1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/*
6 * Licensed to the Apache Software Foundation (ASF) under one or more
7 * contributor license agreements.  See the NOTICE file distributed with
8 * this work for additional information regarding copyright ownership.
9 * The ASF licenses this file to You under the Apache License, Version 2.0
10 * (the "License"); you may not use this file except in compliance with
11 * the License.  You may obtain a copy of the License at
12 *
13 *      http://www.apache.org/licenses/LICENSE-2.0
14 *
15 * Unless required by applicable law or agreed to in writing, software
16 * distributed under the License is distributed on an "AS IS" BASIS,
17 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18 * See the License for the specific language governing permissions and
19 * limitations under the License.
20 */
21
22package com.sun.org.apache.xerces.internal.impl.dtd.models;
23
24import com.sun.org.apache.xerces.internal.xni.QName;
25
26import com.sun.org.apache.xerces.internal.impl.dtd.XMLContentSpec;
27
28/**
29 * SimpleContentModel is a derivative of the abstract content model base
30 * class that handles a small set of simple content models that are just
31 * way overkill to give the DFA treatment.
32 * <p>
33 * This class handles the following scenarios:
34 * <ul>
35 * <li> a
36 * <li> a?
37 * <li> a*
38 * <li> a+
39 * <li> a,b
40 * <li> a|b
41 * </ul>
42 * <p>
43 * These all involve a unary operation with one element type, or a binary
44 * operation with two elements. These are very simple and can be checked
45 * in a simple way without a DFA and without the overhead of setting up a
46 * DFA for such a simple check.
47 *
48 * @xerces.internal
49 *
50 */
51public class SimpleContentModel
52    implements ContentModelValidator {
53
54    //
55    // Constants
56    //
57
58    /** CHOICE */
59    public static final short CHOICE = -1;
60
61    /** SEQUENCE */
62    public static final short SEQUENCE = -1;
63
64    //
65    // Data
66    //
67
68
69    /**
70     * The element decl pool indices of the first (and optional second)
71     * child node. The operation code tells us whether the second child
72     * is used or not.
73     */
74    private QName fFirstChild = new QName();
75
76    /**
77     * The element decl pool indices of the first (and optional second)
78     * child node. The operation code tells us whether the second child
79     * is used or not.
80     */
81    private QName fSecondChild = new QName();
82
83    /**
84     * The operation that this object represents. Since this class only
85     * does simple contents, there is only ever a single operation
86     * involved (i.e. the children of the operation are always one or
87     * two leafs.) This is one of the XMLDTDParams.CONTENTSPECNODE_XXX values.
88     */
89    private int fOperator;
90
91    /* this is the EquivClassComparator object */
92    //private EquivClassComparator comparator = null;
93
94
95    //
96    // Constructors
97    //
98
99    /**
100     * Constructs a simple content model.
101     *
102     * @param operator The content model operator.
103     * @param firstChild qualified name of the first child
104     * @param secondChild qualified name of the second child
105     *
106     */
107    public SimpleContentModel(short operator, QName firstChild, QName secondChild) {
108        //
109        //  Store away the children and operation. This is all we need to
110        //  do the content model check.
111        //
112        //  The operation is one of the ContentSpecNode.NODE_XXX values!
113        //
114        fFirstChild.setValues(firstChild);
115        if (secondChild != null) {
116            fSecondChild.setValues(secondChild);
117        }
118        else {
119            fSecondChild.clear();
120        }
121        fOperator = operator;
122    }
123
124    //
125    // ContentModelValidator methods
126    //
127
128    /**
129     * Check that the specified content is valid according to this
130     * content model. This method can also be called to do 'what if'
131     * testing of content models just to see if they would be valid.
132     * <p>
133     * A value of -1 in the children array indicates a PCDATA node. All other
134     * indexes will be positive and represent child elements. The count can be
135     * zero, since some elements have the EMPTY content model and that must be
136     * confirmed.
137     *
138     * @param children The children of this element.  Each integer is an index within
139     *                 the <code>StringPool</code> of the child element name.  An index
140     *                 of -1 is used to indicate an occurrence of non-whitespace character
141     *                 data.
142     * @param offset Offset into the array where the children starts.
143     * @param length The number of entries in the <code>children</code> array.
144     *
145     * @return The value -1 if fully valid, else the 0 based index of the child
146     *         that first failed. If the value returned is equal to the number
147     *         of children, then the specified children are valid but additional
148     *         content is required to reach a valid ending state.
149     *
150     */
151    public int validate(QName[] children, int offset, int length) {
152
153        //
154        //  According to the type of operation, we do the correct type of
155        //  content check.
156        //
157        switch(fOperator)
158        {
159            case XMLContentSpec.CONTENTSPECNODE_LEAF :
160                // If there is not a child, then report an error at index 0
161                if (length == 0)
162                    return 0;
163
164                // If the 0th child is not the right kind, report an error at 0
165                if (children[offset].rawname != fFirstChild.rawname) {
166                    return 0;
167                }
168
169                // If more than one child, report an error at index 1
170                if (length > 1)
171                    return 1;
172                break;
173
174            case XMLContentSpec.CONTENTSPECNODE_ZERO_OR_ONE :
175                //
176                //  If there is one child, make sure its the right type. If not,
177                //  then its an error at index 0.
178                //
179                if (length == 1) {
180                    if (children[offset].rawname != fFirstChild.rawname) {
181                        return 0;
182                    }
183                }
184
185                //
186                //  If the child count is greater than one, then obviously
187                //  bad, so report an error at index 1.
188                //
189                if (length > 1)
190                    return 1;
191                break;
192
193            case XMLContentSpec.CONTENTSPECNODE_ZERO_OR_MORE :
194                //
195                //  If the child count is zero, that's fine. If its more than
196                //  zero, then make sure that all children are of the element
197                //  type that we stored. If not, report the index of the first
198                //  failed one.
199                //
200                if (length > 0)
201                {
202                    for (int index = 0; index < length; index++) {
203                        if (children[offset + index].rawname != fFirstChild.rawname) {
204                            return index;
205                        }
206                    }
207                }
208                break;
209
210            case XMLContentSpec.CONTENTSPECNODE_ONE_OR_MORE :
211                //
212                //  If the child count is zero, that's an error so report
213                //  an error at index 0.
214                //
215                if (length == 0)
216                    return 0;
217
218                //
219                //  Otherwise we have to check them all to make sure that they
220                //  are of the correct child type. If not, then report the index
221                //  of the first one that is not.
222                //
223                for (int index = 0; index < length; index++) {
224                    if (children[offset + index].rawname != fFirstChild.rawname) {
225                        return index;
226                    }
227                }
228                break;
229
230            case XMLContentSpec.CONTENTSPECNODE_CHOICE :
231                //
232                //  There must be one and only one child, so if the element count
233                //  is zero, return an error at index 0.
234                //
235                if (length == 0)
236                    return 0;
237
238                // If the zeroth element isn't one of our choices, error at 0
239                if ((children[offset].rawname != fFirstChild.rawname) &&
240                    (children[offset].rawname != fSecondChild.rawname)) {
241                    return 0;
242                }
243
244                // If there is more than one element, then an error at 1
245                if (length > 1)
246                    return 1;
247                break;
248
249            case XMLContentSpec.CONTENTSPECNODE_SEQ :
250                //
251                //  There must be two children and they must be the two values
252                //  we stored, in the stored order.
253                //
254                if (length == 2) {
255                    if (children[offset].rawname != fFirstChild.rawname) {
256                        return 0;
257                    }
258                    if (children[offset + 1].rawname != fSecondChild.rawname) {
259                        return 1;
260                    }
261                }
262                else {
263                    if (length > 2) {
264                        return 2;
265                    }
266
267                    return length;
268                }
269
270                break;
271
272            default :
273                throw new RuntimeException("ImplementationMessages.VAL_CST");
274        }
275
276        // We survived, so return success status
277        return -1;
278    } // validate
279
280} // class SimpleContentModel
281