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	/*
	* reserved comment block
	* DO NOT REMOVE OR ALTER!
	*/
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You 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 com.sun.org.apache.xerces.internal.impl.dtd.models;

	import com.sun.org.apache.xerces.internal.xni.QName;

	import com.sun.org.apache.xerces.internal.impl.dtd.XMLContentSpec;

	/**
	* SimpleContentModel is a derivative of the abstract content model base
	* class that handles a small set of simple content models that are just
	* way overkill to give the DFA treatment.
	* <p>
	* This class handles the following scenarios:
	* <ul>
	* <li> a
	* <li> a?
	* <li> a*
	* <li> a+
	* <li> a,b
	* <li> a\|b
	* </ul>
	* <p>
	* These all involve a unary operation with one element type, or a binary
	* operation with two elements. These are very simple and can be checked
	* in a simple way without a DFA and without the overhead of setting up a
	* DFA for such a simple check.
	*
	* @xerces.internal
	*
	*/
	public class SimpleContentModel
	implements ContentModelValidator {

	//
	// Constants
	//

	/** CHOICE */
	public static final short CHOICE = -1;

	/** SEQUENCE */
	public static final short SEQUENCE = -1;

	//
	// Data
	//


	/**
	* The element decl pool indices of the first (and optional second)
	* child node. The operation code tells us whether the second child
	* is used or not.
	*/
	private QName fFirstChild = new QName();

	/**
	* The element decl pool indices of the first (and optional second)
	* child node. The operation code tells us whether the second child
	* is used or not.
	*/
	private QName fSecondChild = new QName();

	/**
	* The operation that this object represents. Since this class only
	* does simple contents, there is only ever a single operation
	* involved (i.e. the children of the operation are always one or
	* two leafs.) This is one of the XMLDTDParams.CONTENTSPECNODE_XXX values.
	*/
	private int fOperator;

	/* this is the EquivClassComparator object */
	//private EquivClassComparator comparator = null;


	//
	// Constructors
	//

	/**
	* Constructs a simple content model.
	*
	* @param operator The content model operator.
	* @param firstChild qualified name of the first child
	* @param secondChild qualified name of the second child
	*
	*/
	public SimpleContentModel(short operator, QName firstChild, QName secondChild) {
	//
	// Store away the children and operation. This is all we need to
	// do the content model check.
	//
	// The operation is one of the ContentSpecNode.NODE_XXX values!
	//
	fFirstChild.setValues(firstChild);
	if (secondChild != null) {
	fSecondChild.setValues(secondChild);
	}
	else {
	fSecondChild.clear();
	}
	fOperator = operator;
	}

	//
	// ContentModelValidator methods
	//

	/**
	* Check that the specified content is valid according to this
	* content model. This method can also be called to do 'what if'
	* testing of content models just to see if they would be valid.
	* <p>
	* A value of -1 in the children array indicates a PCDATA node. All other
	* indexes will be positive and represent child elements. The count can be
	* zero, since some elements have the EMPTY content model and that must be
	* confirmed.
	*
	* @param children The children of this element. Each integer is an index within
	* the <code>StringPool</code> of the child element name. An index
	* of -1 is used to indicate an occurrence of non-whitespace character
	* data.
	* @param offset Offset into the array where the children starts.
	* @param length The number of entries in the <code>children</code> array.
	*
	* @return The value -1 if fully valid, else the 0 based index of the child
	* that first failed. If the value returned is equal to the number
	* of children, then the specified children are valid but additional
	* content is required to reach a valid ending state.
	*
	*/
	public int validate(QName[] children, int offset, int length) {

	//
	// According to the type of operation, we do the correct type of
	// content check.
	//
	switch(fOperator)
	{
	case XMLContentSpec.CONTENTSPECNODE_LEAF :
	// If there is not a child, then report an error at index 0
	if (length == 0)
	return 0;

	// If the 0th child is not the right kind, report an error at 0
	if (children[offset].rawname != fFirstChild.rawname) {
	return 0;
	}

	// If more than one child, report an error at index 1
	if (length > 1)
	return 1;
	break;

	case XMLContentSpec.CONTENTSPECNODE_ZERO_OR_ONE :
	//
	// If there is one child, make sure its the right type. If not,
	// then its an error at index 0.
	//
	if (length == 1) {
	if (children[offset].rawname != fFirstChild.rawname) {
	return 0;
	}
	}

	//
	// If the child count is greater than one, then obviously
	// bad, so report an error at index 1.
	//
	if (length > 1)
	return 1;
	break;

	case XMLContentSpec.CONTENTSPECNODE_ZERO_OR_MORE :
	//
	// If the child count is zero, that's fine. If its more than
	// zero, then make sure that all children are of the element
	// type that we stored. If not, report the index of the first
	// failed one.
	//
	if (length > 0)
	{
	for (int index = 0; index < length; index++) {
	if (children[offset + index].rawname != fFirstChild.rawname) {
	return index;
	}
	}
	}
	break;

	case XMLContentSpec.CONTENTSPECNODE_ONE_OR_MORE :
	//
	// If the child count is zero, that's an error so report
	// an error at index 0.
	//
	if (length == 0)
	return 0;

	//
	// Otherwise we have to check them all to make sure that they
	// are of the correct child type. If not, then report the index
	// of the first one that is not.
	//
	for (int index = 0; index < length; index++) {
	if (children[offset + index].rawname != fFirstChild.rawname) {
	return index;
	}
	}
	break;

	case XMLContentSpec.CONTENTSPECNODE_CHOICE :
	//
	// There must be one and only one child, so if the element count
	// is zero, return an error at index 0.
	//
	if (length == 0)
	return 0;

	// If the zeroth element isn't one of our choices, error at 0
	if ((children[offset].rawname != fFirstChild.rawname) &&
	(children[offset].rawname != fSecondChild.rawname)) {
	return 0;
	}

	// If there is more than one element, then an error at 1
	if (length > 1)
	return 1;
	break;

	case XMLContentSpec.CONTENTSPECNODE_SEQ :
	//
	// There must be two children and they must be the two values
	// we stored, in the stored order.
	//
	if (length == 2) {
	if (children[offset].rawname != fFirstChild.rawname) {
	return 0;
	}
	if (children[offset + 1].rawname != fSecondChild.rawname) {
	return 1;
	}
	}
	else {
	if (length > 2) {
	return 2;
	}

	return length;
	}

	break;

	default :
	throw new RuntimeException("ImplementationMessages.VAL_CST");
	}

	// We survived, so return success status
	return -1;
	} // validate

	} // class SimpleContentModel

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