Save 4 bytes per CFX_ByteString where size_t smaller than long.

core/include/fxcrt/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 _FX_STRING_H_
 #define _FX_STRING_H_
 
+#include <stdint.h>  // For intptr_t.
 #include <algorithm>
 
 #include "fx_memory.h"
 
 class CFX_ByteStringC;
 class CFX_ByteString;
 class CFX_WideStringC;
 class CFX_WideString;
 struct CFX_CharMap;
 class CFX_BinaryBuf;
@@ skipping 141 matching lines @@
 
 private:
     void*                       operator new (size_t) throw()
     {
         return NULL;
     }
 };
 typedef const CFX_ByteStringC& FX_BSTR;
 #define FX_BSTRC(str) CFX_ByteStringC(str, sizeof str-1)
 #define FXBSTR_ID(c1, c2, c3, c4) ((c1 << 24) | (c2 << 16) | (c3 << 8) | (c4))
+
+// To ensure ref counts do not overflow, consider the worst possible case:
+// the entire address space contains nothing but pointers to this object.
+// Since the count increments with each new pointer, the largest value is
+// the number of pointers that can fit into the address space. The size of
+// the address space itself is a good upper bound on it; we need not go
+// larger.
 struct CFX_StringData {
-
-    long                m_nRefs;
-
+    intptr_t    m_nRefs;  // Would prefer ssize_t, but no windows support.
     FX_STRSIZE  m_nDataLength;
-
     FX_STRSIZE  m_nAllocLength;
-
     FX_CHAR             m_String[1];
 };
 class CFX_ByteString 
 {
 public:
     typedef FX_CHAR value_type;
 
     CFX_ByteString()
     {
         m_pData = NULL;
@@ skipping 390 matching lines @@
 
 private:
     void*                       operator new (size_t) throw()
     {
         return NULL;
     }
 };
 typedef const CFX_WideStringC&  FX_WSTR;
 #define FX_WSTRC(wstr) CFX_WideStringC(wstr, FX_ArraySize(wstr) - 1)
 struct CFX_StringDataW {
-
-    long                m_nRefs;
-
+    intptr_t    m_nRefs;  // Would prefer ssize_t, but no windows support.
     FX_STRSIZE  m_nDataLength;
-
     FX_STRSIZE  m_nAllocLength;
-
     FX_WCHAR    m_String[1];
 };
 class CFX_WideString 
 {
 public:
     typedef FX_WCHAR value_type;
 
     CFX_WideString()
     {
         m_pData = NULL;
@@ skipping 229 matching lines @@
 CFX_ByteString  FX_UTF8Encode(FX_LPCWSTR pwsStr, FX_STRSIZE len);
 inline CFX_ByteString   FX_UTF8Encode(FX_WSTR wsStr)
 {
     return FX_UTF8Encode(wsStr.GetPtr(), wsStr.GetLength());
 }
 inline CFX_ByteString   FX_UTF8Encode(const CFX_WideString &wsStr)
 {
     return FX_UTF8Encode(wsStr.c_str(), wsStr.GetLength());
 }
 #endif