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java.lang.Object com.saxonica.pull.VirtualTreeWalker
public class VirtualTreeWalker
A virtual tree walker provides a sequence of pull events describing the structure and content of a tree that is conceptually being constructed by expressions in a query or stylesheet; in fact the tree is not necessarily constructed in memory, and exists only as this stream of pull events.
The tree is physically constructed if operations are requested that depend on the identity of the nodes in the tree, or that navigate within the tree. Operations such as copying or atomizing the tree can be done directly, without building it in memory. (Note however that if such operations are done more than once, the underlying instructions may be evaluated repeatedly.)
Field Summary |
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Fields inherited from interface net.sf.saxon.pull.PullProvider |
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ATOMIC_VALUE, ATTRIBUTE, COMMENT, END_DOCUMENT, END_ELEMENT, END_OF_INPUT, NAMESPACE, PROCESSING_INSTRUCTION, START_DOCUMENT, START_ELEMENT, START_OF_INPUT, TEXT |
Constructor Summary | |
---|---|
VirtualTreeWalker(ParentNodeConstructor instruction,
XPathContext context)
Create a VirtualTreeWalker to navigate the tree constructed by evaluating a given instruction in a given dyamic context |
Method Summary | |
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void |
close()
Close the event reader. |
int |
current()
Get the event most recently returned by next(), or by other calls that change the position, for example getStringValue() and skipToMatchingEnd(). |
AtomicValue |
getAtomicValue()
Get an atomic value. |
AttributeCollection |
getAttributes()
Get the attributes associated with the current element. |
int |
getFingerprint()
Get the fingerprint of the name of the element. |
int |
getNameCode()
Get the nameCode identifying the name of the current node. |
NamePool |
getNamePool()
Get the namepool |
NamespaceBinding |
getNamespaceBinding(int index)
Get the n'th declaration in the list in the form of a namespace code. |
NamespaceBinding[] |
getNamespaceDeclarations()
Get the namespace declarations associated with the current element. |
int |
getNumberOfNamespaces()
Get the number of declarations (and undeclarations) in this list. |
PipelineConfiguration |
getPipelineConfiguration()
Get configuration information. |
String |
getPrefix(int index)
Get the prefix of the n'th declaration (or undeclaration) in the list, counting from zero. |
SchemaType |
getSchemaType()
Get the type annotation of the current attribute or element node, or atomic value. |
SourceLocator |
getSourceLocator()
Get the location of the current event. |
CharSequence |
getStringValue()
Get the string value of the current element, text node, processing-instruction, or top-level attribute or namespace node, or atomic value. |
List |
getUnparsedEntities()
Get a list of unparsed entities. |
String |
getURI(int index)
Get the namespace URI of the n'th declaration (or undeclaration) in the list, counting from zero. |
int |
next()
Get the next event |
void |
setElementName(FingerprintedQName elementName)
|
void |
setNameCode(int nameCode)
Set the initial nameCode |
void |
setPipelineConfiguration(PipelineConfiguration pipe)
Set configuration information. |
int |
skipToMatchingEnd()
Skip the current subtree. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public VirtualTreeWalker(ParentNodeConstructor instruction, XPathContext context)
instruction
- the instruction (this will always be an instruction that creates element or
document nodes)context
- the dynamic evaluation contextMethod Detail |
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public void setPipelineConfiguration(PipelineConfiguration pipe)
setPipelineConfiguration
in interface PullProvider
pipe
- the pipeline configurationpublic PipelineConfiguration getPipelineConfiguration()
getPipelineConfiguration
in interface PullProvider
public NamePool getNamePool()
public int next() throws XPathException
next
in interface PullProvider
PullProvider.END_OF_INPUT
is returned at the end of the sequence.
XPathException
- if a dynamic error occurspublic int current()
current
in interface PullProvider
public AttributeCollection getAttributes() throws XPathException
Attributes may be read before or after reading the namespaces of an element, but must not be read after the first child node has been read, or after calling one of the methods skipToEnd(), getStringValue(), or getTypedValue().
getAttributes
in interface PullProvider
XPathException
- if a dynamic error occurspublic NamespaceBinding[] getNamespaceDeclarations() throws XPathException
It is permissible for this method to return namespace declarations that are redundant.
Namespaces may be read before or after reading the attributes of an element, but must not be read after the first child node has been read, or after calling one of the methods skipToEnd(), getStringValue(), or getTypedValue().
*
getNamespaceDeclarations
in interface PullProvider
XPathException
- if a dynamic error occurspublic int skipToMatchingEnd() throws XPathException
skipToMatchingEnd
in interface PullProvider
IllegalStateException
- if the method is called at any time other than
immediately after a START_DOCUMENT or START_ELEMENT event.
XPathException
- if a dynamic error occurspublic void close()
PullProvider.END_OF_INPUT
has
been reported, but it is recommended to close it if reading terminates
prematurely. Once an event reader has been closed, the effect of further
calls on next() is undefined.
close
in interface PullProvider
public void setNameCode(int nameCode)
nameCode
- the nameCode of the node at the root of the tree being walkedpublic void setElementName(FingerprintedQName elementName)
public int getNameCode()
PullProvider.START_ELEMENT
, PullProvider.END_ELEMENT
, PullProvider.PROCESSING_INSTRUCTION
,
PullProvider.ATTRIBUTE
, or PullProvider.NAMESPACE
events. With some PullProvider implementations,
but not this one, it can also be used after PullProvider.END_ELEMENT
.
If called at other times, the result is undefined and may result in an IllegalStateException.
If called when the current node is an unnamed namespace node (a node representing the default namespace)
the returned value is -1.
getNameCode
in interface PullProvider
public int getFingerprint()
PullProvider.START_ELEMENT
, PullProvider.END_ELEMENT
, PullProvider.PROCESSING_INSTRUCTION
,
PullProvider.ATTRIBUTE
, or PullProvider.NAMESPACE
events.
If called at other times, the result is undefined and may result in an IllegalStateException.
If called when the current node is an unnamed namespace node (a node representing the default namespace)
the returned value is -1.
getFingerprint
in interface PullProvider
public CharSequence getStringValue() throws XPathException
In other situations the result is undefined and may result in an IllegalStateException.
If the most recent event was a PullProvider.START_ELEMENT
, this method causes the content
of the element to be read. The current event on completion of this method will be the
corresponding PullProvider.END_ELEMENT
. The next call of next() will return the event following
the END_ELEMENT event.
getStringValue
in interface PullProvider
XPathException
- if a dynamic error occurspublic AtomicValue getAtomicValue()
getAtomicValue
in interface PullProvider
public SchemaType getSchemaType()
getSchemaType
in interface PullProvider
public SourceLocator getSourceLocator()
getSourceLocator
in interface PullProvider
public int getNumberOfNamespaces()
public String getPrefix(int index)
index
- the index identifying which declaration is required.
IndexOutOfBoundsException
- if the index is out of range.public String getURI(int index)
index
- the index identifying which declaration is required.
IndexOutOfBoundsException
- if the index is out of range.public NamespaceBinding getNamespaceBinding(int index)
index
- the index identifying which declaration is required.
IndexOutOfBoundsException
- if the index is out of range.public List getUnparsedEntities()
getUnparsedEntities
in interface PullProvider
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