Source Code Cross Referenced for EqualsExpression.java in  » Development » JoSQL » org » josql » expressions » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Development » JoSQL » org.josql.expressions 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * Copyright 2004-2007 Gary Bentley 
003:         * 
004:         * Licensed under the Apache License, Version 2.0 (the "License"); you may 
005:         * not use this file except in compliance with the License. 
006:         * You may obtain a copy of the License at 
007:         *    http://www.apache.org/licenses/LICENSE-2.0 
008:         *
009:         * Unless required by applicable law or agreed to in writing, software 
010:         * distributed under the License is distributed on an "AS IS" BASIS, 
011:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
012:         * See the License for the specific language governing permissions and 
013:         * limitations under the License.
014:         */
015:        package org.josql.expressions;
016:
017:        import org.josql.Query;
018:        import org.josql.QueryExecutionException;
019:
020:        import org.josql.internal.Utilities;
021:
022:        /**
023:         * This class represents an "=" or "!=" expression.  This class also provides the
024:         * ability for the developer to prefix the "=" or "!=" with "$" to indicate that a
025:         * case-insensitive comparison should be made, in which case the LHS and RHS
026:         * are converted to strings first.
027:         */
028:        public class EqualsExpression extends BinaryExpression {
029:
030:            private boolean not = false;
031:
032:            public boolean ignoreCase = false;
033:
034:            public void setIgnoreCase(boolean v) {
035:
036:                this .ignoreCase = v;
037:
038:            }
039:
040:            public boolean isIgnoreCase() {
041:
042:                return this .ignoreCase;
043:
044:            }
045:
046:            public boolean isNot() {
047:
048:                return this .not;
049:
050:            }
051:
052:            public void setNot(boolean v) {
053:
054:                this .not = v;
055:
056:            }
057:
058:            /**
059:             * Return whether this expression evaluates to <code>true</code>.
060:             * 
061:             * @param o The current object to perform the expression on.
062:             * @param q The Query object.
063:             * @return <code>true</code> if the expression evaluates to <code>true</code>, <code>false</code>
064:             *         otherwise.
065:             * @throws QueryExecutionException If the expression cannot be evaluated.
066:             */
067:            public boolean isTrue(Object o, Query q)
068:                    throws QueryExecutionException {
069:
070:                // Get the value for the lhs.
071:                Object l = null;
072:
073:                try {
074:
075:                    l = this .left.getValue(o, q);
076:
077:                } catch (Exception e) {
078:
079:                    throw new QueryExecutionException(
080:                            "Unable to get value for LHS of expression: "
081:                                    + this , e);
082:
083:                }
084:
085:                Object r = null;
086:
087:                try {
088:
089:                    r = this .right.getValue(o, q);
090:
091:                } catch (Exception e) {
092:
093:                    throw new QueryExecutionException(
094:                            "Unable to get value for RHS of expression: "
095:                                    + this , e);
096:
097:                }
098:
099:                if ((l == null) && (r == null)) {
100:
101:                    // Debatable about whether 2 nulls make a true...
102:                    if (this .not) {
103:
104:                        return false;
105:
106:                    }
107:
108:                    return true;
109:
110:                }
111:
112:                if ((l == null) || (r == null)) {
113:
114:                    if (this .not) {
115:
116:                        return true;
117:
118:                    }
119:
120:                    // One of them is null, can't do any checking...
121:                    return false;
122:
123:                }
124:
125:                // If we are here then both are NOT NULL.
126:                return Utilities.matches(l, r, this .ignoreCase, 4, this .not);
127:
128:                /*
129:                if (this.ignoreCase)
130:                {
131:
132:                    // This means that we convert to a String for both and 
133:                    // compare case-insensitive.
134:                    String ls = l.toString ();
135:
136:                    String rs = r.toString ();
137:
138:                    if ((ls == null)
139:                	||
140:                	(rs == null)
141:                       )
142:                    {
143:
144:                	// Can't compare nulls.
145:                	return false;
146:
147:                    }
148:
149:                    boolean eq = ls.equalsIgnoreCase (rs);
150:
151:                    if ((this.not)
152:                	&&
153:                	(!eq)
154:                       )
155:                    {
156:
157:                	return true;
158:
159:                    }
160:
161:                    if (eq)
162:                    {
163:
164:                	return true;
165:
166:                    }
167:
168:                    return false;
169:
170:                }
171:
172:                // See if one of the sides is a number.
173:                boolean ln = Utilities.isNumber (l);
174:                boolean rn = Utilities.isNumber (r);
175:
176:                if (ln
177:                    &&
178:                    rn
179:                   )
180:                {
181:
182:                    // They are numbers...
183:                    double ld = Utilities.getDouble (l);
184:                    double rd = Utilities.getDouble (r);
185:
186:                    if (ld == rd)
187:                    {
188:
189:                	if (this.not)
190:                	{
191:
192:                	    return false;
193:
194:                	}
195:
196:                	return true;
197:
198:                    }
199:
200:                    if (this.not)
201:                    {
202:
203:                	return true;
204:
205:                    }
206:
207:                    return false;
208:
209:                }
210:
211:                // See if the 2 sides are "comparable".
212:                // Need to check to see if they are the "same" type... otherwise a CCE will result.
213:                if ((l instanceof Comparable)
214:                    &&
215:                    (r instanceof Comparable)
216:                    &&
217:                    (l.getClass ().isAssignableFrom (r.getClass ()))
218:                   )
219:                {
220:
221:                    Comparable lc = (Comparable) l;
222:                    Comparable rc = (Comparable) r;
223:
224:                    boolean eq = lc.compareTo (rc) == 0;
225:
226:                    if ((this.not)
227:                	&&
228:                	(!eq)
229:                       )
230:                    {
231:
232:                	return true;
233:
234:                    }
235:
236:                    if (eq)
237:                    {
238:
239:                	return true;
240:
241:                    }
242:
243:                    return false;
244:
245:                }
246:
247:                // If we are here then one or more of the items does NOT implement Comparable.
248:                // Force a string comparison.
249:
250:                String ls = l.toString ();
251:
252:                String rs = r.toString ();
253:
254:                if (ls == null)
255:                {
256:
257:                    ls = "";
258:
259:                }
260:
261:                if (rs == null)
262:                {
263:
264:                    rs = "";
265:
266:                }
267:
268:                boolean eq = false;
269:
270:                if (this.ignoreCase)
271:                {
272:
273:                    eq = ls.equalsIgnoreCase (rs);
274:
275:                } else {
276:
277:                    eq = ls.equals (rs);
278:
279:                }
280:
281:                if (eq)
282:                {
283:
284:                    if (this.not)
285:                    {
286:
287:                	return false;
288:
289:                    }
290:
291:                    return true;
292:
293:                } else {
294:
295:                    if (this.not)
296:                    {
297:
298:                	return true;
299:
300:                    }
301:
302:                    return false;	    
303:
304:                }
305:                 */
306:
307:            }
308:
309:            /**
310:             * Return a string version of the expression.
311:             * In the form: {@link Expression#toString() Expression} [ $ ] [ ! ] = {@link Expression#toString() Expression}
312:             *
313:             * @return The string version.
314:             */
315:            public String toString() {
316:
317:                String pred = "=";
318:
319:                if (this .not) {
320:
321:                    pred = "!=";
322:
323:                }
324:
325:                if (this .ignoreCase) {
326:
327:                    pred = "$" + pred;
328:
329:                }
330:
331:                if (this .isBracketed()) {
332:
333:                    return "(" + this .left.toString() + " " + pred + " "
334:                            + this .right.toString() + ")";
335:
336:                }
337:
338:                return this .left.toString() + " " + pred + " "
339:                        + this.right.toString();
340:
341:            }
342:
343:        }
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