org.eclipse.jdt.core.dom.ChildPropertyDescriptor.java Source code

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Here is the source code for org.eclipse.jdt.core.dom.ChildPropertyDescriptor.java

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/*******************************************************************************
 * Copyright (c) 2004, 2013 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.core.dom;

/**
 * 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
 * @noinstantiate This class is not intended to be instantiated by clients.
 */
@SuppressWarnings("rawtypes")
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;
    }
}