• C

Script Parsing

I have a test script syntax of the form:

The first implies that tracks 1 is required AND either if tracks 2 or 3. The second implies that either track 1 or 2 is OK.  These are left associative. READ, WRITE, TRACK_1, TRACK_2, TRACK_3 are the only keywords.

I have to find a general (but efficient) algorithm to do these.  I also want to be able to store the order of evaluation to a structure that I can pass to any routine (that way, I don't have to parse again).  I already have a tokenizing routine so that's one out.

Any ideas?  (This is usually directed to anyone with an experience in compilers and translators).
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To write this from scratch in C would be fairly pointless when there are so many useful tools such as lex, yacc and bison about which can do the job for you quite efficiently.
ealvaAuthor Commented:
No. This is not a full-fledged language. I do not need yacc and lex.
If you already have a tokenizing routine, why not give each token a  number (like LEX) and then call a routine with variable number of parameters. That way you can pass a list of number, representing the parsed sentence
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You could use "strtok".
Elfie:  isn't that what the definition of tokenization is?

Tokenizing is the easy part, the hard part is determining the order of evaluation.

I would go about it by first converting the infix espression to postfix, and then using a stack to evaluate the postfix expression.
Rather than bother with converting and then stacking, I would just do a recursive descent.
>>I also want to be able to store the order of evaluation

If you want to STORE the order of evaluation, a postfix expression is most efficient.
ealvaAuthor Commented:
scrapdog is right. I do have to first convert to postfix in order to determine the order of evaluation. How do I award the answer?

>scrapdog is right. I do have to first convert to postfix in
>order to determine the order of evaluation. How do I award the

If it was my answer you were talking about, grade it :)
.if not, reject it.

Btw, if you need infix to postfix algorithms, I can show you some (in Pascal though...).  These are (almost) generic;  you would have to change them to accommodate your needs.

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ealvaAuthor Commented:
Thanks, scrapdog.
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