Difference between pages "Extending the Rodin Database" and "File:Towards Modular Development in Event-B.pdf"

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There are different ways to extend the Rodin Database:
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Towards Modular Development in Event-B (Thai Son Hoang, Hironobu Kuruma, and Michael Butler)
* adding a new attribute.
 
* adding a new element.
 
 
 
Since Rodin 3.0, when adding an element or an attribute type to the database, you also have to define the relationship it has with other elements types.
 
For an attribute, it consists into defining which elements can carry it. For an element, it consists into defining which elements can parent it, and defining which elements can be considered as children of it.
 
 
 
== Adding a New Attribute ==
 
=== Declaring its type ===
 
 
 
The extension point <code>org.rodinp.core.attributeTypes</code> allows to declare a new attribute.  The element to add is <code>attributeType</code>.
 
 
 
In the example below, we assume that the extensions are developed within a plug-in project with name '''org.eventb.developer.examples'''
 
 
 
The following extension declares a new string attribute.
 
<extension
 
        point="org.rodinp.core.attributeTypes">
 
      <attributeType
 
            id="stringAttr"
 
            kind="string"
 
            name="%eventBStringAttribute">
 
      </attributeType>
 
  </extension>
 
 
 
* The attribute has an ID (which should be always unique) which also contain the project name, i.e. <code>org.eventb.developer.examples.stringAttr</code>.  This unique ID will be used for access the value corresponding to this attribute of an element later.
 
 
 
* The name of the attribute is a string that could be externalised to be used for displaying to the users in the future.
 
 
 
* There are five different attribute kinds: ''boolean'', ''handle'', ''integer'', ''long'', ''string''.
 
 
 
=== Declaring its relationship with existing elements ===
 
Imagine we want our newly create attribute type <tt>stringAttr</tt> be an attribute for the "variable" elements of Event-B models. We have to declare the fact that "variable" elements "can carry" our type of attribute.
 
The extension point <code>org.rodinp.core.itemRelations</code> allows to declare such a relation.
 
 
 
The following extension declares our new string attribute <tt>stringAttr</tt> as carried by "variable" elements.
 
 
 
<extension
 
        point="org.rodinp.core.itemRelations">
 
      <relationship parentTypeId="org.eventb.core.variable">
 
        <attributeType typeId="org.eventb.developer.examples.stringAttr">
 
        </attributeType>
 
      </relationship>
 
</extension>
 
 
 
Note that for a given parent element type identified by <tt>parentTypeId</tt>, one can set multiple <tt>attributeType</tt> which denotes they are all carried by this parent element.
 
 
 
=== Accessing (Programmatically) the Newly Created Attribute ===
 
 
 
After declaring the attribute with the ID and the kind of the attribute, we need to access the value corresponding to the attribute of any internal element.
 
 
 
==== Getting the corresponding Java attribute kind ====
 
Firstly, we need to get the corresponding Java attribute kind.
 
 
 
* '''boolean''': org.rodinp.core.IAttributeType.Boolean
 
 
 
* '''handle''': org.rodinp.core.IAttributeType.Handle
 
 
 
* '''integer''': org.rodinp.core.IAttributeType.Integer
 
 
 
* '''long''': org.rodinp.core.IAttributeType.Long
 
 
 
* '''string''': org.rodinp.core.IAttributeType.String
 
 
 
The following methods get the corresponding Java attribute kind, given an unique ID and the kind (as declared via the extension point).
 
 
 
* <code>org.rodinp.core.IAttributeType.Boolean RodinCore.getBoolAttrType(String ID)</code>
 
 
* <code>org.rodinp.core.IAttributeType.Handle RodinCore.getHandleAttrType(String ID)</code>
 
 
 
* <code>org.rodinp.core.IAttributeType.Integer RodinCore.getIntegerAttrType(String ID)</code>
 
 
 
* <code>org.rodinp.core.IAttributeType.Long RodinCore.getLongAttrType(String ID)</code>
 
 
 
* <code>org.rodinp.core.IAttributeType.String RodinCore.getStringAttrType(String ID)</code>
 
 
 
Note: There is a general method for getting the Java attribute kind given an unique ID (without knowing in advance the kind as declared via the extension point).
 
 
 
* <code>org.rodinp.core.IAttributeType RodinCore.getAttrubuteType(String ID)</code>
 
 
 
As an example with the previously declare attribute, we can use the following code to get the attribute type:
 
 
 
  org.rodinp.core.IAttributeType.String attrType = RodinCore.getStringAttrType("org.eventb.developer.examples");
 
 
 
==== Checking for existence of the attribute for an element ====
 
Given an internal element (i.e. <code>IInternalElement</code>), and given an attribute type (i.e. <code>IAttributeType</code>), method <code>boolean IInternalElement.hasAttribute(IAttributeType)</code> checks for the existence of this attribute for the input element.
 
 
 
==== Getting the value corresponding to the attribute of an element ====
 
 
 
Depending on the Java attribute kind, we have different methods for getting the value corresponding to the attribute of an internal element (i.e. <code>IInternalElement</code>).
 
 
 
* <code>boolean IInternalElement.getAttributeValue(IAttributeType.Boolean)</code>
 
 
 
* <code>IRodinElement IInternalElement.getAttributeValue(IAttributeType.Handle)</code>
 
 
 
* <code>int IInternalElement.getAttributeValue(IAttributeType.Integer)</code>
 
 
 
* <code>long IInternalElement.getAttributeValue(IAttributeType.Long)</code>
 
 
 
* <code>String IInternalElement.getAttributeValue(IAttributeType.String)</code>
 
 
 
As an example, we can use the following code to set our previously declared attribute of an internal element (e.g. <code>elem</code>)
 
 
 
String attrValue = elem.getAttributeValue(attrType);
 
 
 
==== Setting the value corresponding to the attribute of an element ====
 
 
 
Depending on the Java attribute kind, we have different methods for setting the value corresponding to the attribute of an internal element (i.e. <code>IInternalElement</code>).
 
 
 
* <code>void IInternalElement.setAttributeValue(IAttributeType.Boolean, boolean, IProgressMonitor)</code>
 
 
 
* <code>void IInternalElement.setAttributeValue(IAttributeType.Handle, IRodinElement, IProgressMonitor)</code>
 
 
 
* <code>void IInternalElement.setAttributeValue(IAttributeType.Integer, int, IProgressMonitor)</code>
 
 
 
* <code>void IInternalElement.setAttributeValue(IAttributeType.Long, long, IProgressMonitor)</code>
 
 
 
* <code>void IInternalElement.setAttributeValue(IAttributeType.String, String, IProgressMonitor)</code>
 
 
 
As an example, we can use the following code to set our previously declared attribute of an internal element (e.g. <code>elem</code>)
 
 
 
elem.setAttributeValue(attrType, "My new value", new NullProgressMonitor());
 
 
 
== Adding a New Element ==
 
=== Declaring its type ===
 
The extension point <code>org.rodinp.core.internalElementTypes</code> allows to declare a new element.  The element to add is <code>internalElementType</code>.
 
The following extension declares a new element:
 
  <extension
 
        point="org.rodinp.core.internalElementTypes">
 
      <internalElementType
 
            id="myElement"
 
            class="package.MyClass"
 
            name="%eventBElement">
 
      </internalElementType>
 
  </extension>
 
 
 
An element has a unique ID, a name, and a class. This class shall be a subclass of <tt>org.eventb.core.basis.EventBElement</tt>, and it shall implement the following interfaces, depending on the attributes that will be associated to this newly created element:
 
* If the element will be commented, this class shall implement <tt>ICommentedElement</tt>.
 
* If the element will be labelled, this class shall implement <tt>ILabeledElement</tt>.
 
* If the element will be identified, this class shall implement <tt>IIdentifierElement</tt>.
 
* If the element will carry an expression, this class shall implement <tt>IExpressionElement</tt>.
 
* If the element will carry a predicate, this class shall implement <tt>IPredicateElement</tt>.
 
* If the element will carry an assignment, this class shall implement <tt>IAssignmentElement</tt>.
 
* If the element will have a convergence, this class shall implement <tt>IConvergenceElement</tt>.
 
=== Declaring its relationship with existing elements ===
 
After having declared the new element type <tt>myElement</tt>, one has to define at which place this element can appear in the database.<br />
 
Indeed, just registering the type will not allow any element of this type be part of a file in the database.
 
 
 
To declare relationships one has to contribute to the extension point <code>org.rodinp.core.itemRelations</code>. <br />
 
Now suppose we want to register the elements of type <tt>myElement</tt> as children of machine files, like Event-B variables for example, then hereafter is the definition of such an item relation:
 
<extension
 
        point="org.rodinp.core.itemRelations">
 
      <relationship
 
            parentTypeId="org.eventb.core.machineFile">
 
        <childType
 
              typeId="org.xxxx.myElement">
 
        </childType>
 
      </relationship>
 
</extension>
 
[[Category:Developer documentation]]
 

Latest revision as of 20:50, 30 April 2020

Towards Modular Development in Event-B (Thai Son Hoang, Hironobu Kuruma, and Michael Butler)