4 Apr 2001 00:23:40 -0400

Related articles |
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EBNF Grammar help - part II paul.meaney@qa.com_NOSPAM.star.co.uk (Paul Meaney) (2001-04-04) |

Re: EBNF Grammar help - part II joachim_d@gmx.de (Joachim Durchholz) (2001-04-10) |

Re: EBNF Grammar help - part II cfc@world.std.com (Chris F Clark) (2001-04-10) |

From: | "Paul Meaney" <paul.meaney@qa.com_NOSPAM.star.co.uk> |

Newsgroups: | comp.compilers,comp.compilers.tools.javacc |

Date: | 4 Apr 2001 00:23:40 -0400 |

Organization: | Compilers Central |

Keywords: | parse |

Posted-Date: | 04 Apr 2001 00:23:40 EDT |

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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