001 /*
002 * Copyright 2005-2006 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package com.sun.source.util;
027
028 import com.sun.source.tree.*;
029
030 /**
031 * A TreeVisitor that visits all the child tree nodes.
032 * To visit nodes of a particular type, just override the
033 * corresponding visitXYZ method.
034 * Inside your method, call super.visitXYZ to visit descendant
035 * nodes.
036 *
037 * <p>The default implementation of the visitXYZ methods will determine
038 * a result as follows:
039 * <ul>
040 * <li>If the node being visited has no children, the result will be null.
041 * <li>If the node being visited has one child, the result will be the
042 * result of calling {@code scan} on that child. The child may be a simple node
043 * or itself a list of nodes.
044 * <li> If the node being visited has more than one child, the result will
045 * be determined by calling {@code scan} each child in turn, and then combining the
046 * result of each scan after the first with the cumulative result
047 * so far, as determined by the {@link #reduce} method. Each child may be either
048 * a simple node of a list of nodes. The default behavior of the {@code reduce}
049 * method is such that the result of the visitXYZ method will be the result of
050 * the last child scanned.
051 * </ul>
052 *
053 * <p>Here is an example to count the number of identifier nodes in a tree:
054 * <pre>
055 * class CountIdentifiers extends TreeScanner<Integer,Void> {
056 * {@literal @}Override
057 * public Integer visitIdentifier(IdentifierTree node, Void p) {
058 * return 1;
059 * }
060 * {@literal @}Override
061 * public Integer reduce(Integer r1, Integer r2) {
062 * return (r1 == null ? 0 : r1) + (r2 == null ? 0 : r2);
063 * }
064 * }
065 * </pre>
066 *
067 * @author Peter von der Ahé
068 * @author Jonathan Gibbons
069 * @since 1.6
070 */
071 public class TreeScanner<R,P> implements TreeVisitor<R,P> {
072
073 /** Scan a single node.
074 */
075 public R scan(Tree node, P p) {
076 return (node == null) ? null : node.accept(this, p);
077 }
078
079 private R scanAndReduce(Tree node, P p, R r) {
080 return reduce(scan(node, p), r);
081 }
082
083 /** Scan a list of nodes.
084 */
085 public R scan(Iterable<? extends Tree> nodes, P p) {
086 R r = null;
087 if (nodes != null) {
088 boolean first = true;
089 for (Tree node : nodes) {
090 r = (first ? scan(node, p) : scanAndReduce(node, p, r));
091 first = false;
092 }
093 }
094 return r;
095 }
096
097 private R scanAndReduce(Iterable<? extends Tree> nodes, P p, R r) {
098 return reduce(scan(nodes, p), r);
099 }
100
101 /**
102 * Reduces two results into a combined result.
103 * The default implementation is to return the first parameter.
104 * The general contract of the method is that it may take any action whatsoever.
105 */
106 public R reduce(R r1, R r2) {
107 return r1;
108 }
109
110
111 /* ***************************************************************************
112 * Visitor methods
113 ****************************************************************************/
114
115 public R visitCompilationUnit(CompilationUnitTree node, P p) {
116 R r = scan(node.getPackageAnnotations(), p);
117 r = scanAndReduce(node.getPackageName(), p, r);
118 r = scanAndReduce(node.getImports(), p, r);
119 r = scanAndReduce(node.getTypeDecls(), p, r);
120 return r;
121 }
122
123 public R visitImport(ImportTree node, P p) {
124 return scan(node.getQualifiedIdentifier(), p);
125 }
126
127 public R visitClass(ClassTree node, P p) {
128 R r = scan(node.getModifiers(), p);
129 r = scanAndReduce(node.getTypeParameters(), p, r);
130 r = scanAndReduce(node.getExtendsClause(), p, r);
131 r = scanAndReduce(node.getImplementsClause(), p, r);
132 r = scanAndReduce(node.getMembers(), p, r);
133 return r;
134 }
135
136 public R visitMethod(MethodTree node, P p) {
137 R r = scan(node.getModifiers(), p);
138 r = scanAndReduce(node.getReturnType(), p, r);
139 r = scanAndReduce(node.getTypeParameters(), p, r);
140 r = scanAndReduce(node.getParameters(), p, r);
141 r = scanAndReduce(node.getThrows(), p, r);
142 r = scanAndReduce(node.getBody(), p, r);
143 return r;
144 }
145
146 public R visitVariable(VariableTree node, P p) {
147 R r = scan(node.getModifiers(), p);
148 r = scanAndReduce(node.getType(), p, r);
149 r = scanAndReduce(node.getInitializer(), p, r);
150 return r;
151 }
152
153 public R visitEmptyStatement(EmptyStatementTree node, P p) {
154 return null;
155 }
156
157 public R visitBlock(BlockTree node, P p) {
158 return scan(node.getStatements(), p);
159 }
160
161 /* emw4: staging stuff */
162 public R visitBracketExpr(BracketExprTree node, P p) {
163 throw new UnsupportedOperationException ("visitBracketExpr in TreeScanner");
164 }
165
166 public R visitBracketStat(BracketStatTree node, P p) {
167 throw new UnsupportedOperationException ("visitBracketStat in TreeScanner");
168 }
169
170 public R visitEscapeExpr(EscapeExprTree node, P p) {
171 throw new UnsupportedOperationException ("visitEscapeExpr in TreeScanner");
172 }
173
174 public R visitEscapeStat(EscapeStatTree node, P p) {
175 throw new UnsupportedOperationException ("visitEscapeStat in TreeScanner");
176 }
177
178 public R visitDoWhileLoop(DoWhileLoopTree node, P p) {
179 R r = scan(node.getStatement(), p);
180 r = scanAndReduce(node.getCondition(), p, r);
181 return r;
182 }
183
184 public R visitWhileLoop(WhileLoopTree node, P p) {
185 R r = scan(node.getCondition(), p);
186 r = scanAndReduce(node.getStatement(), p, r);
187 return r;
188 }
189
190 public R visitForLoop(ForLoopTree node, P p) {
191 R r = scan(node.getInitializer(), p);
192 r = scanAndReduce(node.getCondition(), p, r);
193 r = scanAndReduce(node.getUpdate(), p, r);
194 r = scanAndReduce(node.getStatement(), p, r);
195 return r;
196 }
197
198 public R visitEnhancedForLoop(EnhancedForLoopTree node, P p) {
199 R r = scan(node.getVariable(), p);
200 r = scanAndReduce(node.getExpression(), p, r);
201 r = scanAndReduce(node.getStatement(), p, r);
202 return r;
203 }
204
205 public R visitLabeledStatement(LabeledStatementTree node, P p) {
206 return scan(node.getStatement(), p);
207 }
208
209 public R visitSwitch(SwitchTree node, P p) {
210 R r = scan(node.getExpression(), p);
211 r = scanAndReduce(node.getCases(), p, r);
212 return r;
213 }
214
215 public R visitCase(CaseTree node, P p) {
216 R r = scan(node.getExpression(), p);
217 r = scanAndReduce(node.getStatements(), p, r);
218 return r;
219 }
220
221 public R visitSynchronized(SynchronizedTree node, P p) {
222 R r = scan(node.getExpression(), p);
223 r = scanAndReduce(node.getBlock(), p, r);
224 return r;
225 }
226
227 public R visitTry(TryTree node, P p) {
228 R r = scan(node.getBlock(), p);
229 r = scanAndReduce(node.getCatches(), p, r);
230 r = scanAndReduce(node.getFinallyBlock(), p, r);
231 return r;
232 }
233
234 public R visitCatch(CatchTree node, P p) {
235 R r = scan(node.getParameter(), p);
236 r = scanAndReduce(node.getBlock(), p, r);
237 return r;
238 }
239
240 public R visitConditionalExpression(ConditionalExpressionTree node, P p) {
241 R r = scan(node.getCondition(), p);
242 r = scanAndReduce(node.getTrueExpression(), p, r);
243 r = scanAndReduce(node.getFalseExpression(), p, r);
244 return r;
245 }
246
247 public R visitIf(IfTree node, P p) {
248 R r = scan(node.getCondition(), p);
249 r = scanAndReduce(node.getThenStatement(), p, r);
250 r = scanAndReduce(node.getElseStatement(), p, r);
251 return r;
252 }
253
254 public R visitExpressionStatement(ExpressionStatementTree node, P p) {
255 return scan(node.getExpression(), p);
256 }
257
258 public R visitBreak(BreakTree node, P p) {
259 return null;
260 }
261
262 public R visitContinue(ContinueTree node, P p) {
263 return null;
264 }
265
266 public R visitReturn(ReturnTree node, P p) {
267 return scan(node.getExpression(), p);
268 }
269
270 public R visitThrow(ThrowTree node, P p) {
271 return scan(node.getExpression(), p);
272 }
273
274 public R visitAssert(AssertTree node, P p) {
275 R r = scan(node.getCondition(), p);
276 r = scanAndReduce(node.getDetail(), p, r);
277 return r;
278 }
279
280 public R visitMethodInvocation(MethodInvocationTree node, P p) {
281 R r = scan(node.getTypeArguments(), p);
282 r = scanAndReduce(node.getMethodSelect(), p, r);
283 r = scanAndReduce(node.getArguments(), p, r);
284 return r;
285 }
286
287 public R visitNewClass(NewClassTree node, P p) {
288 R r = scan(node.getEnclosingExpression(), p);
289 r = scanAndReduce(node.getIdentifier(), p, r);
290 r = scanAndReduce(node.getTypeArguments(), p, r);
291 r = scanAndReduce(node.getArguments(), p, r);
292 r = scanAndReduce(node.getClassBody(), p, r);
293 return r;
294 }
295
296 public R visitNewArray(NewArrayTree node, P p) {
297 R r = scan(node.getType(), p);
298 r = scanAndReduce(node.getDimensions(), p, r);
299 r = scanAndReduce(node.getInitializers(), p, r);
300 return r;
301 }
302
303 public R visitParenthesized(ParenthesizedTree node, P p) {
304 return scan(node.getExpression(), p);
305 }
306
307 public R visitAssignment(AssignmentTree node, P p) {
308 R r = scan(node.getVariable(), p);
309 r = scanAndReduce(node.getExpression(), p, r);
310 return r;
311 }
312
313 public R visitCompoundAssignment(CompoundAssignmentTree node, P p) {
314 R r = scan(node.getVariable(), p);
315 r = scanAndReduce(node.getExpression(), p, r);
316 return r;
317 }
318
319 public R visitUnary(UnaryTree node, P p) {
320 return scan(node.getExpression(), p);
321 }
322
323 public R visitBinary(BinaryTree node, P p) {
324 R r = scan(node.getLeftOperand(), p);
325 r = scanAndReduce(node.getRightOperand(), p, r);
326 return r;
327 }
328
329 public R visitTypeCast(TypeCastTree node, P p) {
330 R r = scan(node.getType(), p);
331 r = scanAndReduce(node.getExpression(), p, r);
332 return r;
333 }
334
335 public R visitInstanceOf(InstanceOfTree node, P p) {
336 R r = scan(node.getExpression(), p);
337 r = scanAndReduce(node.getType(), p, r);
338 return r;
339 }
340
341 public R visitArrayAccess(ArrayAccessTree node, P p) {
342 R r = scan(node.getExpression(), p);
343 r = scanAndReduce(node.getIndex(), p, r);
344 return r;
345 }
346
347 public R visitMemberSelect(MemberSelectTree node, P p) {
348 return scan(node.getExpression(), p);
349 }
350
351 public R visitIdentifier(IdentifierTree node, P p) {
352 return null;
353 }
354
355 public R visitLiteral(LiteralTree node, P p) {
356 return null;
357 }
358
359 public R visitPrimitiveType(PrimitiveTypeTree node, P p) {
360 return null;
361 }
362
363 public R visitArrayType(ArrayTypeTree node, P p) {
364 return scan(node.getType(), p);
365 }
366
367 public R visitParameterizedType(ParameterizedTypeTree node, P p) {
368 R r = scan(node.getType(), p);
369 r = scanAndReduce(node.getTypeArguments(), p, r);
370 return r;
371 }
372
373 public R visitTypeParameter(TypeParameterTree node, P p) {
374 return scan(node.getBounds(), p);
375 }
376
377 public R visitWildcard(WildcardTree node, P p) {
378 return scan(node.getBound(), p);
379 }
380
381 public R visitModifiers(ModifiersTree node, P p) {
382 return scan(node.getAnnotations(), p);
383 }
384
385 public R visitAnnotation(AnnotationTree node, P p) {
386 R r = scan(node.getAnnotationType(), p);
387 r = scanAndReduce(node.getArguments(), p, r);
388 return r;
389 }
390
391 public R visitOther(Tree node, P p) {
392 return null;
393 }
394
395 public R visitErroneous(ErroneousTree node, P p) {
396 return null;
397 }
398 }