1 files changed, 83 insertions, 22 deletions

diff --git a/boost/uuid/random_generator.hpp b/boost/uuid/random_generator.hpp
index a635ef03f7..c84fc5472c 100644
--- a/boost/uuid/random_generator.hpp
+++ b/boost/uuid/random_generator.hpp
@@ -1,6 +1,7 @@
 // Boost random_generator.hpp header file  ----------------------------------------------//
 
 // Copyright 2010 Andy Tompkins.
+// Copyright 2017 James E. King III
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
@@ -8,20 +9,43 @@
 #ifndef BOOST_UUID_RANDOM_GENERATOR_HPP
 #define BOOST_UUID_RANDOM_GENERATOR_HPP
 
-#include <boost/uuid/uuid.hpp>
-#include <boost/uuid/detail/seed_rng.hpp>
+#include <boost/assert.hpp>
+#include <boost/core/enable_if.hpp>
+#include <boost/core/null_deleter.hpp>
+#include <boost/random/mersenne_twister.hpp>
 #include <boost/random/uniform_int.hpp>
 #include <boost/random/variate_generator.hpp>
-#include <boost/random/mersenne_twister.hpp>
-#include <boost/core/null_deleter.hpp>
-#include <boost/assert.hpp>
 #include <boost/shared_ptr.hpp>
+#include <boost/tti/has_member_function.hpp>
+#include <boost/uuid/detail/random_provider.hpp>
+#include <boost/uuid/uuid.hpp>
 #include <limits>
 
 namespace boost {
 namespace uuids {
 
-// generate a random-based uuid
+namespace detail {
+    template<class U>
+    U& set_uuid_random_vv(U& u)
+    {
+        // set variant
+        // must be 0b10xxxxxx
+        *(u.begin() + 8) &= 0xBF;
+        *(u.begin() + 8) |= 0x80;
+
+        // set version
+        // must be 0b0100xxxx
+        *(u.begin() + 6) &= 0x4F; //0b01001111
+        *(u.begin() + 6) |= 0x40; //0b01000000
+
+        return u;
+    }
+    
+    BOOST_TTI_HAS_MEMBER_FUNCTION(seed)
+}
+
+//! generate a random-based uuid
+//! \param[in]  UniformRandomNumberGenerator  see Boost.Random documentation
 template <typename UniformRandomNumberGenerator>
 class basic_random_generator {
 private:
@@ -31,7 +55,9 @@ private:
 public:
     typedef uuid result_type;
 
-    // default constructor creates the random number generator
+    // default constructor creates the random number generator and
+    // if the UniformRandomNumberGenerator is a PseudoRandomNumberGenerator
+    // then it gets seeded by a random_provider.
     basic_random_generator()
         : pURNG(new UniformRandomNumberGenerator)
         , generator
@@ -42,8 +68,8 @@ public:
             )
           )
     {
-        // seed the random number generator
-        detail::seed(*pURNG);
+        // seed the random number generator if it is capable
+        seed(*pURNG);
     }
 
     // keep a reference to a random number generator
@@ -74,9 +100,9 @@ public:
         BOOST_ASSERT(pURNG);
     }
 
-    uuid operator()()
+    result_type operator()()
     {
-        uuid u;
+        result_type u;
 
         int i=0;
         unsigned long random_value = generator();
@@ -90,26 +116,61 @@ public:
             *it = static_cast<uuid::value_type>((random_value >> (i*8)) & 0xFF);
         }
 
-        // set variant
-        // must be 0b10xxxxxx
-        *(u.begin()+8) &= 0xBF;
-        *(u.begin()+8) |= 0x80;
+        return detail::set_uuid_random_vv(u);
+    }
 
-        // set version
-        // must be 0b0100xxxx
-        *(u.begin()+6) &= 0x4F; //0b01001111
-        *(u.begin()+6) |= 0x40; //0b01000000
+private:
+    // Detect whether UniformRandomNumberGenerator has a seed() method which indicates that
+    // it is a PseudoRandomNumberGenerator and needs a seed to initialize it.  This allows
+    // basic_random_generator to take any type of UniformRandomNumberGenerator and still
+    // meet the post-conditions for the default constructor.
+
+    template<class MaybePseudoRandomNumberGenerator>
+    typename boost::enable_if<detail::has_member_function_seed<MaybePseudoRandomNumberGenerator, void> >::type
+        seed(MaybePseudoRandomNumberGenerator& rng)
+    {
+        detail::random_provider seeder;
+        rng.seed(seeder);
+    }
 
-        return u;
+    template<class MaybePseudoRandomNumberGenerator>
+    typename boost::disable_if<detail::has_member_function_seed<MaybePseudoRandomNumberGenerator, void> >::type
+        seed(MaybePseudoRandomNumberGenerator&)
+    {
     }
 
-private:
     shared_ptr<UniformRandomNumberGenerator> pURNG;
     generator_type generator;
 };
 
+//! \brief a far less complex random generator that uses
+//!        operating system provided entropy which will
+//!        satisfy the majority of use cases
+class random_generator_pure
+{
+public:
+    typedef uuid result_type;
+
+    //! \returns a random, valid uuid
+    //! \throws entropy_error
+    result_type operator()()
+    {
+        result_type result;
+        prov_.get_random_bytes(&result, sizeof(result_type));
+        return detail::set_uuid_random_vv(result);
+    }
+
+private:
+    detail::random_provider prov_;
+};
+
+#if defined(BOOST_UUID_RANDOM_GENERATOR_COMPAT)
 typedef basic_random_generator<mt19937> random_generator;
+#else
+typedef random_generator_pure random_generator;
+typedef basic_random_generator<mt19937> random_generator_mt19937;
+#endif
 
 }} // namespace boost::uuids
 
-#endif //BOOST_UUID_RANDOM_GENERATOR_HPP
+#endif // BOOST_UUID_RANDOM_GENERATOR_HPP