Parsing grep output

Parses lines of Text, skipping lines that are not valid grep output.

Parses a line of grep output. Returns Nothing if the line cannot be parsed.

The output should consist of a file name, line number and the content, separated by colons:

>>> parseLine "path/to/file:123:foobar"
Just (FileLineReference {_file = File {_fileName = "path/to/file"}, _lineReference = LineReference {_lineNumber = Just 123, _lineText = Text 6 "foobar"}})

Omitting the line number still produces valid output:

>>> parseLine "path/to/file:foobar"
Just (FileLineReference {_file = File {_fileName = "path/to/file"}, _lineReference = LineReference {_lineNumber = Nothing, _lineText = Text 6 "foobar"}})

However, an file name must be present:

>>> parseLine "foobar"
Nothing

ANSI escape codes in the line text are parsed correctly:

>>> parseLine "path/to/file:foo\ESC[31mbar\ESC[mbaz"
Just (FileLineReference {_file = File {_fileName = "path/to/file"}, _lineReference = LineReference {_lineNumber = Nothing, _lineText = Cat 9 [Text 3 "foo",Format 3 (Attr {attrStyle = KeepCurrent, attrForeColor = SetTo (ISOColor 1), attrBackColor = KeepCurrent, attrURL = KeepCurrent}) (Text 3 "bar"),Text 3 "baz"]}})