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## net.sf.saxon.pull
Interface PullProvider

All Known Implementing Classes:
  PullFilter, PullFromIterator, StaxBridge, TinyTreeWalker, TreeWalker, VirtualTreeWalker

public interface PullProvider

PullProvider is Saxon's pull-based interface for reading XML documents. In fact, a PullProvider can deliver any sequence of nodes or atomic values. An atomic value in the sequence is delivered as a single event; a node is delivered as a sequence of events equivalent to a recursive walk of the XML tree. Within this sequence, the start and end of a document, or of an element, are delivered as separate events; other nodes are delivered as individual events.

Field Summary
`static int` | `ATOMIC_VALUE` ATOMIC_VALUE is notified when the PullProvider is reading a sequence of items, and one of the items is an atomic value rather than a node.
`static int` | `ATTRIBUTE` The ATTRIBUTE event is notified only for an attribute node that appears in its own right as a top-level item in the sequence being read.
`static int` | `COMMENT` A COMMENT event is notified for a comment node, which may be either a top-level comment or one nested within an element or document node.
`static int` | `END_DOCUMENT` END_DOCUMENT is notified at the end of processing a document node, that is, after all the descendants of the document node have been notified.
`static int` | `END_ELEMENT` END_ELEMENT is notified at the end of an element node, that is, after all the children and descendants of the element have either been processed or skipped.
`static int` | `END_OF_INPUT` The END_OF_INPUT event is returned to indicate the end of the sequence being read.
`static int` | `NAMESPACE` The NAMESPACE event is notified only for a namespace node that appears in its own right as a top-level item in the sequence being read.
`static int` | `PROCESSING_INSTRUCTION` A PROCESSING_INSTRUCTION event is notified for a processing instruction node, which may be either a top-level comment or one nested within an element or document node.
`static int` | `START_DOCUMENT` START_DOCUMENT is notified when a document node is encountered.
`static int` | `START_ELEMENT` START_ELEMENT is notified when an element node is encountered.
`static int` | `START_OF_INPUT` START_OF_INPUT is the initial state when the PullProvider is instantiated.
`static int` | `TEXT` A TEXT event is notified for a text node.

Method Summary
`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.
`NamespaceDeclarations` | `getNamespaceDeclarations()` Get the namespace declarations associated with the current element.
`PipelineConfiguration` | `getPipelineConfiguration()` Get configuration information.
`javax.xml.transform.SourceLocator` | `getSourceLocator()` Get the location of the current event.
`java.lang.CharSequence` | `getStringValue()` Get the string value of the current element, text node, processing-instruction, or top-level attribute or namespace node, or atomic value.
`int` | `getTypeAnnotation()` Get the type annotation of the current attribute or element node, or atomic value.
`int` | `next()` Get the next event
`void` | `setPipelineConfiguration(PipelineConfiguration pipe)` Set configuration information.
`int` | `skipToMatchingEnd()` Skip the current subtree.

Field Detail

### START_OF_INPUT

    public static final int START_OF_INPUT

  START_OF_INPUT is the initial state when the PullProvider is instantiated. This event is never notified by the next() method, but it is returned from a call of current() prior to the first call on next().

  See Also:
    Constant Field Values

### ATOMIC_VALUE

    public static final int ATOMIC_VALUE

  ATOMIC_VALUE is notified when the PullProvider is reading a sequence of items, and one of the items is an atomic value rather than a node. This will always be a top-level event (it will never be nested in Start/End Document or Start/End Element).

  See Also:
    Constant Field Values

### START_DOCUMENT

    public static final int START_DOCUMENT

  START_DOCUMENT is notified when a document node is encountered. This will always be a top-level event (it will never be nested in Start/End Document or Start/End Element). Note however that multiple document nodes can occur in a sequence, and the start and end of each one will be notified.

  See Also:
    Constant Field Values

### END_DOCUMENT

    public static final int END_DOCUMENT

  END_DOCUMENT is notified at the end of processing a document node, that is, after all the descendants of the document node have been notified. The event will always be preceded by the corresponding START_DOCUMENT event.

  See Also:
    Constant Field Values

### START_ELEMENT

    public static final int START_ELEMENT

  START_ELEMENT is notified when an element node is encountered. This may either be a top-level element (an element node that participates in the sequence being read in its own right) or a nested element (reported because it is a descendant of an element or document node that participates in the sequence.)

  Following the notification of START_ELEMENT, the client may obtain information about the element node, such as its name and type annotation. The client may also call getAttributes() to obtain information about the attributes of the element node, and/or getNamespaceDeclarations to get information about the namespace declarations. The client may then do one of the following:

  - Call skipToEnd() to move straight to the corresponding END_ELEMENT event (which will be the next event notified)
  - Call next(), repeatedly, to be notified of events relating to the children and descendants of this element node
  - Call getStringValue() to obtain the string value of the element node, after which the next event notified will be the corresponding END_ELEMENT event
  - Call getTypedValue() to obtain the typed value of the element node, after which the next event notified will be the corresponding END_ELEMENT event

  See Also:
    Constant Field Values

### END_ELEMENT

    public static final int END_ELEMENT

  END_ELEMENT is notified at the end of an element node, that is, after all the children and descendants of the element have either been processed or skipped. It may relate to a top-level element, or to a nested element. For an empty element (one with no children) the END_ELEMENT event will immediately follow the corresponding START_ELEMENT event. No information (such as the element name) is available after an END_ELEMENT event: if the client requires such information, it must remember it, typically on a Stack.

  See Also:
    Constant Field Values

### ATTRIBUTE

    public static final int ATTRIBUTE

  The ATTRIBUTE event is notified only for an attribute node that appears in its own right as a top-level item in the sequence being read. ATTRIBUTE events are not notified for the attributes of an element that has been notified: such attributes must be read using the `getAttributes()` method.

  See Also:
    Constant Field Values

### NAMESPACE

    public static final int NAMESPACE

  The NAMESPACE event is notified only for a namespace node that appears in its own right as a top-level item in the sequence being read. NAMESPACE events are not notified for the namespaces of an element that has been notified: such attributes must be read using the `getNamespaceDeclarations()` method.

  See Also:
    Constant Field Values

### TEXT

    public static final int TEXT

  A TEXT event is notified for a text node. This may either be a top-level text node, or a text node nested within an element or document node. At the top level, text nodes may be zero-length and may be consecutive in the sequence being read. Nested within an element or document node, text nodes will never be zero-length, and adjacent text nodes will have been coalesced into one. (This might not always be true when reading third-party data models such as a DOM.) Whitespace-only text nodes will be notified unless something has been done (e.g. xsl:strip-space) to remove them.

  See Also:
    Constant Field Values

### COMMENT

    public static final int COMMENT

  A COMMENT event is notified for a comment node, which may be either a top-level comment or one nested within an element or document node.

  See Also:
    Constant Field Values

### PROCESSING_INSTRUCTION

    public static final int PROCESSING_INSTRUCTION

  A PROCESSING_INSTRUCTION event is notified for a processing instruction node, which may be either a top-level comment or one nested within an element or document node. As defined in the XPath data model, the "target" of a processing instruction is represented as the node name (which only has a local part, no prefix or URI), and the "data" of the processing instruction is represented as the string-value of the node.

  See Also:
    Constant Field Values

### END_OF_INPUT

    public static final int END_OF_INPUT

  The END_OF_INPUT event is returned to indicate the end of the sequence being read. After this event, the result of any further calls on the next() method is undefined.

  See Also:
    Constant Field Values

Method Detail

### setPipelineConfiguration

    public void setPipelineConfiguration(PipelineConfiguration pipe)

  Set configuration information. This must only be called before any events have been read.

### getPipelineConfiguration

    public PipelineConfiguration getPipelineConfiguration()

  Get configuration information.

### next

    public int next()
             throws XPathException

  Get the next event

  Returns:
    an integer code indicating the type of event. The code `END_OF_INPUT` is returned at the end of the sequence.
  Throws:
    `XPathException`

### current

    public int current()

  Get the event most recently returned by next(), or by other calls that change the position, for example getStringValue() and skipToMatchingEnd(). This method does not change the position of the PullProvider.

  Returns:
    the current event

### getAttributes

    public AttributeCollection getAttributes()
                                      throws XPathException

  Get the attributes associated with the current element. This method must be called only after a START_ELEMENT event has been notified. The contents of the returned AttributeCollection are guaranteed to remain unchanged until the next START_ELEMENT event, but may be modified thereafter. The object should not be modified by the client.

  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().

  Returns:
    an AttributeCollection representing the attributes of the element that has just been notified.
  Throws:
    `XPathException`

### getNamespaceDeclarations

    public NamespaceDeclarations getNamespaceDeclarations()
                                                   throws XPathException

  Get the namespace declarations associated with the current element. This method must be called only after a START_ELEMENT event has been notified. In the case of a top-level START_ELEMENT event (that is, an element that either has no parent node, or whose parent is not included in the sequence being read), the NamespaceDeclarations object returned will contain a namespace declaration for each namespace that is in-scope for this element node. In the case of a non-top-level element, the NamespaceDeclarations will contain a set of namespace declarations and undeclarations, representing the differences between this element and its parent.

  It is permissible for this method to return namespace declarations that are redundant.

  The NamespaceDeclarations object is guaranteed to remain unchanged until the next START_ELEMENT event, but may then be overwritten. The object should not be modified by the client.

  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().

  *

  Throws:
    `XPathException`

### skipToMatchingEnd

    public int skipToMatchingEnd()
                          throws XPathException

  Skip the current subtree. This method may be called only immediately after a START_DOCUMENT or START_ELEMENT event. This call returns the matching END_DOCUMENT or END_ELEMENT event; the next call on next() will return the event following the END_DOCUMENT or END_ELEMENT.

  Throws:
    `java.lang.IllegalStateException` - if the method is called at any time other than immediately after a START_DOCUMENT or START_ELEMENT event.
    `XPathException`

### close

    public void close()

  Close the event reader. This indicates that no further events are required. It is not necessary to close an event reader after `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.

### getNameCode

    public int getNameCode()

  Get the nameCode identifying the name of the current node. This method can be used after the `START_ELEMENT`, `PROCESSING_INSTRUCTION`, `ATTRIBUTE`, or `NAMESPACE` events. With some PullProvider implementations, it can also be used after `END_ELEMENT`, but this is not guaranteed: a client who requires the information at that point (for example, to do serialization) should insert an `ElementNameTracker` into the pipeline. 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.

  Returns:
    the nameCode. The nameCode can be used to obtain the prefix, local name, and namespace URI from the name pool.

### getFingerprint

    public int getFingerprint()

  Get the fingerprint of the name of the element. This is similar to the nameCode, except that it does not contain any information about the prefix: so two elements with the same fingerprint have the same name, excluding prefix. This method can be used after the `START_ELEMENT`, `END_ELEMENT`, `PROCESSING_INSTRUCTION`, `ATTRIBUTE`, or `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.

  Returns:
    the fingerprint. The fingerprint can be used to obtain the local name and namespace URI from the name pool.

### getStringValue

    public java.lang.CharSequence getStringValue()
                                          throws XPathException

  Get the string value of the current element, text node, processing-instruction, or top-level attribute or namespace node, or atomic value.

  In other situations the result is undefined and may result in an IllegalStateException.

  If the most recent event was a `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 `END_ELEMENT`. The next call of next() will return the event following the END_ELEMENT event.

  Returns:
    the String Value of the node in question, defined according to the rules in the XPath data model.
  Throws:
    `XPathException`

### getTypeAnnotation

    public int getTypeAnnotation()

  Get the type annotation of the current attribute or element node, or atomic value. The result of this method is undefined unless the most recent event was START_ELEMENT, ATTRIBUTE, or ATOMIC_VALUE. In the case of an attribute node, the additional bit NodeInfo.IS_DTD_TYPE may be set to indicate a DTD-derived ID or IDREF/S type.

  Returns:
    the type annotation. This code is the fingerprint of a type name, which may be resolved to a `SchemaType` by access to the Configuration.

### getAtomicValue

    public AtomicValue getAtomicValue()

  Get an atomic value. This call may be used only when the last event reported was ATOMIC_VALUE. This indicates that the PullProvider is reading a sequence that contains a free-standing atomic value; it is never used when reading the content of a node.

### getSourceLocator

    public javax.xml.transform.SourceLocator getSourceLocator()

  Get the location of the current event. For an event stream representing a real document, the location information should identify the location in the lexical XML source. For a constructed document, it should identify the location in the query or stylesheet that caused the node to be created. A value of null can be returned if no location information is available.

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