Evolution of the RegExp pattern for the macro used in the xls-to-sql script

xls-to-sql_patterns.re

\{(?P<noun>(?:cols?|range))\:(?:(?<=col:)(?P<col>(?:[a-zA-Z]+|[0-9]+))|(?<=cols:)(?P<cols>(?:[a-zA-Z0-9\-\,]+))|(?<=range:)(?P<col_start>(?:[a-zA-Z]+|[0-9]+))\-(?P<col_stop>(?:[a-zA-Z]+|[0-9]+)))\}(?P<modifier>(?:[\?\!]))?


\{													(?# Opening delimiter match) 
	(?P<noun>(?:cols?|range))						(?# Match the noun (col, cols, or range)) 
	\:
	(?:
		(?<=col:)									(?# Look-behind conditional for the 'col' noun) 
			(?P<col>(?:[a-zA-Z]+|[0-9]+))			(?# Creates named group 'col' with either alpha or numeric value(s) (but not both))
		|
		(?<=cols:)									(?# Look-behind conditional for the 'cols' noun) 
			(?P<cols>(?:[a-zA-Z0-9\-\,]+))			(?# Creates named group 'cols' with a comma delimited list of columns) 
		|
		(?<=range:)									(?# Look-behind conditional for the 'range' noun)
			(?P<col_start>(?:[a-zA-Z]+|[0-9]+))		(?# Creates named group 'col_start' with the beginning range number/letter) 
			\-
			(?P<col_stop>(?:[a-zA-Z]+|[0-9]+))		(?# Creates named group 'col_stop' with the ending range number/letter) 
	)
\}													(?# Closing delimiter match) 
(?P<modifier>(?:[\?\!]))?							(?# Check for the modifier (? means its optional, ! means its required))