IndentingXMLStreamWriter.java

/*
 * Copyright (c) 2023 Contributors to the Eclipse Foundation
 * Copyright (c) 2007, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.jvnet.hk2.config;

import javax.xml.stream.XMLStreamWriter;
import javax.xml.stream.XMLStreamException;
import java.util.Stack;

/**
 * @author Kohsuke Kawaguchi
 */
public class IndentingXMLStreamWriter extends DelegatingXMLStreamWriter {
    private final static Object SEEN_NOTHING = new Object();
    private final static Object SEEN_ELEMENT = new Object();
    private final static Object SEEN_DATA = new Object();

    private Object state = SEEN_NOTHING;
    private Stack<Object> stateStack = new Stack<Object>();

    private String indentStep = "  ";
    private int depth = 0;

    public IndentingXMLStreamWriter(XMLStreamWriter writer) {
        super(writer);
    }

    /**
     * Return the current indent step.
     *
     * <p>Return the current indent step: each start tag will be
     * indented by this number of spaces times the number of
     * ancestors that the element has.</p>
     *
     * @return The number of spaces in each indentation step,
     *         or 0 or less for no indentation.
     * @see #setIndentStep(int)
     *
     * @deprecated
     *      Only return the length of the indent string.
     */
    public int getIndentStep() {
        return indentStep.length();
    }


    /**
     * Set the current indent step.
     *
     * @param indentStep The new indent step (0 or less for no
     *        indentation).
     * @see #getIndentStep()
     *
     * @deprecated
     *      Should use the version that takes string.
     */
    public void setIndentStep(int indentStep) {
        StringBuilder s = new StringBuilder();
        for (; indentStep > 0; indentStep--) s.append(' ');
        setIndentStep(s.toString());
    }

    public void setIndentStep(String s) {
        this.indentStep = s;
    }

    private void onStartElement() throws XMLStreamException {
        stateStack.push(SEEN_ELEMENT);
        state = SEEN_NOTHING;
        if (depth > 0) {
            super.writeCharacters("\n");
        }
        doIndent();
        depth++;
    }

    private void onEndElement() throws XMLStreamException {
        depth--;
        if (state == SEEN_ELEMENT) {
            super.writeCharacters("\n");
            doIndent();
        }
        state = stateStack.pop();
    }

    private void onEmptyElement() throws XMLStreamException {
        state = SEEN_ELEMENT;
        if (depth > 0) {
            super.writeCharacters("\n");
        }
        doIndent();
    }

    /**
     * Print indentation for the current level.
     *
     * @exception org.xml.sax.SAXException If there is an error
     *            writing the indentation characters, or if a filter
     *            further down the chain raises an exception.
     */
    private void doIndent() throws XMLStreamException {
        if (depth > 0) {
            for (int i = 0; i < depth; i++)
                super.writeCharacters(indentStep);
        }
    }


    public void writeStartDocument() throws XMLStreamException {
        super.writeStartDocument();
        super.writeCharacters("\n");
    }

    public void writeStartDocument(String version) throws XMLStreamException {
        super.writeStartDocument(version);
        super.writeCharacters("\n");
    }

    public void writeStartDocument(String encoding, String version) throws XMLStreamException {
        super.writeStartDocument(encoding, version);
        super.writeCharacters("\n");
    }

    public void writeStartElement(String localName) throws XMLStreamException {
        onStartElement();
        super.writeStartElement(localName);
    }

    public void writeStartElement(String namespaceURI, String localName) throws XMLStreamException {
        onStartElement();
        super.writeStartElement(namespaceURI, localName);
    }

    public void writeStartElement(String prefix, String localName, String namespaceURI) throws XMLStreamException {
        onStartElement();
        super.writeStartElement(prefix, localName, namespaceURI);
    }

    public void writeEmptyElement(String namespaceURI, String localName) throws XMLStreamException {
        onEmptyElement();
        super.writeEmptyElement(namespaceURI, localName);
    }

    public void writeEmptyElement(String prefix, String localName, String namespaceURI) throws XMLStreamException {
        onEmptyElement();
        super.writeEmptyElement(prefix, localName, namespaceURI);
    }

    public void writeEmptyElement(String localName) throws XMLStreamException {
        onEmptyElement();
        super.writeEmptyElement(localName);
    }

    public void writeEndElement() throws XMLStreamException {
        onEndElement();
        super.writeEndElement();
    }

    public void writeCharacters(String text) throws XMLStreamException {
        state = SEEN_DATA;
        super.writeCharacters(text);
    }

    public void writeCharacters(char[] text, int start, int len) throws XMLStreamException {
        state = SEEN_DATA;
        super.writeCharacters(text, start, len);
    }

    public void writeCData(String data) throws XMLStreamException {
        state = SEEN_DATA;
        super.writeCData(data);
    }
}