How to get possibly overlapping matches in a string

Question

I\'m looking for a way, either in Ruby or Javascript, that will give me all matches, possibly overlapping, within a string against a regexp.

---

Let\'s say I have

Answer 1

▶ str = "abcadc"
▶ from = str.split(/(?=\p{L})/).map.with_index { |c, i| i if c == 'a' }.compact
▶ to   = str.split(/(?=\p{L})/).map.with_index { |c, i| i if c == 'c' }.compact
▶ from.product(to).select { |f,t| f < t }.map { |f,t| str[f..t] }
#⇒ [
#  [0] "abc",
#  [1] "abcadc",
#  [2] "adc"
# ]

I believe, that there is a fancy way to find all indices of a character in a string, but I was unable to find it :( Any ideas?

Splitting on “unicode char boundary” makes it to work with strings like 'ábĉ' or 'Üve Østergaard'.

For more generic solution, that accepts any “from” and “to” sequences, one should introduce just a little modification: find all indices of “from” and “to” in the string.