001 /**
002 * =========================================
003 * LibFormula : a free Java formula library
004 * =========================================
005 *
006 * Project Info: http://reporting.pentaho.org/libformula/
007 *
008 * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors.
009 *
010 * This library is free software; you can redistribute it and/or modify it under the terms
011 * of the GNU Lesser General Public License as published by the Free Software Foundation;
012 * either version 2.1 of the License, or (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
015 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
016 * See the GNU Lesser General Public License for more details.
017 *
018 * You should have received a copy of the GNU Lesser General Public License along with this
019 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
020 * Boston, MA 02111-1307, USA.
021 *
022 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
023 * in the United States and other countries.]
024 *
025 *
026 * ------------
027 * $Id: Term.java 3521 2007-10-16 10:55:14Z tmorgner $
028 * ------------
029 * (C) Copyright 2006-2007, by Pentaho Corporation.
030 */
031 package org.jfree.formula.lvalues;
032
033 import java.util.ArrayList;
034
035 import org.jfree.formula.EvaluationException;
036 import org.jfree.formula.FormulaContext;
037 import org.jfree.formula.operators.InfixOperator;
038
039 /**
040 * An term is a list of LValues connected by operators. For the sake of
041 * efficiency, this is not stored as tree. We store the term as a list in the
042 * following format: (headValue)(OP value)* ...
043 *
044 * @author Thomas Morgner
045 */
046 public class Term extends AbstractLValue
047 {
048 private LValue optimizedHeadValue;
049 private LValue headValue;
050 private ArrayList operators;
051 private ArrayList operands;
052 private InfixOperator[] operatorArray;
053 private LValue[] operandsArray;
054 private boolean initialized;
055 private static final LValue[] EMPTY_L_VALUE = new LValue[0];
056 private static final InfixOperator[] EMPTY_OPERATOR = new InfixOperator[0];
057
058 public Term(final LValue headValue)
059 {
060 if (headValue == null)
061 {
062 throw new NullPointerException();
063 }
064
065 this.headValue = headValue;
066 }
067
068 public TypeValuePair evaluate() throws EvaluationException
069 {
070 TypeValuePair result = optimizedHeadValue.evaluate();
071 for (int i = 0; i < operandsArray.length; i++)
072 {
073 final LValue value = operandsArray[i];
074 final InfixOperator op = operatorArray[i];
075 result = op.evaluate(getContext(), result, value.evaluate());
076 }
077 return result;
078 }
079
080 public void add(final InfixOperator operator, final LValue operand)
081 {
082 if (operator == null)
083 {
084 throw new NullPointerException();
085 }
086 if (operand == null)
087 {
088 throw new NullPointerException();
089 }
090
091 if (operands == null || operators == null)
092 {
093 this.operands = new ArrayList();
094 this.operators = new ArrayList();
095 }
096
097 operands.add(operand);
098 operators.add(operator);
099 initialized = false;
100 }
101
102 public void initialize(final FormulaContext context) throws EvaluationException
103 {
104 super.initialize(context);
105 if (operands == null || operators == null)
106 {
107 this.optimizedHeadValue = headValue;
108 this.optimizedHeadValue.initialize(context);
109 this.operandsArray = EMPTY_L_VALUE;
110 this.operatorArray = EMPTY_OPERATOR;
111 return;
112 }
113
114 if (initialized)
115 {
116 optimizedHeadValue.initialize(context);
117 for (int i = 0; i < operandsArray.length; i++)
118 {
119 final LValue lValue = operandsArray[i];
120 lValue.initialize(context);
121 }
122 return;
123 }
124
125 optimize(context);
126 }
127
128 private void optimize(final FormulaContext context) throws EvaluationException
129 {
130 final ArrayList operators = (ArrayList) this.operators.clone();
131 final ArrayList operands = (ArrayList) this.operands.clone();
132 this.optimizedHeadValue = headValue;
133
134 while (true)
135 {
136 // now start to optimize everything.
137 // first, search the operator with the highest priority..
138 final InfixOperator op = (InfixOperator) operators.get(0);
139 int level = op.getLevel();
140 boolean moreThanOne = false;
141 for (int i = 1; i < operators.size(); i++)
142 {
143 final InfixOperator operator = (InfixOperator) operators.get(i);
144 final int opLevel = operator.getLevel();
145 if (opLevel != level)
146 {
147 moreThanOne = true;
148 level = Math.min(opLevel, level);
149 }
150 }
151
152 if (moreThanOne == false)
153 {
154 // No need to optimize the operators ..
155 break;
156 }
157
158 // There are at least two op-levels in this term.
159 Term subTerm = null;
160 for (int i = 0; i < operators.size(); i++)
161 {
162 final InfixOperator operator = (InfixOperator) operators.get(i);
163 if (operator.getLevel() != level)
164 {
165 subTerm = null;
166 continue;
167 }
168
169 if (subTerm == null)
170 {
171 if (i == 0)
172 {
173 subTerm = new Term(optimizedHeadValue);
174 optimizedHeadValue = subTerm;
175 }
176 else
177 {
178 final LValue lval = (LValue) operands.get(i - 1);
179 subTerm = new Term(lval);
180 operands.set(i - 1, subTerm);
181 }
182 }
183
184 // OK, now a term exists, and we should join it.
185 final LValue operand = (LValue) operands.get(i);
186 subTerm.add(operator, operand);
187 operands.remove(i);
188 operators.remove(i);
189 // Rollback the current index ..
190 //noinspection AssignmentToForLoopParameter
191 i -= 1;
192 }
193 }
194
195 this.operatorArray = (InfixOperator[])
196 operators.toArray(new InfixOperator[operators.size()]);
197 this.operandsArray = (LValue[])
198 operands.toArray(new LValue[operands.size()]);
199 this.optimizedHeadValue.initialize(context);
200 for (int i = 0; i < operandsArray.length; i++)
201 {
202 final LValue value = operandsArray[i];
203 value.initialize(context);
204 }
205
206 }
207
208 /**
209 * Returns any dependent lvalues (parameters and operands, mostly).
210 *
211 * @return
212 */
213 public LValue[] getChildValues()
214 {
215 final LValue[] values = new LValue[operandsArray.length + 1];
216 values[0] = headValue;
217 System.arraycopy(operandsArray, 0, values, 1, operandsArray.length);
218 return values;
219 }
220
221
222 public String toString()
223 {
224 final StringBuffer b = new StringBuffer();
225
226 b.append("(");
227 b.append(headValue);
228 if (operands != null && operators != null)
229 {
230 for (int i = 0; i < operands.size(); i++)
231 {
232 final InfixOperator op = (InfixOperator) operators.get(i);
233 final LValue value = (LValue) operands.get(i);
234 b.append(op);
235 b.append(value);
236 }
237 }
238 b.append(")");
239 //
240 // b.append(";OPTIMIZED(");
241 // b.append(optimizedHeadValue);
242 // if (operandsArray != null && operatorArray != null)
243 // {
244 // for (int i = 0; i < operandsArray.length; i++)
245 // {
246 // final InfixOperator op = operatorArray[i];
247 // final LValue value = operandsArray[i];
248 // b.append(op);
249 // b.append(value);
250 // }
251 // }
252 // b.append(")");
253
254 return b.toString();
255 }
256
257 /**
258 * Checks, whether the LValue is constant. Constant lvalues always return the
259 * same value.
260 *
261 * @return
262 */
263 public boolean isConstant()
264 {
265 if (headValue.isConstant() == false)
266 {
267 return false;
268 }
269
270 for (int i = 0; i < operands.size(); i++)
271 {
272 final LValue value = (LValue) operands.get(i);
273 if (value.isConstant() == false)
274 {
275 return false;
276 }
277 }
278 return true;
279 }
280
281 public Object clone() throws CloneNotSupportedException
282 {
283 final Term o = (Term) super.clone();
284 if (operands != null)
285 {
286 o.operands = (ArrayList) operands.clone();
287 }
288 if (operators != null)
289 {
290 o.operators = (ArrayList) operators.clone();
291 }
292 o.headValue = (LValue) headValue.clone();
293 o.optimizedHeadValue = null;
294 o.operandsArray = null;
295 o.operatorArray = null;
296 o.initialized = false;
297 return o;
298 }
299
300 public InfixOperator[] getOperands ()
301 {
302 return (InfixOperator[]) operands.toArray(new InfixOperator[operands.size()]);
303 }
304
305 public LValue[] getOperators ()
306 {
307 return (LValue[]) operators.toArray(new LValue[operators.size()]);
308 }
309
310 public LValue getHeadValue()
311 {
312 return headValue;
313 }
314
315 /**
316 * Allows access to the post optimized head value
317 * note that without the optimization, it's difficult to traverse
318 * libformula's object model.
319 *
320 * @return optimized head value
321 */
322 public LValue getOptimizedHeadValue()
323 {
324 return optimizedHeadValue;
325 }
326
327 /**
328 * Allows access to the post optimized operator array
329 *
330 * @return optimized operator array
331 */
332 public InfixOperator[] getOptimizedOperators()
333 {
334 return operatorArray;
335 }
336
337 /**
338 * Allows access to the post optimized operand array
339 *
340 * @return optimized operand array
341 */
342 public LValue[] getOptimizedOperands()
343 {
344 return operandsArray;
345 }
346 }