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Groovy example source code file (FilteredNodeChildren.java)

This example Groovy source code file (FilteredNodeChildren.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

closure, closure, filterednodechildren, filterednodechildren, gpathresult, iterator, iterator, map, nodechild, nodechildren, object, object, string, unsupportedoperationexception, util

The Groovy FilteredNodeChildren.java source code

/*
 * Copyright 2003-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package groovy.util.slurpersupport;

import java.util.Iterator;
import java.util.Map;

import org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation;

import groovy.lang.Closure;

/**
 * Lazy evaluated representation of child nodes filtered by a Closure.
 *
 * @author John Wilson
 */
public class FilteredNodeChildren extends NodeChildren {
    private final Closure closure;

    /**
     * @param parent the GPathResult prior to the application of the expression creating this GPathResult
     * @param closure the Closure to use to filter the nodes
     * @param namespaceTagHints the known tag to namespace mappings
     */
    public FilteredNodeChildren(final GPathResult parent, final Closure closure, final Map<String, String> namespaceTagHints) {
        super(parent, parent.name, namespaceTagHints);
        this.closure = closure;
    }

    public Iterator iterator() {
        return new Iterator() {
            final Iterator iter = FilteredNodeChildren.this.parent.iterator();
            Object next = null;

            public boolean hasNext() {
                while (this.iter.hasNext()) {
                    final Object childNode = this.iter.next();
                    if (closureYieldsTrueForNode(childNode)) {
                        this.next = childNode;
                        return true;
                    }
                }
                return false;
            }

            public Object next() {
                return this.next;
            }

            public void remove() {
                throw new UnsupportedOperationException();
            }
        };
    }

    public Iterator nodeIterator() {
        return new NodeIterator(this.parent.nodeIterator()) {
            protected Object getNextNode(final Iterator iter) {
                while (iter.hasNext()) {
                    final Object node = iter.next();
                    if (closureYieldsTrueForNode(new NodeChild((Node) node, FilteredNodeChildren.this.parent, FilteredNodeChildren.this.namespaceTagHints))) {
                        return node;
                    }
                }
                return null;
            }
        };
    }

    private boolean closureYieldsTrueForNode(Object childNode) {
        return DefaultTypeTransformation.castToBoolean(FilteredNodeChildren.this.closure.call(new Object[]{childNode}));
    }
}

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