Package t-rex is a Tiny Regular EXpressions implementation, heavilly inspired by "A Regular Expression Matcher" and https://github.com/monolifed/tiny-regex-mod
'^' Start anchor, matches start of string
'$' End anchor, matches end of string
'*' Asterisk, match zero or more (greedy, *? lazy)
'+' Plus, match one or more (greedy, +? lazy)
'{m,n}' Quantifier, match min. 'm' and max. 'n' (greedy, {m,n}? lazy)
'{m}' exactly 'm'
'{m,}' match min 'm' and max. MAX_QUANT
'?' Question, match zero or one (greedy, ?? lazy)
'.' Dot, matches any character except newline (\r, \n)
'[abc]' Character class, match if one of {'a', 'b', 'c'}
'[^abc]' Inverted class, match if NOT one of {'a', 'b', 'c'}
'[a-zA-Z]' Character ranges, the character set of the ranges { a-z | A-Z }
'\s' Whitespace, \t \f \r \n \v and spaces
'\S' Non-whitespace
'\w' Alphanumeric, [a-zA-Z0-9_]
'\W' Non-alphanumeric
'\d' Digits, [0-9]
'\D' Non-digits
'\X' Character itself; X in [^sSwWdD] (e.g. '\\' is '\')