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comp.lang.ruby

redefining word boundaries?

jmb-d

6/17/2007 1:06:00 AM

Is it possible to redefine (temporarily) the meaning of \b in RegExp
situations?

Here's the scenario: I've got some data that looks something like,
"ABCD.E", which I stuff into an array as I encounter each new
instance. Eventually, I will join(", ") these together having
surrounded each of them with single quotes, for use in an SQL "IN
(...)" clause.

At first, I tried doing this with gsub(/\b/, "'"), but found out the
hard way that the period was wreaking havoc with my intended results,
and I got this: 'ABCD'.'E' instead.

My next attempt was to do it by hand, like this: gsub(/^/, "'").gsub(/
$/, "'"). This worked, but seems a bit like a hack.

So my question is whether there's any way to temporarily declare that
a period is NOT to be considered a word boundary.

Thanks, in advance,
jmb-d
3 Answers

Harry Kakueki

6/17/2007 4:04:00 AM

0

On 6/17/07, jmb-d <jon.budardanoff@gmail.com> wrote:
>
> My next attempt was to do it by hand, like this: gsub(/^/, "'").gsub(/
> $/, "'"). This worked, but seems a bit like a hack.
>
Does this give you the proper format?

arr = ["ABCD.E","FGHI.J","KLMN.O"]
puts arr.map{|x|"'#{x}'"}.join(",")

Harry

--

A Look into Japanese Ruby List in English
http://www.ka...

byronsalty

6/17/2007 5:41:00 AM

0

On Jun 16, 9:06 pm, jmb-d <jon.budardan...@gmail.com> wrote:
> Is it possible to redefine (temporarily) the meaning of \b in RegExp
> situations?

I think the only way to do this would be to redefine all the
circumstances in which a \b could occur yourself. For instance the 6
cases that I can think of are: ^\w, \W\w, \s\w, \w$, \w\W, \w\s. This
is a pain as you can see here I've done four and it's very ugly:

>"ABCD.E foo FG.HI".gsub(/^(\w)/, "'\\1").gsub(/(\w)$/, "\\1'").gsub(/(\w)(\s)/, "\\1'\\2").gsub(/(\s)(\w)/, "\\1'\\2")
=> "'ABCD.E' 'foo' 'FG.HI'"


Alternatively you could pre and post process by replacing "." with
something that doesn't break the boundary "zyzyzy" and then replace
back with "." when you're done inserting the ticks:
> "ABCD.E foo FG.HI".gsub(/\./, "zyzyzy").gsub(/\b/, "'").gsub(/zyzyzy/, ".")
=> "'ABCD.E' 'foo' 'FG.HI'"


Neither are very nice solutions.

- Byron
-----
http://www.salt...

jmb-d

6/18/2007 12:33:00 PM

0

On Jun 17, 12:03 am, "Harry Kakueki" <list.p...@gmail.com> wrote:
>
> Does this give you the proper format?
>
> arr = ["ABCD.E","FGHI.J","KLMN.O"]
> puts arr.map{|x|"'#{x}'"}.join(",")

Harry --

Yes, that's the result I'm looking for.

Thanks!