Ruby scan Regular Expression

Question

I'm trying to split the string:

"[test| blah] \n [foo |bar bar bar]\n[test| abc |123 | 456 789]"

into the following array:

[
  ["test","blah"]
  ["foo","bar bar bar"]
  ["test","abc","123","456 789"]
]

I tried the following, but it isn't quite right:

"[test| blah] \n [foo |bar bar bar]\n[test| abc |123 | 456 789]"
.scan(/\[(.*?)\s*\|\s*(.*?)\]/)
# =>
# [
#   ["test", "blah"]
#   ["foo", "bar bar bar"]
#   ["test", "abc |123 | 456 789"]
# ]

I need to split at every pipe instead of the first pipe. What would be the correct regular expression to achieve this?

Answer 1

 s = "[test| blah] \n [foo |bar bar bar]\n[test| abc |123 | 456 789]"
 arr = s.scan(/\[(.*?)\]/).map {|m| m[0].split(/ *\| */)}

Answer 2

Two alternatives:

s = "[test| blah] \n [foo |bar bar bar]\n[test| abc |123 | 456 789]"

s.split(/\s*\n\s*/).map{ |p| p.scan(/[^|\[\]]+/).map(&:strip) }
#=> [["test", "blah"], ["foo", "bar bar bar"], ["test", "abc", "123", "456 789"]]

irb> s.split(/\s*\n\s*/).map do |line|
  line.sub(/^\s*\[\s*/,'').sub(/\s*\]\s*$/,'').split(/\s*\|\s*/)
end
#=> [["test", "blah"], ["foo", "bar bar bar"], ["test", "abc", "123", "456 789"]]

Both of them start by splitting on newlines (throwing away surrounding whitespace).

The first one then splits each chunk by looking for anything that is not a [, |, or ] and then throws away extra whitespace (calling strip on each).

The second one then throws away leading [ and trailing ] (with whitespace) and then splits on | (with whitespace).

---

You cannot get the final result you want with a single scan. About the closest you can get is this:

s.scan /\[(?:([^|\]]+)\|)*([^|\]]+)\]/
#=> [["test", " blah"], ["foo ", "bar bar bar"], ["123 ", " 456 789"]]

…which drops information, or this:

s.scan /\[((?:[^|\]]+\|)*[^|\]]+)\]/
#=> [["test| blah"], ["foo |bar bar bar"], ["test| abc |123 | 456 789"]]

…which captures the contents of each "array" as a single capture, or this:

s.scan /\[(?:([^|\]]+)\|)?(?:([^|\]]+)\|)?(?:([^|\]]+)\|)?([^|\]]+)\]/
#=> [["test", nil, nil, " blah"], ["foo ", nil, nil, "bar bar bar"], ["test", " abc ", "123 ", " 456 789"]]

…which is hardcoded to a maximum of four items, and inserts nil entries that you would need to .compact away.

There is no way to use Ruby's scan to take a regex like /(?:(aaa)b)+/ and get multiple captures for each time the repetition is matched.