DefaultValueExpression.java

/*
 * (C) Copyright 2013 Nuxeo SA (http://nuxeo.com/) and others.
 *
 * 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.
 *
 * Contributors:
 *     Anahide Tchertchian
 */
package org.nuxeo.ecm.platform.ui.web.binding;

import java.util.Collection;

import javax.el.ELContext;
import javax.el.PropertyNotFoundException;
import javax.el.ValueExpression;

/**
 * Value expression holding a default value expression for resolve on get, when original value expression defaults to
 * null.
 * <p>
 * Accepts a null original value expression in case default value should be resolved even if no mapping should be done.
 *
 * @since 5.7.3
 */
public class DefaultValueExpression extends ValueExpression {

    private static final long serialVersionUID = 1L;

    protected final ValueExpression originalExpression;

    protected final ValueExpression defaultExpression;

    public DefaultValueExpression(ValueExpression originalExpression, ValueExpression defaultExpression) {
        super();
        this.originalExpression = originalExpression;
        this.defaultExpression = defaultExpression;
    }

    @Override
    public Class<?> getExpectedType() {
        if (originalExpression != null) {
            return originalExpression.getExpectedType();
        } else {
            return defaultExpression.getExpectedType();
        }
    }

    @Override
    public Class<?> getType(ELContext arg0) throws PropertyNotFoundException {
        if (originalExpression != null) {
            return originalExpression.getType(arg0);
        } else {
            return defaultExpression.getType(arg0);
        }
    }

    @Override
    @SuppressWarnings("rawtypes")
    public Object getValue(ELContext arg0) throws PropertyNotFoundException {
        Object value = null;
        if (originalExpression != null) {
            value = originalExpression.getValue(arg0);
        }
        if (value == null || ((value instanceof Object[]) && ((Object[]) value).length == 0)
                || ((value instanceof Collection) && ((Collection) value).size() == 0)) {
            value = defaultExpression.getValue(arg0);
        }
        return value;
    }

    @Override
    public boolean isReadOnly(ELContext arg0) throws PropertyNotFoundException {
        if (originalExpression != null) {
            return originalExpression.isReadOnly(arg0);
        } else {
            return true;
        }
    }

    @Override
    public void setValue(ELContext arg0, Object arg1) throws PropertyNotFoundException {
        if (originalExpression != null) {
            originalExpression.setValue(arg0, arg1);
        }
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (!(obj instanceof DefaultValueExpression)) {
            return false;
        }
        DefaultValueExpression other = (DefaultValueExpression) obj;
        if (originalExpression != null) {
            return originalExpression.equals(other.originalExpression)
                    && defaultExpression.equals(other.defaultExpression);
        } else {
            return defaultExpression.equals(other.defaultExpression);
        }
    }

    @Override
    public String getExpressionString() {
        if (originalExpression != null) {
            return originalExpression.getExpressionString();
        }
        return null;
    }

    @Override
    public int hashCode() {
        if (originalExpression != null) {
            return originalExpression.hashCode() + defaultExpression.hashCode();
        } else {
            return defaultExpression.hashCode();
        }
    }

    @Override
    public boolean isLiteralText() {
        return (originalExpression != null && originalExpression.isLiteralText())
                || (defaultExpression != null && defaultExpression.isLiteralText());
    }
}