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

core/fxcrt/include/fx_string.h

 // 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
 
 #ifndef CORE_FXCRT_INCLUDE_FX_STRING_H_
 #define CORE_FXCRT_INCLUDE_FX_STRING_H_
 
 #include <stdint.h>  // For intptr_t.
@@ skipping 149 matching lines @@
   ~CFX_ByteString();
 
   // Deprecated -- use clear().
   void Empty() { m_pData.Reset(); }
   void clear() { m_pData.Reset(); }
 
   static CFX_ByteString FromUnicode(const FX_WCHAR* ptr, FX_STRSIZE len = -1);
   static CFX_ByteString FromUnicode(const CFX_WideString& str);
 
   // Explicit conversion to C-style string.
-  // Note: |this| must outlive the use of the result.
+  // Note: Any subsequent modification of |this| will invalidate the result.
   const FX_CHAR* c_str() const { return m_pData ? m_pData->m_String : ""; }
 
   // Implicit conversion to C-style string -- deprecated.
   operator const FX_CHAR*() const { return m_pData ? m_pData->m_String : ""; }
 
   // Explicit conversion to uint8_t*.
-  // Note: |this| must outlive the use of the result.
+  // Note: Any subsequent modification of |this| will invalidate the result.
   const uint8_t* raw_str() const {
     return m_pData ? reinterpret_cast<const uint8_t*>(m_pData->m_String)
                    : nullptr;
   }
 
   // Implicit conversion to uint8_t* -- deprecated.
   operator const uint8_t*() const {
     return m_pData ? reinterpret_cast<const uint8_t*>(m_pData->m_String)
                    : nullptr;
   }
 
   // Explicit conversion to CFX_ByteStringC.
-  // Note: |this| must outlive the use of the result.
+  // Note: Any subsequent modification of |this| will invalidate the result.
   CFX_ByteStringC AsStringC() const {
     return CFX_ByteStringC(raw_str(), GetLength());
   }
 
   FX_STRSIZE GetLength() const { return m_pData ? m_pData->m_nDataLength : 0; }
   bool IsEmpty() const { return !GetLength(); }
 
   int Compare(const CFX_ByteStringC& str) const;
   bool EqualNoCase(const CFX_ByteStringC& str) const;
 
@@ skipping 295 matching lines @@
   static CFX_WideString FromLocal(const CFX_ByteStringC& str);
   static CFX_WideString FromCodePage(const CFX_ByteStringC& str,
                                      uint16_t codepage);
 
   static CFX_WideString FromUTF8(const CFX_ByteStringC& str);
   static CFX_WideString FromUTF16LE(const unsigned short* str, FX_STRSIZE len);
 
   static FX_STRSIZE WStringLength(const unsigned short* str);
 
   // Explicit conversion to C-style wide string.
-  // Note: |this| must outlive the use of the result.
+  // Note: Any subsequent modification of |this| will invalidate the result.
   const FX_WCHAR* c_str() const { return m_pData ? m_pData->m_String : L""; }
 
   // Implicit conversion to C-style wide string -- deprecated.
-  // Note: |this| must outlive the use of the result.
+  // Note: Any subsequent modification of |this| will invalidate the result.
   operator const FX_WCHAR*() const { return m_pData ? m_pData->m_String : L""; }
 
   // Explicit conversion to CFX_WideStringC.
-  // Note: |this| must outlive the use of the result.
+  // Note: Any subsequent modification of |this| will invalidate the result.
   CFX_WideStringC AsStringC() const {
     return CFX_WideStringC(c_str(), GetLength());
   }
 
   // Deprecated -- use clear().
   void Empty() { m_pData.Reset(); }
   void clear() { m_pData.Reset(); }
 
   FX_STRSIZE GetLength() const { return m_pData ? m_pData->m_nDataLength : 0; }
   bool IsEmpty() const { return !GetLength(); }
@@ skipping 162 matching lines @@
 }
 
 FX_FLOAT FX_atof(const CFX_ByteStringC& str);
 inline FX_FLOAT FX_atof(const CFX_WideStringC& wsStr) {
   return FX_atof(FX_UTF8Encode(wsStr.c_str(), wsStr.GetLength()).c_str());
 }
 void FX_atonum(const CFX_ByteStringC& str, FX_BOOL& bInteger, void* pData);
 FX_STRSIZE FX_ftoa(FX_FLOAT f, FX_CHAR* buf);
 
 #endif  // CORE_FXCRT_INCLUDE_FX_STRING_H_