Subj : File Syntax checking: need logical help
To   : comp.programming
From : Abbacabba
Date : Mon Aug 01 2005 12:28 pm

I'm trying to create an efficient and manageable way to define a file
format and check it during processing.  Our file formats are both fixed
record length, and variable record/delimited.

I would like to be able to define a format, and have the program
generate the applicable rules.

Given a generic data structure definition: (example only)

A - manditory - A structure ends with H record
B - manditory - B structure ends with G Record
C - manditory - C Structure ends with D Record
C2 - Optional
C3 - Optional
D - Optional
E - Manditory
E1 - conditional - (E "packet" must have an E1, E1/E2, E2 or E3)
E2 - conditional - (E "packet" must have an E1, E1/E2, E2 or E3)
E3 - conditional - (E "packet" must have an E1, E1/E2, E2 or E3)
F - manditory
G - Manditory
H - Manditory

What type of logic structure would be the best to use?

I've looked at State machines and trees, but don't feel either(or my
implementation of either) comes across as flexable or efficient.


Example of logic:

If the program has just finished with an "A" record the only possible
correct record type to process would be a "B".

If the program has just finshed with a "C1" record, possible records
would be both a "C" or a "D" record.


I'm just needing some general ideas for a direction to pursue, not an
actual solution(although that would be most helpful).

Thank you,
JF

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