/*
 * 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.wayang.core.util.mathex.model;

import org.apache.wayang.core.util.mathex.Context;
import org.apache.wayang.core.util.mathex.Expression;
import org.apache.wayang.core.util.mathex.exceptions.EvaluationException;

/**
 * An operation {@link Expression}.
 */
public class UnaryOperation implements Expression {

    private final char operator;

    private final Expression operand;

    public UnaryOperation(char operator, Expression operand) {
        this.operator = operator;
        this.operand = operand;
    }

    @Override
    public double evaluate(Context context) {
        switch (this.operator) {
            case '+':
                return this.operand.evaluate(context);
            case '-':
                return -this.operand.evaluate(context);
            default:
                throw new EvaluationException(String.format("Unknown operator: \"%s\"", this.operator));
        }
    }

    @Override
    public String toString() {
        return String.format("%s(%s)", this.operator, this.operand);
    }

}
