Aha.. thanks for that explanation.
Jako Menkveld wrote:[color=blue]
> You can try
http://babelfish.altavista.com to translate the German to[/color]
[color=blue]
> English (or whatever other language you'd prefer), try it, it's quite[/color]
good.[color=blue]
>
> As for what tokens are, in java speak, a token is a part of[/color]
something. If[color=blue]
> for instance you have a string "abc,def,ghi" (comma-seperated), you[/color]
can use[color=blue]
> what Java calls a StringTokenizer to break the string up into it's[/color]
parts (or[color=blue]
> tokens). It is similar to string.Split, which returns an array, the
> StringTokenizer however returns a collection which you can iterate[/color]
through[color=blue]
> using methods like NextToken().
>
>
> "Mad Scientist Jr" <usenet_daughter@yahoo.com> wrote in message
> news:1108049812.859574.94520@g14g2000cwa.googlegro ups.com...[color=green]
> > Has anyone worked on code that that can parse evaluation[/color][/color]
expressions[color=blue][color=green]
> > (could be numbers or strings) like
> >
> > ( ( "dog" = "dog" ) or "foo" = "bar" ) and ("cow" = "bat" and[/color][/color]
"bye" =[color=blue][color=green]
> > "hi") or ("math" = "fun")
> >
> > or
> >
> > ( ( 1 = 5 ) or ( 2 < 3 ) ) and (1 <= 6)
> >
> > or (here it gets a little complicated with math expressions)
> >
> > ( ( 1 = ((5*2)+1) ) or ( 2 < 3 ) ) and (1 <= 6)
> >
> > ?
> >
> > I have a compare functions to evaluate <, <=, =, !=, >=, > for[/color][/color]
strings[color=blue][color=green]
> > and numbers, and a math parser, and all the values would be[/color][/color]
literal. I[color=blue][color=green]
> > am looking either to figure out how to do it, or find existing code
> > that would work.
> >
> > I am not sure recursion is correct to do this, or how to put it all
> > together, parsing out the "AND"s and "OR"s, and keeping track of[/color][/color]
the[color=blue][color=green]
> > parenthesis hierarchy (while ignoring math expressions which also[/color][/color]
have[color=blue][color=green]
> > parenthesis) in the correct order of precedence, and ultimately
> > returning a single boolean value for the entire thing.
> >
> > Here is some pseudocode I put together to work it out - any help[/color][/color]
would[color=blue][color=green]
> > be appreciated.
> >
> > EVALUATE A BOOLEAN EXPRESSION IN A STRING
> > AND RETURN TRUE OR FALSE:
> > if odd # of parens (not part of quoted string) return error
> > if quotes, string mode, else math mode
> > has parens?
> > yes: analyze further
> > iPosNextEnd = next closing parens
> > find closing parens by adding +1 evertime an open paren
> > (not part of quoted text) found, -1 every time a closed
> > paren found. when parencount back to 0 we know we have
> > reached the end of the current paren block.
> > between iStart and iPosNextEnd
> > look inside (outside of quotes)
> > for comparison operator
> > yes? break down further
> > no? found value.
> > if math mode
> > send contents to math parser to evaluate
> > use string value as is
> > no: evaluate
> > look inside (outside of quotes)
> > for AND/OR
> > if 1 AND/OR
> > evaluate left side vs right side
> > else MULTIPLE AND/ORs (see below):
> > look for all ANDs, all ORs, store position in list (OPERATOR,[/color][/color]
VAL[color=blue][color=green]
> > 1, VAL 2, RESULT)
> > traverse list and evaluate
> > evaluate ANDs, store result
> > evaluate ORs, store result
> >
> > MULTIPLE AND/OR WITHOUT PARENS:
> > it seems expressions with "and" are evaluated first.
> > take a statement like:
> > If T1 = 1 And T2 = 2 Or T3 = 3 Then
> >
> > T1 T2 T3 Evaluates to
> > -- -- -- ------------
> > 1 2 3 true
> > 1 2 4 true
> > 1 5 4 false
> > 1 5 3 true
> >
> > PS I found some Java code on a Deutch site that looks like it might[/color][/color]
be[color=blue][color=green]
> > similar to what I need to do. I know vb.net not Java, and the[/color][/color]
comments[color=blue][color=green]
> > aren't in English, so I don't really understand all it is doing,[/color][/color]
but I[color=blue][color=green]
> > see it is using some kind of lists or tokens (what's a token?) to[/color][/color]
keep[color=blue][color=green]
> > track of things. Can anyone convert this to .NET without too much
> > trouble?
> >
> >
http://www.brian-schroeder.de/parser/
> >[/color][/color]
