Add a new hash class in __gnu_ext for the extension containers. There

are two motivations for this.

First, this allows users who are specializing __gnu_ext::hash to
continue doing so without changing their code.

Second, SGI specifies hash overloads for char* and const char* that
perform a hash of the string, not of the pointer.

In order to support this, the hashing code for string is factored out.

llvm-svn: 136539

3 files changed, 49 insertions, 1 deletions

diff --git a/libcxx/include/ext/__hash b/libcxx/include/ext/__hash
new file mode 100644
index 00000000000..8e9635d07f5
--- /dev/null
+++ b/libcxx/include/ext/__hash
@@ -0,0 +1,46 @@
+// -*- C++ -*-
+//===------------------------- hash_set ------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_EXT_HASH
+#define _LIBCPP_EXT_HASH
+
+#pragma GCC system_header
+
+#include <string>
+#include <cstring>
+
+namespace __gnu_cxx {
+using namespace std;
+
+template <typename T> struct _LIBCPP_VISIBLE hash : public std::hash<T>
+    { };
+
+template <> struct _LIBCPP_VISIBLE hash<const char*>
+    : public unary_function<const char*, size_t>
+{
+    _LIBCPP_INLINE_VISIBILITY
+    size_t operator()(const char *__c) const _NOEXCEPT
+    {
+        return __do_string_hash(__c, __c + strlen(__c));
+    }
+};
+
+template <> struct _LIBCPP_VISIBLE hash<char *>
+    : public unary_function<char*, size_t>
+{
+    _LIBCPP_INLINE_VISIBILITY
+    size_t operator()(char *__c) const _NOEXCEPT
+    {
+        return __do_string_hash<const char *>(__c, __c + strlen(__c));
+    }
+};
+}
+
+#endif _LIBCPP_EXT_HASH
diff --git a/libcxx/include/ext/hash_map b/libcxx/include/ext/hash_map
index 21ce3be8a18..9e62e7a777d 100644
--- a/libcxx/include/ext/hash_map
+++ b/libcxx/include/ext/hash_map
@@ -203,6 +203,7 @@ template <class Key, class T, class Hash, class Pred, class Alloc>
 #include <__hash_table>
 #include <functional>
 #include <stdexcept>
+#include <ext/__hash>
 
 #if __DEPRECATED
 #warning Use of the header <ext/hash_map> is deprecated.  Migrate to <unordered_map>
diff --git a/libcxx/include/ext/hash_set b/libcxx/include/ext/hash_set
index daad847afb3..14daf7bc29e 100644
--- a/libcxx/include/ext/hash_set
+++ b/libcxx/include/ext/hash_set
@@ -196,6 +196,7 @@ template <class Value, class Hash, class Pred, class Alloc>
 #include <__config>
 #include <__hash_table>
 #include <functional>
+#include <ext/__hash>
 
 #if __DEPRECATED
 #warning Use of the header <ext/hash_set> is deprecated.  Migrate to <unordered_set>
@@ -205,7 +206,7 @@ namespace __gnu_cxx {
 
 using namespace std;
 
-template <class _Value, class _Hash = std::hash<_Value>, class _Pred = equal_to<_Value>,
+template <class _Value, class _Hash = hash<_Value>, class _Pred = equal_to<_Value>,
           class _Alloc = allocator<_Value> >
 class _LIBCPP_VISIBLE hash_set
 {