Re: Parsing - is this a sensible idea?

I wrote a class like that a few years ago and it turned out to be quite
useful

Example code:

   string Part1, Part2, Key;
   parse_str(Line) >> Part1 >> "%" >> Key >> "%" >> Part2 >> "";
   if (Key.size() != 0) ...

The class was modelled after the Rexx parse command so it uses some
special strings like
"." for word
"10" to go to position 10 in the string
"+10" to go 10 positions forward in the string
"," to go to the next line in the string etc.

The construction of the class is as follows

parse_str(const string& in_s) ...
Constructor that just saves the string variable internally

//method that picks up integer variable to assign value to and returns the
object to enable
//continuing using >> operators
parse_str& operator>>(int& ival)
{
   wordstep();
   (this->*m_try_assign)();
   m_pvar = (void*)&ival;
   m_try_assign = &parse_str::try_assign_int;
   m_wordmatch = 1;
   return *this;
}

// method that recognizes special strings and search items
parse_str& operator>>(const char* in_psz)...

// method that converts a part of the parse string to an integer
int try_assign_int() ...
 

// variables

void* m_pvar; // pointer to variable to set value to
const string m_str; // string passed in as argument to constructor
int (t_parse_string::* m_try_assign)(void); function pointer to method
that assigns variable

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