Avoid copying in TrimRight() and TrimLeft() if possible.

core/fxcrt/fx_basic_wstring.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <cctype>
@@ skipping 822 matching lines @@
   if (str)
     while (str[len])
       len++;
   return len;
 }
 
 void CFX_WideString::TrimRight(const CFX_WideStringC& pTargets) {
   if (!m_pData || pTargets.IsEmpty()) {
     return;
   }
-  ReallocBeforeWrite(m_pData->m_nDataLength);
   FX_STRSIZE pos = GetLength();
   if (pos < 1) {
     return;
   }
   while (pos) {
     if (!FXSYS_wcschr(pTargets.c_str(), m_pData->m_String[pos - 1])) {
       break;
     }
     pos--;
   }
   if (pos < m_pData->m_nDataLength) {
+    ReallocBeforeWrite(m_pData->m_nDataLength);
     m_pData->m_String[pos] = 0;
     m_pData->m_nDataLength = pos;
   }
 }
 
 void CFX_WideString::TrimRight(FX_WCHAR chTarget) {
   FX_WCHAR str[2] = {chTarget, 0};
   TrimRight(str);
 }
 
 void CFX_WideString::TrimRight() {
   TrimRight(L"\x09\x0a\x0b\x0c\x0d\x20");
 }
 
 void CFX_WideString::TrimLeft(const CFX_WideStringC& pTargets) {
   if (!m_pData || pTargets.IsEmpty())
     return;
 
   FX_STRSIZE len = GetLength();
   if (len < 1)
     return;
 
-  ReallocBeforeWrite(len);
-  const FX_WCHAR* lpsz = m_pData->m_String;
-  while (*lpsz != 0) {
-    if (!FXSYS_wcschr(pTargets.c_str(), *lpsz)) {
+  FX_STRSIZE pos = 0;
+  while (pos < len) {
+    FX_STRSIZE i = 0;
+    while (i < pTargets.GetLength() && pTargets[i] != m_pData->m_String[pos]) {
+      i++;
+    }
+    if (i == pTargets.GetLength()) {
       break;
     }
-    lpsz++;
+    pos++;
   }
-  if (lpsz != m_pData->m_String) {
-    int nDataLength =
-        m_pData->m_nDataLength - (FX_STRSIZE)(lpsz - m_pData->m_String);
-    FXSYS_memmove(m_pData->m_String, lpsz,
+  if (pos) {
+    ReallocBeforeWrite(len);
+    FX_STRSIZE nDataLength = len - pos;
+    FXSYS_memmove(m_pData->m_String, m_pData->m_String + pos,
                   (nDataLength + 1) * sizeof(FX_WCHAR));
     m_pData->m_nDataLength = nDataLength;
   }
 }
 
 void CFX_WideString::TrimLeft(FX_WCHAR chTarget) {
   FX_WCHAR str[2] = {chTarget, 0};
   TrimLeft(str);
 }
 
@@ skipping 68 matching lines @@
       FXSYS_MultiByteToWideChar(codepage, 0, bstr.c_str(), src_len, nullptr, 0);
   CFX_WideString wstr;
   if (dest_len) {
     FX_WCHAR* dest_buf = wstr.GetBuffer(dest_len);
     FXSYS_MultiByteToWideChar(codepage, 0, bstr.c_str(), src_len, dest_buf,
                               dest_len);
     wstr.ReleaseBuffer(dest_len);
   }
   return wstr;
 }