From: "Robert K." <shortcutter@...>
Date: 2011-07-15T18:17:04+09:00
Subject: Re: regex to match a , and seperate.

irb(main):007:0> str =
"server[1,2].localhost.com,server[2-5].localhost.com,server1.localhost.com"
=>
"server[1,2].localhost.com,server[2-5].localhost.com,server1.localhost.com"

irb(main):008:0> str.scan %r{(?:[^,\[\]]+|\[[^\]]*\])+}
=> ["server[1,2].localhost.com", "server[2-5].localhost.com",
"server1.localhost.com"]

Now, if you want to be safe against multiple nesting levels you can use
recursive matching:

irb(main):033:0> str =
"server[1,2].localhost.com,server[2-5[3-9]].localhost.com,server1.localhost.com"
=>
"server[1,2].localhost.com,server[2-5[3-9]].localhost.com,server1.localhost.com"

irb(main):034:0> str.scan( %r{ (?<name> (?: [^,\[\]]+ | (?<gr> \[ (?:
[^\[\]] | \g<gr> )* \] ) )+ ) }x ).map { $~[:name] }
=> ["server1.localhost.com", "server1.localhost.com",
"server1.localhost.com"]

with a bit friendlier formatting

irb(main):046:0* str.scan(
irb(main):047:1*   %r{
irb(main):048:1/     (?<name>
irb(main):049:1/       (?:
irb(main):050:1/           [^,\[\]]+
irb(main):051:1/         | (?<gr> \[ (?: [^\[\]]+ | \g<gr> )* \] )
irb(main):052:1/       )+
irb(main):053:1/     )
irb(main):054:1/   }x ).map { $~[:name] }
=> ["server1.localhost.com", "server1.localhost.com",
"server1.localhost.com"]


or (basically the same regexp without the outer named group):

irb(main):035:0> str.scan %r{ (?: [^,\[\]]+ | (?<gr> \[ (?: [^\[\]]+ |
\g<gr> )* \] ) )+ }x do puts $& end
server[1,2].localhost.com
server[2-5[3-9]].localhost.com
server1.localhost.com
=>
"server[1,2].localhost.com,server[2-5[3-9]].localhost.com,server1.localhost.com"

SCNR :-)

Cheers

robert

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