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
  12 #ifndef _LIBCPP_HAS_NO_THREADS
  13 #  include <mutex>
  14 #  if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
  15 #    pragma comment(lib, "pthread")
  16 #  endif
  17 #endif
  18
  19 _LIBCPP_BEGIN_NAMESPACE_STD
  20
  21 #ifndef _LIBCPP_HAS_NO_THREADS
  22 static constinit __libcpp_mutex_t __rs_mut = _LIBCPP_MUTEX_INITIALIZER;
  23 #endif
  24 unsigned __rs_default::__c_ = 0;
  25
  26 __rs_default::__rs_default()
  27 {
  28 #ifndef _LIBCPP_HAS_NO_THREADS
  29     __libcpp_mutex_lock(&__rs_mut);
  30 #endif
  31     __c_ = 1;
  32 }
  33
  34 __rs_default::__rs_default(const __rs_default&)
  35 {
  36     ++__c_;
  37 }
  38
  39 __rs_default::~__rs_default()
  40 {
  41 #ifndef _LIBCPP_HAS_NO_THREADS
  42     if (--__c_ == 0)
  43        __libcpp_mutex_unlock(&__rs_mut);
  44 #else
  45     --__c_;
  46 #endif
  47 }
  48
  49 __rs_default::result_type
  50 __rs_default::operator()()
  51 {
  52     static mt19937 __rs_g;
  53     return __rs_g();
  54 }
  55
  56 __rs_default
  57 __rs_get()
  58 {
  59     return __rs_default();
  60 }
  61
  62 _LIBCPP_END_NAMESPACE_STD