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| 1 | +/* | |
| 2 | + * Copyright (c) 2008, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | +package com.sun.beans.decoder; | |
| 26 | + | |
| 27 | +/** | |
| 28 | + * The base class for element handlers. | |
| 29 | + * | |
| 30 | + * @since 1.7 | |
| 31 | + * | |
| 32 | + * @author Sergey A. Malenkov | |
| 33 | + * | |
| 34 | + * @see DocumentHandler | |
| 35 | + */ | |
| 36 | +public abstract class ElementHandler { | |
| 37 | + private DocumentHandler owner; | |
| 38 | + private ElementHandler parent; | |
| 39 | + | |
| 40 | + private String id; | |
| 41 | + | |
| 42 | + /** | |
| 43 | + * Returns the document handler that creates this element handler. | |
| 44 | + * | |
| 45 | + * @return the owner document handler | |
| 46 | + */ | |
| 47 | + public final DocumentHandler getOwner() { | |
| 48 | + return this.owner; | |
| 49 | + } | |
| 50 | + | |
| 51 | + /** | |
| 52 | + * Sets the document handler that creates this element handler. | |
| 53 | + * The owner document handler should be set after instantiation. | |
| 54 | + * Such approach is used to simplify the extensibility. | |
| 55 | + * | |
| 56 | + * @param owner the owner document handler | |
| 57 | + * @see DocumentHandler#startElement | |
| 58 | + */ | |
| 59 | + final void setOwner(DocumentHandler owner) { | |
| 60 | + if (owner == null) { | |
| 61 | + throw new IllegalArgumentException("Every element should have owner"); | |
| 62 | + } | |
| 63 | + this.owner = owner; | |
| 64 | + } | |
| 65 | + | |
| 66 | + /** | |
| 67 | + * Returns the element handler that contains this one. | |
| 68 | + * | |
| 69 | + * @return the parent element handler | |
| 70 | + */ | |
| 71 | + public final ElementHandler getParent() { | |
| 72 | + return this.parent; | |
| 73 | + } | |
| 74 | + | |
| 75 | + /** | |
| 76 | + * Sets the element handler that contains this one. | |
| 77 | + * The parent element handler should be set after instantiation. | |
| 78 | + * Such approach is used to simplify the extensibility. | |
| 79 | + * | |
| 80 | + * @param parent the parent element handler | |
| 81 | + * @see DocumentHandler#startElement | |
| 82 | + */ | |
| 83 | + final void setParent(ElementHandler parent) { | |
| 84 | + this.parent = parent; | |
| 85 | + } | |
| 86 | + | |
| 87 | + /** | |
| 88 | + * Returns the value of the variable with specified identifier. | |
| 89 | + * | |
| 90 | + * @param id the identifier | |
| 91 | + * @return the value of the variable | |
| 92 | + */ | |
| 93 | + protected final Object getVariable(String id) { | |
| 94 | + if (id.equals(this.id)) { | |
| 95 | + ValueObject value = getValueObject(); | |
| 96 | + if (value.isVoid()) { | |
| 97 | + throw new IllegalStateException("The element does not return value"); | |
| 98 | + } | |
| 99 | + return value.getValue(); | |
| 100 | + } | |
| 101 | + return (this.parent != null) | |
| 102 | + ? this.parent.getVariable(id) | |
| 103 | + : this.owner.getVariable(id); | |
| 104 | + } | |
| 105 | + | |
| 106 | + /** | |
| 107 | + * Returns the value of the parent element. | |
| 108 | + * | |
| 109 | + * @return the value of the parent element | |
| 110 | + */ | |
| 111 | + protected Object getContextBean() { | |
| 112 | + if (this.parent != null) { | |
| 113 | + ValueObject value = this.parent.getValueObject(); | |
| 114 | + if (!value.isVoid()) { | |
| 115 | + return value.getValue(); | |
| 116 | + } | |
| 117 | + throw new IllegalStateException("The outer element does not return value"); | |
| 118 | + } else { | |
| 119 | + Object value = this.owner.getOwner(); | |
| 120 | + if (value != null) { | |
| 121 | + return value; | |
| 122 | + } | |
| 123 | + throw new IllegalStateException("The topmost element does not have context"); | |
| 124 | + } | |
| 125 | + } | |
| 126 | + | |
| 127 | + /** | |
| 128 | + * Parses attributes of the element. | |
| 129 | + * By default, the following atribute is supported: | |
| 130 | + * <dl> | |
| 131 | + * <dt>id | |
| 132 | + * <dd>the identifier of the variable that is intended to store the result | |
| 133 | + * </dl> | |
| 134 | + * | |
| 135 | + * @param name the attribute name | |
| 136 | + * @param value the attribute value | |
| 137 | + */ | |
| 138 | + public void addAttribute(String name, String value) { | |
| 139 | + if (name.equals("id")) { // NON-NLS: the attribute name | |
| 140 | + this.id = value; | |
| 141 | + } else { | |
| 142 | + throw new IllegalArgumentException("Unsupported attribute: " + name); | |
| 143 | + } | |
| 144 | + } | |
| 145 | + | |
| 146 | + /** | |
| 147 | + * This method is called before parsing of the element's body. | |
| 148 | + * All attributes are parsed at this point. | |
| 149 | + * By default, do nothing. | |
| 150 | + */ | |
| 151 | + public void startElement() { | |
| 152 | + } | |
| 153 | + | |
| 154 | + /** | |
| 155 | + * This method is called after parsing of the element's body. | |
| 156 | + * By default, it calculates the value of this element. | |
| 157 | + * The following tasks are executing for any non-void value: | |
| 158 | + * <ol> | |
| 159 | + * <li>If the {@code id} attribute is set | |
| 160 | + * the value of the variable with the specified identifier | |
| 161 | + * is set to the value of this element.</li> | |
| 162 | + * <li>This element is used as an argument of parent element if it is possible.</li> | |
| 163 | + * </ol> | |
| 164 | + * | |
| 165 | + * @see #isArgument | |
| 166 | + */ | |
| 167 | + public void endElement() { | |
| 168 | + // do nothing if no value returned | |
| 169 | + ValueObject value = getValueObject(); | |
| 170 | + if (!value.isVoid()) { | |
| 171 | + if (this.id != null) { | |
| 172 | + this.owner.setVariable(this.id, value.getValue()); | |
| 173 | + } | |
| 174 | + if (isArgument()) { | |
| 175 | + if (this.parent != null) { | |
| 176 | + this.parent.addArgument(value.getValue()); | |
| 177 | + } else { | |
| 178 | + this.owner.addObject(value.getValue()); | |
| 179 | + } | |
| 180 | + } | |
| 181 | + } | |
| 182 | + } | |
| 183 | + | |
| 184 | + /** | |
| 185 | + * Adds the character that contained in this element. | |
| 186 | + * By default, only whitespaces are acceptable. | |
| 187 | + * | |
| 188 | + * @param ch the character | |
| 189 | + */ | |
| 190 | + public void addCharacter(char ch) { | |
| 191 | + if ((ch != ' ') && (ch != '\n') && (ch != '\t') && (ch != '\r')) { | |
| 192 | + throw new IllegalStateException("Illegal character with code " + (int) ch); | |
| 193 | + } | |
| 194 | + } | |
| 195 | + | |
| 196 | + /** | |
| 197 | + * Adds the argument that is used to calculate the value of this element. | |
| 198 | + * By default, no arguments are acceptable. | |
| 199 | + * | |
| 200 | + * @param argument the value of the element that contained in this one | |
| 201 | + */ | |
| 202 | + protected void addArgument(Object argument) { | |
| 203 | + throw new IllegalStateException("Could not add argument to simple element"); | |
| 204 | + } | |
| 205 | + | |
| 206 | + /** | |
| 207 | + * Tests whether the value of this element can be used | |
| 208 | + * as an argument of the element that contained in this one. | |
| 209 | + * | |
| 210 | + * @return {@code true} if the value of this element can be used | |
| 211 | + * as an argument of the element that contained in this one, | |
| 212 | + * {@code false} otherwise | |
| 213 | + */ | |
| 214 | + protected boolean isArgument() { | |
| 215 | + return this.id == null; | |
| 216 | + } | |
| 217 | + | |
| 218 | + /** | |
| 219 | + * Returns the value of this element. | |
| 220 | + * | |
| 221 | + * @return the value of this element | |
| 222 | + */ | |
| 223 | + protected abstract ValueObject getValueObject(); | |
| 224 | +} | |