CUtlString CUtlString::Replace( const char *pszFrom, const char *pszTo ) const
{
Assert( pszTo ); // Can be 0 length, but not null
Assert( pszFrom && *pszFrom ); // Must be valid and have one character.
const char *pos = V_strstr( String(), pszFrom );
if ( !pos )
{
return *this;
}
const char *pFirstFound = pos;
// count number of search string
int nSearchCount = 0;
int nSearchLength = V_strlen( pszFrom );
while ( pos )
{
nSearchCount++;
int nSrcOffset = ( pos - String() ) + nSearchLength;
pos = V_strstr( String() + nSrcOffset, pszFrom );
}
// allocate the new string
int nReplaceLength = V_strlen( pszTo );
int nAllocOffset = nSearchCount * ( nReplaceLength - nSearchLength );
size_t srcLength = Length();
CUtlString strDest;
size_t destLength = srcLength + nAllocOffset;
strDest.SetLength( destLength );
// find and replace the search string
pos = pFirstFound;
int nDestOffset = 0;
int nSrcOffset = 0;
while ( pos )
{
// Found an instance
int nCurrentSearchOffset = pos - String();
int nCopyLength = nCurrentSearchOffset - nSrcOffset;
V_strncpy( strDest.GetForModify() + nDestOffset, String() + nSrcOffset, nCopyLength + 1 );
nDestOffset += nCopyLength;
V_strncpy( strDest.GetForModify() + nDestOffset, pszTo, nReplaceLength + 1 );
nDestOffset += nReplaceLength;
nSrcOffset = nCurrentSearchOffset + nSearchLength;
pos = V_strstr( String() + nSrcOffset, pszFrom );
}
// making sure that the left over string from the source is the same size as the left over dest buffer
Assert( destLength - nDestOffset == srcLength - nSrcOffset );
if ( destLength - nDestOffset > 0 )
{
V_strncpy( strDest.GetForModify() + nDestOffset, String() + nSrcOffset, destLength - nDestOffset + 1 );
}
return strDest;
}
