## Package net.sf.saxon.om

This package defines the interface to the Saxon tree structure.

See:
Description

Interface Summary
AttributeCollection: AttributeCollection represents the collection of attributes available on a particular element node.
DocumentInfo: This interface represents a document node as defined in the XPath 2.0 data model.
FingerprintedNode: This is a marker interface used to identify nodes that contain a namepool fingerprint.
FunctionItem: XQuery 1.1 introduces a third kind of item, beyond nodes and atomic values: the function item.
GroundedValue: A value that exists in memory and that can be directly addressed
Item: An Item is an object that can occur as a member of a sequence.
MutableDocumentInfo: Interface representing the document node of a mutable document
MutableNodeInfo: An extension of the NodeInfo interface defining a node that can be updated.
NamespaceDeclarations: This interface represents a collection of namespace declarations or undeclarations, typically those appearing together in an element start tag.
NamespaceResolver: Abstract class that supports lookup of a lexical QName to get the expanded QName.
NodeInfo: The NodeInfo interface represents a node in Saxon's implementation of the XPath 2.0 data model.
NotationSet: A set of declared notations (in the sense of XSD xs:notation)
SequenceIterator: A SequenceIterator is used to iterate over any XPath 2 sequence (of values or nodes).
ValueRepresentation: A ValueRepresentation is a representation of a Value.

Class Summary
Axis: An axis, that is a direction of navigation in the document structure.
CopyOptions: Non-instantiable class to define options for the `NodeInfo.copy(net.sf.saxon.event.Receiver, int, int)` method
DocumentPool: An object representing the collection of documents handled during a single transformation.
DocumentURI: This class encapsulates a string used as the value of the document-uri() property of a document, together with a normalized representation of the string used for equality comparisons.
EmptyNamespaceDeclarationList: A class representing an empty set of namespace declarations
InscopeNamespaceResolver: A NamespaceResolver that resolves namespace prefixes by reference to a node in a document for which those namespaces are in-scope.
Name10Checker: The class checks names and characters against the rules of the XML 1.0 and XML Namespaces 1.0 specification
Name11Checker: The class checks names against the rules of the XML 1.1 and XML Namespaces 1.1 specification
NameChecker: A NameChecker performs validation and analysis of XML names.
NamePool: A NamePool holds a collection of expanded names, each containing a namespace URI, a namespace prefix, and a local name; plus a collection of namespaces, each consisting of a prefix/URI pair.
StandardNames: Well-known names used in XSLT processing.
StructuredQName: This class provides an economical representation of a QName triple (prefix, URI, and localname).
TreeModel: A TreeModel represents an implementation of the Saxon NodeInfo interface, which itself is essentially an implementation of the XDM model defined in W3C specifications (except that Saxon's NodeInfo understands the 13 XPath axes, rather than merely supporting parent and child properties).

Exception Summary
NamePool.NamePoolLimitException: Uncaught Exception raised when some limit in the design of the name pool is exceeded
NamespaceException: A NamespaceException represents an error condition whereby a QName (for example a variable name or template name) uses a namespace prefix that is not declared
QNameException: A QNameException represents an error condition whereby a QName (for example a variable name or template name) is malformed

## Package net.sf.saxon.om Description

This package defines the interface to the Saxon tree structure. This structure is used to represent both the source document and the stylesheet. Essentially, this class represents Saxon's realization of the XPath data model.

The classes in the package are rather a miscellany. What they have in common is that they describe the way the Saxon tree structure is accessed, in a way that it independent of the two tree implementations (in packages `net.sf.saxon.tree` and `net.sf.saxon.tinytree`).

Broadly speaking, the classes fall into four categories:

- Interface classes: DocumentInfo, NodeInfo, Item, ValueRepresentation. These describe the interface offered by the object model to the rest of the system, including the application.
- Iterator classes: SequenceIterator, AxisIterator, ArrayIterator, EmptyIterator, SingletonIterator, and others. These classes provide mechanisms for iterating over sequences. The most general, and the one which applications are most likely to use, is the SequenceIterator interface itself. AxisIterator is a specialization of this interface whose main difference is that it cannot throw exceptions. The other classes are implementations of SequenceIterator for use in particular circumstances.
<liul>Shared implementation classes: DocumentPool, NamePool, Navigator, XMLChar. These contain functionality that is shared between the various tree implementations. (However, there is also some shared functionality in the `net.sf.saxon.tree` package). These classes are not generally needed by applications, with the exception of NamePool, which complex applications may need to manipulate.
- Information classes: Axis, NamespaceConstant. These contain constants.

Michael H. Kay
Saxonica Limited
9 February 2005

Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.