| Developing ColdFusion Applications |
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Using Regular Expressions in Functions |
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| Developing ColdFusion Applications |
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Using Regular Expressions in Functions |
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The REFind and REFindNoCase functions allow you to get information about matched subexpressions. If you set these functions' fourth parameter, ReturnSubExpression, to True, the function returns a CFML structure with two arrays containing the positions and lengths of text strings that match the subexpressions of the first instance of a matched regular expression pattern.
The returned structure has two keys, pos and len. The pos array contains the position of the subexpressions. The len array has the length of each subexpression. The first element of each array contains information about the complete matched expression, and indices 2 onwards contain information about the parenthesized elements. If there are no occurrences of the regular expression, the pos and len arrays each contain 1 element with a value of 0.
In the following example the first match for the expression ([A-Aa-z]+)[ ]+, is "is is". The expression [A-Za-z]+ is a subexpression of the complete regular expression.
<cfset subExprs=REFind("([A-Za-z]+)[ ]+\1",
"There is is a cat in in the kitchen",1,"True")>
When ColdFusion executes the ReFind function, subExprs.pos[1]=7, subExprs.len[1]=5, subExprs.pos[2]=7, and subExprs.len[2]=2.
The entries subExprs.pos[1] and subExprs.len[1] refer to the entire matched expression ("is is"), while subExprs.pos[2] and subExprs.len[2] refer to the first parenthesized subexpression ("is"). Because REFind returns information on the first regular expression match only, the subExprs structure does not contain information about the second match to the regular expression, "in in".
For a full discussion of subexpression usage, see the sections on REFind and REFindNoCase in the ColdFusion Functions chapter of the CFML Reference.
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