com.ibm.xtools.transform.core

Class AbstractMetatype

java.lang.Object

com.ibm.xtools.transform.core.AbstractMetatype

Direct Known Subclasses:

AbstractCompositeMetatype, BooleanMetatype, ChoiceMetatype, DCMPMetatype, EMFMetatype, IntegerMetatype, ResourceMetatype, StringMetatype

public abstract class AbstractMetatype
extends java.lang.Object

This class defines the main class for a metatype converter. Metatype authors should subclass this class when defining their metatype converter.

A metatype converter is defined as an extension to the point com.ibm.xtools.transform.core.metatypeConverters. The extension enables the following data to be defined for a metatype converter:

• a unique ID (identifies the converter to use for resolving persistable strings)
• the logical name of the metatype (name is case insensitive - not localized)
• the fully qualified name of the class that data objects are an instance of
• a class (subclasses this class) for doing object conversions
• a boolean to indicate whether a selection can be adapted to an object
• a boolean to indicate whether a string representing an object can be edited by the user and then resolved back into an object

All metatype converters must implement the following methods:

• getDisplayName() - returns a displayable name that identifies the data object
• getReference() - returns a persistable string that references the data object
• resolveReference() - converts a string reference back into the data object

If the metatype is to be used as either a source or target model type for a transformation then the converter must be able to adapt a selection to a data object. The order of the metatypes in the transformation descriptor determines which metatype converter will be used. To support this feature, the converter must implement the following methods:

• adaptSelection() - returns the data object that the selected object represents

If the metatype will only be used for transformation properties, support for this feature is not required.

If the metatype is to be used for read-write transformation properties then a mechanism is needed for the user to change the value of the property before executing the transformation. This can be achieved in several ways. The transformation itself can define its own transform configuration tab to change property values, or the editable string support can be implemented by the converter. In this case, the editable string will be displayed in the UI property sheet (as text) and the modified string will be resolved back into a data object. If the converter supports this feature then it must implement the following methods:

• getEditString() - return a string representing the object that the user can edit
• resolveEditString() - converts the user edited string back into the data object

In many cases, the above two methods simply call the getReference() and resovleReference() methods. However, there are some cases where the persistable string is cryptic (e.g., a URI) and the user would be unable to edit it properly. Obviously if the edited string is incorrect, the resolveEditString() method would retun null and the property sheet would display an error.

The extension definition contains the fully qualified class (type class) that object must be an instance of for this metatype converter. This may not be sufficient for selecting the correct converter for a data object. The converter can perform more fine grained control by overriding the following method:

• isMetatypeObject() - return true is the data object is for this metatype

Constructor Summary

Constructors

Constructor and Description
AbstractMetatype() Constructor

Method Summary

Modifier and Type	Method and Description
java.lang.Object	adaptSelection(java.lang.Object selection) Adapt a selected UI object into a metatype data object.
abstract java.lang.String	getDisplayName(java.lang.Object dataObject) Obtain a displayable name that represents the metatype data object.
java.lang.String	getEditString(java.lang.Object dataObject) Obtain a string representation of the metatype data object that a user can edit.
abstract java.lang.String	getReference(java.lang.Object dataObject) Return a string representing the data object that can be persisted.
java.lang.Object	getViewerObject(java.lang.Object dataObject) Returns the object used to display the data object in a viewer such as the common viewer.
boolean	isMetatypeObject(java.lang.Object dataObject) Verfiy that the data object is valid for this metatype.
AbstractMetatypeDataManager	newMetatypeDataManager(ITransformationProperty property) Returns a new instance of the metatype data manager for this converter.
java.lang.Object	resolveEditString(java.lang.String editString) Resolve a user editable string back into a metatype data object.
abstract java.lang.Object	resolveReference(java.lang.String refString) Resolve a string reference back into the corresponding data object.
java.lang.Object	resolveReference(java.lang.String refString, ITransformationProperty prop) Resolve a string reference back into the corresponding data object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AbstractMetatype

public AbstractMetatype()

Constructor

Method Detail

adaptSelection

public java.lang.Object adaptSelection(java.lang.Object selection)

Adapt a selected UI object into a metatype data object. This method must only be implemented if the converter extension definition (in XML) indicates that it can adapt the selection. If this metatype is to be used as either a source or target model type for a transformation then the converter must support selection adaptation.

Parameters:

selection - the selected object in the UI

Returns:

the data object that the selected object represents

isMetatypeObject

public boolean isMetatypeObject(java.lang.Object dataObject)

Verfiy that the data object is valid for this metatype. Before this method is called, the data object is verified to be an instance of the specified typeClass (defined in metatype extension). Therefore, at this point, the converter knows that the object is of the correct type but if more fine grained verification is needed, it can be done here.

Since the initial check against the typeClass is usually sufficient, this default implementation of the method will usually be sufficient.

Parameters:

dataObject - the metatype data type object being verified

Returns:

boolean - true indicates the object is for this metatype

getDisplayName

public abstract java.lang.String getDisplayName(java.lang.Object dataObject)

Obtain a displayable name that represents the metatype data object. This string will be used in the UI when a string is needed to identify the data object. For example, this string could indicate the selected object or could represent the value of a read-only transformation property.

Parameters:

dataObject - the metatype data object

Returns:

a displayable string that represents the data object

getReference

public abstract java.lang.String getReference(java.lang.Object dataObject)

Return a string representing the data object that can be persisted. This string does not need to identify the converter that was used to create it. The metatype registry will ensure the same converter is used to resolve the reference.

Parameters:

dataObject - the metatype data object to be persisted

Returns:

a persistable string that represents the data object

resolveReference

public abstract java.lang.Object resolveReference(java.lang.String refString)

Resolve a string reference back into the corresponding data object.

Parameters:

refString - a persistable string that represents the data object

Returns:

the corresponding metatype data object

resolveReference

public java.lang.Object resolveReference(java.lang.String refString,
                                         ITransformationProperty prop)

Resolve a string reference back into the corresponding data object.

Parameters:

refString - a persistable string that represents the data object

prop - The transformation property that the data object is the value of. It may contain metatype data needed to resolve the property.

Returns:

the corresponding metatype data object

getEditString

public java.lang.String getEditString(java.lang.Object dataObject)

Obtain a string representation of the metatype data object that a user can edit.

Parameters:

dataObject - the metatype data object

Returns:

a user editable string that represents the data object

resolveEditString

public java.lang.Object resolveEditString(java.lang.String editString)

Resolve a user editable string back into a metatype data object.

Parameters:

editString - a user editable string that represents the data object

Returns:

the corresponding metatype data object

newMetatypeDataManager

public AbstractMetatypeDataManager newMetatypeDataManager(ITransformationProperty property)

Returns a new instance of the metatype data manager for this converter.

Parameters:

property - The transformation property that contains the metatype data.

Returns:

The metatype data manager if this converter uses one. Otherwise null.

getViewerObject

public java.lang.Object getViewerObject(java.lang.Object dataObject)

Returns the object used to display the data object in a viewer such as the common viewer. Typically the same object is used, so the default implementation simply returns the data object if the data object is a type that this metatype understands. If not it returns null. Subclasses should override this method if a different object is needed.

Parameters:

dataObject - The object for which to find a viewer object.

Returns:

The object used to display the given object or null if the viewer object cannot be determined.