CHAR_CLASS = \[^?\]?-?([^]-]-[^]-]|[^]-])+-?\]|\[^?(-|\]|\]-)\]

#All the escape sequences
TAB = \\t
NEWLINE = \\n
CARRIAGE_RETURN = \\r
BACKSPACE = \\b
SPACE = \\s|\s
BELL = \\a
FORMFEED = \\f
VTAB = \\v

BACKSLASH = \\\\
ESCAPED_STAR = \\\*
ESCAPED_PLUS = \\\+
ESCAPED_PIPE = \\\|
ESCAPED_LPAREN = \\\(
ESCAPED_RPAREN = \\\)
ESCAPED_LBRACKET = \\\[
ESCAPED_RBRACKET = \\\]
ESCAPED_QUESTIONMARK = \\\?
ESCAPED_DOT = \\\.

# The special chars
DOT = \.
STAR = \*
PLUS = \+
QUESTIONMARK = \?
PIPE = \|
LPAREN = \(
RPAREN = \)

# Anything other than these is valid
# It cannot be ] or [, since those should be handled by CHAR_CLASS
# If it is a \, it is an invalid escape sequence
CHAR = [^][\]

ERROR = .