Add string pools to save storage.

Adds string hashes so CFX strings will interoperate with
STL unordered containers.

These will be employed per-document in a subsequent cl.

BUG=pdfium:597

Review-Url: https://codereview.chromium.org/2341683005

3 files changed, 61 insertions, 9 deletions

diff --git a/core/fxcrt/include/cfx_string_pool_template.h b/core/fxcrt/include/cfx_string_pool_template.h
new file mode 100644
index 0000000000..a59d13a61d
--- /dev/null
+++ b/core/fxcrt/include/cfx_string_pool_template.h
@@ -0,0 +1,30 @@
+// Copyright 2016 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_CFX_STRING_POOL_TEMPLATE_H_
+#define CORE_FXCRT_INCLUDE_CFX_STRING_POOL_TEMPLATE_H_
+
+#include <unordered_set>
+
+#include "core/fxcrt/include/fx_string.h"
+
+template <typename StringType>
+class CFX_StringPoolTemplate {
+ public:
+  StringType Intern(const StringType& str) { return *m_Pool.insert(str).first; }
+  void Clear() { m_Pool.clear(); }
+
+ private:
+  std::unordered_set<StringType> m_Pool;
+};
+
+using CFX_ByteStringPool = CFX_StringPoolTemplate<CFX_ByteString>;
+using CFX_WideStringPool = CFX_StringPoolTemplate<CFX_WideString>;
+
+extern template class CFX_StringPoolTemplate<CFX_ByteString>;
+extern template class CFX_StringPoolTemplate<CFX_WideString>;
+
+#endif  // CORE_FXCRT_INCLUDE_CFX_STRING_POOL_TEMPLATE_H_
diff --git a/core/fxcrt/include/fx_ext.h b/core/fxcrt/include/fx_ext.h
index f7aca68d64..e33d57bdb7 100644
--- a/core/fxcrt/include/fx_ext.h
+++ b/core/fxcrt/include/fx_ext.h
@@ -83,19 +83,11 @@ inline int FXSYS_toDecimalDigit(const FX_WCHAR c) {
 FX_FLOAT FXSYS_FractionalScale(size_t scale_factor, int value);
 int FXSYS_FractionalScaleCount();
 
-uint32_t FX_HashCode_GetA(const CFX_ByteStringC& str, bool bIgnoreCase);
-uint32_t FX_HashCode_GetW(const CFX_WideStringC& Str, bool bIgnoreCase);
-
 void* FX_Random_MT_Start(uint32_t dwSeed);
-
-uint32_t FX_Random_MT_Generate(void* pContext);
-
 void FX_Random_MT_Close(void* pContext);
-
+uint32_t FX_Random_MT_Generate(void* pContext);
 void FX_Random_GenerateBase(uint32_t* pBuffer, int32_t iCount);
-
 void FX_Random_GenerateMT(uint32_t* pBuffer, int32_t iCount);
-
 void FX_Random_GenerateCrypto(uint32_t* pBuffer, int32_t iCount);
 
 #ifdef PDF_ENABLE_XFA
diff --git a/core/fxcrt/include/fx_string.h b/core/fxcrt/include/fx_string.h
index 48378586d3..6e9af221ca 100644
--- a/core/fxcrt/include/fx_string.h
+++ b/core/fxcrt/include/fx_string.h
@@ -8,7 +8,9 @@
 #define CORE_FXCRT_INCLUDE_FX_STRING_H_
 
 #include <stdint.h>  // For intptr_t.
+
 #include <algorithm>
+#include <functional>
 
 #include "core/fxcrt/cfx_string_c_template.h"
 #include "core/fxcrt/cfx_string_data_template.h"
@@ -166,7 +168,9 @@ class CFX_ByteString {
   void Concat(const FX_CHAR* lpszSrcData, FX_STRSIZE nSrcLen);
 
   CFX_RetainPtr<StringData> m_pData;
+
   friend class fxcrt_ByteStringConcat_Test;
+  friend class fxcrt_ByteStringPool_Test;
 };
 
 inline bool operator==(const char* lhs, const CFX_ByteString& rhs) {
@@ -357,7 +361,9 @@ class CFX_WideString {
   void Concat(const FX_WCHAR* lpszSrcData, FX_STRSIZE nSrcLen);
 
   CFX_RetainPtr<StringData> m_pData;
+
   friend class fxcrt_WideStringConcatInPlace_Test;
+  friend class fxcrt_WideStringPool_Test;
 };
 
 inline CFX_WideString operator+(const CFX_WideStringC& str1,
@@ -432,4 +438,28 @@ inline FX_FLOAT FX_atof(const CFX_WideStringC& wsStr) {
 bool FX_atonum(const CFX_ByteStringC& str, void* pData);
 FX_STRSIZE FX_ftoa(FX_FLOAT f, FX_CHAR* buf);
 
+uint32_t FX_HashCode_GetA(const CFX_ByteStringC& str, bool bIgnoreCase);
+uint32_t FX_HashCode_GetW(const CFX_WideStringC& str, bool bIgnoreCase);
+
+namespace std {
+
+template <>
+struct hash<CFX_ByteString> {
+  std::size_t operator()(const CFX_ByteString& str) const {
+    return FX_HashCode_GetA(str.AsStringC(), false);
+  }
+};
+
+template <>
+struct hash<CFX_WideString> {
+  std::size_t operator()(const CFX_WideString& str) const {
+    return FX_HashCode_GetW(str.AsStringC(), false);
+  }
+};
+
+}  // namespace std
+
+extern template struct std::hash<CFX_ByteString>;
+extern template struct std::hash<CFX_WideString>;
+
 #endif  // CORE_FXCRT_INCLUDE_FX_STRING_H_