regexps.xreate
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	===========================
	DATA


	patternAB = [Sequence,
	[[ZeroOrMore, "a"],
	[Text, "b"]]].

	==========================
	HANDLERS

	Matcher = type variant (Sequence, ZeroOrMore, Text)

	matchSequence = function(text::string, sequence::undef):: int{
	textLength = length(text):: int.

	loop fold(sequence-> matcher:: undef, 0->pos){
	n = match(mid(text, pos, textLength), matcher).

	if (n == pos_FAIL:: break){
	pos

	} else {
	pos+n
	}
	}
	}

	matchZeroOrMore= function(text::string, matcher::string):: int{
	textLength = length(text):: int.

	loop fold inf(0->pos, n==pos_FAIL){ //<--- infinite loop?
	n = match(matcherChild, mid(text, pos, textLength)).

	if (n == pos_FAIL:: break){
	pos

	} else {
	pos+n
	}
	}
	}

	matchText = function(text::string, matcher::string):: int {
	textLength = length(text):: int.

	if (length(matcher) <= textLength, mid(text, 0, length(matcher)) == matcher)
	{
	textLength;

	} else {
	pos_FAIL;
	}
	}

	match = function(text::string, pattern::undef)::string{

	n = switch (pattern[0]) :: int
	case (Sequence) {matchSequence(text, pattern[1])}
	case (ZeroOrMore) {matchZeroOrMore(text, pattern[1])}
	case (Text) {matchText(text, pattern[1])}
	case default {pos_FAIL}

	if (n != pos_FAIL)
	{mid(text, 0, n)}
	else
	{text_FAIL}
	}

	=================================
	CLIENT

	test = function(){
	match(patternAB, "aaaaab").
	match(patternAB, "baaaaa").
	}