From 670e7b3736d8c7cba1cb640d98dc7d9b1f023788 Mon Sep 17 00:00:00 2001
From: Daniel James <daniel@calamity.org.uk>
Date: Thu, 8 Aug 2013 20:30:04 +0000
Subject: [PATCH] Simpler test for appropriate floats for binary hashing. Refs
 #8822.

No idea if this will actually fix it.

[SVN r85246]
---
 .../functional/hash/detail/hash_float.hpp     | 31 ++++++++-----------
 1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/include/boost/functional/hash/detail/hash_float.hpp b/include/boost/functional/hash/detail/hash_float.hpp
index a98cd70..2ac22da 100644
--- a/include/boost/functional/hash/detail/hash_float.hpp
+++ b/include/boost/functional/hash/detail/hash_float.hpp
@@ -90,15 +90,20 @@ namespace boost
             return seed;
         }
 
+        template <typename Float, unsigned digits, unsigned max_exponent>
+        struct enable_binary_hash
+        {
+            BOOST_STATIC_CONSTANT(bool, value =
+                std::numeric_limits<Float>::is_iec559 &&
+                std::numeric_limits<Float>::digits == digits &&
+                std::numeric_limits<Float>::radix == 2 &&
+                std::numeric_limits<Float>::max_exponent == max_exponent);
+        };
+
         template <typename Float>
         inline std::size_t float_hash_impl(Float v,
             BOOST_DEDUCED_TYPENAME boost::enable_if_c<
-                std::numeric_limits<Float>::is_iec559 &&
-                std::numeric_limits<Float>::digits == 24 &&
-                std::numeric_limits<Float>::radix == 2 &&
-                std::numeric_limits<Float>::max_exponent == 128,
-                int>::type
-            )
+                enable_binary_hash<Float, 24, 128>::value, int>::type)
         {
             return hash_binary((char*) &v, 4);
         }
@@ -107,12 +112,7 @@ namespace boost
         template <typename Float>
         inline std::size_t float_hash_impl(Float v,
             BOOST_DEDUCED_TYPENAME boost::enable_if_c<
-                std::numeric_limits<Float>::is_iec559 &&
-                std::numeric_limits<Float>::digits == 53 &&
-                std::numeric_limits<Float>::radix == 2 &&
-                std::numeric_limits<Float>::max_exponent == 1024,
-                int>::type
-            )
+                enable_binary_hash<Float, 53, 1024>::value, int>::type)
         {
             return hash_binary((char*) &v, 8);
         }
@@ -120,12 +120,7 @@ namespace boost
         template <typename Float>
         inline std::size_t float_hash_impl(Float v,
             BOOST_DEDUCED_TYPENAME boost::enable_if_c<
-                std::numeric_limits<Float>::is_iec559 &&
-                std::numeric_limits<Float>::digits == 64 &&
-                std::numeric_limits<Float>::radix == 2 &&
-                std::numeric_limits<Float>::max_exponent == 16384,
-                int>::type
-            )
+                enable_binary_hash<Float, 64, 16384>::value, int>::type)
         {
             return hash_binary((char*) &v, 10);
         }