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package com.sun.source.util;

import com.sun.source.doctree.*;


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.

The default implementation of the visitXYZ methods will determine a result as follows:

  • If the node being visited has no children, the result will be null.
  • If the node being visited has one child, the result will be the result of calling scan on that child. The child may be a simple node or itself a list of nodes.
  • If the node being visited has more than one child, the result will be determined by calling 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 reduce method. Each child may be either a simple node of a list of nodes. The default behavior of the reduce method is such that the result of the visitXYZ method will be the result of the last child scanned.

Here is an example to count the number of erroneous nodes in a tree:

 class CountErrors extends DocTreeScanner<Integer,Void> { @Override public Integer visitErroneous(ErroneousTree node, Void p) { return 1; } @Override public Integer reduce(Integer r1, Integer r2) { return (r1 == null ? 0 : r1) + (r2 == null ? 0 : r2); } } 
Since:1.8
/** * 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&lt;Integer,Void&gt; { * {@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.
Params:
  • node – the node to be scanned
  • p – a parameter value passed to the visit method
Returns:the result value from the visit method
/** * 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.
Params:
  • nodes – the nodes to be scanned
  • p – a parameter value to be passed to the visit method for each node
Returns:the combined return value from the visit methods. The values are combined using the reduce method.
/** * 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.
Params:
  • r1 – the first of the values to be combined
  • r2 – the second of the values to be combined
Returns:the result of combining the two parameters
/** * 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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 scans the children in left to right order.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 visitProvides(ProvidesTree node, P p) { R r = scan(node.getServiceType(), p); r = scanAndReduce(node.getDescription(), p, r); return r; }
{@inheritDoc} This implementation returns null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 visitUses(UsesTree node, P p) { R r = scan(node.getServiceType(), p); r = scanAndReduce(node.getDescription(), p, r); return r; }
{@inheritDoc} This implementation scans the children in left to right order.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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 null.
Params:
  • node – {@inheritDoc}
  • p – {@inheritDoc}
Returns:the result of scanning
/** * {@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; } }