ceph/src/boost/libs/regex/example/snippets/partial_regex_iterate.cpp

   1 /*
   2  *
   3  * Copyright (c) 1998-2007
   4  * John Maddock
   5  *
   6  * Use, modification and distribution are subject to the
   7  * Boost Software License, Version 1.0. (See accompanying file
   8  * LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   9  *
  10  */
  11
  12  /*
  13   *   LOCATION:    see http://www.boost.org for most recent version.
  14   *   FILE         partial_regex_iterate.cpp
  15   *   VERSION      see <boost/version.hpp>
  16   *   DESCRIPTION: Search example using partial matches.
  17   */
  18
  19 #include <iostream>
  20 #include <fstream>
  21 #include <sstream>
  22 #include <string>
  23 #include <cstring>
  24 #include <boost/regex.hpp>
  25
  26 #ifdef BOOST_NO_STDC_NAMESPACE
  27 namespace std{ using ::memmove; }
  28 #endif
  29
  30 // match some kind of html tag:
  31 boost::regex e("<[^>]*>");
  32 // count how many:
  33 unsigned int tags = 0;
  34
  35 void search(std::istream& is)
  36 {
  37    // buffer we'll be searching in:
  38    char buf[4096];
  39    // saved position of end of partial match:
  40    const char* next_pos = buf + sizeof(buf);
  41    // flag to indicate whether there is more input to come:
  42    bool have_more = true;
  43
  44    while(have_more)
  45    {
  46       // how much do we copy forward from last try:
  47       std::ptrdiff_t leftover = (buf + sizeof(buf)) - next_pos;
  48       // and how much is left to fill:
  49       std::ptrdiff_t size = next_pos - buf;
  50       // copy forward whatever we have left:
  51       std::memmove(buf, next_pos, leftover);
  52       // fill the rest from the stream:
  53       is.read(buf + leftover, size);
  54       std::streamsize read = is.gcount();
  55       // check to see if we've run out of text:
  56       have_more = read == size;
  57       // reset next_pos:
  58       next_pos = buf + sizeof(buf);
  59       // and then iterate:
  60       boost::cregex_iterator a(
  61          buf,
  62          buf + read + leftover,
  63          e,
  64          boost::match_default | boost::match_partial);
  65       boost::cregex_iterator b;
  66
  67       while(a != b)
  68       {
  69          if((*a)[0].matched == false)
  70          {
  71             // Partial match, save position and break:
  72             next_pos = (*a)[0].first;
  73             break;
  74          }
  75          else
  76          {
  77             // full match:
  78             ++tags;
  79          }
  80
  81          // move to next match:
  82          ++a;
  83       }
  84    }
  85 }
  86
  87 int main(int argc, char* argv[])
  88 {
  89    if(argc > 1)
  90    {
  91       for(int i = 1; i < argc; ++i)
  92       {
  93          std::ifstream fs(argv[i]);
  94          if(fs.bad()) continue;
  95          search(fs);
  96          fs.close();
  97       }
  98    }
  99    else
 100    {
 101       std::string one("<META NAME=\"keywords\" CONTENT=\"regex++, regular expressions, regular expression library, C++\">");
 102       std::string what;
 103       while(what.size() < 10000)
 104       {
 105          what.append(one);
 106          what.append(13, ' ');
 107       }
 108       std::stringstream ss;
 109       ss.str(what);
 110       search(ss);
 111    }
 112    std::cout << "total tag count was " << tags << std::endl;
 113    return 0;
 114 }
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