parser uses string descriptors

3.3: adda/translate/parser/use string descriptors:
. one way to parse a string
is use the lexical analyzer to find the relevant substrings,
and then make lexical nodes that point at copies of string;
the way I'm thinking of now
uses string descriptors instead of copies:
put the string in an array of characters,
and then a descriptor is an index into that array,
along with intended length .
. the advantage to this way is that
if the parser gets confused,
a repair algorithm can work with the result
searching not only the tree,
but also the string,
and seeing how they relate .