EBNF Grammar help - part II

All,


        Many thanks to all the people who replied to my original post requesting
help with EBNF Grammar. The general consensus appears to be that I could
probably accomplish my objectives by developing a top- down recursive-
descent parsing algorithm. I have read about these and sort of comprehend
their function and objectives however I am still unclear as to how to go
about developing such a routine in Java.


        If I can explain my objective:


        in order to advance throughout our software a user must have
achieved a set of objectives. these are held in a text file
format. The objectives read like "you must have done A and (B or C) or
(D and E and F) and one out of (G, H, I)". The operators are well
defined, encompass basic logic (and, or, not) and elementary
sets. There is also a well documented set of operator precedence
rules. Operators take the standard form: '|', '+', '!', '{}'.


        The objective is to read in this expression from a file and parse
it so that I can arrive at a set of Java expressions that I can
serially step through and evaluate. If a user fails to achieve an
objective I can return false and the routine will exit. My stumbling
block is how to parse the string expression to derive a set of
concrete java expressions which I can the evaluate. For instance the
''one out of three' expression would be treated as an array that I can
step through and evaluate, but I have no Idea how to generate this.


        The reason I thought of using JavaCC is that it would have
generated JavaCode from the input expression which I could have then
evaluated. From a description of my problem, is this still viable?


        Any advice or suggestions would be most grateful.


        Paul

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