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/*******************************************************************************
 * Copyright (c) 2011 itemis AG (http://www.itemis.eu) and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *******************************************************************************/
package org.eclipse.xtext.xbase.lib;

import org.eclipse.xtext.xbase.lib.Functions.Function0;
import org.eclipse.xtext.xbase.lib.Functions.Function1;
import org.eclipse.xtext.xbase.lib.Functions.Function2;
import org.eclipse.xtext.xbase.lib.Functions.Function3;
import org.eclipse.xtext.xbase.lib.Functions.Function4;
import org.eclipse.xtext.xbase.lib.Functions.Function5;
import org.eclipse.xtext.xbase.lib.Functions.Function6;

import com.google.common.annotations.GwtCompatible;

/**
 * This is an extension library for {@link Functions functions}, e.g. closures.
 * 
 * @author Sven Efftinge - Initial contribution and API
 * @see Functions
 */
@GwtCompatible public class FunctionExtensions {

	/**
	 * Curries a function that takes one argument.
	 * 
	 * @param function
	 *            the original function. May not be null.
	 * @param argument
	 *            the fixed argument.
	 * @return a function that takes no arguments. Never null.
	 */
	@Pure
	public static  Function0 curry(final Function1 function, final P1 argument) {
		if (function == null)
			throw new NullPointerException("function");
		return new Function0() {
			public RESULT apply() {
				return function.apply(argument);
			}
		};
	}

	/**
	 * Curries a function that takes two arguments.
	 * 
	 * @param function
	 *            the original function. May not be null.
	 * @param argument
	 *            the fixed first argument of {@code function}.
	 * @return a function that takes one argument. Never null.
	 */
	@Pure
	public static  Function1 curry(final Function2 function,
			final P1 argument) {
		if (function == null)
			throw new NullPointerException("function");
		return new Function1() {
			public RESULT apply(P2 p) {
				return function.apply(argument, p);
			}
		};
	}

	/**
	 * Curries a function that takes three arguments.
	 * 
	 * @param function
	 *            the original function. May not be null.
	 * @param argument
	 *            the fixed first argument of {@code function}.
	 * @return a function that takes two arguments. Never null.
	 */
	@Pure
	public static  Function2 curry(final Function3 function,
			final P1 argument) {
		if (function == null)
			throw new NullPointerException("function");
		return new Function2() {
			public RESULT apply(P2 p2, P3 p3) {
				return function.apply(argument, p2, p3);
			}
		};
	}

	/**
	 * Curries a function that takes four arguments.
	 * 
	 * @param function
	 *            the original function. May not be null.
	 * @param argument
	 *            the fixed first argument of {@code function}.
	 * @return a function that takes three arguments. Never null.
	 */
	@Pure
	public static  Function3 curry(
			final Function4 function, final P1 argument) {
		if (function == null)
			throw new NullPointerException("function");
		return new Function3() {
			public RESULT apply(P2 p2, P3 p3, P4 p4) {
				return function.apply(argument, p2, p3, p4);
			}
		};
	}

	/**
	 * Curries a function that takes five arguments.
	 * 
	 * @param function
	 *            the original function. May not be null.
	 * @param argument
	 *            the fixed first argument of {@code function}.
	 * @return a function that takes four arguments. Never null.
	 */
	@Pure
	public static  Function4 curry(
			final Function5 function, final P1 argument) {
		if (function == null)
			throw new NullPointerException("function");
		return new Function4() {
			public RESULT apply(P2 p2, P3 p3, P4 p4, P5 p5) {
				return function.apply(argument, p2, p3, p4, p5);
			}
		};
	}

	/**
	 * Curries a function that takes six arguments.
	 * 
	 * @param function
	 *            the original function. May not be null.
	 * @param argument
	 *            the fixed first argument of {@code function}.
	 * @return a function that takes five arguments. Never null.
	 */
	@Pure
	public static  Function5 curry(
			final Function6 function, final P1 argument) {
		if (function == null)
			throw new NullPointerException("function");
		return new Function5() {
			public RESULT apply(P2 p2, P3 p3, P4 p4, P5 p5, P6 p6) {
				return function.apply(argument, p2, p3, p4, p5, p6);
			}
		};
	}
}