ReaderDepthState.java

/*
 * Copyright (C) 2006 Joe Walnes.
 * Copyright (C) 2006, 2007 XStream Committers.
 * All rights reserved.
 *
 * The software in this package is published under the terms of the BSD
 * style license a copy of which has been included with this distribution in
 * the LICENSE.txt file.
 * 
 * Created on 04. June 2006 by Joe Walnes
 */
package com.thoughtworks.xstream.io.binary;

import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Collections;

/**
 * Maintains the state of a pull reader at various states in the document depth.
 *
 * Used by the {@link BinaryStreamReader}
 *
 * @author Joe Walnes
 * @since 1.2
 */
class ReaderDepthState {

    private static final String EMPTY_STRING = "";

    private static class State {
        String name;
        String value;
        List attributes;
        boolean hasMoreChildren;
        State parent;
    }

    private static class Attribute {
        String name;
        String value;
    }

    private State current;

    public void push() {
        State newState = new State();
        newState.parent = current;
        current = newState;
    }

    public void pop() {
        current = current.parent;
    }

    public String getName() {
        return current.name;
    }

    public void setName(String name) {
        current.name = name;
    }

    public String getValue() {
        return current.value == null ? EMPTY_STRING : current.value;
    }

    public void setValue(String value) {
        current.value = value;
    }

    public boolean hasMoreChildren() {
        return current.hasMoreChildren;
    }

    public void setHasMoreChildren(boolean hasMoreChildren) {
        current.hasMoreChildren = hasMoreChildren;
    }

    public void addAttribute(String name, String value) {
        Attribute attribute = new Attribute();
        attribute.name = name;
        attribute.value = value;
        if (current.attributes == null) {
            current.attributes = new ArrayList();
        }
        current.attributes.add(attribute);
    }

    public String getAttribute(String name) {
        if (current.attributes == null) {
            return null;
        } else {
            // For short maps, it's faster to iterate then do a hashlookup.
            for (Iterator iterator = current.attributes.iterator(); iterator.hasNext();) {
                Attribute attribute = (Attribute) iterator.next();
                if (attribute.name.equals(name)) {
                    return attribute.value;
                }
            }
            return null;
        }
    }

    public String getAttribute(int index) {
        if (current.attributes == null) {
            return null;
        } else {
            Attribute attribute = (Attribute) current.attributes.get(index);
            return attribute.value;
        }
    }

    public String getAttributeName(int index) {
        if (current.attributes == null) {
            return null;
        } else {
            Attribute attribute = (Attribute) current.attributes.get(index);
            return attribute.name;
        }
    }

    public int getAttributeCount() {
        return current.attributes == null ? 0 : current.attributes.size();
    }

    public Iterator getAttributeNames() {
        if (current.attributes == null) {
            return Collections.EMPTY_SET.iterator();
        } else {
            final Iterator attributeIterator = current.attributes.iterator();
            return new Iterator() {
                public boolean hasNext() {
                    return attributeIterator.hasNext();
                }

                public Object next() {
                    Attribute attribute = (Attribute) attributeIterator.next();
                    return attribute.name;
                }

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

}