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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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*
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package com.sun.source.util;
import com.sun.source.doctree.*;
import com.sun.tools.javac.tree.DCTree.DCIndex;
/**
* 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 {@code 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 erroneous nodes in a tree:
* <pre>
* class CountErrors extends DocTreeScanner<Integer,Void> {
* {@literal @}Override
* public Integer visitErroneous(ErroneousTree node, Void p) {
* return 1;
* }
* {@literal @}Override
* public Integer reduce(Integer r1, Integer r2) {
* return (r1 == null ? 0 : r1) + (r2 == null ? 0 : r2);
* }
* }
* </pre>
*
* @since 1.8
*/
public class DocTreeScanner<R,P> implements DocTreeVisitor<R,P> {
/**
* Scans a single node.
* @param node the node to be scanned
* @param p a parameter value passed to the visit method
* @return the result value from the visit method
*/
public R scan(DocTree node, P p) {
return (node == null) ? null : node.accept(this, p);
}
private R scanAndReduce(DocTree node, P p, R r) {
return reduce(scan(node, p), r);
}
/**
* Scans a sequence of nodes.
* @param nodes the nodes to be scanned
* @param p a parameter value to be passed to the visit method for each node
* @return the combined return value from the visit methods.
* The values are combined using the {@link #reduce reduce} method.
*/
public R scan(Iterable<? extends DocTree> nodes, P p) {
R r = null;
if (nodes != null) {
boolean first = true;
for (DocTree node : nodes) {
r = (first ? scan(node, p) : scanAndReduce(node, p, r));
first = false;
}
}
return r;
}
private R scanAndReduce(Iterable<? extends DocTree> 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.
* @param r1 the first of the values to be combined
* @param r2 the second of the values to be combined
* @return the result of combining the two parameters
*/
public R reduce(R r1, R r2) {
return r1;
}
/* ***************************************************************************
* Visitor methods
****************************************************************************/
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitAttribute(AttributeTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitAuthor(AuthorTree node, P p) {
return scan(node.getName(), p);
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitComment(CommentTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitDeprecated(DeprecatedTree node, P p) {
return scan(node.getBody(), p);
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitDocComment(DocCommentTree node, P p) {
R r = scan(node.getFirstSentence(), p);
r = scanAndReduce(node.getBody(), p, r);
r = scanAndReduce(node.getBlockTags(), p, r);
return r;
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitDocRoot(DocRootTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitEndElement(EndElementTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitEntity(EntityTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitErroneous(ErroneousTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitHidden(HiddenTree node, P p) {
return scan(node.getBody(), p);
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitIdentifier(IdentifierTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitIndex(IndexTree node, P p) {
R r = scan(node.getSearchTerm(), p);
r = scanAndReduce(node.getDescription(), p, r);
return r;
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitInheritDoc(InheritDocTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitLink(LinkTree node, P p) {
R r = scan(node.getReference(), p);
r = scanAndReduce(node.getLabel(), p, r);
return r;
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitLiteral(LiteralTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitParam(ParamTree node, P p) {
R r = scan(node.getName(), p);
r = scanAndReduce(node.getDescription(), p, r);
return r;
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitReference(ReferenceTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitReturn(ReturnTree node, P p) {
return scan(node.getDescription(), p);
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitSee(SeeTree node, P p) {
return scan(node.getReference(), p);
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitSerial(SerialTree node, P p) {
return scan(node.getDescription(), p);
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitSerialData(SerialDataTree node, P p) {
return scan(node.getDescription(), p);
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitSerialField(SerialFieldTree node, P p) {
R r = scan(node.getName(), p);
r = scanAndReduce(node.getType(), p, r);
r = scanAndReduce(node.getDescription(), p, r);
return r;
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitSince(SinceTree node, P p) {
return scan(node.getBody(), p);
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitStartElement(StartElementTree node, P p) {
return scan(node.getAttributes(), p);
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitText(TextTree node, P p) {
return null;
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitThrows(ThrowsTree node, P p) {
R r = scan(node.getExceptionName(), p);
r = scanAndReduce(node.getDescription(), p, r);
return r;
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitUnknownBlockTag(UnknownBlockTagTree node, P p) {
return scan(node.getContent(), p);
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitUnknownInlineTag(UnknownInlineTagTree node, P p) {
return scan(node.getContent(), p);
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitValue(ValueTree node, P p) {
return scan(node.getReference(), p);
}
/**
* {@inheritDoc} This implementation scans the children in left to right order.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitVersion(VersionTree node, P p) {
return scan(node.getBody(), p);
}
/**
* {@inheritDoc} This implementation returns {@code null}.
*
* @param node {@inheritDoc}
* @param p {@inheritDoc}
* @return the result of scanning
*/
@Override
public R visitOther(DocTree node, P p) {
return null;
}
}