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A Sinatra inspired java web framework

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/*
 * Copyright 2011- Per Wendel
 *
 *  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 spark.exception;

import java.util.HashMap;
import java.util.Map;

public class ExceptionMapper {
    /**
     * Holds a default instance for the exception mapper
     */
    private static ExceptionMapper defaultInstance;

    /**
     * Returns the default instance for the exception mapper
     *
     * @return Default instance
     */
    public static ExceptionMapper getInstance() {
        if (defaultInstance == null) {
            defaultInstance = new ExceptionMapper();
        }
        return defaultInstance;
    }

    /**
     * Holds a map of Exception classes and associated handlers
     */
    private Map, ExceptionHandler> exceptionMap;

    /**
     * Class constructor
     */
    public ExceptionMapper() {
        this.exceptionMap = new HashMap<>();
    }

    /**
     * Maps the given handler to the provided exception type. If a handler was already registered to the same type, the
     * handler is overwritten.
     *
     * @param exceptionClass Type of exception
     * @param handler        Handler to map to exception
     */
    public void map(Class exceptionClass, ExceptionHandler handler) {
        this.exceptionMap.put(exceptionClass, handler);
    }

    /**
     * Returns the handler associated with the provided exception class
     *
     * @param exceptionClass Type of exception
     * @return Associated handler
     */
    public ExceptionHandler getHandler(Class exceptionClass) {
        return this.exceptionMap.get(exceptionClass);
    }

    /**
     * Returns the handler associated with the provided exception class
     *
     * @param exception Exception that occurred
     * @return Associated handler
     */
    public ExceptionHandler getHandler(Exception exception) {
        return this.getHandler(exception.getClass());
    }
}