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/**
 *  Copyright (c) 1997-2013, www.tinygroup.org ([email protected]).
 *
 *  Licensed under the GPL, Version 3.0 (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.gnu.org/licenses/gpl.html
 *
 *  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.tinygroup.jspengine.el;

import org.tinygroup.jspengine.el.lang.ELSupport;
import org.tinygroup.jspengine.el.util.MessageFactory;
import org.tinygroup.jspengine.el.util.ReflectionUtil;

import javax.el.ELContext;
import javax.el.ELException;
import javax.el.PropertyNotWritableException;
import javax.el.ValueExpression;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;


public final class ValueExpressionLiteral extends ValueExpression implements
        Externalizable {

    private static final long serialVersionUID = 1L;

    private Object value;

    private Class expectedType;

    public ValueExpressionLiteral() {
        super();
    }
    
    public ValueExpressionLiteral(Object value, Class expectedType) {
        this.value = value;
        this.expectedType = expectedType;
    }

    public Object getValue(ELContext context) {
        if (this.expectedType != null) {
            try {
                return ELSupport.coerceToType(this.value, this.expectedType);
            } catch (IllegalArgumentException ex) {
                throw new ELException(ex);
            }
        }
        return this.value;
    }

    public void setValue(ELContext context, Object value) {
        throw new PropertyNotWritableException(MessageFactory.get(
                "error.value.literal.write", this.value));
    }

    public boolean isReadOnly(ELContext context) {
        return true;
    }

    public Class getType(ELContext context) {
        return (this.value != null) ? this.value.getClass() : null;
    }

    public Class getExpectedType() {
        return this.expectedType;
    }

    public String getExpressionString() {
        return (this.value != null) ? this.value.toString() : null;
    }

    public boolean equals(Object obj) {
        return (obj instanceof ValueExpressionLiteral && this
                .equals((ValueExpressionLiteral) obj));
    }

    public boolean equals(ValueExpressionLiteral ve) {
        return (ve != null && (this.value != null && ve.value != null && (this.value == ve.value || this.value
                .equals(ve.value))));
    }

    public int hashCode() {
        return (this.value != null) ? this.value.hashCode() : 0;
    }

    public boolean isLiteralText() {
        return true;
    }

    public void writeExternal(ObjectOutput out) throws IOException {
        out.writeObject(this.value);
        out.writeUTF((this.expectedType != null) ? this.expectedType.getName()
                : "");
    }

    public void readExternal(ObjectInput in) throws IOException,
            ClassNotFoundException {
        this.value = in.readObject();
        String type = in.readUTF();
        if (!"".equals(type)) {
            this.expectedType = ReflectionUtil.forName(type);
        }
    }
}