/*******************************************************************************
* Copyright (c) 2009 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
*
* Contributors:
* IBM Corporation - initial API and implementation
* Zend Technologies
*******************************************************************************/
package org.eclipse.php.core.ast.nodes;
/**
* Descriptor for a child property of an AST node. A child property is one whose
* value is an {@link ASTNode}.
*
* @see org.eclipse.jdt.core.dom.ASTNode#getStructuralProperty(StructuralPropertyDescriptor)
* @see org.eclipse.jdt.core.dom.ASTNode#setStructuralProperty(StructuralPropertyDescriptor,
* Object)
* @since 3.0
*/
public final class ChildPropertyDescriptor extends StructuralPropertyDescriptor {
/**
* Child type. For example, for a node type like CompilationUnit, the
* "package" property is PackageDeclaration.class
*/
private final Class childClass;
/**
* Indicates whether the child is mandatory. A child property is allowed to
* be <code>null</code> only if it is not mandatory.
*/
private final boolean mandatory;
/**
* Indicates whether a cycle is possible. Field is private, but marked
* package-visible for fast access from ASTNode.
*/
final boolean cycleRisk;
/**
* Creates a new child property descriptor with the given property id. Note
* that this constructor is declared package-private so that property
* descriptors can only be created by the AST implementation.
*
* @param nodeClass
* concrete AST node type that owns this property
* @param propertyId
* the property id
* @param childType
* the child type of this property
* @param mandatory
* <code>true</code> if the property is mandatory, and
* <code>false</code> if it is may be <code>null</code>
* @param cycleRisk
* <code>true</code> if this property is at risk of cycles, and
* <code>false</code> if there is no worry about cycles
*/
ChildPropertyDescriptor(Class nodeClass, String propertyId, Class childType, boolean mandatory, boolean cycleRisk) {
super(nodeClass, propertyId);
if (childType == null || !ASTNode.class.isAssignableFrom(childType)) {
throw new IllegalArgumentException();
}
this.childClass = childType;
this.mandatory = mandatory;
this.cycleRisk = cycleRisk;
}
/**
* Returns the child type of this property.
* <p>
* For example, for a node type like CompilationUnit, the "package" property
* returns <code>PackageDeclaration.class</code>.
* </p>
*
* @return the child type of the property
*/
public final Class getChildType() {
return this.childClass;
}
/**
* Returns whether this property is mandatory. A property value is not
* allowed to be <code>null</code> if it is mandatory.
*
* @return <code>true</code> if the property is mandatory, and
* <code>false</code> if it is may be <code>null</code>
*/
public final boolean isMandatory() {
return this.mandatory;
}
/**
* Returns whether this property is vulnerable to cycles.
* <p>
* A property is vulnerable to cycles if a node of the owning type (that is,
* the type that owns this property) could legally appear in the AST subtree
* below this property. For example, the body property of a
* {@link MethodDeclaration} node admits a body which might include
* statement that embeds another {@link MethodDeclaration} node. On the
* other hand, the name property of a MethodDeclaration node admits only
* names, and thereby excludes another MethodDeclaration node.
* </p>
*
* @return <code>true</code> if cycles are possible, and <code>false</code>
* if cycles are impossible
*/
public final boolean cycleRisk() {
return this.cycleRisk;
}
}