Eclipse Community Forums: XML Schema Definition (XSD) » A question about walkers/visitors

Help

Home

Home » Archived » XML Schema Definition (XSD) » A question about walkers/visitors

Show: Today's Messages :: Show Polls :: Message Navigator

A question about walkers/visitors [message #44318]

Wed, 12 May 2004 22:51

Eclipse User

Originally posted by: vranganath.sbcglobal.net

Hi,

I am new to EMF/XSD. I am planning on using XSD to load up a schema
and visit parts of it. However, I could not find a visitor or a
walker that will enable me to do this. So, is there such a class
available in XSD? If so, can you point me to it? If not, is there a
reason for it's absence? Also, how can I contribute one if I do
implement such a class?

waiting for reply,

--

Venkatesh Prasad Ranganath,
Dept. Computing and Information Science,
Kansas State University, US.
web: http://www.cis.ksu.edu/~rvprasad

Report message to a moderator

Re: A question about walkers/visitors [message #44350 is a reply to message #44318]

Wed, 12 May 2004 23:39

Eclipse User

Originally posted by: merks.ca.ibm.com

Venkatesh,

EcoreUtil.getAllContents and/or EObject.eAllContents can be used to walk
the containment tree and the generated XSDSwitch can be used to do
visiting.

Venkatesh Prasad Ranganath wrote:

> Hi,
>
> I am new to EMF/XSD. I am planning on using XSD to load up a schema
> and visit parts of it. However, I could not find a visitor or a
> walker that will enable me to do this. So, is there such a class
> available in XSD? If so, can you point me to it? If not, is there a
> reason for it's absence? Also, how can I contribute one if I do
> implement such a class?
>
> waiting for reply,
>
> --
>
> Venkatesh Prasad Ranganath,
> Dept. Computing and Information Science,
> Kansas State University, US.
> web: http://www.cis.ksu.edu/~rvprasad

Report message to a moderator

Re: A question about walkers/visitors [message #45103 is a reply to message #44350]

Fri, 21 May 2004 01:38

Eclipse User

Originally posted by: comfortably007numb-python.yahoo.com

Ed Merks wrote:

>Venkatesh,
>
>EcoreUtil.getAllContents and/or EObject.eAllContents can be used to walk
>the containment tree and the generated XSDSwitch can be used to do
>visiting.
>
>
>
Thanks for the pointer. However, I have questions about your suggestion.

I looked at the docs for XSDSwitch.doSwitch() says

"The *Switch* for the model's inheritance hierarchy. It supports the
call |doSwitch(object)|
< http://download.eclipse.org/technology/xsd/javadoc/org/eclip se/xsd/util/XSDSwitch.html#doSwitch%28org.eclipse.emf.ecore. EObject%29>
to invoke the |caseXXX| method for each class of the model, starting
with the actual class of the object and proceeding up the inheritance
hierarchy until a non-null result is returned, which is the result of
the switch."

Does this mean it is not a model/instance walker? In other words, given
a object of type X which inherits from Y, the switch will call caseX(),
then caseY(), and so on depending on the return value. If X contains a
reference to an object Z, it will not call caseX() followed by caseZ().
Am I right?

If so, as you suggested I can use TreeIterator to visit the elements
reachable from the root element. The only question is that what is the
ordering of iteration? Is it implicit that if elem1 occurs before elem2
in the container then the TreeIterator will return elem1 before
returning elem2 via next()?

waiting for reply,

- Venkatesh

>Venkatesh Prasad Ranganath wrote:
>
>
>
>>Hi,
>>
>>I am new to EMF/XSD. I am planning on using XSD to load up a schema
>>and visit parts of it. However, I could not find a visitor or a
>>walker that will enable me to do this. So, is there such a class
>>available in XSD? If so, can you point me to it? If not, is there a
>>reason for it's absence? Also, how can I contribute one if I do
>>implement such a class?
>>
>>waiting for reply,
>>
>>--
>>
>>Venkatesh Prasad Ranganath,
>>Dept. Computing and Information Science,
>>Kansas State University, US.
>>web: http://www.cis.ksu.edu/~rvprasad
>>
>>
>
>
>

Report message to a moderator

Re: A question about walkers/visitors [message #45163 is a reply to message #45103]

Fri, 21 May 2004 14:51

Frank Budinsky

Messages: 478
Registered: July 2009

Senior Member

You're right that a switch is only for a single instance. The switch on
object X won't call caseZ() in your example.

The TreeIterator will do a depth-first traversal of the containment
structure.

This visitor pattern is described in the EMF book (starting on page
337), if you can get your hands on a copy.

Frank.

Venkatesh Prasad Ranganath wrote:

> Ed Merks wrote:
>
>> Venkatesh,
>>
>> EcoreUtil.getAllContents and/or EObject.eAllContents can be used to walk
>> the containment tree and the generated XSDSwitch can be used to do
>> visiting.
>>
>>
>>
> Thanks for the pointer. However, I have questions about your suggestion.
>
> I looked at the docs for XSDSwitch.doSwitch() says
>
> "The *Switch* for the model's inheritance hierarchy. It supports the
> call |doSwitch(object)|
> < http://download.eclipse.org/technology/xsd/javadoc/org/eclip se/xsd/util/XSDSwitch.html#doSwitch%28org.eclipse.emf.ecore. EObject%29>
> to invoke the |caseXXX| method for each class of the model, starting
> with the actual class of the object and proceeding up the inheritance
> hierarchy until a non-null result is returned, which is the result of
> the switch."
>
> Does this mean it is not a model/instance walker? In other words,
> given a object of type X which inherits from Y, the switch will call
> caseX(), then caseY(), and so on depending on the return value. If X
> contains a reference to an object Z, it will not call caseX() followed
> by caseZ(). Am I right?
>
> If so, as you suggested I can use TreeIterator to visit the elements
> reachable from the root element. The only question is that what is
> the ordering of iteration? Is it implicit that if elem1 occurs before
> elem2 in the container then the TreeIterator will return elem1 before
> returning elem2 via next()?
>
> waiting for reply,
>
> - Venkatesh
>
>> Venkatesh Prasad Ranganath wrote:
>>
>>
>>
>>> Hi,
>>>
>>> I am new to EMF/XSD. I am planning on using XSD to load up a schema
>>> and visit parts of it. However, I could not find a visitor or a
>>> walker that will enable me to do this. So, is there such a class
>>> available in XSD? If so, can you point me to it? If not, is there a
>>> reason for it's absence? Also, how can I contribute one if I do
>>> implement such a class?
>>>
>>> waiting for reply,
>>>
>>> --
>>>
>>> Venkatesh Prasad Ranganath,
>>> Dept. Computing and Information Science,
>>> Kansas State University, US.
>>> web: http://www.cis.ksu.edu/~rvprasad
>>>
>>
>>
>>
>>

Report message to a moderator

Re: A question about walkers/visitors [message #587039 is a reply to message #44318]

Wed, 12 May 2004 23:39

Ed Merks

Messages: 33141
Registered: July 2009

Senior Member

Venkatesh,

EcoreUtil.getAllContents and/or EObject.eAllContents can be used to walk
the containment tree and the generated XSDSwitch can be used to do
visiting.

Venkatesh Prasad Ranganath wrote:

> Hi,
>
> I am new to EMF/XSD. I am planning on using XSD to load up a schema
> and visit parts of it. However, I could not find a visitor or a
> walker that will enable me to do this. So, is there such a class
> available in XSD? If so, can you point me to it? If not, is there a
> reason for it's absence? Also, how can I contribute one if I do
> implement such a class?
>
> waiting for reply,
>
> --
>
> Venkatesh Prasad Ranganath,
> Dept. Computing and Information Science,
> Kansas State University, US.
> web: http://www.cis.ksu.edu/~rvprasad

Ed Merks
Professional Support: https://www.macromodeling.com/

Report message to a moderator