Re: [xml-dev] A better way to construct regular expressions in XMLSchema

This seems like a validation requirement better suited to Schematron or maybe custom code.

I can’t think of a better way to manage the composition of this kind of complex regex within the source of an XSD schema.

To debug it I’d probably do the debugging outside of the XSD content, e.g., in Oxygen or another editor that lets me construct and test regular expressions.

Or maybe create a set of automated tests in the appropriate language that let you quickly test a large set of cases so that you can then be confident the expression in the XSD is correct. For example, could probably put together an XSLT transform that would do the same regex evaluation as your XSD validator and that would make testing and debugging the expression much easier.

Cheers,

Eliot Kimber

http://contrext.com

From: "Costello, Roger L." <costello@mitre.org>
Date: Monday, November 20, 2017 at 6:35 AM
To: "xml-dev@lists.xml.org" <xml-dev@lists.xml.org>
Subject: [xml-dev] A better way to construct regular expressions in XML Schemas?

Hi Folks,

I have an XML Schema that needs some complex regular expressions. I have been using <!ENTITY> to construct the regexes. See below. I find it pretty hard to debug these regular expressions. Is there a better way to construct regexes? /Roger

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE xsl:schema [
<!ENTITY Language-Tag "(&lang-tag;)|(&private-use;)|(&grandfathered;)">
<!ENTITY lang-tag "(&language;)(-&script;)?(-&region;)?(-&variant;)*(-&extension;)*(-&private-use;)?">
<!ENTITY language "([&ALPHA;]{2,3}(-&extlang;)?)|([&ALPHA;]{4})|([&ALPHA;]{5,8})">
<!ENTITY extlang "[&ALPHA;]{3}(-[&ALPHA;]{3}){0,2}">
<!ENTITY script "[&ALPHA;]{4}">
<!ENTITY region "([&ALPHA;]{2})|([&DIGIT;]{3})">
<!ENTITY variant "([&alphanum;]{5,8})|([&DIGIT;][&alphanum;]{3})">
<!ENTITY extension "((&singleton;)(-[&alphanum;]{2,8})+)">
<!ENTITY singleton "([&DIGIT;])|([A-W])|([Y-Z])|([a-w])|(y-z)">
<!ENTITY private-use "x(-[&alphanum;]{1,8})+">
<!ENTITY grandfathered "(&irregular;)|(&regular;)">
<!ENTITY irregular "(en-GB-oed)|(i-ami)|(i-bnn)|(i-default)|(i-enochian)|(i-hak)|(i-klingon)|(i-lux)|(i-mingo)|(i-navajo)|(i-pwn)|(i-tao)|(i-tay)|(i-tsu)|(sgn-BE-FR)|(sgn-BE-NL)|(sgn-CH-DE)">
<!ENTITY regular "(art-lojban)|(cel-gaulish)|(no-bok)|(no-nyn)|(zh-guoyu)|(zh-hakka)|(zh-min)|(zh-min-nan)|(zh-xiang)">
<!ENTITY ALPHA "a-zA-Z">
<!ENTITY DIGIT "0-9">
<!ENTITY alphanum "(&ALPHA;)|(&DIGIT;)">
]>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

    <xs:element name="language">
        <xs:simpleType>
            <xs:restriction base="xs:string">
                <xs:pattern value="&Language-Tag;" />
            </xs:restriction>
        </xs:simpleType>
    </xs:element>

</xs:schema>