Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup
Good question - I must admit that I put that in as an afterthought. There's an attempted explanation below, which might be off target. Consider this sequence: <xs:sequence dfdl:sequenceKind="ordered" dfdl:initiatedContent="true" dfdl:separator=":" dfdl:separatorPosition="infix" dfdl:separatorPolicy="require"
<xs:element dfdl:initiator=":a:" lengthKind="delimited" minOccurs="0"/> <xs:element dfdl:initiator=":b:" lengthKind="delimited" minOccurs="0"/> </xs:sequence> It could have the following representations: {:a:valueOfA::b:valueOfB} {::b:valueOfB} {,} After parsing the { the next item could be either a's initiator, or the group's separator. I'm saying that a's intiator takes precedence here. ( in other words, when parsing a group's content we look for the initiator of the first element before scanning for terminating markup ) Alternatively, we could specify the opposite behaviour and insist that in-scope terminating markup is always checked before any other group content. That would make the above difficult or impossible to parse using DFDL, I think. regards, Tim Kimber, Common Transformation Team, Hursley, UK Internet: kimbert@uk.ibm.com Tel. 01962-816742 Internal tel. 246742 From: Steve Hanson/UK/IBM To: Tim Kimber/UK/IBM@IBMGB Cc: dfdl-wg@ogf.org Date: 04/02/2010 15:53 Subject: Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup Tim - can you clarify the last sentence please - is the terminating markup that of the preceding peer element, or the enclosing parent? Regards Steve Hanson Programming Model Architect, WebSphere Message Broker, OGF DFDL WG Co-Chair, Hursley, UK, Internet: smh@uk.ibm.com, Phone (+44)/(0) 1962-815848 From: Tim Kimber/UK/IBM@IBMGB To: dfdl-wg@ogf.org Date: 03/02/2010 17:47 Subject: Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup Sent by: dfdl-wg-bounces@ogf.org These rules seem to work: a) separators and terminators are collectively called 'terminating markup'. b) initiators are not 'terminating markup' c) when two items of in-scope terminating markup have a common prefix, the parser must give precedence to the longest item. d) when two items of in-scope terminating markup have exactly the same value, the parser must give precedence to the innermost ( most deeply nested ) item. e) when the separator and terminator on a group have exactly the same value, the parser must give precedence to the separator. If an initiated component can occur at the same point as an item of terminating markup, the initiator takes precedence. regards, Tim Kimber, Common Transformation Team, Hursley, UK Internet: kimbert@uk.ibm.com Tel. 01962-816742 Internal tel. 246742 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- dfdl-wg mailing list dfdl-wg@ogf.org http://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
Aren't there two different cases 1. When looking for a 'new' element look for its initiator first 2. when looking for the end of a delimited element look for a terminator or separator. These may occur at the same place in the data. You cannot have the initiator of the next element terminating the current element. Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell@uk.ibm.com From: Tim Kimber/UK/IBM@IBMGB To: dfdl-wg@ogf.org Date: 04/02/2010 16:38 Subject: Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup Good question - I must admit that I put that in as an afterthought. There's an attempted explanation below, which might be off target. Consider this sequence: <xs:sequence dfdl:sequenceKind="ordered" dfdl:initiatedContent="true" dfdl:separator=":" dfdl:separatorPosition="infix" dfdl:separatorPolicy="require"
<xs:element dfdl:initiator=":a:" lengthKind="delimited" minOccurs="0"/> <xs:element dfdl:initiator=":b:" lengthKind="delimited" minOccurs="0"/> </xs:sequence> It could have the following representations: {:a:valueOfA::b:valueOfB} {::b:valueOfB} {,} After parsing the { the next item could be either a's initiator, or the group's separator. I'm saying that a's intiator takes precedence here. ( in other words, when parsing a group's content we look for the initiator of the first element before scanning for terminating markup ) Alternatively, we could specify the opposite behaviour and insist that in-scope terminating markup is always checked before any other group content. That would make the above difficult or impossible to parse using DFDL, I think. regards, Tim Kimber, Common Transformation Team, Hursley, UK Internet: kimbert@uk.ibm.com Tel. 01962-816742 Internal tel. 246742 From: Steve Hanson/UK/IBM To: Tim Kimber/UK/IBM@IBMGB Cc: dfdl-wg@ogf.org Date: 04/02/2010 15:53 Subject: Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup Tim - can you clarify the last sentence please - is the terminating markup that of the preceding peer element, or the enclosing parent? Regards Steve Hanson Programming Model Architect, WebSphere Message Broker, OGF DFDL WG Co-Chair, Hursley, UK, Internet: smh@uk.ibm.com, Phone (+44)/(0) 1962-815848 From: Tim Kimber/UK/IBM@IBMGB To: dfdl-wg@ogf.org Date: 03/02/2010 17:47 Subject: Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup Sent by: dfdl-wg-bounces@ogf.org These rules seem to work: a) separators and terminators are collectively called 'terminating markup'. b) initiators are not 'terminating markup' c) when two items of in-scope terminating markup have a common prefix, the parser must give precedence to the longest item. d) when two items of in-scope terminating markup have exactly the same value, the parser must give precedence to the innermost ( most deeply nested ) item. e) when the separator and terminator on a group have exactly the same value, the parser must give precedence to the separator. If an initiated component can occur at the same point as an item of terminating markup, the initiator takes precedence. regards, Tim Kimber, Common Transformation Team, Hursley, UK Internet: kimbert@uk.ibm.com Tel. 01962-816742 Internal tel. 246742 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- dfdl-wg mailing list dfdl-wg@ogf.org http://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- dfdl-wg mailing list dfdl-wg@ogf.org http://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
Thanks Tim. I understand now. Your rule is fine. That's what IBM WTX does. It is just looking for the initiator at that point, and nothing else. Regards Steve Hanson Programming Model Architect, WebSphere Message Broker, OGF DFDL WG Co-Chair, Hursley, UK, Internet: smh@uk.ibm.com, Phone (+44)/(0) 1962-815848 From: Tim Kimber/UK/IBM@IBMGB To: dfdl-wg@ogf.org Date: 04/02/2010 16:38 Subject: Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup Sent by: dfdl-wg-bounces@ogf.org Good question - I must admit that I put that in as an afterthought. There's an attempted explanation below, which might be off target. Consider this sequence: <xs:sequence dfdl:sequenceKind="ordered" dfdl:initiatedContent="true" dfdl:separator=":" dfdl:separatorPosition="infix" dfdl:separatorPolicy="require"
<xs:element dfdl:initiator=":a:" lengthKind="delimited" minOccurs="0"/> <xs:element dfdl:initiator=":b:" lengthKind="delimited" minOccurs="0"/> </xs:sequence> It could have the following representations: {:a:valueOfA::b:valueOfB} {::b:valueOfB} {:a:valueOfA:} After parsing the { the next item could be either a's initiator, or the group's separator. I'm saying that a's intiator takes precedence here. ( in other words, when parsing a group's content we look for the initiator of the first element before scanning for terminating markup ) Alternatively, we could specify the opposite behaviour and insist that in-scope terminating markup is always checked before any other group content. That would make the above difficult or impossible to parse using DFDL, I think. regards, Tim Kimber, Common Transformation Team, Hursley, UK Internet: kimbert@uk.ibm.com Tel. 01962-816742 Internal tel. 246742 From: Steve Hanson/UK/IBM To: Tim Kimber/UK/IBM@IBMGB Cc: dfdl-wg@ogf.org Date: 04/02/2010 15:53 Subject: Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup Tim - can you clarify the last sentence please - is the terminating markup that of the preceding peer element, or the enclosing parent? Regards Steve Hanson Programming Model Architect, WebSphere Message Broker, OGF DFDL WG Co-Chair, Hursley, UK, Internet: smh@uk.ibm.com, Phone (+44)/(0) 1962-815848 From: Tim Kimber/UK/IBM@IBMGB To: dfdl-wg@ogf.org Date: 03/02/2010 17:47 Subject: Re: [DFDL-WG] Rules for resolving ambiguity in the in-scope terminating markup Sent by: dfdl-wg-bounces@ogf.org These rules seem to work: a) separators and terminators are collectively called 'terminating markup'. b) initiators are not 'terminating markup' c) when two items of in-scope terminating markup have a common prefix, the parser must give precedence to the longest item. d) when two items of in-scope terminating markup have exactly the same value, the parser must give precedence to the innermost ( most deeply nested ) item. e) when the separator and terminator on a group have exactly the same value, the parser must give precedence to the separator. If an initiated component can occur at the same point as an item of terminating markup, the initiator takes precedence. regards, Tim Kimber, Common Transformation Team, Hursley, UK Internet: kimbert@uk.ibm.com Tel. 01962-816742 Internal tel. 246742 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- dfdl-wg mailing list dfdl-wg@ogf.org http://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU -- dfdl-wg mailing list dfdl-wg@ogf.org http://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
participants (3)
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Alan Powell -
Steve Hanson -
Tim Kimber