JCppFacet.hh

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#ifndef __JLANG__JCPPFACET__
#define __JLANG__JCPPFACET__

#include <istream>
#include <ostream>
#include <locale>
#include <string>
#include <iterator>
#include <limits>


#include "JLang/JStringFacet.hh"

/**
 * \author mdejong
 */

namespace JLANG {}
namespace JPP { using namespace JLANG; }

namespace JLANG {


  /**
   * Facet class to specify parsing of a C[++] variable name.
   */
  class JCppFacet: 
     public JStringFacet
  {
  public:
    /**
     * Constructor.
     */
    JCppFacet()
    {}


    /**
     * Clone this facet.
     *
     * \return           pointer to newly created facet
     */
    virtual JCppFacet* clone() const override 
    {
      return new JCppFacet();
    }


    static inline bool is_eol (const char c) { return c == ';'; }

    static inline bool is_begin_single_line_comment(const char c1, const char c2) { return c1 == '/' && c2 == '/'; }
    static inline bool is_begin_multi_line_comment (const char c1, const char c2) { return c1 == '/' && c2 == '*'; }

    static inline bool is_end_single_line_comment  (const char c1)                { return c1 == '\n'; }
    static inline bool is_end_multi_line_comment   (const char c1, const char c2) { return c1 == '*' && c2 == '/'; }


    /**
     * Get string.
     *
     * \param  __begin   begin position of input stream
     * \param  __end     end   position of input stream
     * \param  format    format
     * \param  result    status after input operation
     * \param  buffer    output string
     * \return           position of input stream
     */
    istreambuf_iterator get(const istreambuf_iterator __begin,
                            const istreambuf_iterator __end,
                            const std::ios_base&      format,
                            std::ios_base::iostate&   result,
                            std::string&              buffer) const
    {
      return do_get(__begin, __end, format, result, buffer);
    }


    /**
     * Put string.
     *
     * \param  out       begin position of output stream
     * \param  format    format
     * \param  c         fill character
     * \param  buffer    input string
     * \return           position of output stream buffer
     */
    ostreambuf_iterator put(ostreambuf_iterator  out,
                            const std::ios_base& format,
                            const char           c,
                            const std::string&   buffer) const
    {
      return do_put(out, format, c, buffer);
    }


  protected:
    /**
     * Get string.
     *
     * \param  __begin   begin position of input stream
     * \param  __end     end   position of input stream
     * \param  format    format
     * \param  result    status after input operation
     * \param  buffer    output string
     * \return           position of input stream
     */
    virtual istreambuf_iterator do_get(const istreambuf_iterator __begin,
                                       const istreambuf_iterator __end,
                                       const std::ios_base&      format,
                                       std::ios_base::iostate&   result,
                                       std::string&              buffer) const
    {
      using namespace std;

      result = (ios_base::iostate) 0;  // reset I/O status

      streamsize n = format.width();   // number of characters to read

      if (n == 0) {
        n = numeric_limits<streamsize>::max();
      }

      istreambuf_iterator i = __begin;

      if (i == __end || (i = do_ignore(i, __end)) == __end) {

        result |= ios_base::failbit;    
        result |= ios_base::eofbit;

      } else {

        char c = *i;

        for (++i; i != __end; c = *i, ++i) {

          // skip comment line(s)

          if      (is_begin_single_line_comment(c,*i))
            i = do_ignore_single_line_comment(i, __end);
          else if (is_begin_multi_line_comment (c,*i))
            i = do_ignore_multi_line_comment (i, __end);
          else if (c == '_' || isalpha(c))                  // first character must be letter or underscore
            break;

          i = do_ignore(i, __end);
        }

        if (i == __end) {

          result |= ios_base::failbit;  
          result |= ios_base::eofbit;

        } else {

          buffer.clear();
          buffer.push_back(c);
          
          for (--n; i != __end && n != 0 && (*i == '_' ||
                                             isalnum(*i));  // following characters may also be digits
               ++i, --n) {
            buffer.push_back(*i);
          }
          
          if (i == __end) {
            result |= ios_base::eofbit;
          }
        }
      }

      return i;
    }


    /**
     * Put string.
     *
     * \param  out       begin position of output stream
     * \param  format    format
     * \param  c         fill character
     * \param  buffer    input string
     * \return           current position of output stream
     */
    virtual ostreambuf_iterator do_put(ostreambuf_iterator  out,
                                       const std::ios_base& format,
                                       const char           c,
                                       const std::string&   buffer) const
    {
      using namespace std;

      if (format.flags() & ios_base::right) {
        for (streamsize i = buffer.size(); i < format.width(); ++i, ++out) {
          *out = c;
        }
      }

      for (string::const_iterator i = buffer.begin(); i != buffer.end(); ++i, ++out) {
        *out = *i;
      }
        
      if (format.flags() & ios_base::left) {
        for (streamsize i = buffer.size(); i < format.width(); ++i, ++out) {
          *out = c;
        }
      }

      return out;
    }


    /**
     * Ignore white space and end of line characters.
     *
     * \param  __begin   begin position of input stream
     * \param  __end     end   position of input stream
     * \return           position of input stream
     */
    virtual istreambuf_iterator do_ignore(const istreambuf_iterator __begin,
                                          const istreambuf_iterator __end) const
    {
      istreambuf_iterator i = __begin;

      while (i != __end && (isspace(*i) || is_eol(*i))) {
        ++i;
      }

      return i;
    }


    /**
     * Ignore characters until end of line.
     *
     * \param  __begin   begin position of input stream
     * \param  __end     end   position of input stream
     * \return           position of input stream
     */
    virtual istreambuf_iterator do_ignore_single_line_comment(const istreambuf_iterator __begin,
                                                              const istreambuf_iterator __end) const
    {
      istreambuf_iterator i = __begin;

      for ( ; i != __end && !is_end_single_line_comment(*i); ++i) {}

      if (i != __end) {
        ++i;          // skip end of line
      }

      return i;
    }


    /**
     * Ignore characters until next end of comment.
     *
     * \param  __begin   begin position of input stream
     * \param  __end     end   position of input stream
     * \return           position of input stream
     */
    virtual istreambuf_iterator do_ignore_multi_line_comment(const istreambuf_iterator __begin,
                                                             const istreambuf_iterator __end) const
    {
      istreambuf_iterator i = __begin;

      if (i != __end) {

        char c = *i;

        for (++i; i != __end && !is_end_multi_line_comment(c,*i); c = *i, ++i) {}

        if (i != __end) {
          ++i;          // skip end of line
        }
      }

      return i;
    }

  private:

    JCppFacet(const JCppFacet&);        // not defined
    void operator=(const JCppFacet&);   // not defined
  };
}

#endif