Converts the given FirstConsumedChar to a FirstLookChar.
This is conceptually equivalent to wrapping the given consumed character into a lookaround.
This is semantically equivalent to a|(?=b|$) -> (?=a|(?=b|$)) == (?=[ab]|$).
a|(?=b|$)
(?=a|(?=b|$))
(?=[ab]|$)
Converts the given FirstConsumedChar to a FirstLookChar.
This is conceptually equivalent to wrapping the given consumed character into a lookaround.
This is semantically equivalent to
a|(?=b|$)->(?=a|(?=b|$))==(?=[ab]|$).