Name      : rSubstitute
 Author    : JasonGrossman?
 Revision  : IoWiki? 0.87

// Regular expression substitutions, with wild cards. Jason.Grossman@staff.usyd.edu.au

// usage example: "wombats are cuddly" rSubstitute ("([a-z][ao][a-z])([a-z][ao][a-z])", "\\2-\\1") // ==> "bat-woms are cuddly"

regexCache := Map clone Buffer rSubstitute := method (findRegex, substituteRegex,

	r := regexCache atIfAbsentPut (findRegex, Regex clone setPattern (findRegex)) // cache compiled regular expressions, for speed
	r setString (self asString)
	regexMap := Map clone
	maxSubstitutionTerms := (substituteRegex length / 3 + 1 roundUp) // a safe upper bound on the number of substitution terms, each of which takes 3 chars to specify ("\\1" etc.)
	r allMatches foreach (i, v,
		if (v type != "List") then (v := list (v))
		for (n, maxSubstitutionTerms, 0,
			groupN := v at (n)
			regexMap atPut ("\\" .. n asString, groupN or "")
		)
		self := self replace (v at (0), substituteRegex replaceMap (regexMap))
	)
	self

)