Answer to Exercise 75

ANSWER TO EXERCISE 75

(Cf. the blackboard code in 'Toyshop'.)

Global from_char; Global to_char;
[ QuotedText i j f;
   i = parse->((++wn)*4-3);
   if (buffer->i=='"')
   {   for (j=i+1:j<=(buffer->1)+1:j++)
           if (buffer->j=='"') f=j;
       if (f==0) return -1;
       from_char = i+1; to_char=f-1;
       if (from_char>to_char) return -1;
       while (f> (parse->(wn*4-3))) wn++; wn++;
       return 0;
   }
   return -1;
];

Note that in the case of success, the word marker wn is moved beyond the last word accepted (since the Z-machine automatically tokenises a double-quote as a single word). The text is treated as though it were a preposition, and the positions where the quoted text starts and finishes in the raw text buffer are recorded, so that an action routine can easily extract the text and use it later. (Note that "" with no text inside is not matched by this routine but only because the last if statement throws out that one case.)

Back to the exercise in section 27