private letter_sequence Parse_letter_sequence(letter_sequence _self = null)
{
/* letter-sequence:
* letter
| letter letter-sequence */
var _letter = Parse_letter();
if (_letter != null)
{
var _letter_sequence = new letter_sequence(_letter, _self);
_self = Parse_letter_sequence(_letter_sequence);
}
return(_self);
}
public word(letter_sequence _letter_sequence)
{
letter_sequence = _letter_sequence;
expression = letter_sequence.expression;
}
public letter_sequence(letter _letter, letter_sequence _letter_sequence)
{
letter = _letter;
self_letter_sequence = _letter_sequence;
expression = self_letter_sequence?.expression + letter.expression;
}