[REBOL] Re: Big parse rules
From: brett:codeconscious at: 20-Jul-2003 18:40
Hi Martin,
I'm not entirely sure how you want to partition your function's logic,
however I do have a couple of suggestions but no idea
if they will be useful for you.
It does seem though that you need a way to "contextualise" your sectional
rules.
1) Volker mentioned objects. One program I made recently had all the rules
together in a file call it eg. %lexical.r
Some of these rules had variable names to set and names of functions to call
from inside parens. Ie the variables
are state variables and the functions are equivalent to scanner events.
I then "late bound" the lexcial rules to the scanner like this...
scanner: copy [
tkType: tkStart: tkEnd: tkBeginLine: tkEndLine: tkEmit: none
tkResult: copy []
tkEmit: does [do-body tkType tkStart subtract index? tkEnd index?
tkStart]
]
scanner: make context scanner load %lexical.r
...where tkType, tkStart etc are words embedded in the rules stored in
%lexical. The scanner was was created inside a function to keep things tidy.
In this way I could possibly use different generated scanners to achieve
different purposes while reusing the same lexical rules.
2) functions
I'm interested in the way code/data can be exploited by converting it into a
function
eg this block stores a tree
sample-tree: [node 1 [node 2 [] node 3 []] node 4 []]
it can be transformed into a function body and each tree node evaluated by
doing something like
eval-tree: func [node] sample-tree
eval-tree func [label subtrees] [probe label reduce subtrees]
Hope one of these ideas helps!
Regards,
Brett.
