bundles/org.eclipse.wst.xml.xpath2.processor/src/org/eclipse/wst/xml/xpath2/processor/internal/function/FnMin.java

/*******************************************************************************
 * Copyright (c) 2005, 2009 Andrea Bittau, University College London, 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
 *
 * Contributors:
 *     Andrea Bittau - initial API and implementation from the PsychoPath XPath 2.0 
 *******************************************************************************/

package org.eclipse.wst.xml.xpath2.processor.internal.function;

import org.eclipse.wst.xml.xpath2.processor.DynamicError;
import org.eclipse.wst.xml.xpath2.processor.ResultSequence;
import org.eclipse.wst.xml.xpath2.processor.ResultSequenceFactory;
import org.eclipse.wst.xml.xpath2.processor.internal.*;
import org.eclipse.wst.xml.xpath2.processor.internal.types.*;

import java.util.*;

/**
 * selects an item from the input sequence $arg whose value is less than or
 * equal to the value of every other item in the input sequence. If there are
 * two or more such items, then the specific item whose value is returned is
 * implementation independent.
 */
public class FnMin extends Function {
	/**
	 * Constructor for FnMin.
	 */
	public FnMin() {
		super(new QName("min"), 1);
	}

	/**
	 * Evaluate arguments.
	 * 
	 * @param args
	 *            argument expressions.
	 * @throws DynamicError
	 *             Dynamic error.
	 * @return Result of evaluation.
	 */
	@Override
	public ResultSequence evaluate(Collection args) throws DynamicError {
		return min(args);
	}

	/**
	 * Min operation.
	 * 
	 * @param args
	 *            Result from the expressions evaluation.
	 * @throws DynamicError
	 *             Dynamic error.
	 * @return Result of fn:min operation.
	 */
	public static ResultSequence min(Collection args) throws DynamicError {

		// XXX fix this
		ResultSequence arg = FnMax.get_arg(args, CmpLt.class);
		if (arg.empty())
			return ResultSequenceFactory.create_new();

		CmpLt min = null;

		for (Iterator i = arg.iterator(); i.hasNext();) {
			AnyType at = (AnyType) i.next();

			if (!(at instanceof CmpLt))
				DynamicError.throw_type_error();

			CmpLt item = (CmpLt) at;

			if (min == null)
				min = item;
			else {
				boolean res = item.lt((AnyType) min);

				if (res)
					min = item;
			}
		}

		return ResultSequenceFactory.create_new((AnyType) min);
	}
}