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Non-domain infrastructure code that is common to many Neo4j components.
There is a newer version: 3.6.2
/*
 * Copyright (c) 2018-2020 "Graph Foundation,"
 * Graph Foundation, Inc. [https://graphfoundation.org]
 *
 * This file is part of ONgDB.
 *
 * ONgDB is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
/*
 * Copyright (c) 2002-2020 "Neo4j,"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.function;

import java.util.Optional;
import java.util.function.Function;

/**
 * Represents a function that accepts one argument and produces a result, or throws an exception.
 *
 * @param  the type of the input to the function
 * @param  the type of the result of the function
 * @param  the type of exception that may be thrown from the function
 */
public interface ThrowingFunction
{
    /**
     * Apply a value to this function
     *
     * @param t the function argument
     * @return the function result
     * @throws E an exception if the function fails
     */
    R apply( T t ) throws E;

    /**
     * Construct a regular function that calls a throwing function and catches all checked exceptions
     * declared and thrown by the throwing function and rethrows them as {@link UncaughtCheckedException}
     * for handling further up the stack.
     *
     * @see UncaughtCheckedException
     *
     * @param throwing the throwing function to wtap
     * @param  type of arguments
     * @param  type of results
     * @param  type of checked exceptions thrown by the throwing function
     * @return a new, non-throwing function
     * @throws IllegalStateException if an unexpected exception is caught (ie. neither of type E or a runtime exception)
     */
    static  Function catchThrown( Class clazz, ThrowingFunction throwing )
    {
        return input ->
        {
            try
            {
                return throwing.apply( input );
            }
            catch ( Exception e )
            {
                if ( clazz.isInstance( e ) )
                {
                    throw new UncaughtCheckedException( throwing, clazz.cast( e ) );
                }
                else if ( e instanceof RuntimeException )
                {
                    throw (RuntimeException) e;
                }
                else
                {
                    throw new IllegalStateException( "Unexpected exception", e );
                }
            }
        };
    }

    @SuppressWarnings( "OptionalUsedAsFieldOrParameterType" )
    static  void throwIfPresent( Optional exception ) throws E
    {
        if ( exception.isPresent() )
        {
            throw exception.get();
        }
    }
}