[R] make all customizations to meet strict standard of cran

src/common/common.cc

@@ -7,8 +7,8 @@
 
 namespace xgboost {
 namespace common {
-RandomEngine& GlobalRandom() {
-  static RandomEngine inst;
+GlobalRandomEngine& GlobalRandom() {
+  static GlobalRandomEngine inst;
   return inst;
 }
 }

src/common/math.h

@@ -113,7 +113,7 @@ inline bool CheckNAN(T v) {
 #ifdef _MSC_VER
   return (_isnan(v) != 0);
 #else
-  return isnan(v);
+  return std::isnan(v);
 #endif
 }
 template<typename T>

src/common/random.h

@@ -8,6 +8,7 @@
 #define XGBOOST_COMMON_RANDOM_H_
 
 #include <random>
+#include <limits>
 
 namespace xgboost {
 namespace common {
@@ -15,11 +16,54 @@ namespace common {
  * \brief Define mt19937 as default type Random Engine.
  */
 typedef std::mt19937 RandomEngine;
+
+#if XGBOOST_CUSTOMIZE_GLOBAL_PRNG
+/*!
+ * \brief An customized random engine, used to be plugged in PRNG from other systems.
+ *  The implementation of this library is not provided by xgboost core library.
+ *  Instead the other library can implement this class, which will be used as GlobalRandomEngine
+ *  If XGBOOST_RANDOM_CUSTOMIZE = 1, by default this is switched off.
+ */
+class CustomGlobalRandomEngine {
+ public:
+  /*! \brief The result type */
+  typedef size_t result_type;
+  /*! \brief The minimum of random numbers generated */
+  inline static constexpr result_type min() {
+    return 0;
+  }
+  /*! \brief The maximum random numbers generated */
+  inline static constexpr result_type max() {
+    return std::numeric_limits<size_t>::max();
+  }
+  /*!
+   * \brief seed function, to be implemented
+   * \param val The value of the seed.
+   */
+  void seed(result_type val);
+  /*!
+   * \return next random number.
+   */
+  result_type operator()();
+};
+
+/*!
+ * \brief global random engine
+ */
+typedef CustomGlobalRandomEngine GlobalRandomEngine;
+
+#else
+/*!
+ * \brief global random engine
+ */
+typedef RandomEngine GlobalRandomEngine;
+#endif
+
 /*!
  * \brief global singleton of a random engine.
  *  Only use this engine when necessary, not thread-safe.
  */
-RandomEngine& GlobalRandom(); // NOLINT(*)
+GlobalRandomEngine& GlobalRandom(); // NOLINT(*)
 
 }  // namespace common
 }  // namespace xgboost