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List:       xsl-list
Subject:    Re:=?UTF-8?B?wqA=?=[xsl] Need an XPath expression which returns all xs:pattern elements containing a
From:       "Roger L Costello costello () mitre ! org" <xsl-list-service () lists ! mulberrytech ! com>
Date:       2024-04-04 15:46:47
Message-ID: 20240404114619.f5d5bb64 () lists ! mulberrytech ! com
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David Carlisle devised a brilliant approach:

Do a series of replace operations:

remove all whitespace: 

    replace(@value,'\s','')

replace \-quoted characters by x:

    replace(@value,'\\.','x')
    
replace {99,} constructs by *

    replace(@value,'\{[0-9]+,\}','*')
    
Here are the replaces, inlined:

replace(replace(replace(@value,'\{[0-9]+,\}','*'),'\\.','x'),'\s','')

Here are the results of applying the replaces to some regexes:

A*  --> apply replaces --> A*
A+  --> apply replaces --> A+
A\*  --> apply replaces --> Ax
A\+  --> apply replaces --> Ax
A{0,} --> apply replaces --> A*
A{1,} --> apply replaces --> A*
A{5,} --> apply replaces --> A*
\\* --> apply replaces --> x*

To implement "Find all xs:pattern elements that permit an unbounded number of characters" do this:

	If the string resulting from applying the replaces 
 	contains * or +, then the regex permits an 
 	unbounded number of characters.

David (or anyone), is this correct?

/Roger
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