Boost.Range support for ATL/WTL CString

• Download demo project - 96.3 Kb

Introduction

Tomato.String provides Boost.Range support for ATL/WTL CString. CString cannot be a model of Sequence, because Sequence requirements are defined using member functions. But Boost.Range concepts are somewhat new and those are defined using free (non-member) functions. So you can pass CString to any algorithm that accepts Random Access Range by using this article.

Requirements

• Microsoft Visual C++ .NET Version 7.1
• WTL Version 7.5
• Boost C++ Libraries Version 1.33.0 (no compilation required unless building a demo)
• The Ketchup Message Map Library (if you want the newest version)

Quick start

1. Include the header:

   #include "ketchup/tomato/string.hpp"

2. Call algorithms:

   #include <boost/algorithm/string.hpp>
   
   void quick_start()
   {
     WTL::CString str(_T("hello range!"));
     boost::to_upper(str);
     ATLASSERT( str == _T("HELLO RANGE!") );
   }

I'll introduce some algorithms that ATL/WTL CString can work with.

Boost.String algorithm

Boost.StringAlgorithm works well:

#include <boost/algorithm/string.hpp>

void test_string_algo()
{
  ATL::CFixedStringT<ATL::CString, 50> str(_T("123xxx321"));

  ATLASSERT( boost::starts_with(str, _T("123")) );
  ATLASSERT( !boost::starts_with(str, _T("1234")) );
}

tomato::back_inserter

As ATL/WTL CString cannot conform to Sequence, you cannot directly replace characters of CString. But you have the Output Iterator:

#include "ketchup/tomato/iterator.hpp"

void test_back_inserter()
{
  ATL::CString strout;
  boost::replace_first_copy( tomato::back_inserter(strout), 
                      _T("1abc3abc2"), _T("abc"), _T("YYY"));
  ATLASSERT( strout == _T("1YYY3abc2") ); 
}

tomato::back_inserter accepts Back Insertion Sequence like std::string.

STL algorithms

STL algorithms also work well. As STL doesn't know the Boost.Range concepts, you need the help of boost::begin and end that Boost.Range functions contain:

#include <algorithm>
#include <boost/range.hpp>

void test_std_algo()
{

  WTL::CString str(_T("acbfdge"));
  std::sort(boost::begin(str), boost::end(str));
  ATLASSERT( str == _T("abcdefg") );
}

All the algorithms that accept Random Access Iterator can work. Keep in mind that Boost.Range functions are replacements for the corresponding members of Container. You shouldn't use members like GetBuffer, GetString and begin from here on.

Boost.Regex

Boost.Regex already supports ATL::CString, but WTL::CString that I support is missing:

#include <boost/regex.hpp>
// for boost::tregex
#include <boost/regex/mfc.hpp>

void test_regex()
{
  WTL::CString str(_T("123a1cxxxa23cXXXa456c321"));
  boost::tregex rx(_T("a([0-9]+)c"));
  WTL::CString fmt(_T("_A$1C_"));

  WTL::CString strout = boost::regex_replace(str, rx, fmt);
  ATLASSERT( boost::equals( strout, 
                   _T("123_A1C_xxx_A23C_XXX_A456C_321")) );
}

Another way is to use the thin wrappers that Boost.StringAlgorithm provides:

#include <string>
// yet required
#include <boost/algorithm/string/regex.hpp>
// for boost::tregex
#include <boost/regex/mfc.hpp>

void test_algo_regex()
{
  // works around missing overloads
  typedef std::basic_string<TCHAR> fmt_string_t; 

  ATL::CString str(_T("123a1cxxxa23cXXXa456c321"));
  boost::tregex rx(_T("a([0-9]+)c"));
  fmt_string_t fmt(_T("_A$1C_"));

  WTL::CString strout;
  boost::replace_regex_copy( tomato::back_inserter(strout), 
                                              str, rx, fmt );
  ATLASSERT( boost::equals( strout, 
                         _T("123_A1C_xxxa23cXXXa456c321")) );
}

Points of interest

Why CString should conform to Boost.Range concept? Now that we have three string types; std::string, ATL::CString and WTL::CString, which one will you select while writing your own algorithm? Will you define _CSTRING_NS like poor WTL? Boost.Range solves these problems.

By the way, why should we write hundreds of begin and end for STL algorithms? Boost.RangeEx (unofficial) provides thin wrapper functions:

#include <boost/range_ex/algorithm.hpp>

void test_range_algo()
{
  WTL::CString str(_T("acbfdge"));
  boost::sort(str);
  ATLASSERT( str == _T("abcdefg") );
}

References

• Tomato.String
• P-Stade
• Boost C++ Libraries
• Boost.Range
• Boost.RangeEx
• Boost.Regex
• Boost.StringAlgorithm

Release notes

• Version 0.90.0 - Initial release.