net.sf.saxon.pattern

Class PatternThatSetsCurrent

java.lang.Object

net.sf.saxon.pattern.Pattern

net.sf.saxon.pattern.PatternThatSetsCurrent

All Implemented Interfaces:

Serializable, SourceLocator, Container, PatternFinder

public class PatternThatSetsCurrent
extends Pattern

This class represents a pattern that sets the value of current() to the node being matched, and then wraps another pattern that uses the value of current()

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
PatternThatSetsCurrent(Pattern wrappedPattern)

Method Summary

Methods

Modifier and Type	Method and Description
int	allocateSlots(SlotManager slotManager, int nextFree) Allocate slots to any variables used within the pattern
Pattern	analyze(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Type-check the pattern.
Binding	getCurrentBinding() Get the binding of the item being matched by the pattern, that is, the binding that represents the value of the current() function
double	getDefaultPriority() Determine the default priority to use if this pattern appears as a match pattern for a template with no explicit priority attribute.
int	getFingerprint() Determine the name fingerprint of nodes to which this pattern applies.
int	getHostLanguage() Get the host language (XSLT, XQuery, XPath) used to implement the code in this container
ItemType	getItemType() Get an ItemType that all the items matching this pattern must satisfy
int	getNodeKind() Determine the types of nodes to which this pattern applies.
boolean	isMotionless(boolean allowExtensions) Test whether a pattern is motionless, that is, whether it can be evaluated against a node without repositioning the input stream.
Iterator<Expression>	iterateSubExpressions() Iterate over the subexpressions within this pattern
boolean	matches(Item item, XPathContext context) Determine whether this Pattern matches the given item.
boolean	matchesBeneathAnchor(NodeInfo node, NodeInfo anchor, XPathContext context) Determine whether this pattern matches a given Node within the subtree rooted at a given anchor node.
boolean	replaceSubExpression(Expression original, Expression replacement) Replace a subexpression by a replacement subexpression
Pattern	simplify(ExpressionVisitor visitor) Simplify the pattern by applying any context-independent optimisations.
String	toString() Get the original pattern text

Methods inherited from class net.sf.saxon.pattern.Pattern

bindCurrent, getColumnNumber, getContainerGranularity, getDependencies, getExecutable, getLineNumber, getLocationProvider, getPublicId, getSystemId, make, promote, replaceCurrent, selectNodes, setExecutable, setLineNumber, setOriginalText, setSystemId

Methods inherited from class java.lang.Object

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

Constructor Detail

PatternThatSetsCurrent

public PatternThatSetsCurrent(Pattern wrappedPattern)

Method Detail

getCurrentBinding

public Binding getCurrentBinding()

Get the binding of the item being matched by the pattern, that is, the binding that represents the value of the current() function

Returns:

the binding of the item being matched by the pattern

allocateSlots

public int allocateSlots(SlotManager slotManager,
                int nextFree)

Allocate slots to any variables used within the pattern

Overrides:

allocateSlots in class Pattern

Parameters:

slotManager - the slot manager representing the stack frame for local variables

nextFree - the next slot that is free to be allocated

Returns:

the next slot that is free to be allocated

iterateSubExpressions

public Iterator<Expression> iterateSubExpressions()

Iterate over the subexpressions within this pattern

Overrides:

iterateSubExpressions in class Pattern

Returns:

an iterator over the subexpressions. Default implementation returns an empty sequence

matches

public boolean matches(Item item,
              XPathContext context)
                throws XPathException

Determine whether this Pattern matches the given item. This is the main external interface for matching patterns: it sets current() to the node being tested

Specified by:

matches in class Pattern

Parameters:

item - The item to be tested against the Pattern

context - The dynamic context. Only relevant if the pattern uses variables, or contains calls on functions such as document() or key().

Returns:

true if the item matches the Pattern, false otherwise

Throws:

XPathException - if an error occurs while matching the pattern (the caller will usually treat this the same as a false result)

getItemType

public ItemType getItemType()

Get an ItemType that all the items matching this pattern must satisfy

Specified by:

getItemType in class Pattern

Returns:

an ItemType, as specific as possible, which all the matching items satisfy

simplify

public Pattern simplify(ExpressionVisitor visitor)
                 throws XPathException

Simplify the pattern by applying any context-independent optimisations. Default implementation does nothing.

Overrides:

simplify in class Pattern

Parameters:

visitor - the expression visitor

Returns:

the optimised Pattern

Throws:

XPathException

analyze

public Pattern analyze(ExpressionVisitor visitor,
              ExpressionVisitor.ContextItemType contextItemType)
                throws XPathException

Type-check the pattern.

Overrides:

analyze in class Pattern

Parameters:

visitor - the expression visitor

contextItemType - the type of the context item at the point where the pattern is defined. Set to null if it is known that the context item is undefined.

Returns:

the optimised Pattern

Throws:

XPathException

getNodeKind

public int getNodeKind()

Determine the types of nodes to which this pattern applies. Used for optimisation. For patterns that match nodes of several types, return Type.NODE. For patterns that do not match nodes, return -1.

Overrides:

getNodeKind in class Pattern

Returns:

the type of node matched by this pattern. e.g. Type.ELEMENT or Type.TEXT

getFingerprint

public int getFingerprint()

Determine the name fingerprint of nodes to which this pattern applies. Used for optimisation.

Overrides:

getFingerprint in class Pattern

Returns:

A fingerprint that the nodes must match, or -1 if it can match multiple fingerprints, or it if matches atomic values

getDefaultPriority

public double getDefaultPriority()

Determine the default priority to use if this pattern appears as a match pattern for a template with no explicit priority attribute.

Overrides:

getDefaultPriority in class Pattern

Returns:

the default priority for the pattern

toString

public String toString()

Get the original pattern text

Overrides:

toString in class Pattern

getHostLanguage

public int getHostLanguage()

Get the host language (XSLT, XQuery, XPath) used to implement the code in this container

Specified by:

getHostLanguage in interface Container

Overrides:

getHostLanguage in class Pattern

Returns:

typically Configuration.XSLT or Configuration.XQUERY

replaceSubExpression

public boolean replaceSubExpression(Expression original,
                           Expression replacement)

Replace a subexpression by a replacement subexpression

Overrides:

replaceSubExpression in class Pattern

Parameters:

original - the expression to be replaced

replacement - the new expression to be inserted in its place

Returns:

true if the replacement was carried out

isMotionless

public boolean isMotionless(boolean allowExtensions)

Test whether a pattern is motionless, that is, whether it can be evaluated against a node without repositioning the input stream. This is a necessary condition for patterns used as the match pattern of a streamed template rule.

Overrides:

isMotionless in class Pattern

Parameters:

allowExtensions - if false, the result is determined strictly according to the W3C "guaranteed streamability rules. If true, Saxon extensions are permitted: that is, constructs may be recognized as motionless by Saxon even if they are not recognized as motionless by the W3C rules.

Returns:

true if the pattern is motionless, that is, if it can be evaluated against a streamed node without changing the position in the streamed input file

matchesBeneathAnchor

public boolean matchesBeneathAnchor(NodeInfo node,
                           NodeInfo anchor,
                           XPathContext context)
                             throws XPathException

Determine whether this pattern matches a given Node within the subtree rooted at a given anchor node. This method is used when the pattern is used for streaming.

Overrides:

matchesBeneathAnchor in class Pattern

Parameters:

node - The NodeInfo representing the Element or other node to be tested against the Pattern

anchor - The anchor node, which must match any AnchorPattern subpattern

context - The dynamic context. Only relevant if the pattern uses variables, or contains calls on functions such as document() or key().

Returns:

true if the node matches the Pattern, false otherwise

Throws:

XPathException - if an error occurs while matching the pattern (the caller will usually treat this the same as a false result)