1 /*
2 * Copyright (c) 2005, 2013, 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
26 package com.sun.source.util;
27
28 import com.sun.source.tree.*;
29
30 /**
31 * A TreeVisitor that visits all the child tree nodes.
32 * To visit nodes of a particular type, just override the
33 * corresponding visitXYZ method.
34 * Inside your method, call super.visitXYZ to visit descendant
35 * nodes.
36 *
37 * <p>The default implementation of the visitXYZ methods will determine
38 * a result as follows:
39 * <ul>
40 * <li>If the node being visited has no children, the result will be null.
41 * <li>If the node being visited has one child, the result will be the
42 * result of calling {@code scan} on that child. The child may be a simple node
43 * or itself a list of nodes.
44 * <li> If the node being visited has more than one child, the result will
45 * be determined by calling {@code scan} each child in turn, and then combining the
46 * result of each scan after the first with the cumulative result
47 * so far, as determined by the {@link #reduce} method. Each child may be either
48 * a simple node of a list of nodes. The default behavior of the {@code reduce}
49 * method is such that the result of the visitXYZ method will be the result of
50 * the last child scanned.
51 * </ul>
52 *
53 * <p>Here is an example to count the number of identifier nodes in a tree:
54 * <pre>
55 * class CountIdentifiers extends TreeScanner<Integer,Void> {
56 * {@literal @}Override
57 * public Integer visitIdentifier(IdentifierTree node, Void p) {
58 * return 1;
59 * }
60 * {@literal @}Override
61 * public Integer reduce(Integer r1, Integer r2) {
62 * return (r1 == null ? 0 : r1) + (r2 == null ? 0 : r2);
63 * }
64 * }
65 * </pre>
66 *
67 * @author Peter von der Ahé
68 * @author Jonathan Gibbons
69 * @since 1.6
70 */
71 public class TreeScanner<R,P> implements TreeVisitor<R,P> {
72
73 /** Scan a single node.
74 */
75 public R scan(Tree node, P p) {
76 return (node == null) ? null : node.accept(this, p);
77 }
78
79 private R scanAndReduce(Tree node, P p, R r) {
80 return reduce(scan(node, p), r);
81 }
82
83 /** Scan a list of nodes.
84 */
85 public R scan(Iterable<? extends Tree> nodes, P p) {
86 R r = null;
87 if (nodes != null) {
88 boolean first = true;
89 for (Tree node : nodes) {
90 r = (first ? scan(node, p) : scanAndReduce(node, p, r));
91 first = false;
92 }
93 }
94 return r;
95 }
96
97 private R scanAndReduce(Iterable<? extends Tree> nodes, P p, R r) {
98 return reduce(scan(nodes, p), r);
99 }
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.getReceiverParameter(), p, r);
142 r = scanAndReduce(node.getThrows(), p, r);
143 r = scanAndReduce(node.getBody(), p, r);
144 r = scanAndReduce(node.getDefaultValue(), p, r);
145 return r;
146 }
147
148 public R visitVariable(VariableTree node, P p) {
149 R r = scan(node.getModifiers(), p);
150 r = scanAndReduce(node.getType(), p, r);
151 r = scanAndReduce(node.getInitializer(), p, r);
152 return r;
153 }
154
155 public R visitEmptyStatement(EmptyStatementTree node, P p) {
156 return null;
157 }
158
159 public R visitBlock(BlockTree node, P p) {
160 return scan(node.getStatements(), p);
161 }
162
163 public R visitDoWhileLoop(DoWhileLoopTree node, P p) {
164 R r = scan(node.getStatement(), p);
165 r = scanAndReduce(node.getCondition(), p, r);
166 return r;
167 }
168
169 public R visitWhileLoop(WhileLoopTree node, P p) {
170 R r = scan(node.getCondition(), p);
171 r = scanAndReduce(node.getStatement(), p, r);
172 return r;
173 }
174
175 public R visitForLoop(ForLoopTree node, P p) {
176 R r = scan(node.getInitializer(), p);
177 r = scanAndReduce(node.getCondition(), p, r);
178 r = scanAndReduce(node.getUpdate(), p, r);
179 r = scanAndReduce(node.getStatement(), p, r);
180 return r;
181 }
182
183 public R visitEnhancedForLoop(EnhancedForLoopTree node, P p) {
184 R r = scan(node.getVariable(), p);
185 r = scanAndReduce(node.getExpression(), p, r);
186 r = scanAndReduce(node.getStatement(), p, r);
187 return r;
188 }
189
190 public R visitLabeledStatement(LabeledStatementTree node, P p) {
191 return scan(node.getStatement(), p);
192 }
193
194 public R visitSwitch(SwitchTree node, P p) {
195 R r = scan(node.getExpression(), p);
196 r = scanAndReduce(node.getCases(), p, r);
197 return r;
198 }
199
200 public R visitCase(CaseTree node, P p) {
201 R r = scan(node.getExpression(), p);
202 r = scanAndReduce(node.getStatements(), p, r);
203 return r;
204 }
205
206 public R visitSynchronized(SynchronizedTree node, P p) {
207 R r = scan(node.getExpression(), p);
208 r = scanAndReduce(node.getBlock(), p, r);
209 return r;
210 }
211
212 public R visitTry(TryTree node, P p) {
213 R r = scan(node.getResources(), p);
214 r = scanAndReduce(node.getBlock(), p, r);
215 r = scanAndReduce(node.getCatches(), p, r);
216 r = scanAndReduce(node.getFinallyBlock(), p, r);
217 return r;
218 }
219
220 public R visitCatch(CatchTree node, P p) {
221 R r = scan(node.getParameter(), p);
222 r = scanAndReduce(node.getBlock(), p, r);
223 return r;
224 }
225
226 public R visitConditionalExpression(ConditionalExpressionTree node, P p) {
227 R r = scan(node.getCondition(), p);
228 r = scanAndReduce(node.getTrueExpression(), p, r);
229 r = scanAndReduce(node.getFalseExpression(), p, r);
230 return r;
231 }
232
233 public R visitIf(IfTree node, P p) {
234 R r = scan(node.getCondition(), p);
235 r = scanAndReduce(node.getThenStatement(), p, r);
236 r = scanAndReduce(node.getElseStatement(), p, r);
237 return r;
238 }
239
240 public R visitExpressionStatement(ExpressionStatementTree node, P p) {
241 return scan(node.getExpression(), p);
242 }
243
244 public R visitBreak(BreakTree node, P p) {
245 return null;
246 }
247
248 public R visitContinue(ContinueTree node, P p) {
249 return null;
250 }
251
252 public R visitReturn(ReturnTree node, P p) {
253 return scan(node.getExpression(), p);
254 }
255
256 public R visitThrow(ThrowTree node, P p) {
257 return scan(node.getExpression(), p);
258 }
259
260 public R visitAssert(AssertTree node, P p) {
261 R r = scan(node.getCondition(), p);
262 r = scanAndReduce(node.getDetail(), p, r);
263 return r;
264 }
265
266 public R visitMethodInvocation(MethodInvocationTree node, P p) {
267 R r = scan(node.getTypeArguments(), p);
268 r = scanAndReduce(node.getMethodSelect(), p, r);
269 r = scanAndReduce(node.getArguments(), p, r);
270 return r;
271 }
272
273 public R visitNewClass(NewClassTree node, P p) {
274 R r = scan(node.getEnclosingExpression(), p);
275 r = scanAndReduce(node.getIdentifier(), p, r);
276 r = scanAndReduce(node.getTypeArguments(), p, r);
277 r = scanAndReduce(node.getArguments(), p, r);
278 r = scanAndReduce(node.getClassBody(), p, r);
279 return r;
280 }
281
282 public R visitNewArray(NewArrayTree node, P p) {
283 R r = scan(node.getType(), p);
284 r = scanAndReduce(node.getDimensions(), p, r);
285 r = scanAndReduce(node.getInitializers(), p, r);
286 return r;
287 }
288
289 public R visitLambdaExpression(LambdaExpressionTree node, P p) {
290 R r = scan(node.getParameters(), p);
291 r = scanAndReduce(node.getBody(), p, r);
292 return r;
293 }
294
295 public R visitParenthesized(ParenthesizedTree node, P p) {
296 return scan(node.getExpression(), p);
297 }
298
299 public R visitAssignment(AssignmentTree node, P p) {
300 R r = scan(node.getVariable(), p);
301 r = scanAndReduce(node.getExpression(), p, r);
302 return r;
303 }
304
305 public R visitCompoundAssignment(CompoundAssignmentTree node, P p) {
306 R r = scan(node.getVariable(), p);
307 r = scanAndReduce(node.getExpression(), p, r);
308 return r;
309 }
310
311 public R visitUnary(UnaryTree node, P p) {
312 return scan(node.getExpression(), p);
313 }
314
315 public R visitBinary(BinaryTree node, P p) {
316 R r = scan(node.getLeftOperand(), p);
317 r = scanAndReduce(node.getRightOperand(), p, r);
318 return r;
319 }
320
321 public R visitTypeCast(TypeCastTree node, P p) {
322 R r = scan(node.getType(), p);
323 r = scanAndReduce(node.getExpression(), p, r);
324 return r;
325 }
326
327 public R visitInstanceOf(InstanceOfTree node, P p) {
328 R r = scan(node.getExpression(), p);
329 r = scanAndReduce(node.getType(), p, r);
330 return r;
331 }
332
333 public R visitArrayAccess(ArrayAccessTree node, P p) {
334 R r = scan(node.getExpression(), p);
335 r = scanAndReduce(node.getIndex(), p, r);
336 return r;
337 }
338
339 public R visitMemberSelect(MemberSelectTree node, P p) {
340 return scan(node.getExpression(), p);
341 }
342
343 public R visitMemberReference(MemberReferenceTree node, P p) {
344 R r = scan(node.getQualifierExpression(), p);
345 r = scanAndReduce(node.getTypeArguments(), p, r);
346 return r;
347 }
348
349 public R visitIdentifier(IdentifierTree node, P p) {
350 return null;
351 }
352
353 public R visitLiteral(LiteralTree node, P p) {
354 return null;
355 }
356
357 public R visitPrimitiveType(PrimitiveTypeTree node, P p) {
358 return null;
359 }
360
361 public R visitArrayType(ArrayTypeTree node, P p) {
362 return scan(node.getType(), p);
363 }
364
365 public R visitParameterizedType(ParameterizedTypeTree node, P p) {
366 R r = scan(node.getType(), p);
367 r = scanAndReduce(node.getTypeArguments(), p, r);
368 return r;
369 }
370
371 public R visitUnionType(UnionTypeTree node, P p) {
372 return scan(node.getTypeAlternatives(), p);
373 }
374
375 public R visitIntersectionType(IntersectionTypeTree node, P p) {
376 return scan(node.getBounds(), p);
377 }
378
379 public R visitTypeParameter(TypeParameterTree node, P p) {
380 R r = scan(node.getAnnotations(), p);
381 r = scanAndReduce(node.getBounds(), p, r);
382 return r;
383 }
384
385 public R visitWildcard(WildcardTree node, P p) {
386 return scan(node.getBound(), p);
387 }
388
389 public R visitModifiers(ModifiersTree node, P p) {
390 return scan(node.getAnnotations(), p);
391 }
392
393 public R visitAnnotation(AnnotationTree node, P p) {
394 R r = scan(node.getAnnotationType(), p);
395 r = scanAndReduce(node.getArguments(), p, r);
396 return r;
397 }
398
399 public R visitAnnotatedType(AnnotatedTypeTree node, P p) {
400 R r = scan(node.getAnnotations(), p);
401 r = scanAndReduce(node.getUnderlyingType(), p, r);
402 return r;
403 }
404
405 public R visitOther(Tree node, P p) {
406 return null;
407 }
408
409 public R visitErroneous(ErroneousTree node, P p) {
410 return null;
411 }
412 }