Upstream android string implementation etc.

base/hash_tables.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 
 //
 // Deal with the differences between Microsoft and GNU implemenations
 // of hash_map. Allows all platforms to use |base::hash_map| and
 // |base::hash_set|.
 //  eg:
@@ skipping 11 matching lines @@
 #define BASE_HASH_TABLES_H_
 #pragma once
 
 #include "build/build_config.h"
 
 #include "base/string16.h"
 
 #if defined(COMPILER_MSVC)
 #include <hash_map>
 #include <hash_set>
+
+#define BASE_HASH_NAMESPACE stdext
+
 namespace base {
-using stdext::hash_map;
-using stdext::hash_set;
+using BASE_HASH_NAMESPACE::hash_map;
+using BASE_HASH_NAMESPACE::hash_set;
 }
 #elif defined(COMPILER_GCC)

[brettw, 2011/06/24 23:57:04]

CAn you add blank lines around this for readability now that the ifdefs are
getting more complicated?

[michaelbai, 2011/06/27 16:14:09]

Done.

+#if defined(OS_ANDROID)
+#define BASE_HASH_NAMESPACE std
+#else
+#define BASE_HASH_NAMESPACE __gnu_cxx
+#endif
+
 // This is a hack to disable the gcc 4.4 warning about hash_map and hash_set
 // being deprecated.  We can get rid of this when we upgrade to VS2008 and we
 // can use <tr1/unordered_map> and <tr1/unordered_set>.
 #ifdef __DEPRECATED
 #define CHROME_OLD__DEPRECATED __DEPRECATED
 #undef __DEPRECATED
 #endif
 
+#if defined(OS_ANDROID)
+#include <hash_map>
+#include <hash_set>
+#else
 #include <ext/hash_map>
 #include <ext/hash_set>
+#endif
+
 #include <string>
 
 #ifdef CHROME_OLD__DEPRECATED
 #define __DEPRECATED CHROME_OLD__DEPRECATED
 #undef CHROME_OLD__DEPRECATED
 #endif
 
 namespace base {

[darin (slow to review), 2011/06/24 23:41:12]

i guess it would be nice to not repeat this code.  maybe you can just move this
down to the end of the file?

[michaelbai, 2011/06/24 23:45:35]

I thought about it before, the whole structure in this file like

#if defined(COMPILER_MSVC)

#elif defined(COMPILER_GCC)

#endif

There is no #else

Is it ok for me to add a #else like

#else
#define BASE_HASH_NAMESPACE
#endif

[brettw, 2011/06/24 23:57:04]

Do we support any other compilers? In these cases we've often done:
#else
#error define BASE_HASH_NAMESPACE for your compiler
#endif

[michaelbai, 2011/06/27 16:14:09]

Done.

-using __gnu_cxx::hash_map;
-using __gnu_cxx::hash_set;
+using BASE_HASH_NAMESPACE::hash_map;
+using BASE_HASH_NAMESPACE::hash_set;
 }  // namespace base
 
-namespace __gnu_cxx {
+namespace BASE_HASH_NAMESPACE {
 
+#if !defined(OS_ANDROID)
 // The GNU C++ library provides identity hash functions for many integral types,
 // but not for |long long|.  This hash function will truncate if |size_t| is
 // narrower than |long long|.  This is probably good enough for what we will
 // use it for.
 
 #define DEFINE_TRIVIAL_HASH(integral_type) \
     template<> \
     struct hash<integral_type> { \
       std::size_t operator()(integral_type value) const { \
         return static_cast<std::size_t>(value); \
       } \
     }
 
 DEFINE_TRIVIAL_HASH(long long);
 DEFINE_TRIVIAL_HASH(unsigned long long);
 
 #undef DEFINE_TRIVIAL_HASH
+#endif  // !defined(OS_ANDROID)
 
 // Implement string hash functions so that strings of various flavors can
 // be used as keys in STL maps and sets.  The hash algorithm comes from the
 // GNU C++ library, in <tr1/functional>.  It is duplicated here because GCC
 // versions prior to 4.3.2 are unable to compile <tr1/functional> when RTTI
 // is disabled, as it is in our build.
 
 #define DEFINE_STRING_HASH(string_type) \
     template<> \
     struct hash<string_type> { \
       std::size_t operator()(const string_type& s) const { \
         std::size_t result = 0; \
         for (string_type::const_iterator i = s.begin(); i != s.end(); ++i) \
           result = (result * 131) + *i; \
         return result; \
       } \
     }
 
 DEFINE_STRING_HASH(std::string);
 DEFINE_STRING_HASH(string16);
 
 #undef DEFINE_STRING_HASH
 
-}  // namespace __gnu_cxx
+}  // namespace BASE_HASH_NAMESPACE
 
 #endif  // COMPILER
 
 #endif  // BASE_HASH_TABLES_H_