Smack/core/src/main/java/org/jivesoftware/smack/util/XmlStringBuilder.java

/**
 *
 * Copyright 2014 Florian Schmaus
 *
 * 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 org.jivesoftware.smack.util;

import org.jivesoftware.smack.packet.PacketExtension;

public class XmlStringBuilder implements Appendable, CharSequence {
    public static final String RIGHT_ANGEL_BRACKET = Character.toString('>');

    private final LazyStringBuilder sb;

    public XmlStringBuilder() {
        sb = new LazyStringBuilder();
    }

    public XmlStringBuilder(PacketExtension pe) {
        this();
        prelude(pe);
    }

    /**
     * Does nothing if content is null.
     *
     * @param name
     * @param content
     * @return the XmlStringBuilder
     */
    public XmlStringBuilder element(String name, String content) {
        assert content != null;
        openElement(name);
        escape(content);
        closeElement(name);
        return this;
    }

    public XmlStringBuilder element(String name, Enum<?> content) {
        assert content != null;
        element(name, content.name());
        return this;
    }

    public XmlStringBuilder optElement(String name, String content) {
        if (content != null) {
            element(name, content);
        }
        return this;
    }

    public XmlStringBuilder optElement(String name, Enum<?> content) {
        if (content != null) {
            element(name, content);
        }
        return this;
    }

    public XmlStringBuilder halfOpenElement(String name) {
        sb.append('<').append(name);
        return this;
    }

    public XmlStringBuilder openElement(String name) {
        halfOpenElement(name).rightAngelBracket();
        return this;
    }

    public XmlStringBuilder closeElement(String name) {
        sb.append("</").append(name);
        rightAngelBracket();
        return this;
    }

    public XmlStringBuilder closeElement(PacketExtension pe) {
        closeElement(pe.getElementName());
        return this;
    }

    public XmlStringBuilder closeEmptyElement() {
        sb.append("/>");
        return this;
    }

    public XmlStringBuilder rightAngelBracket() {
        sb.append(RIGHT_ANGEL_BRACKET);
        return this;
    }

    /**
     * Does nothing if value is null.
     *
     * @param name
     * @param value
     * @return the XmlStringBuilder
     */
    public XmlStringBuilder attribute(String name, String value) {
        assert value != null;
        sb.append(' ').append(name).append("='");
        escape(value);
        sb.append('\'');
        return this;
    }

    public XmlStringBuilder attribute(String name, Enum<?> value) {
        assert value != null;
        attribute(name, value.name());
        return this;
    }

    public XmlStringBuilder optAttribute(String name, String value) {
        if (value != null) {
            attribute(name, value);
        }
        return this;
    }

    public XmlStringBuilder optAttribute(String name, Enum<?> value) {
        if (value != null) {
            attribute(name, value.name());
        }
        return this;
    }

    public XmlStringBuilder xmlnsAttribute(String value) {
        optAttribute("xmlns", value);
        return this;
    }

    public XmlStringBuilder xmllangAttribute(String value) {
        optAttribute("xml:lang", value);
        return this;
    }
 
    public XmlStringBuilder escape(String text) {
        assert text != null;
        sb.append(StringUtils.escapeForXML(text));
        return this;
    }

    public XmlStringBuilder prelude(PacketExtension pe) {
        halfOpenElement(pe.getElementName());
        xmlnsAttribute(pe.getNamespace());
        return this;
    }

    public XmlStringBuilder optAppend(CharSequence csq) {
        if (csq != null) {
            append(csq);
        }
        return this;
    }

    public XmlStringBuilder append(XmlStringBuilder xsb) {
        assert xsb != null;
        sb.append(xsb.sb);
        return this;
    }

    @Override
    public XmlStringBuilder append(CharSequence csq) {
        assert csq != null;
        sb.append(csq);
        return this;
    }

    @Override
    public XmlStringBuilder append(CharSequence csq, int start, int end) {
        assert csq != null;
        sb.append(csq, start, end);
        return this;
    }

    @Override
    public XmlStringBuilder append(char c) {
        sb.append(c);
        return this;
    }

    @Override
    public int length() {
        return sb.length();
    }

    @Override
    public char charAt(int index) {
        return sb.charAt(index);
    }

    @Override
    public CharSequence subSequence(int start, int end) {
        return sb.subSequence(start, end);
    }

    @Override
    public String toString() {
        return sb.toString();
    }
}