[REBOL] Re: [algorithm] Algorithm challenge: selecting a range from multiple blocks
From: sant4:wanadoo at: 20-Sep-2007 22:38
Ho, hi
i give it a try
(sorry folks, my code is not tested)
Some comments on my code:
-First object found is cloned (always)
-Last object is cloned (if needed)
-all intermediate objects are just inserted as-is in the result block (out)
(if only one object is returned, he may be cloned two times before being added)
get-subset: func [
data [block!]
range [block!]
/local obj start rest len
][
out: make block! 50
start: range/1
;skip data until i found the first object
while [start > len: length? data/1/items][
data: next data
start: start - len
]
; hey !!! it's the first object (perhaps the only)
obj: make data/1 [items: cp at data/1/items start]
; insert objects in the result until there is no rest
rest: range/2 - range/1 + 1
while [rest >= len: length? obj/items][
unless len = 0 [
insert tail out obj
rest: rest - len
]
data: next data
obj: first data
]
; may I clone the last object ?
if len > rest [
insert tail out make obj [items: cp/part obj/items rest]
]
out
]
==Steeve
