rand: conform to the std generator concept

rand/lcg.cpp

@@ -3,7 +3,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  *
- * Copyright 2015 Danny Robson <danny@nerdcruft.net>
+ * Copyright 2015-2019 Danny Robson <danny@nerdcruft.net>
  */
 
 #include "lcg.hpp"
@@ -50,24 +50,6 @@ lcg<T,M,A,C>::operator() (void)
 }
 
 
-///////////////////////////////////////////////////////////////////////////////
-template <typename T, T M, T A, T C>
-typename lcg<T,M,A,C>::result_type
-lcg<T,M,A,C>::min (void)
-{
-    return std::numeric_limits<result_type>::min ();
-}
-
-
-//-----------------------------------------------------------------------------
-template <typename T, T M, T A, T C>
-typename lcg<T,M,A,C>::result_type
-lcg<T,M,A,C>::max (void)
-{
-    return std::numeric_limits<result_type>::max ();
-}
-
-
 ///////////////////////////////////////////////////////////////////////////////
 template <typename T, T M, T A, T C>
 void

rand/lcg.hpp

@@ -3,14 +3,15 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  *
- * Copyright 2015 Danny Robson <danny@nerdcruft.net>
+ * Copyright 2015-2019 Danny Robson <danny@nerdcruft.net>
  */
 
-#ifndef __UTIL_RAND_LCG_HPP
+#pragma once
-#define __UTIL_RAND_LCG_HPP
+
+#include "../std.hpp"
 
-#include <cstdint>
 #include <type_traits>
+#include <limits>
 
 
 namespace cruft::rand {
@@ -25,14 +26,13 @@ namespace cruft::rand {
     public:
         using result_type = T;
 
-        static_assert (std::is_unsigned<T>::value,
+        static_assert (std::is_unsigned_v<T>);
-                       "LCG generates integer overflow which is undefined behaviour for signed types");
         explicit lcg (T seed);
 
         result_type operator() (void);
 
-        static result_type min (void);
+        static constexpr auto min (void) { return std::numeric_limits<T>::min (); }
-        static result_type max (void);
+        static constexpr auto max (void) { return std::numeric_limits<T>::max (); }
 
         void discard (unsigned);
 
@@ -40,8 +40,6 @@ namespace cruft::rand {
         T m_x;
     };
 
-    // glibc: typedef lcg<uint32_t, pow2(31), 1103515245, 12345> lcg_t;
+    // glibc: typedef lcg<u64, pow2(31), 1103515245, 12345> lcg_t;
-    using lcg_t = lcg<uint64_t,0u,6364136223846793005ul, 1ul>;
+    using lcg_t = lcg<u64,0u,6364136223846793005ul, 1ul>;
 }
-
-#endif

rand/mwc64x.cpp

@@ -23,7 +23,7 @@ mwc64x::mwc64x (seed_type _seed):
 
 
 ///////////////////////////////////////////////////////////////////////////////
-mwc64x::value_type
+mwc64x::result_type
 mwc64x::operator() (void)
 {
     CHECK_NEZ (m_state);

rand/mwc64x.hpp

@@ -3,13 +3,16 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  *
- * Copyright 2016 Danny Robson <danny@nerdcruft.net>
+ * Copyright 2016-2019 Danny Robson <danny@nerdcruft.net>
  */
 
-#ifndef __UTIL_RAND_MWC64X_HPP
+#pragma once
-#define __UTIL_RAND_MWC64X_HPP
+
+#include "../std.hpp"
 
 #include <cstdint>
+#include <limits>
+
 
 namespace cruft::rand {
     // multiply-with-carry style generator suitable for rapid seeking and
@@ -19,17 +22,17 @@ namespace cruft::rand {
     // don't allow either half of the uint64_t to be zero.
     struct mwc64x {
     public:
-        using value_type = uint32_t;
+        using result_type = u32;
-        using seed_type  = uint64_t;
+        using seed_type   = u64;
 
         explicit mwc64x (seed_type);
 
-        value_type operator() (void);
+        result_type operator() (void);
+
+        static constexpr auto max (void) noexcept { return std::numeric_limits<result_type>::max (); }
+        static constexpr auto min (void) noexcept { return std::numeric_limits<result_type>::min (); }
 
     private:
         uint64_t m_state;
     };
 }
-
-
-#endif

rand/xorshift.cpp

@@ -3,7 +3,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  *
- * Copyright 2015-2016 Danny Robson <danny@nerdcruft.net>
+ * Copyright 2015-2019 Danny Robson <danny@nerdcruft.net>
  */
 
 #include "xorshift.hpp"
@@ -63,23 +63,6 @@ xorshift<T>::operator() (void)
 
     CHECK_NEZ (m_state);
     return m_state;
-};
-
-
-///////////////////////////////////////////////////////////////////////////////
-template <typename T>
-typename xorshift<T>::result_type
-xorshift<T>::min (void)
-{
-    return 1u;
-}
-
-//-----------------------------------------------------------------------------
-template <typename T>
-typename xorshift<T>::result_type
-xorshift<T>::max (void)
-{
-    return std::numeric_limits<T>::max ();
 }
 
 

rand/xorshift.hpp

@@ -3,35 +3,33 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  *
- * Copyright 2015-2016 Danny Robson <danny@nerdcruft.net>
+ * Copyright 2015-2019 Danny Robson <danny@nerdcruft.net>
  */
 
-#ifndef __UTIL_RAND_XORSHIFT_HPP
+#pragma once
-#define __UTIL_RAND_XORSHIFT_HPP
+
+#include <limits>
 
 namespace cruft::rand {
     // implements a naive xorshift random generator.
     //
-    // * does not comply with the c++11 rng class requirements
     // * users may not rely on identical output across executions or library
     //   updates. internal constants may change across releases
-    template <typename T>
+    template <typename ValueT>
     struct xorshift {
     public:
-        using result_type = T;
+        using result_type = ValueT;
 
-        explicit xorshift (T seed);
+        explicit xorshift (ValueT seed);
 
         result_type operator() (void);
 
-        static result_type min (void);
+        static constexpr result_type min (void) noexcept { return 1u; }
-        static result_type max (void);
+        static constexpr auto max (void) noexcept { return std::numeric_limits<result_type>::max (); }
 
         void discard (unsigned);
 
     private:
-        T m_state;
+        ValueT m_state;
     };
 }
-
-#endif

test/rand/buckets.cpp

@@ -34,15 +34,15 @@ test_buckets (cruft::TAP::logger &tap, Args&& ...args)
 {
     constexpr unsigned BUCKET_BITS  = 8u;
     constexpr size_t   BUCKET_COUNT = 1u << BUCKET_BITS;
-    constexpr unsigned BUCKET_MASK  = BUCKET_COUNT - 1u;
     constexpr unsigned EXPECTED     = 1024u;
     constexpr unsigned ITERATIONS = BUCKET_COUNT * EXPECTED;
 
-    unsigned buckets[BUCKET_COUNT] = {};
     G gen (std::forward<Args> (args)...);
+    std::uniform_int_distribution<int> dist (0, BUCKET_COUNT - 1);
 
+    unsigned buckets[BUCKET_COUNT] = {};
     for (unsigned i = 0; i < ITERATIONS; ++i)
-        ++buckets[gen () & BUCKET_MASK];
+        ++buckets[dist (gen)];
 
     tap.expect (
         std::find_if (std::cbegin (buckets),