Java Module jdk.compiler Package com.sun.source.util Class DocTreeScanner<R,P>（JDK11）

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java.lang.Object
- com.sun.source.util.DocTreeScanner<R,P>

All Implemented Interfaces:

DocTreeVisitor<R,P>

Direct Known Subclasses:

DocTreePathScanner
```
public class DocTreeScanner<R,P>
extends Object
implements DocTreeVisitor<R,P>
```
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(R, R) 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

Constructor Summary

Constructors
Constructor	Description
`DocTreeScanner()`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`R`	`reduce(R r1, R r2)`	Reduces two results into a combined result.
`R`	`scan(DocTree node, P p)`	Scans a single node.
`R`	`scan(Iterable<? extends DocTree> nodes, P p)`	Scans a sequence of nodes.
`R`	`visitAttribute(AttributeTree node, P p)`	Visits an AttributeTree node.
`R`	`visitAuthor(AuthorTree node, P p)`	Visits an AuthorTree node.
`R`	`visitComment(CommentTree node, P p)`	Visits a CommentTree node.
`R`	`visitDeprecated(DeprecatedTree node, P p)`	Visits a DeprecatedTree node.
`R`	`visitDocComment(DocCommentTree node, P p)`	Visits a DocCommentTree node.
`R`	`visitDocRoot(DocRootTree node, P p)`	Visits a DocRootTree node.
`R`	`visitDocType(DocTypeTree node, P p)`	Visits a DocTypeTree node.
`R`	`visitEndElement(EndElementTree node, P p)`	Visits an EndElementTree node.
`R`	`visitEntity(EntityTree node, P p)`	Visits an EntityTree node.
`R`	`visitErroneous(ErroneousTree node, P p)`	Visits an ErroneousTree node.
`R`	`visitHidden(HiddenTree node, P p)`	Visits a HiddenTree node.
`R`	`visitIdentifier(IdentifierTree node, P p)`	Visits an IdentifierTree node.
`R`	`visitIndex(IndexTree node, P p)`	Visits an IndexTree node.
`R`	`visitInheritDoc(InheritDocTree node, P p)`	Visits an InheritDocTree node.
`R`	`visitLink(LinkTree node, P p)`	Visits a LinkTree node.
`R`	`visitLiteral(LiteralTree node, P p)`	Visits an LiteralTree node.
`R`	`visitOther(DocTree node, P p)`	Visits an unknown type of DocTree node.
`R`	`visitParam(ParamTree node, P p)`	Visits a ParamTree node.
`R`	`visitProvides(ProvidesTree node, P p)`	Visits a ProvidesTree node.
`R`	`visitReference(ReferenceTree node, P p)`	Visits a ReferenceTree node.
`R`	`visitReturn(ReturnTree node, P p)`	Visits a ReturnTree node.
`R`	`visitSee(SeeTree node, P p)`	Visits a SeeTree node.
`R`	`visitSerial(SerialTree node, P p)`	Visits a SerialTree node.
`R`	`visitSerialData(SerialDataTree node, P p)`	Visits a SerialDataTree node.
`R`	`visitSerialField(SerialFieldTree node, P p)`	Visits a SerialFieldTree node.
`R`	`visitSince(SinceTree node, P p)`	Visits a SinceTree node.
`R`	`visitStartElement(StartElementTree node, P p)`	Visits a StartElementTree node.
`R`	`visitSummary(SummaryTree node, P p)`	Visits a SummaryTree node.
`R`	`visitText(TextTree node, P p)`	Visits a TextTree node.
`R`	`visitThrows(ThrowsTree node, P p)`	Visits a ThrowsTree node.
`R`	`visitUnknownBlockTag(UnknownBlockTagTree node, P p)`	Visits an UnknownBlockTagTree node.
`R`	`visitUnknownInlineTag(UnknownInlineTagTree node, P p)`	Visits an UnknownInlineTagTree node.
`R`	`visitUses(UsesTree node, P p)`	Visits a UsesTree node.
`R`	`visitValue(ValueTree node, P p)`	Visits a ValueTree node.
`R`	`visitVersion(VersionTree node, P p)`	Visits a VersionTreeTree node.

Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - DocTreeScanner
```
public DocTreeScanner()
```
- Method Detail
  - scan
```
public R scan(DocTree node,
              P p)
```
    Scans a single node.
    
    Parameters:
    
    node - the node to be scanned
    
    p - a parameter value passed to the visit method
    
    Returns:
    
    the result value from the visit method
  - scan
```
public R scan(Iterable<? extends DocTree> nodes,
              P p)
```
    Scans a sequence of nodes.
    
    Parameters:
    
    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.
  - reduce
```
public R reduce(R r1,
                R r2)
```
    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.
    
    Parameters:
    
    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
  - visitAttribute
```
public R visitAttribute(AttributeTree node,
                        P p)
```
    Visits an AttributeTree node. This implementation returns null.
    
    Specified by:
    
    visitAttribute in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitAuthor
```
public R visitAuthor(AuthorTree node,
                     P p)
```
    Visits an AuthorTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitAuthor in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitComment
```
public R visitComment(CommentTree node,
                      P p)
```
    Visits a CommentTree node. This implementation returns null.
    
    Specified by:
    
    visitComment in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitDeprecated
```
public R visitDeprecated(DeprecatedTree node,
                         P p)
```
    Visits a DeprecatedTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitDeprecated in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitDocComment
```
public R visitDocComment(DocCommentTree node,
                         P p)
```
    Visits a DocCommentTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitDocComment in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitDocRoot
```
public R visitDocRoot(DocRootTree node,
                      P p)
```
    Visits a DocRootTree node. This implementation returns null.
    
    Specified by:
    
    visitDocRoot in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitDocType
```
public R visitDocType(DocTypeTree node,
                      P p)
```
    Visits a DocTypeTree node. This implementation returns null.
    
    Specified by:
    
    visitDocType in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitEndElement
```
public R visitEndElement(EndElementTree node,
                         P p)
```
    Visits an EndElementTree node. This implementation returns null.
    
    Specified by:
    
    visitEndElement in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitEntity
```
public R visitEntity(EntityTree node,
                     P p)
```
    Visits an EntityTree node. This implementation returns null.
    
    Specified by:
    
    visitEntity in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitErroneous
```
public R visitErroneous(ErroneousTree node,
                        P p)
```
    Visits an ErroneousTree node. This implementation returns null.
    
    Specified by:
    
    visitErroneous in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitHidden
```
public R visitHidden(HiddenTree node,
                     P p)
```
    Visits a HiddenTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitHidden in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitIdentifier
```
public R visitIdentifier(IdentifierTree node,
                         P p)
```
    Visits an IdentifierTree node. This implementation returns null.
    
    Specified by:
    
    visitIdentifier in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitIndex
```
public R visitIndex(IndexTree node,
                    P p)
```
    Visits an IndexTree node. This implementation returns null.
    
    Specified by:
    
    visitIndex in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitInheritDoc
```
public R visitInheritDoc(InheritDocTree node,
                         P p)
```
    Visits an InheritDocTree node. This implementation returns null.
    
    Specified by:
    
    visitInheritDoc in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitLink
```
public R visitLink(LinkTree node,
                   P p)
```
    Visits a LinkTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitLink in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitLiteral
```
public R visitLiteral(LiteralTree node,
                      P p)
```
    Visits an LiteralTree node. This implementation returns null.
    
    Specified by:
    
    visitLiteral in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitParam
```
public R visitParam(ParamTree node,
                    P p)
```
    Visits a ParamTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitParam in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitProvides
```
public R visitProvides(ProvidesTree node,
                       P p)
```
    Visits a ProvidesTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitProvides in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitReference
```
public R visitReference(ReferenceTree node,
                        P p)
```
    Visits a ReferenceTree node. This implementation returns null.
    
    Specified by:
    
    visitReference in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitReturn
```
public R visitReturn(ReturnTree node,
                     P p)
```
    Visits a ReturnTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitReturn in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitSee
```
public R visitSee(SeeTree node,
                  P p)
```
    Visits a SeeTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitSee in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitSerial
```
public R visitSerial(SerialTree node,
                     P p)
```
    Visits a SerialTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitSerial in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitSerialData
```
public R visitSerialData(SerialDataTree node,
                         P p)
```
    Visits a SerialDataTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitSerialData in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitSerialField
```
public R visitSerialField(SerialFieldTree node,
                          P p)
```
    Visits a SerialFieldTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitSerialField in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitSince
```
public R visitSince(SinceTree node,
                    P p)
```
    Visits a SinceTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitSince in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitStartElement
```
public R visitStartElement(StartElementTree node,
                           P p)
```
    Visits a StartElementTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitStartElement in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitSummary
```
public R visitSummary(SummaryTree node,
                      P p)
```
    Visits a SummaryTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitSummary in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
    
    Since:
    
    10
  - visitText
```
public R visitText(TextTree node,
                   P p)
```
    Visits a TextTree node. This implementation returns null.
    
    Specified by:
    
    visitText in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitThrows
```
public R visitThrows(ThrowsTree node,
                     P p)
```
    Visits a ThrowsTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitThrows in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitUnknownBlockTag
```
public R visitUnknownBlockTag(UnknownBlockTagTree node,
                              P p)
```
    Visits an UnknownBlockTagTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitUnknownBlockTag in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitUnknownInlineTag
```
public R visitUnknownInlineTag(UnknownInlineTagTree node,
                               P p)
```
    Visits an UnknownInlineTagTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitUnknownInlineTag in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitUses
```
public R visitUses(UsesTree node,
                   P p)
```
    Visits a UsesTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitUses in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitValue
```
public R visitValue(ValueTree node,
                    P p)
```
    Visits a ValueTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitValue in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitVersion
```
public R visitVersion(VersionTree node,
                      P p)
```
    Visits a VersionTreeTree node. This implementation scans the children in left to right order.
    
    Specified by:
    
    visitVersion in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning
  - visitOther
```
public R visitOther(DocTree node,
                    P p)
```
    Visits an unknown type of DocTree node. This can occur if the set of tags evolves and new kinds of nodes are added to the DocTree hierarchy. This implementation returns null.
    
    Specified by:
    
    visitOther in interface DocTreeVisitor<R,P>
    
    Parameters:
    
    node - the node being visited
    
    p - a parameter value
    
    Returns:
    
    the result of scanning

Java Module jdk.compiler Package com.sun.source.util Class DocTreeScanner<R,P>（JDK11）

Class DocTreeScanner<R,​P>

Constructor Summary

Method Summary

Methods declared in class java.lang.Object

Constructor Detail

DocTreeScanner

Method Detail

scan

scan

reduce

visitAttribute

visitAuthor

visitComment

visitDeprecated

visitDocComment

visitDocRoot

visitDocType

visitEndElement

visitEntity

visitErroneous

visitHidden

visitIdentifier

visitIndex

visitInheritDoc

visitLink

visitLiteral

visitParam

visitProvides

visitReference

visitReturn

visitSee

visitSerial

visitSerialData

visitSerialField

visitSince

visitStartElement

visitSummary

visitText

visitThrows

visitUnknownBlockTag

visitUnknownInlineTag

visitUses

visitValue

visitVersion

visitOther

Class DocTreeScanner<R,P>