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GMF Element Type Bindings

###### Identifier:

org.eclipse.gmf.runtime.emf.type.core.elementTypeBindings

###### Description:

This extension point allows clients of the GMF extensible type registry to define "client contexts" that describe the objects that they are interested in editing, and to bind them to element types and advice that they wish to have applied to these objects.

###### Configuration Markup:

<!ELEMENT extension (clientContext* , binding*)>

<!ATTLIST extension

point CDATA #REQUIRED

id CDATA #IMPLIED

name CDATA #IMPLIED>

<!ELEMENT clientContext (enablement | matcher)>

<!ATTLIST clientContext

id CDATA #REQUIRED>

Definition of a client context, representing a class of objects that a client wishes to edit using a set of element types and advice.

A client context can declare an `<enablement>` expression that matches model elements that are included in the context. Where that is not sufficient, an alternative is to define a matcher class using a `<matcher>` element.

- id - The unique ID of the client context.

<!ELEMENT matcher EMPTY>

<!ATTLIST matcher

class CDATA #REQUIRED>

This element is used to specify the class that will determine whether or not an existing model element matches this client context.

- class - The fully qualified name of a class that implements `org.eclipse.gmf.runtime.emf.type.core.IElementMatcher`.

<!ELEMENT binding (elementType* , advice*)>

<!ATTLIST binding

context CDATA #REQUIRED>

Declares a binding between a client context and one or more element types or advice. The context can, itself, be declared by the same plug-in or by a different plug-in.

The constraints to be bound may be specified by any number of nested `<elementType>` and/or `<advice>` elements to reference multiple element types and/or advice.

- context - References the ID of a context that is bound to one or more element types or advice.

<!ELEMENT elementType EMPTY>

<!ATTLIST elementType

ref CDATA #IMPLIED

pattern CDATA #IMPLIED>

Includes an element type or a pattern of element type IDs in a client context `<binding>`.

- ref - References the ID of an element type to bind the client context to. This attribute may not be used in conjunection with the `pattern` attribute.
- pattern - The pattern of element type IDs to be bound. Patterns are regular expressions which match unique identifiers. Please see the Java documentation for java.util.regex.Pattern for further details. This attribute may not be used in conjunection with the `ref` attribute.

<!ELEMENT advice EMPTY>

<!ATTLIST advice

ref CDATA #IMPLIED

pattern CDATA #IMPLIED>

Includes an advice or a pattern of advice IDs in a client context `<binding>`.

- ref - References the ID of an advice to bind the client context to. This attribute may not be used in conjunection with the `pattern` attribute.
- pattern - The pattern of advice IDs to be bound. Patterns are regular expressions which match unique identifiers. Please see the Java documentation for java.util.regex.Pattern for further details. This attribute may not be used in conjunection with the `ref` attribute.

<!ELEMENT enablement (not , and , or , instanceof , test , systemTest , equals , count , with , resolve , adapt , iterate)*>

A generic root element. The element can be used inside an extension point to define its enablement expression. The children of an enablement expression are combined using the and operator.

<!ELEMENT not (not | and | or | instanceof | test | systemTest | equals | count | with | resolve | adapt | iterate)>

This element represent a NOT operation on the result of evaluating it's sub-element expression.

<!ELEMENT and (not , and , or , instanceof , test , systemTest , equals , count , with , resolve , adapt , iterate)*>

This element represent an AND operation on the result of evaluating all it's sub-elements expressions.

<!ELEMENT or (not , and , or , instanceof , test , systemTest , equals , count , with , resolve , adapt , iterate)*>

This element represent an OR operation on the result of evaluating all it's sub-element expressions.

<!ELEMENT instanceof EMPTY>

<!ATTLIST instanceof

value CDATA #REQUIRED>

This element is used to perform an instanceof check of the object in focus. The expression returns EvaluationResult.TRUE if the object's type is a sub type of the type specified by the attribute value. Otherwise EvaluationResult.FALSE is returned.

- value - a fully qualified name of a class or interface.

<!ELEMENT test EMPTY>

<!ATTLIST test

property CDATA #REQUIRED

args CDATA #IMPLIED

value CDATA #IMPLIED>

This element is used to evaluate the property state of the object in focus. The set of testable properties can be extended using the propery tester extension point. The test expression returns EvaluationResult.NOT_LOADED if teh property tester doing the actual testing isn't loaded yet.

- property - the name of an object's property to test.
- args - additional arguments passed to the property tester. Multiple arguments are seperated by commas. Each individual argument is converted into a Java base type using the same rules as defined for the value attribute of the test expression.
- value - the expected value of the property. Can be omitted if the property is a boolean property. The test expression is supposed to return EvaluationResult.TRUE if the property matches the value and EvaluationResult.FALSE otherwise. The value attribute is converted into a Java base type using the following rules:
  - the string "true" is converted into Boolean.TRUE
  - the string "false" is converted into Boolean.FALSE
  - if the string contains a dot then the interpreter tries to convert the value into a Float object. If this fails the string is treated as a java.lang.String
  - if the string only consists of numbers then the interpreter converts the value in an Integer object.
  - in all other cases the string is treated as a java.lang.String
  - the conversion of the string into a Boolean, Float, or Integer can be suppressed by surrounding the string with single quotes. For example, the attribute value="'true'" is converted into the string "true"

<!ELEMENT systemTest EMPTY>

<!ATTLIST systemTest

property CDATA #REQUIRED

value CDATA #REQUIRED>

Tests a system property by calling the System.getProperty method and compares the result with the value specified through the value attribute.

- property - the name of an system property to test.
- value - the expected value of the property. The value is interpreted as a string value.

<!ELEMENT equals EMPTY>

<!ATTLIST equals

value CDATA #REQUIRED>

This element is used to perform an equals check of the object in focus. The expression returns EvaluationResult.TRUE if the object is equal to the value provided by the attribute value. Otherwise EvaluationResult.FALSE is returned.

- value - the operatand of the equals tests. The value provided as a string is converted into a Java base type using the same rules as for the value attribute of the test expression.

<!ELEMENT count EMPTY>

<!ATTLIST count

value CDATA #REQUIRED>

This element is used to test the number of elements in a collection.

- value - an expression to specify the number of elements in a list. Following wildcard characters can be used:
  *
    any number of elements
  ?
    no elements or one element
  +
    one or more elements
  !
    no elements
  integer value
    the list must contain the exact number of elements

<!ELEMENT with (not , and , or , instanceof , test , systemTest , equals , count , with , resolve , adapt , iterate)*>

<!ATTLIST with

variable CDATA #REQUIRED>

This element changes the object to be inspected for all its child element to the object referneced by the given variable. If the variable can not be resolved then the expression will throw a ExpressionException when evaluating it. The children of a with expression are combined using the and operator.

- variable - the name of the variable to be used for further inspection. It is up to the evaluator of an extension point to provide the variable in the variable pool.

<!ELEMENT resolve (not , and , or , instanceof , test , systemTest , equals , count , with , resolve , adapt , iterate)*>

<!ATTLIST resolve

variable CDATA #REQUIRED

args CDATA #IMPLIED>

This element changes the object to be inspected for all its child element to the object referneced by the given variable. If the variable can not be resolved then the expression will throw a ExpressionException when evaluating it. The children of a with expression are combined using the and operator.

- variable - the name of the variable to be resolved. This variable is then used as the object in focus for child element evaluation. It is up to the evaluator of an extension point to provide a corresponding variable resolver (see IVariableResolver) through the evaluation context passed to the root expression element when evaluating the expression.
- args - additional arguments passed to the variable resolver. Multiple arguments are seperated by commas. Each individual argument is converted into a Java base type using the same rules as defined for the value attribute of the test expression.

<!ELEMENT adapt (not , and , or , instanceof , test , systemTest , equals , count , with , resolve , adapt , iterate)*>

<!ATTLIST adapt

type CDATA #REQUIRED>

This element is used to adapt the object in focus to the type specified by the attribute type. The expression returns not loaded if either the adapter or the type referenced isn't loaded yet. It throws a ExpressionException during evaluation if the type name doesn't exist at all. The children of an adapt expression are combined using the and operator.

- type - the type to which the object in focus is to be adapted.

<!ELEMENT iterate (not , and , or , instanceof , test , systemTest , equals , count , with , resolve , adapt , iterate)*>

<!ATTLIST iterate

operator (or|and) >

This element is used to iterate over a variable that is of type java.util.Collection. If the object in focus is not of type java.util.Collection then an ExpressionException will be thrown while evaluating the expression.

- operator - either "and" or "or". The operator defines how the child elements will be combined. If not specified, "and" will be used.

###### Examples:

Example of a context which only includes `EObjects` from the logic example's editing domain:

       <extension point="org.eclipse.gmf.runtime.emf.type.core.elementTypeBindings">
          <clientContext id="org.eclipse.gmf.examples.runtime.diagram.logic">
             <enablement>
                <test
                   property="org.eclipse.gmf.runtime.emf.core.editingDomain"
                   value="org.eclipse.gmf.examples.runtime.diagram.logicEditingDomain"/>
             </enablement>
          </clientContext>
       </extension>

Example of a binding of a single advice to the logic context:

       <extension point="org.eclipse.gmf.runtime.emf.type.core.elementTypeBindings">
          <binding context="org.eclipse.gmf.examples.runtime.diagram.logic"/>
             <advice ref="org.eclipse.gmf.runtime.diagram.core.advice.notationDepdendents"/>
          </binding>
       </extension>

Example of binding multiple element types and advice to the logic context:

       <extension point="org.eclipse.gmf.runtime.emf.type.core.elementTypeBindings">
          <binding context="org.eclipse.gmf.examples.runtime.diagram.logic"/>
             <elementType pattern="logic.*"/>
             <advice pattern="logic.*"/>
          </binding>
       </extension>

Copyright (c) 2006 IBM Corporation and others.
All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse Public License v1.0 which accompanies this distribution, and is available at http://www.eclipse.org/legal/epl-v10.html