ceph/src/boost/libs/sort/example/reverseintsample.cpp

   1 //! \file
   2 //! \brief integer sort with a rightshift functor reverse sorting example.
   3 //
   4 //  Copyright Steven Ross 2009-2014.
   5 //
   6 // Distributed under the Boost Software License, Version 1.0.
   7 //    (See accompanying file LICENSE_1_0.txt or copy at
   8 //          http://www.boost.org/LICENSE_1_0.txt)
   9
  10 //  See http://www.boost.org/libs/sort for library home page.
  11
  12 // Caution: this file contains Quickbook markup as well as code
  13 // and comments, don't change any of the special comment markups!
  14
  15 #include <boost/sort/spreadsort/spreadsort.hpp>
  16 #include <time.h>
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <algorithm>
  20 #include <vector>
  21 #include <string>
  22 #include <fstream>
  23 #include <iostream>
  24 #include <functional>
  25 using namespace boost::sort::spreadsort;
  26
  27 #define DATA_TYPE int
  28
  29 struct negrightshift {
  30   inline int operator()(const int &x, const unsigned offset) {
  31     return -(x >> offset);
  32   }
  33 };
  34
  35 //Pass in an argument to test std::sort
  36 int main(int argc, const char ** argv) {
  37   size_t uCount,uSize=sizeof(DATA_TYPE);
  38   bool stdSort = false;
  39   unsigned loopCount = 1;
  40   for (int u = 1; u < argc; ++u) {
  41     if (std::string(argv[u]) == "-std")
  42       stdSort = true;
  43     else
  44       loopCount = atoi(argv[u]);
  45   }
  46   std::ifstream input("input.txt", std::ios_base::in | std::ios_base::binary);
  47   if (input.fail()) {
  48     printf("input.txt could not be opened\n");
  49     return 1;
  50   }
  51   double total = 0.0;
  52   std::vector<DATA_TYPE> array;
  53   input.seekg (0, std::ios_base::end);
  54     size_t length = input.tellg();
  55   uCount = length/uSize;
  56   //Run multiple loops, if requested
  57   for (unsigned u = 0; u < loopCount; ++u) {
  58     input.seekg (0, std::ios_base::beg);
  59     //Conversion to a vector
  60     array.resize(uCount);
  61     unsigned v = 0;
  62     while (input.good() && v < uCount)
  63       input.read(reinterpret_cast<char *>(&(array[v++])), uSize );
  64     if (v < uCount)
  65       array.resize(v);
  66     clock_t start, end;
  67     double elapsed;
  68     start = clock();
  69     if (stdSort)
  70
  71 //[reverse_int_1
  72       std::sort(array.begin(), array.end(), std::greater<DATA_TYPE>());
  73 //] [/reverse_int_1]
  74     else
  75 //[reverse_int_2
  76       integer_sort(array.begin(), array.end(), negrightshift(), std::greater<DATA_TYPE>());
  77 //] [/reverse_int_2]
  78     end = clock();
  79     elapsed = static_cast<double>(end - start) ;
  80     std::ofstream ofile;
  81     if (stdSort)
  82       ofile.open("standard_sort_out.txt", std::ios_base::out |
  83                  std::ios_base::binary | std::ios_base::trunc);
  84     else
  85       ofile.open("boost_sort_out.txt", std::ios_base::out |
  86                  std::ios_base::binary | std::ios_base::trunc);
  87     if (ofile.good()) {
  88       for (unsigned v = 0; v < array.size(); ++v) {
  89         ofile.write(reinterpret_cast<char *>(&(array[v])), sizeof(array[v]));
  90       }
  91       ofile.close();
  92     }
  93     total += elapsed;
  94     array.clear();
  95   }
  96   if (stdSort)
  97     printf("std::sort elapsed time %f\n", total / CLOCKS_PER_SEC);
  98   else
  99     printf("spreadsort elapsed time %f\n", total / CLOCKS_PER_SEC);
 100   return 0;
 101 }