A simple project (for studying purposes) to parse regex with combine library.

RegexpParser.parse("er?lx.r\\s[^abc]+\\w?\\W{2}\\d") 
> [
    %RegexpParser.Character{char: "e", quantifier: nil},
    %RegexpParser.Character{char: "r", quantifier: %RegexpParser.Quantifier{max: 1, min: 0}},
    %RegexpParser.Character{char: "l", quantifier: nil},
    %RegexpParser.Character{char: "x", quantifier: nil},
    %RegexpParser.Dot{quantifier: nil},
    %RegexpParser.Character{char: "r", quantifier: nil},
    %RegexpParser.BackslashLetter{backslash_letter: "s", quantifier: nil},
    %RegexpParser.List{characters: ["a", "b", "c"], except: true, quantifier: %RegexpParser.Quantifier{max: nil, min: 1}},
    %RegexpParser.BackslashLetter{backslash_letter: "w", quantifier: %RegexpParser.Quantifier{max: 1, min: 0}},
    %RegexpParser.BackslashLetter{backslash_letter: "W", quantifier: %RegexpParser.Quantifier{max: 2, min: 2}},
    %RegexpParser.BackslashLetter{backslash_letter: "d", quantifier: nil}
  ]

TODO

Metacharacters	Implemented
Dot	Yes!
Backslash-letter	Yes!
Lists	Yes!
Quantifiers	Yes!
Anchors	No
Escape	No
Or	No
Group	No