libcxx/src/random_shuffle.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "algorithm"
  10 #include "random"
  11 #ifndef _LIBCPP_HAS_NO_THREADS
  12 #   include "mutex"
  13 #   if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
  14 #       pragma comment(lib, "pthread")
  15 #   endif
  16 #endif
  17
  18 _LIBCPP_BEGIN_NAMESPACE_STD
  19
  20 #ifndef _LIBCPP_HAS_NO_THREADS
  21 _LIBCPP_SAFE_STATIC static __libcpp_mutex_t __rs_mut = _LIBCPP_MUTEX_INITIALIZER;
  22 #endif
  23 unsigned __rs_default::__c_ = 0;
  24
  25 __rs_default::__rs_default()
  26 {
  27 #ifndef _LIBCPP_HAS_NO_THREADS
  28     __libcpp_mutex_lock(&__rs_mut);
  29 #endif
  30     __c_ = 1;
  31 }
  32
  33 __rs_default::__rs_default(const __rs_default&)
  34 {
  35     ++__c_;
  36 }
  37
  38 __rs_default::~__rs_default()
  39 {
  40 #ifndef _LIBCPP_HAS_NO_THREADS
  41     if (--__c_ == 0)
  42        __libcpp_mutex_unlock(&__rs_mut);
  43 #else
  44     --__c_;
  45 #endif
  46 }
  47
  48 __rs_default::result_type
  49 __rs_default::operator()()
  50 {
  51     static mt19937 __rs_g;
  52     return __rs_g();
  53 }
  54
  55 __rs_default
  56 __rs_get()
  57 {
  58     return __rs_default();
  59 }
  60
  61 _LIBCPP_END_NAMESPACE_STD