/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.el.lang;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.HashMap;
import java.util.Map;

import javax.el.ValueExpression;
import javax.el.VariableMapper;

/**
 * Implementation of VariableMapper that stores variables in a map.
 */
public class VariableMapperImpl extends VariableMapper implements Externalizable {

    private static final long serialVersionUID = 1L;

    private Map<String,ValueExpression> vars = new HashMap<>();

    /**
     * Constructs a new VariableMapperImpl for deserialization.
     */
    public VariableMapperImpl() {
        super();
    }

    @Override
    public ValueExpression resolveVariable(String variable) {
        return this.vars.get(variable);
    }

    @Override
    public ValueExpression setVariable(String variable, ValueExpression expression) {
        if (expression == null) {
            return vars.remove(variable);
        } else {
            return vars.put(variable, expression);
        }
    }

    @SuppressWarnings("unchecked")
    @Override
    public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
        this.vars = (Map<String,ValueExpression>) in.readObject();
    }

    @Override
    public void writeExternal(ObjectOutput out) throws IOException {
        out.writeObject(this.vars);
    }
}
