Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.beanutils.expression;
018
019/**
020 * Default Property Name Expression {@link Resolver} Implementation.
021 * <p>
022 * This class assists in resolving property names in the following five formats,
023 * with the layout of an identifying String in parentheses:
024 * <ul>
025 * <li><strong>Simple (<code>name</code>)</strong> - The specified
026 *     <code>name</code> identifies an individual property of a particular
027 *     JavaBean.  The name of the actual getter or setter method to be used
028 *     is determined using standard JavaBeans instrospection, so that (unless
029 *     overridden by a <code>BeanInfo</code> class, a property named "xyz"
030 *     will have a getter method named <code>getXyz()</code> or (for boolean
031 *     properties only) <code>isXyz()</code>, and a setter method named
032 *     <code>setXyz()</code>.</li>
033 * <li><strong>Nested (<code>name1.name2.name3</code>)</strong> The first
034 *     name element is used to select a property getter, as for simple
035 *     references above.  The object returned for this property is then
036 *     consulted, using the same approach, for a property getter for a
037 *     property named <code>name2</code>, and so on.  The property value that
038 *     is ultimately retrieved or modified is the one identified by the
039 *     last name element.</li>
040 * <li><strong>Indexed (<code>name[index]</code>)</strong> - The underlying
041 *     property value is assumed to be an array, or this JavaBean is assumed
042 *     to have indexed property getter and setter methods.  The appropriate
043 *     (zero-relative) entry in the array is selected.  <code>List</code>
044 *     objects are now also supported for read/write.  You simply need to define
045 *     a getter that returns the <code>List</code></li>
046 * <li><strong>Mapped (<code>name(key)</code>)</strong> - The JavaBean
047 *     is assumed to have an property getter and setter methods with an
048 *     additional attribute of type <code>java.lang.String</code>.</li>
049 * <li><strong>Combined (<code>name1.name2[index].name3(key)</code>)</strong> -
050 *     Combining mapped, nested, and indexed references is also
051 *     supported.</li>
052 * </ul>
053 *
054 * @version $Id$
055 * @since 1.8.0
056 */
057public class DefaultResolver implements Resolver {
058
059    private static final char NESTED        = '.';
060    private static final char MAPPED_START  = '(';
061    private static final char MAPPED_END    = ')';
062    private static final char INDEXED_START = '[';
063    private static final char INDEXED_END   = ']';
064
065    /**
066     * Default Constructor.
067     */
068    public DefaultResolver() {
069    }
070
071    /**
072     * Return the index value from the property expression or -1.
073     *
074     * @param expression The property expression
075     * @return The index value or -1 if the property is not indexed
076     * @throws IllegalArgumentException If the indexed property is illegally
077     * formed or has an invalid (non-numeric) value.
078     */
079    public int getIndex(final String expression) {
080        if (expression == null || expression.length() == 0) {
081            return -1;
082        }
083        for (int i = 0; i < expression.length(); i++) {
084            final char c = expression.charAt(i);
085            if (c == NESTED || c == MAPPED_START) {
086                return -1;
087            } else if (c == INDEXED_START) {
088                final int end = expression.indexOf(INDEXED_END, i);
089                if (end < 0) {
090                    throw new IllegalArgumentException("Missing End Delimiter");
091                }
092                final String value = expression.substring(i + 1, end);
093                if (value.length() == 0) {
094                    throw new IllegalArgumentException("No Index Value");
095                }
096                int index = 0;
097                try {
098                    index = Integer.parseInt(value, 10);
099                } catch (final Exception e) {
100                    throw new IllegalArgumentException("Invalid index value '"
101                            + value + "'");
102                }
103                return index;
104            }
105        }
106        return -1;
107    }
108
109    /**
110     * Return the map key from the property expression or <code>null</code>.
111     *
112     * @param expression The property expression
113     * @return The index value
114     * @throws IllegalArgumentException If the mapped property is illegally formed.
115     */
116    public String getKey(final String expression) {
117        if (expression == null || expression.length() == 0) {
118            return null;
119        }
120        for (int i = 0; i < expression.length(); i++) {
121            final char c = expression.charAt(i);
122            if (c == NESTED || c == INDEXED_START) {
123                return null;
124            } else if (c == MAPPED_START) {
125                final int end = expression.indexOf(MAPPED_END, i);
126                if (end < 0) {
127                    throw new IllegalArgumentException("Missing End Delimiter");
128                }
129                return expression.substring(i + 1, end);
130            }
131        }
132        return null;
133    }
134
135    /**
136     * Return the property name from the property expression.
137     *
138     * @param expression The property expression
139     * @return The property name
140     */
141    public String getProperty(final String expression) {
142        if (expression == null || expression.length() == 0) {
143            return expression;
144        }
145        for (int i = 0; i < expression.length(); i++) {
146            final char c = expression.charAt(i);
147            if (c == NESTED) {
148                return expression.substring(0, i);
149            } else if (c == MAPPED_START || c == INDEXED_START) {
150                return expression.substring(0, i);
151            }
152        }
153        return expression;
154    }
155
156    /**
157     * Indicates whether or not the expression
158     * contains nested property expressions or not.
159     *
160     * @param expression The property expression
161     * @return The next property expression
162     */
163    public boolean hasNested(final String expression) {
164        if (expression == null || expression.length() == 0) {
165            return false;
166        } else {
167            return (remove(expression) != null);
168        }
169    }
170
171    /**
172     * Indicate whether the expression is for an indexed property or not.
173     *
174     * @param expression The property expression
175     * @return <code>true</code> if the expresion is indexed,
176     *  otherwise <code>false</code>
177     */
178    public boolean isIndexed(final String expression) {
179        if (expression == null || expression.length() == 0) {
180            return false;
181        }
182        for (int i = 0; i < expression.length(); i++) {
183            final char c = expression.charAt(i);
184            if (c == NESTED || c == MAPPED_START) {
185                return false;
186            } else if (c == INDEXED_START) {
187                return true;
188            }
189        }
190        return false;
191    }
192
193    /**
194     * Indicate whether the expression is for a mapped property or not.
195     *
196     * @param expression The property expression
197     * @return <code>true</code> if the expresion is mapped,
198     *  otherwise <code>false</code>
199     */
200    public boolean isMapped(final String expression) {
201        if (expression == null || expression.length() == 0) {
202            return false;
203        }
204        for (int i = 0; i < expression.length(); i++) {
205            final char c = expression.charAt(i);
206            if (c == NESTED || c == INDEXED_START) {
207                return false;
208            } else if (c == MAPPED_START) {
209                return true;
210            }
211        }
212        return false;
213    }
214
215    /**
216     * Extract the next property expression from the
217     * current expression.
218     *
219     * @param expression The property expression
220     * @return The next property expression
221     */
222    public String next(final String expression) {
223        if (expression == null || expression.length() == 0) {
224            return null;
225        }
226        boolean indexed = false;
227        boolean mapped  = false;
228        for (int i = 0; i < expression.length(); i++) {
229            final char c = expression.charAt(i);
230            if (indexed) {
231                if (c == INDEXED_END) {
232                    return expression.substring(0, i + 1);
233                }
234            } else if (mapped) {
235                if (c == MAPPED_END) {
236                    return expression.substring(0, i + 1);
237                }
238            } else {
239                if (c == NESTED) {
240                    return expression.substring(0, i);
241                } else if (c == MAPPED_START) {
242                    mapped = true;
243                } else if (c == INDEXED_START) {
244                    indexed = true;
245                }
246            }
247        }
248        return expression;
249    }
250
251    /**
252     * Remove the last property expresson from the
253     * current expression.
254     *
255     * @param expression The property expression
256     * @return The new expression value, with first property
257     * expression removed - null if there are no more expressions
258     */
259    public String remove(final String expression) {
260        if (expression == null || expression.length() == 0) {
261            return null;
262        }
263        final String property = next(expression);
264        if (expression.length() == property.length()) {
265            return null;
266        }
267        int start = property.length();
268        if (expression.charAt(start) == NESTED) {
269            start++;
270        }
271        return expression.substring(start);
272    }
273}