterator<BidiIterator>::value)
    {
       BidiIterator end = position;
-      std::advance(end, (std::min)((std::size_t)::boost::re_detail::distance(position, last), desired));
+      // Move end forward by "desired", preferably without using distance or advance if we can
+      // as these can be slow for some iterator types.
+      std::size_t len = (desired == (std::numeric_limits<std::size_t>::max)()) ? 0u : ::boost::re_detail::distance(position, last);
+      if(desired >= len)
+         end = last;
+      else
+         std::advance(end, desired);
       BidiIterator origin(position);
       while((position != end) && (position != re_is_set_member(position, last, set, re.get_data(), icase)))
       {

Modified: trunk/boost/regex/v4/perl_matcher_recursive.hpp
==============================================================================
--- trunk/boost/regex/v4/perl_matcher_recursive.hpp	Wed Jul 10 12:08:57 2013	(r84998)
+++ trunk/boost/regex/v4/perl_matcher_recursive.hpp	2013-07-10 12:10:44 EDT (Wed, 10 Jul 2013)	(r84999)
@@ -641,7 +641,13 @@
    if(::boost::is_random_access_iterator<BidiIterator>::value)
    {
       BidiIterator end = position;
-      std::advance(end, (std::min)((std::size_t)::boost::re_detail::distance(position, last), desired));
+      // Move end forward by "desired", preferably without using distance or advance if we can
+      // as these can be slow for some iterator types.
+      std::size_t len = (desired == (std::numeric_limits<std::size_t>::max)()) ? 0u : ::boost::re_detail::distance(position, last);
+      if(desired >= len)
+         end = last;
+      else
+         std::advance(end, desired);
       BidiIterator origin(position);
       while((position != end) && map[static_cast<unsigned char>(traits_inst.translate(*position, icase))])
       {
@@ -731,7 +737,13 @@
    if(::boost::is_random_access_iterator<BidiIterator>::value)
    {
       BidiIterator end = position;
-      std::advance(end, (std::min)((std::size_t)::boost::re_detail::distance(position, last), desired));
+      // Move end forward by "desired", preferably without using distance or advance if we can
+      // as these can be slow for some iterator types.
+      std::size_t len = (desired == (std::numeric_limits<std::size_t>::max)()) ? 0u : ::boost::re_detail::distance(position, last);
+      if(desired >= len)
+         end = last;
+      else
+         std::advance(end, desired);
       BidiIterator origin(position);
       while((position != end) && (position != re_is_set_member(position, last, set, re.get_data(), icase)))
       {