regex_test.cpp -- learning boost.regex

最新推荐文章于 2019-02-24 14:20:00 发布

原创最新推荐文章于 2019-02-24 14:20:00 发布 · 257 阅读

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文章标签：

#regex #class #whitespace #string #parameters #processing

本文介绍了一个使用 Boost.Regex 库从文件中查找 C++ 类定义的实际案例。通过正则表达式匹配类名及其位置，并将结果存入 map 结构。示例展示了如何加载文件内容、设置正则表达式及迭代匹配结果。

boost.regex 库的用法，看来这可能是 boost 当中写法最“常规”的库之一了。

regex_test.cpp:

#include
#include
#include
#include
#include

using namespace std;

// purpose:
// takes the contents of a file in the form of a string
// and searches for all the C++ class definitions, storing
// their locations in a map of strings/int's

typedef map > map_type;

const char* re =
   // possibly leading whitespace:
   "^[[:space:]]*"
   // possible template declaration:
   "(template[[:space:]]*<[^;:{]+>[[:space:]]*)?"
   // class or struct:
   "(class|struct)[[:space:]]*"
   // leading declspec macros etc:
   "("
      "//<//w+//>"
      "("
         "[[:blank:]]*//([^)]*//)"
      ")?"
      "[[:space:]]*"
   ")*"
   // the class name
   "(//<//w*//>)[[:space:]]*"
   // template specialisation parameters
   "(<[^;:{]+>)?[[:space:]]*"
   // terminate in { or :
   "(//{|:[^;//{()]*//{)";

boost::regex expression(re);
map_type class_index;

bool regex_callback(const boost::match_results& what)
{
// what[0] contains the whole string
// what[5] contains the class name.
// what[6] contains the template specialisation if any.
// add class name and position to map:
class_index[what[5].str() + what[6].str()] = what.position(5);
return true;
}

void load_file(string& s, istream& is)
{
s.erase();
s.reserve(is.rdbuf()->in_avail());
cout << s.capacity();
char c;
while(is.get(c))
{
    if(s.capacity() == s.size())
      s.reserve(s.capacity() * 3);
    s.append(1, c);
}
}

int main(int argc, const char** argv)
{
string text;
for(int i = 1; i < argc; ++i)
{
    cout << "Processing file " << argv[i] << endl;
    ifstream fs(argv[i]);
    load_file(text, fs);
    // construct our iterators:
    boost::sregex_iterator m1(text.begin(), text.end(), expression);
    boost::sregex_iterator m2;
    for_each(m1, m2, ®ex_callback);
    // copy results:
    cout << class_index.size() << " matches found" << endl;
    map_type::iterator c, d;
    c = class_index.begin();
    d = class_index.end();
    while(c != d)
    {
      cout << "class /"" << (*c).first << "/" found at index: " << (*c).second << endl;
      ++c;
    }
    class_index.erase(class_index.begin(), class_index.end());
}

return 0;
}

//========== For Test =============
class Person
{};

template
class Temp
{
};

template <>
class Temp
{
};

=================================================================================
cl /EHsc regex_test.cpp

regex_test regex_test.cpp

OUTPUT:

Processing file regex_test.cpp
153 matches found
class "Person" found at index: 2331
class "Temp" found at index: 2368
class "Temp" found at index: 2397