[REBOL] Re: [FIND] [FoxPro] Re: Find? Copy/Part?
From: greggirwin:mindspring at: 18-Jan-2005 13:02
Hi Carlos,
CL> Would it be very nice to have an AT-like native function in
CL> REBOL/Core, don't you think so?
Submit a wish request to RAMBO for a refinement on FIND. It could be
very useful at times.
I have to admit that I haven't found a deep need for it myself,
because REBOL has different ways of dealing with things, but it could
be a nice thing to make people more comfortable (and productive) when
they move to REBOL from another language.
I did the following to test the new PARSE feature that allows you to
return from a parse action, so it will only work under the newest
releases, but the idea could be adapted for the official releases.
find-Nth: func [
"Returns the series at occurrence N of value or none."
series [series!]
value
n [integer!]
/local count pos
][
count: 0
parse series [
some [
to value pos: (
count: count + 1
if count = n [return pos]
) skip
]
]
none
]
test-Nth: func [ser val occ] [print mold find-Nth ser val occ]
repeat i 6 [
test-Nth "aaa*bbb*ccc*ddd*eee*fff" #"*" i
]
test-Nth "aaa bbb ccc ddd eee fff" #"*" 2
repeat i 5 [
test-Nth [aaa 0 bbb 1 ccc 0.0 ddd 2 eee 1.1 fff 3] integer! i
]
repeat i 3 [
test-Nth [aaa 0 bbb 1 ccc 0.0 ddd 2 eee 1.1 fff 3] decimal! i
]
repeat i 7 [
test-Nth [aaa 0 bbb 1 ccc 0.0 ddd 2 eee 1.1 fff 3] number! i
]
test-Nth [aaa 0 bbb 1 ccc 0.0 ddd 2 eee 1.1 fff 3 x] number! 7
test-Nth [aaa 0 bbb 1 ccc 0.0 ddd 2 eee 1.1 fff 3 x] issue! 1
Then you can easily emulate what you want from Fox.
>> s: "aaa*bbb*ccc*ddd*eee*fff"
>> left: func [series pos] [copy/part series pos]
>> left s find-Nth s #"*" 2
== "aaa*bbb"
Or even go a step further.
>> up-to-Nth: func [series value n] [left series find-Nth series value n]
>> up-to-Nth s #"*" 2
== "aaa*bbb"
-- Gregg
