Starting to add examples for using the unordered container library.

[SVN r3046]

examples/hash_functions/fnv-1.hpp

@@ -0,0 +1,66 @@
+// See: http://www.isthe.com/chongo/tech/comp/fnv/
+
+#include <string>
+
+namespace hash
+{
+    template <std::size_t FnvPrime, std::size_t OffsetBias>
+    struct basic_fnv_1
+    {
+        std::size_t operator()(std::string const& text)
+        {
+            std::size_t hash = OffsetBias;
+            for(std::string::const_iterator it = text.begin(), end = text.end();
+                    it != end; ++it)
+            {
+                hash *= FnvPrime;
+                hash ^= *it;
+            }
+
+            return hash;
+        }
+    };
+
+    template <std::size_t FnvPrime, std::size_t OffsetBias>
+    struct basic_fnv_1a
+    {
+        std::size_t operator()(std::string const& text)
+        {
+            std::size_t hash = OffsetBias;
+            for(std::string::const_iterator it = text.begin(), end = text.end();
+                    it != end; ++it)
+            {
+                hash ^= *it;
+                hash *= FnvPrime;
+            }
+
+            return hash;
+        }
+    };
+
+    // TODO: Select Bias & Prime base on the size of std::size_t.
+    //
+    // 32 bit FNV_prime = 16777619
+    // 64 bit FNV_prime = 1099511628211
+    // 128 bit FNV_prime = 309485009821345068724781401
+    // 256 bit FNV_prime = 374144419156711147060143317175368453031918731002211
+    //
+    // 32 bit offset_basis = 2166136261
+    // 64 bit offset_basis = 14695981039346656037
+    // 128 bit offset_basis = 275519064689413815358837431229664493455
+    // 256 bit offset_basis = 100029257958052580907070968620625704837092796014241193945225284501741471925557
+
+    const std::size_t fnv_prime = 16777619;
+    // 64 bit FNV_prime = 1099511628211
+    // 128 bit FNV_prime = 309485009821345068724781401
+    // 256 bit FNV_prime = 374144419156711147060143317175368453031918731002211
+
+    const std::size_t fnv_offset_bias = 2166136261;
+    // 64 bit offset_basis = 14695981039346656037
+    // 128 bit offset_basis = 275519064689413815358837431229664493455
+    // 256 bit offset_basis = 100029257958052580907070968620625704837092796014241193945225284501741471925557
+
+    typedef basic_fnv_1<fnv_prime, fnv_offset_bias> fnv_1;
+    typedef basic_fnv_1a<fnv_prime, fnv_offset_bias> fnv_1a;
+
+}