/**
* @(#)TreeScanner.java 1.5 06/06/22
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
* Use and Distribution is subject to the Java Research License available
* at <http://wwws.sun.com/software/communitysource/jrl.html>.
*/
package com.sun.source.util;
import com.sun.source.tree.*;
/**
* A TreeVisitor that visits all the child tree nodes.
* To visit nodes of a particular type, just override the
* corresponding visitXYZ method.
* Inside your method, call super.visitXYZ to visit descendant
* nodes.
*
* <p>The default implementation of the visitXYZ methods will determine
* a result as follows:
* <ul>
* <li>If the node being visited has no children, the result will be null.
* <li>If the node being visited has one child, the result will be the
* result of calling {@code scan} on that child. The child may be a simple node
* or itself a list of nodes.
* <li> If the node being visited has more than one child, the result will
* be determined by calling {@code scan} each child in turn, and then combining the
* result of each scan after the first with the cumulative result
* so far, as determined by the {@link #reduce} method. Each child may be either
* a simple node of a list of nodes. The default behavior of the {@code reduce}
* method is such that the result of the visitXYZ method will be the result of
* the last child scanned.
* </ul>
*
* <p>Here is an example to count the number of identifier nodes in a tree:
* <pre>
* class CountIdentifiers extends TreeScanner<Integer,Void> {
* {@literal @}Override
* public Integer visitIdentifier(IdentifierTree node, Void p) {
* return 1;
* }
* {@literal @}Override
* public Integer reduce(Integer r1, Integer r2) {
* return (r1 == null ? 0 : r1) + (r2 == null ? 0 : r2);
* }
* }
* </pre>
*
* @author Peter von der Ahé
* @author Jonathan Gibbons
* @since 1.6
*/
public class TreeScanner<R,P> implements TreeVisitor<R,P> {
/** Scan a single node.
*/
public R scan(Tree node, P p) {
return (node == null) ? null : node.accept(this, p);
}
private R scanAndReduce(Tree node, P p, R r) {
return reduce(scan(node, p), r);
}
/** Scan a list of nodes.
*/
public R scan(Iterable<? extends Tree> nodes, P p) {
R r = null;
if (nodes != null) {
boolean first = true;
for (Tree node : nodes) {
r = (first ? scan(node, p) : scanAndReduce(node, p, r));
first = false;
}
}
return r;
}
private R scanAndReduce(Iterable<? extends Tree> nodes, P p, R r) {
return reduce(scan(nodes, p), r);
}
/**
* Reduces two results into a combined result.
* The default implementation is to return the first parameter.
* The general contract of the method is that it may take any action whatsoever.
*/
public R reduce(R r1, R r2) {
return r1;
}
/* ***************************************************************************
* Visitor methods
****************************************************************************/
public R visitCompilationUnit(CompilationUnitTree node, P p) {
R r = scan(node.getPackageAnnotations(), p);
r = scanAndReduce(node.getPackageName(), p, r);
r = scanAndReduce(node.getImports(), p, r);
r = scanAndReduce(node.getTypeDecls(), p, r);
return r;
}
public R visitImport(ImportTree node, P p) {
return scan(node.getQualifiedIdentifier(), p);
}
public R visitClass(ClassTree node, P p) {
R r = scan(node.getModifiers(), p);
r = scanAndReduce(node.getTypeParameters(), p, r);
r = scanAndReduce(node.getExtendsClause(), p, r);
r = scanAndReduce(node.getImplementsClause(), p, r);
r = scanAndReduce(node.getMembers(), p, r);
return r;
}
public R visitMethod(MethodTree node, P p) {
R r = scan(node.getModifiers(), p);
r = scanAndReduce(node.getReturnType(), p, r);
r = scanAndReduce(node.getTypeParameters(), p, r);
r = scanAndReduce(node.getParameters(), p, r);
r = scanAndReduce(node.getThrows(), p, r);
r = scanAndReduce(node.getBody(), p, r);
return r;
}
public R visitVariable(VariableTree node, P p) {
R r = scan(node.getModifiers(), p);
r = scanAndReduce(node.getType(), p, r);
r = scanAndReduce(node.getInitializer(), p, r);
return r;
}
public R visitEmptyStatement(EmptyStatementTree node, P p) {
return null;
}
public R visitBlock(BlockTree node, P p) {
return scan(node.getStatements(), p);
}
public R visitDoWhileLoop(DoWhileLoopTree node, P p) {
R r = scan(node.getStatement(), p);
r = scanAndReduce(node.getCondition(), p, r);
return r;
}
public R visitWhileLoop(WhileLoopTree node, P p) {
R r = scan(node.getCondition(), p);
r = scanAndReduce(node.getStatement(), p, r);
return r;
}
public R visitForLoop(ForLoopTree node, P p) {
R r = scan(node.getInitializer(), p);
r = scanAndReduce(node.getCondition(), p, r);
r = scanAndReduce(node.getUpdate(), p, r);
r = scanAndReduce(node.getStatement(), p, r);
return r;
}
public R visitEnhancedForLoop(EnhancedForLoopTree node, P p) {
R r = scan(node.getVariable(), p);
r = scanAndReduce(node.getExpression(), p, r);
r = scanAndReduce(node.getStatement(), p, r);
return r;
}
public R visitLabeledStatement(LabeledStatementTree node, P p) {
return scan(node.getStatement(), p);
}
public R visitSwitch(SwitchTree node, P p) {
R r = scan(node.getExpression(), p);
r = scanAndReduce(node.getCases(), p, r);
return r;
}
public R visitCase(CaseTree node, P p) {
R r = scan(node.getExpression(), p);
r = scanAndReduce(node.getStatements(), p, r);
return r;
}
public R visitSynchronized(SynchronizedTree node, P p) {
R r = scan(node.getExpression(), p);
r = scanAndReduce(node.getBlock(), p, r);
return r;
}
public R visitTry(TryTree node, P p) {
R r = scan(node.getBlock(), p);
r = scanAndReduce(node.getCatches(), p, r);
r = scanAndReduce(node.getFinallyBlock(), p, r);
return r;
}
public R visitCatch(CatchTree node, P p) {
R r = scan(node.getParameter(), p);
r = scanAndReduce(node.getBlock(), p, r);
return r;
}
public R visitConditionalExpression(ConditionalExpressionTree node, P p) {
R r = scan(node.getCondition(), p);
r = scanAndReduce(node.getTrueExpression(), p, r);
r = scanAndReduce(node.getFalseExpression(), p, r);
return r;
}
public R visitIf(IfTree node, P p) {
R r = scan(node.getCondition(), p);
r = scanAndReduce(node.getThenStatement(), p, r);
r = scanAndReduce(node.getElseStatement(), p, r);
return r;
}
public R visitExpressionStatement(ExpressionStatementTree node, P p) {
return scan(node.getExpression(), p);
}
public R visitBreak(BreakTree node, P p) {
return null;
}
public R visitContinue(ContinueTree node, P p) {
return null;
}
public R visitReturn(ReturnTree node, P p) {
return scan(node.getExpression(), p);
}
public R visitThrow(ThrowTree node, P p) {
return scan(node.getExpression(), p);
}
public R visitAssert(AssertTree node, P p) {
R r = scan(node.getCondition(), p);
r = scanAndReduce(node.getDetail(), p, r);
return r;
}
public R visitMethodInvocation(MethodInvocationTree node, P p) {
R r = scan(node.getTypeArguments(), p);
r = scanAndReduce(node.getMethodSelect(), p, r);
r = scanAndReduce(node.getArguments(), p, r);
return r;
}
public R visitNewClass(NewClassTree node, P p) {
R r = scan(node.getEnclosingExpression(), p);
r = scanAndReduce(node.getIdentifier(), p, r);
r = scanAndReduce(node.getTypeArguments(), p, r);
r = scanAndReduce(node.getArguments(), p, r);
r = scanAndReduce(node.getClassBody(), p, r);
return r;
}
public R visitNewArray(NewArrayTree node, P p) {
R r = scan(node.getType(), p);
r = scanAndReduce(node.getDimensions(), p, r);
r = scanAndReduce(node.getInitializers(), p, r);
return r;
}
public R visitParenthesized(ParenthesizedTree node, P p) {
return scan(node.getExpression(), p);
}
public R visitAssignment(AssignmentTree node, P p) {
R r = scan(node.getVariable(), p);
r = scanAndReduce(node.getExpression(), p, r);
return r;
}
public R visitCompoundAssignment(CompoundAssignmentTree node, P p) {
R r = scan(node.getVariable(), p);
r = scanAndReduce(node.getExpression(), p, r);
return r;
}
public R visitUnary(UnaryTree node, P p) {
return scan(node.getExpression(), p);
}
public R visitBinary(BinaryTree node, P p) {
R r = scan(node.getLeftOperand(), p);
r = scanAndReduce(node.getRightOperand(), p, r);
return r;
}
public R visitTypeCast(TypeCastTree node, P p) {
R r = scan(node.getType(), p);
r = scanAndReduce(node.getExpression(), p, r);
return r;
}
public R visitInstanceOf(InstanceOfTree node, P p) {
R r = scan(node.getExpression(), p);
r = scanAndReduce(node.getType(), p, r);
return r;
}
public R visitArrayAccess(ArrayAccessTree node, P p) {
R r = scan(node.getExpression(), p);
r = scanAndReduce(node.getIndex(), p, r);
return r;
}
public R visitMemberSelect(MemberSelectTree node, P p) {
return scan(node.getExpression(), p);
}
public R visitIdentifier(IdentifierTree node, P p) {
return null;
}
public R visitLiteral(LiteralTree node, P p) {
return null;
}
public R visitPrimitiveType(PrimitiveTypeTree node, P p) {
return null;
}
public R visitArrayType(ArrayTypeTree node, P p) {
return scan(node.getType(), p);
}
public R visitParameterizedType(ParameterizedTypeTree node, P p) {
R r = scan(node.getType(), p);
r = scanAndReduce(node.getTypeArguments(), p, r);
return r;
}
public R visitTypeParameter(TypeParameterTree node, P p) {
return scan(node.getBounds(), p);
}
public R visitWildcard(WildcardTree node, P p) {
return scan(node.getBound(), p);
}
public R visitModifiers(ModifiersTree node, P p) {
return scan(node.getAnnotations(), p);
}
public R visitAnnotation(AnnotationTree node, P p) {
R r = scan(node.getAnnotationType(), p);
r = scanAndReduce(node.getArguments(), p, r);
return r;
}
public R visitOther(Tree node, P p) {
return null;
}
public R visitErroneous(ErroneousTree node, P p) {
return null;
}
}
|
