bundles/org.eclipse.wst.xml.xpath2.processor/src/org/eclipse/wst/xml/xpath2/processor/internal/function/FnDeepEqual.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.*;
import org.w3c.dom.*;

/**
 * The function assesses whether two sequences are deep-equal to each other. To
 * be deep-equal, they must contain items that are pairwise deep-equal; and for
 * two items to be deep-equal, they must either by atomic values that compare
 * equal, or nodes of the same kind, with the same name, whose children are
 * deep-equal. This is defined in more detail below. The $collation argument
 * identifies a collation which is used at all levels of recursion when strings
 * are compared (but not when names are compared), according to the rules in
 * 7.3.1 Collations in the specification.
 */
public class FnDeepEqual extends Function {
	/**
	 * Constructor for FnDeepEqual.
	 */
	public FnDeepEqual() {
		super(new QName("deep-equal"), 2);
	}

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

	/**
	 * Deep-Equal expression operation.
	 * 
	 * @param args
	 *            Result from the expressions evaluation.
	 * @throws DynamicError
	 *             Dynamic error.
	 * @return Result of fn:deep-equal operation.
	 */
	public static ResultSequence deep_equal(Collection args)
			throws DynamicError {

		assert args.size() == 2;

		// get args
		Iterator citer = args.iterator();
		ResultSequence arg1 = (ResultSequence) citer.next();
		ResultSequence arg2 = (ResultSequence) citer.next();

		boolean result = deep_equal(arg1, arg2);

		return ResultSequenceFactory.create_new(new XSBoolean(result));
	}

	/**
	 * Deep-Equal boolean operation.
	 * 
	 * @param one
	 *            input1 xpath expression/variable.
	 * @param two
	 *            input2 xpath expression/variable.
	 * @return Result of fn:deep-equal operation.
	 */
	public static boolean deep_equal(ResultSequence one, ResultSequence two) {
		if (one.empty() && two.empty())
			return true;

		if (one.size() != two.size())
			return false;

		Iterator onei = one.iterator();
		Iterator twoi = two.iterator();

		while (onei.hasNext()) {
			AnyType a = (AnyType) onei.next();
			AnyType b = (AnyType) twoi.next();

			if (!deep_equal(a, b))
				return false;
		}
		return true;
	}

	/**
	 * Deep-Equal boolean operation for inputs of any type.
	 * 
	 * @param one
	 *            input1 xpath expression/variable.
	 * @param two
	 *            input2 xpath expression/variable.
	 * @return Result of fn:deep-equal operation.
	 */
	public static boolean deep_equal(AnyType one, AnyType two) {
		if ((one instanceof AnyAtomicType) && (two instanceof AnyAtomicType))
			return deep_equal((AnyAtomicType) one, (AnyAtomicType) two);

		else if (((one instanceof AnyAtomicType) && (two instanceof NodeType))
				|| ((one instanceof NodeType) && (two instanceof AnyAtomicType)))
			return false;
		else if ((one instanceof NodeType) && (two instanceof NodeType))
			return deep_equal((NodeType) one, (NodeType) two);
		else {
			assert false;
			return false;
		}
	}

	/**
	 * Deep-Equal boolean operation for inputs of any atomic type.
	 * 
	 * @param one
	 *            input1 xpath expression/variable.
	 * @param two
	 *            input2 xpath expression/variable.
	 * @return Result of fn:deep-equal operation.
	 */
	public static boolean deep_equal(AnyAtomicType one, AnyAtomicType two) {
		if (!(one instanceof CmpEq))
			return false;
		if (!(two instanceof CmpEq))
			return false;

		CmpEq a = (CmpEq) one;

		try {
			if (a.eq(two))
				return true;
			return false;
		} catch (DynamicError err) {
			return false; // XXX ???
		}
	}

	/**
	 * Deep-Equal boolean operation for inputs of node type.
	 * 
	 * @param one
	 *            input1 xpath expression/variable.
	 * @param two
	 *            input2 xpath expression/variable.
	 * @return Result of fn:deep-equal operation.
	 */
	public static boolean deep_equal(NodeType one, NodeType two) {
		Node a = one.node_value();
		Node b = two.node_value();

		if (a.getNodeType() != b.getNodeType())
			return false;

		// XXX implement
		assert false;
		return false;
	}
}