uk.ac.sheffield.jast.filter

Class Filter

java.lang.Object

uk.ac.sheffield.jast.filter.Filter

Direct Known Subclasses:

AndFilter, MaskFilter, NotFilter, OrFilter, TypeFilter

public abstract class Filter
extends java.lang.Object

Filter is the abstract root of filters accepting different XML content. A Filter is a pattern for selecting different kinds of XML content. A Filter may be supplied as an argument to the getContents(Filter) and removeContents(Filter) methods to restrict what kinds of child-Content are selected, or removed from under the current Content node. A Filter can be created to match just one kind of Content (such as Text, Element, Comment, Data, etc.) or several kinds of Content. A Filter can be created to match Element or Attribute nodes with particular names, or sets of names, or with particular Attribute values or Element contents, or with content that satisfies an inequality comparison.

A Filter has an accept(Content) method, which returns true, if the type of the Content is accepted by the Filter. Internally, filtering is performed by different kinds of algorithm, according to the Filter subclass. If disparate kinds of Filter are combined using logical-AND and logical-OR, this may return an AndFilter or OrFilter for compound filtering. Similarly, the logical-NOT method may return a NotFilter for complementary filtering.

Version:

2.5

Author:

Anthony J H Simons

Field Summary

Fields

Modifier and Type	Field and Description
static int	ALLCONTENT Bit-mask matching all Content node types, including the Document node.
static int	NAMENODES Bit-mask matching all Markup nodes with user-defined XML name tags.
static int	PARENTNODES Bit-mask matching all nodes that may be the parents of other nodes.
static int	PROPERTYNODES Bit-mask matching all nodes that can have XML attributes.
static int	VALUENODES Bit-mask matching all nodes containing XML data values.
static int	XPATHNODES Bit-mask matching all accessible XPath content, which excludes the Declaration and Doctype nodes.
static int	XPATHTEXT Bit-mask matching all nodes that are treated as text by the XPath text() selector.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Filter() Creates a Filter.

Method Summary

Modifier and Type	Method and Description
abstract boolean	accept(Content node) Reports whether a given Content node is accepted by this Filter.
Filter	and(Filter filter) Creates a Filter that is the logical AND of this and another Filter.
protected IndexFilter	andIndexFilter(IndexFilter filter) Creates a Filter that is the logical AND of this and an IndexFilter.
protected Filter	andNodeFilter(NodeFilter filter) Creates a Filter that is the logical AND of this and a NodeFilter.
Filter	not() Creates a Filter that is the logical NOT of this Filter.
Filter	or(Filter filter) Creates a Filter that is the logical OR of this and another Filter.
protected Filter	orNodeFilter(NodeFilter filter) Creates a Filter that is the logical OR of this and a NodeFilter.
java.lang.String	toString() Returns a pretty representation of this Filter.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

ALLCONTENT

public static final int ALLCONTENT

Bit-mask matching all Content node types, including the Document node. This is the bitwise-OR of every content-type listed in class Content. Relies on the fact that the DOCUMENT content-type has the highest bit value. ALLCONTENT is one less than twice this value.

See Also:

Constant Field Values

NAMENODES

public static final int NAMENODES

Bit-mask matching all Markup nodes with user-defined XML name tags. Includes the node types: Element and Attribute. These are the nodes for which getName() returns a name with user-defined semantics, rather than just the content-type name of the node.

See Also:

Constant Field Values

VALUENODES

public static final int VALUENODES

Bit-mask matching all nodes containing XML data values. Includes the node types: Element, Attribute, Text and Data; but excludes Comment nodes. These are the nodes for which getText() returns some kind of value with user-defined semantics.

See Also:

Constant Field Values

PARENTNODES

public static final int PARENTNODES

Bit-mask matching all nodes that may be the parents of other nodes. Includes the node types: Document and Element; but excludes other nodes, which cannot have child-content.

See Also:

Constant Field Values

PROPERTYNODES

public static final int PROPERTYNODES

Bit-mask matching all nodes that can have XML attributes. Includes the node types: Element, Declaration, Instruction and Doctype.

See Also:

Constant Field Values

XPATHNODES

public static final int XPATHNODES

Bit-mask matching all accessible XPath content, which excludes the Declaration and Doctype nodes.

See Also:

Constant Field Values

XPATHTEXT

public static final int XPATHTEXT

Bit-mask matching all nodes that are treated as text by the XPath text() selector. Includes the node types: Data and Text.

See Also:

Constant Field Values

Constructor Detail

Filter

protected Filter()

Creates a Filter.

Method Detail

accept

public abstract boolean accept(Content node)

Reports whether a given Content node is accepted by this Filter. This method is defined variously according to the class of Filter.

Parameters:

node - a Content node.

Returns:

true, if the node is accepted, otherwise false.

not

public Filter not()

Creates a Filter that is the logical NOT of this Filter. The new Filter accepts Content that was rejected by this Filter.

Returns:

a new Filter, the complement of this Filter.

and

public Filter and(Filter filter)

Creates a Filter that is the logical AND of this and another Filter. The new Filter accepts Content that was accepted both by this, and the other Filter. By default, creates an AndFilter with this and the other filter as its component filters. If the other filter is a NodeFilter, dispatches to a special case method that may create a more efficient conjunction.

Parameters:

filter - the other Filter.

Returns:

a new Filter, the conjunction of this and the other Filter.

or

public Filter or(Filter filter)

Creates a Filter that is the logical OR of this and another Filter. The new Filter accepts Content that was accepted either by this, or the other Filter. By default, creates an OrFilter with this and the other filter as its component filters. If the other filter is a NodeFilter, dispatches to a special case method that may create a more efficient disjunction.

Parameters:

filter - the other Filter.

Returns:

a new Filter, the disjunction of this and the other Filter.

andIndexFilter

protected IndexFilter andIndexFilter(IndexFilter filter)

Creates a Filter that is the logical AND of this and an IndexFilter. Constructs a new IndexFilter containing this filter as its internal filter. This is so that other filtering is always performed before any indexing counting is performed.

Parameters:

filter - the other IndexFilter.

Returns:

a new Filter, an IndexFilter containing this prior filter.

andNodeFilter

protected Filter andNodeFilter(NodeFilter filter)

Creates a Filter that is the logical AND of this and a NodeFilter. By default, constructs an AndFilter out of this and the NodeFilter; but in subclasses of Filter, this may be overridden to merge two bit-masks.

Parameters:

filter - the other NodeFilter.

Returns:

a new Filter, the conjunction of this and the other NodeFilter.

orNodeFilter

protected Filter orNodeFilter(NodeFilter filter)

Creates a Filter that is the logical OR of this and a NodeFilter. By default, constructs an OrFilter out of this and the NodeFilter; but in subclasses of Filter, this may be overridden to merge two bit-masks.

Parameters:

filter - the other NodeFilter.

Returns:

a new Filter, the disjunction of this and the other NodeFilter.

toString

public java.lang.String toString()

Returns a pretty representation of this Filter. By default, returns the class-name of the Filter. Subclasses may also show the nested structure of compound Filters.

Overrides:

toString in class java.lang.Object