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JSefa (Java Simple exchange format api) is a simple library for stream-based serialization of java objects to XML, CSV, FLR or any other format and back again using an iterator-style interface independent of the serialization format. The mapping between java object types and types of the serialization format (e. g. xml complex element types) can be defined either by annotating the java classes or programmatically using a simple API. The current implementation supports XML, CSV and FLR - for XML it is based on JSR 173.

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/*
 * Copyright 2007 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 net.sf.jsefa.xml.mapping;

import net.sf.jsefa.xml.namespace.QName;

/**
 * Descriptor for an xml element.
 * 
 * Instances of this class are immutable and thread safe.
 * 
 * @author Norman Lahme-Huetig
 * 
 */
public final class ElementDescriptor implements XmlNodeDescriptor {

    private final QName name;

    private final QName dataTypeName;

    private final int hashCode;

    /**
     * Constructs a new ElementDescriptor.
     * 
     * @param name the name of the element - may be null if the node is virtual, i. e. if the node groups other
     *                nodes without having an own representation, e. g. an implicit list.
     * @param dataTypeName the name of its data type - may be null for simplified element descriptors. If null the
     *                name must not be null.
     */
    public ElementDescriptor(QName name, QName dataTypeName) {
        if (name == null && dataTypeName == null) {
            throw new IllegalArgumentException(
                    "Both parameters (name, dataTypeName) are null but one of them must not be null!");
        }
        this.name = name;
        this.dataTypeName = dataTypeName;
        this.hashCode = calculateHashCode();
    }

    /**
     * {@inheritDoc}
     */
    public XmlNodeType getType() {
        return XmlNodeType.ELEMENT;
    }

    /**
     * Returns the name of the element.
     * 
     * May be null if the node is virtual, i. e. if the node groups other nodes without having an own
     * representation, e. g. an implicit list.
     * 
     * @return the element name
     */
    public QName getName() {
        return this.name;
    }

    /**
     * Returns the name of the data type of the element.
     * 
     * @return the data type name
     */
    public QName getDataTypeName() {
        return this.dataTypeName;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int hashCode() {
        return this.hashCode;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (!(obj instanceof ElementDescriptor)) {
            return false;
        }
        final ElementDescriptor other = (ElementDescriptor) obj;
        if (name == null) {
            if (other.name != null) {
                return false;
            }
        } else if (!name.equals(other.name)) {
            return false;
        }
        if (dataTypeName == null) {
            if (other.dataTypeName != null) {
                return false;
            }
        } else if (!dataTypeName.equals(other.dataTypeName)) {
            return false;
        }
        return true;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String toString() {
        if (this.name == null) {
            return this.dataTypeName.toString();
        } else if (this.dataTypeName == null) {
            return this.name.toString();
        } else {
            return getName().toString() + ":" + getDataTypeName();
        }
    }

    private int calculateHashCode() {
        int resultCode = 1;
        if (this.name != null) {
            resultCode = 31 * resultCode + name.hashCode();
        }
        if (dataTypeName != null) {
            resultCode = 31 * resultCode + dataTypeName.hashCode();
        }
        return resultCode;
    }

}