aoqi@0: /*
aoqi@0:  * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.  Oracle designates this
aoqi@0:  * particular file as subject to the "Classpath" exception as provided
aoqi@0:  * by Oracle in the LICENSE file that accompanied this code.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  */
aoqi@0: 
aoqi@0: package com.sun.source.util;
aoqi@0: 
aoqi@0: import com.sun.source.tree.*;
aoqi@0: 
aoqi@0: /**
aoqi@0:  * A TreeVisitor that visits all the child tree nodes.
aoqi@0:  * To visit nodes of a particular type, just override the
aoqi@0:  * corresponding visitXYZ method.
aoqi@0:  * Inside your method, call super.visitXYZ to visit descendant
aoqi@0:  * nodes.
aoqi@0:  *
aoqi@0:  * <p>The default implementation of the visitXYZ methods will determine
aoqi@0:  * a result as follows:
aoqi@0:  * <ul>
aoqi@0:  * <li>If the node being visited has no children, the result will be null.
aoqi@0:  * <li>If the node being visited has one child, the result will be the
aoqi@0:  * result of calling {@code scan} on that child. The child may be a simple node
aoqi@0:  * or itself a list of nodes.
aoqi@0:  * <li> If the node being visited has more than one child, the result will
aoqi@0:  * be determined by calling {@code scan} each child in turn, and then combining the
aoqi@0:  * result of each scan after the first with the cumulative result
aoqi@0:  * so far, as determined by the {@link #reduce} method. Each child may be either
aoqi@0:  * a simple node of a list of nodes. The default behavior of the {@code reduce}
aoqi@0:  * method is such that the result of the visitXYZ method will be the result of
aoqi@0:  * the last child scanned.
aoqi@0:  * </ul>
aoqi@0:  *
aoqi@0:  * <p>Here is an example to count the number of identifier nodes in a tree:
aoqi@0:  * <pre>
aoqi@0:  *   class CountIdentifiers extends TreeScanner&lt;Integer,Void&gt; {
aoqi@0:  *      {@literal @}Override
aoqi@0:  *      public Integer visitIdentifier(IdentifierTree node, Void p) {
aoqi@0:  *          return 1;
aoqi@0:  *      }
aoqi@0:  *      {@literal @}Override
aoqi@0:  *      public Integer reduce(Integer r1, Integer r2) {
aoqi@0:  *          return (r1 == null ? 0 : r1) + (r2 == null ? 0 : r2);
aoqi@0:  *      }
aoqi@0:  *   }
aoqi@0:  * </pre>
aoqi@0:  *
aoqi@0:  * @author Peter von der Ah&eacute;
aoqi@0:  * @author Jonathan Gibbons
aoqi@0:  * @since 1.6
aoqi@0:  */
aoqi@0: @jdk.Exported
aoqi@0: public class TreeScanner<R,P> implements TreeVisitor<R,P> {
aoqi@0: 
aoqi@0:     /** Scan a single node.
aoqi@0:      */
aoqi@0:     public R scan(Tree node, P p) {
aoqi@0:         return (node == null) ? null : node.accept(this, p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     private R scanAndReduce(Tree node, P p, R r) {
aoqi@0:         return reduce(scan(node, p), r);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Scan a list of nodes.
aoqi@0:      */
aoqi@0:     public R scan(Iterable<? extends Tree> nodes, P p) {
aoqi@0:         R r = null;
aoqi@0:         if (nodes != null) {
aoqi@0:             boolean first = true;
aoqi@0:             for (Tree node : nodes) {
aoqi@0:                 r = (first ? scan(node, p) : scanAndReduce(node, p, r));
aoqi@0:                 first = false;
aoqi@0:             }
aoqi@0:         }
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     private R scanAndReduce(Iterable<? extends Tree> nodes, P p, R r) {
aoqi@0:         return reduce(scan(nodes, p), r);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Reduces two results into a combined result.
aoqi@0:      * The default implementation is to return the first parameter.
aoqi@0:      * The general contract of the method is that it may take any action whatsoever.
aoqi@0:      */
aoqi@0:     public R reduce(R r1, R r2) {
aoqi@0:         return r1;
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0: /* ***************************************************************************
aoqi@0:  * Visitor methods
aoqi@0:  ****************************************************************************/
aoqi@0: 
aoqi@0:     public R visitCompilationUnit(CompilationUnitTree node, P p) {
aoqi@0:         R r = scan(node.getPackageAnnotations(), p);
aoqi@0:         r = scanAndReduce(node.getPackageName(), p, r);
aoqi@0:         r = scanAndReduce(node.getImports(), p, r);
aoqi@0:         r = scanAndReduce(node.getTypeDecls(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitImport(ImportTree node, P p) {
aoqi@0:         return scan(node.getQualifiedIdentifier(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitClass(ClassTree node, P p) {
aoqi@0:         R r = scan(node.getModifiers(), p);
aoqi@0:         r = scanAndReduce(node.getTypeParameters(), p, r);
aoqi@0:         r = scanAndReduce(node.getExtendsClause(), p, r);
aoqi@0:         r = scanAndReduce(node.getImplementsClause(), p, r);
aoqi@0:         r = scanAndReduce(node.getMembers(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitMethod(MethodTree node, P p) {
aoqi@0:         R r = scan(node.getModifiers(), p);
aoqi@0:         r = scanAndReduce(node.getReturnType(), p, r);
aoqi@0:         r = scanAndReduce(node.getTypeParameters(), p, r);
aoqi@0:         r = scanAndReduce(node.getParameters(), p, r);
aoqi@0:         r = scanAndReduce(node.getReceiverParameter(), p, r);
aoqi@0:         r = scanAndReduce(node.getThrows(), p, r);
aoqi@0:         r = scanAndReduce(node.getBody(), p, r);
aoqi@0:         r = scanAndReduce(node.getDefaultValue(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitVariable(VariableTree node, P p) {
aoqi@0:         R r = scan(node.getModifiers(), p);
aoqi@0:         r = scanAndReduce(node.getType(), p, r);
aoqi@0:         r = scanAndReduce(node.getNameExpression(), p, r);
aoqi@0:         r = scanAndReduce(node.getInitializer(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitEmptyStatement(EmptyStatementTree node, P p) {
aoqi@0:         return null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitBlock(BlockTree node, P p) {
aoqi@0:         return scan(node.getStatements(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitDoWhileLoop(DoWhileLoopTree node, P p) {
aoqi@0:         R r = scan(node.getStatement(), p);
aoqi@0:         r = scanAndReduce(node.getCondition(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitWhileLoop(WhileLoopTree node, P p) {
aoqi@0:         R r = scan(node.getCondition(), p);
aoqi@0:         r = scanAndReduce(node.getStatement(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitForLoop(ForLoopTree node, P p) {
aoqi@0:         R r = scan(node.getInitializer(), p);
aoqi@0:         r = scanAndReduce(node.getCondition(), p, r);
aoqi@0:         r = scanAndReduce(node.getUpdate(), p, r);
aoqi@0:         r = scanAndReduce(node.getStatement(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitEnhancedForLoop(EnhancedForLoopTree node, P p) {
aoqi@0:         R r = scan(node.getVariable(), p);
aoqi@0:         r = scanAndReduce(node.getExpression(), p, r);
aoqi@0:         r = scanAndReduce(node.getStatement(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitLabeledStatement(LabeledStatementTree node, P p) {
aoqi@0:         return scan(node.getStatement(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitSwitch(SwitchTree node, P p) {
aoqi@0:         R r = scan(node.getExpression(), p);
aoqi@0:         r = scanAndReduce(node.getCases(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitCase(CaseTree node, P p) {
aoqi@0:         R r = scan(node.getExpression(), p);
aoqi@0:         r = scanAndReduce(node.getStatements(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitSynchronized(SynchronizedTree node, P p) {
aoqi@0:         R r = scan(node.getExpression(), p);
aoqi@0:         r = scanAndReduce(node.getBlock(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitTry(TryTree node, P p) {
aoqi@0:         R r = scan(node.getResources(), p);
aoqi@0:         r = scanAndReduce(node.getBlock(), p, r);
aoqi@0:         r = scanAndReduce(node.getCatches(), p, r);
aoqi@0:         r = scanAndReduce(node.getFinallyBlock(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitCatch(CatchTree node, P p) {
aoqi@0:         R r = scan(node.getParameter(), p);
aoqi@0:         r = scanAndReduce(node.getBlock(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitConditionalExpression(ConditionalExpressionTree node, P p) {
aoqi@0:         R r = scan(node.getCondition(), p);
aoqi@0:         r = scanAndReduce(node.getTrueExpression(), p, r);
aoqi@0:         r = scanAndReduce(node.getFalseExpression(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitIf(IfTree node, P p) {
aoqi@0:         R r = scan(node.getCondition(), p);
aoqi@0:         r = scanAndReduce(node.getThenStatement(), p, r);
aoqi@0:         r = scanAndReduce(node.getElseStatement(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitExpressionStatement(ExpressionStatementTree node, P p) {
aoqi@0:         return scan(node.getExpression(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitBreak(BreakTree node, P p) {
aoqi@0:         return null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitContinue(ContinueTree node, P p) {
aoqi@0:         return null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitReturn(ReturnTree node, P p) {
aoqi@0:         return scan(node.getExpression(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitThrow(ThrowTree node, P p) {
aoqi@0:         return scan(node.getExpression(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitAssert(AssertTree node, P p) {
aoqi@0:         R r = scan(node.getCondition(), p);
aoqi@0:         r = scanAndReduce(node.getDetail(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitMethodInvocation(MethodInvocationTree node, P p) {
aoqi@0:         R r = scan(node.getTypeArguments(), p);
aoqi@0:         r = scanAndReduce(node.getMethodSelect(), p, r);
aoqi@0:         r = scanAndReduce(node.getArguments(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitNewClass(NewClassTree node, P p) {
aoqi@0:         R r = scan(node.getEnclosingExpression(), p);
aoqi@0:         r = scanAndReduce(node.getIdentifier(), p, r);
aoqi@0:         r = scanAndReduce(node.getTypeArguments(), p, r);
aoqi@0:         r = scanAndReduce(node.getArguments(), p, r);
aoqi@0:         r = scanAndReduce(node.getClassBody(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitNewArray(NewArrayTree node, P p) {
aoqi@0:         R r = scan(node.getType(), p);
aoqi@0:         r = scanAndReduce(node.getDimensions(), p, r);
aoqi@0:         r = scanAndReduce(node.getInitializers(), p, r);
aoqi@0:         r = scanAndReduce(node.getAnnotations(), p, r);
aoqi@0:         for (Iterable< ? extends Tree> dimAnno : node.getDimAnnotations()) {
aoqi@0:             r = scanAndReduce(dimAnno, p, r);
aoqi@0:         }
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitLambdaExpression(LambdaExpressionTree node, P p) {
aoqi@0:         R r = scan(node.getParameters(), p);
aoqi@0:         r = scanAndReduce(node.getBody(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitParenthesized(ParenthesizedTree node, P p) {
aoqi@0:         return scan(node.getExpression(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitAssignment(AssignmentTree node, P p) {
aoqi@0:         R r = scan(node.getVariable(), p);
aoqi@0:         r = scanAndReduce(node.getExpression(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitCompoundAssignment(CompoundAssignmentTree node, P p) {
aoqi@0:         R r = scan(node.getVariable(), p);
aoqi@0:         r = scanAndReduce(node.getExpression(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitUnary(UnaryTree node, P p) {
aoqi@0:         return scan(node.getExpression(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitBinary(BinaryTree node, P p) {
aoqi@0:         R r = scan(node.getLeftOperand(), p);
aoqi@0:         r = scanAndReduce(node.getRightOperand(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitTypeCast(TypeCastTree node, P p) {
aoqi@0:         R r = scan(node.getType(), p);
aoqi@0:         r = scanAndReduce(node.getExpression(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitInstanceOf(InstanceOfTree node, P p) {
aoqi@0:         R r = scan(node.getExpression(), p);
aoqi@0:         r = scanAndReduce(node.getType(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitArrayAccess(ArrayAccessTree node, P p) {
aoqi@0:         R r = scan(node.getExpression(), p);
aoqi@0:         r = scanAndReduce(node.getIndex(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitMemberSelect(MemberSelectTree node, P p) {
aoqi@0:         return scan(node.getExpression(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitMemberReference(MemberReferenceTree node, P p) {
aoqi@0:         R r = scan(node.getQualifierExpression(), p);
aoqi@0:         r = scanAndReduce(node.getTypeArguments(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitIdentifier(IdentifierTree node, P p) {
aoqi@0:         return null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitLiteral(LiteralTree node, P p) {
aoqi@0:         return null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitPrimitiveType(PrimitiveTypeTree node, P p) {
aoqi@0:         return null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitArrayType(ArrayTypeTree node, P p) {
aoqi@0:         return scan(node.getType(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitParameterizedType(ParameterizedTypeTree node, P p) {
aoqi@0:         R r = scan(node.getType(), p);
aoqi@0:         r = scanAndReduce(node.getTypeArguments(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitUnionType(UnionTypeTree node, P p) {
aoqi@0:         return scan(node.getTypeAlternatives(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitIntersectionType(IntersectionTypeTree node, P p) {
aoqi@0:         return scan(node.getBounds(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitTypeParameter(TypeParameterTree node, P p) {
aoqi@0:         R r = scan(node.getAnnotations(), p);
aoqi@0:         r = scanAndReduce(node.getBounds(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitWildcard(WildcardTree node, P p) {
aoqi@0:         return scan(node.getBound(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitModifiers(ModifiersTree node, P p) {
aoqi@0:         return scan(node.getAnnotations(), p);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitAnnotation(AnnotationTree node, P p) {
aoqi@0:         R r = scan(node.getAnnotationType(), p);
aoqi@0:         r = scanAndReduce(node.getArguments(), p, r);
aoqi@0:         return r;
aoqi@0:     }
aoqi@0: 
aoqi@0:    public R visitAnnotatedType(AnnotatedTypeTree node, P p) {
aoqi@0:        R r = scan(node.getAnnotations(), p);
aoqi@0:        r = scanAndReduce(node.getUnderlyingType(), p, r);
aoqi@0:        return r;
aoqi@0:    }
aoqi@0: 
aoqi@0:     public R visitOther(Tree node, P p) {
aoqi@0:         return null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public R visitErroneous(ErroneousTree node, P p) {
aoqi@0:         return null;
aoqi@0:     }
aoqi@0: }