Amebis/wxWidgets
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

optimize Replace() to use a linear algorithm (closes #9135)

Browse Source 
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@59420 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin
2009-03-07 16:07:58 +00:00
parent 101b242093
commit 072682ce44
4 changed files with 70 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

69
src/common/string.cpp
View File

@@ -36,6 +36,7 @@
#include <stdlib.h>
#include "wx/hashmap.h"
#include "wx/vector.h"
// string handling functions used by wxString:
#if wxUSE_UNICODE_UTF8
@@ -1397,30 +1398,62 @@ size_t wxString::Replace(const wxString& strOld,
break;
}
}
else // general case
else if ( !bReplaceAll)
{
size_t pos = m_impl.find(strOld, 0);
if ( pos != npos )
{
m_impl.replace(pos, strOld.m_impl.length(), strNew.m_impl);
uiCount = 1;
}
}
else // replace all occurrences
{
const size_t uiOldLen = strOld.m_impl.length();
const size_t uiNewLen = strNew.m_impl.length();
for ( size_t pos = 0; ; )
// first scan the string to find all positions at which the replacement
// should be made
wxVector<size_t> replacePositions;
size_t pos;
for ( pos = m_impl.find(strOld.m_impl, 0);
pos != npos;
pos = m_impl.find(strOld.m_impl, pos + uiOldLen))
{
pos = m_impl.find(strOld.m_impl, pos);
if ( pos == npos )
break;
// replace this occurrence of the old string with the new one
m_impl.replace(pos, uiOldLen, strNew.m_impl);
// move up pos past the string that was replaced
pos += uiNewLen;
// increase replace count
uiCount++;
// stop after the first one?
if ( !bReplaceAll )
break;
replacePositions.push_back(pos);
++uiCount;
}
if ( !uiCount )
return 0;
// allocate enough memory for the whole new string
wxString tmp;
tmp.m_impl.reserve(m_impl.length() + uiCount*(uiNewLen - uiOldLen));
// copy this string to tmp doing replacements on the fly
size_t replNum = 0;
for ( pos = 0; replNum < uiCount; replNum++ )
{
const size_t nextReplPos = replacePositions[replNum];
if ( pos != nextReplPos )
{
tmp.m_impl.append(m_impl, pos, nextReplPos - pos);
}
tmp.m_impl.append(strNew.m_impl);
pos = nextReplPos + uiOldLen;
}
if ( pos != m_impl.length() )
{
// append the rest of the string unchanged
tmp.m_impl.append(m_impl, pos, m_impl.length() - pos);
}
swap(tmp);
}
return uiCount;