org.apache.pdfbox.pdmodel.interactive.form.PDFieldTree Maven / Gradle / Ivy
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The Apache PDFBox library is an open source Java tool for working with PDF documents.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.pdfbox.pdmodel.interactive.form;
import java.util.ArrayDeque;
import java.util.Iterator;
import java.util.Queue;
import java.util.List;
import java.util.NoSuchElementException;
/**
* The field tree.
*/
public class PDFieldTree implements Iterable
{
private final PDAcroForm acroForm;
/**
* Constructor for reading.
*
* @param acroForm the AcroForm containing the fields.
*/
public PDFieldTree(PDAcroForm acroForm)
{
if (acroForm == null)
{
throw new IllegalArgumentException("root cannot be null");
}
this.acroForm = acroForm;
}
/**
* Returns an iterator which walks all fields in the tree, in order.
*/
@Override
public Iterator iterator()
{
return new FieldIterator(acroForm);
}
/**
* Iterator which walks all fields in the tree, in order.
*/
private static final class FieldIterator implements Iterator
{
private final Queue queue = new ArrayDeque();
private FieldIterator(PDAcroForm form)
{
List fields = form.getFields();
for (PDField field : fields)
{
enqueueKids(field);
}
}
@Override
public boolean hasNext()
{
return !queue.isEmpty();
}
@Override
public PDField next()
{
if(!hasNext()){
throw new NoSuchElementException();
}
return queue.poll();
}
@Override
public void remove()
{
throw new UnsupportedOperationException();
}
private void enqueueKids(PDField node)
{
queue.add(node);
if (node instanceof PDNonTerminalField)
{
List kids = ((PDNonTerminalField) node).getChildren();
for (PDField kid : kids)
{
enqueueKids(kid);
}
}
}
}
}