Complex Layout Problem

Dar Scott dsc at
Fri Oct 31 19:03:12 EST 2003

On Thursday, October 30, 2003, at 12:53 PM, Bojsza wrote:

> Example: The user enters sAddr dAddr and wants 
> this combination OR sAddr AND NOT dAddr
> This builds the expression
> (sAddr AND dAddr OR (sAddr NOT dAddr 

You might try an RPN calculator that build expressions rather than 
evaluate them.  You can design it in such a way that only valid 
expressions can be built.  You can even make sensitive to the type of 
data (based on the operator that created it) and dim buttons not 
applicable.  This can be expanded to other IP packet and TCP packet 
header fields as well as other relational operators.

You might alternately try allowing a user to type in an expression.  
This runs into a parsing problem, of course.

Some of the online search engines greatly limit the kinds of 
expressions using some fields for values.  This might be too 
restrictive for you.

(You didn't ask, I know...  Users like to have the option of seeing the 
relational operator and maybe the long name of the field.  Like this:  
"source IP address = and TTL < 23"  A quarter century ago I 
created a method for "factoring" logical expressions so one could do 
things like this:  "source or destination IP address = 10,10.2.3, or")

Dar Scott

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