net.sf.saxon.pattern

Class PatternWithPredicate

java.lang.Object

net.sf.saxon.pattern.Pattern

net.sf.saxon.pattern.PatternWithPredicate

All Implemented Interfaces:

Serializable, SourceLocator, Container, PatternFinder

public class PatternWithPredicate
extends Pattern

Class for handling patterns with simple non-positional boolean predicates

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
PatternWithPredicate(Pattern basePattern, Expression predicate)

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.
void	bindCurrent(Binding binding) Replace any calls on current() by a variable reference bound to the supplied binding
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.
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 Node.
void	promote(PromotionOffer offer, Expression parent) Offer promotion for subexpressions within this pattern.

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

getColumnNumber, getContainerGranularity, getDependencies, getExecutable, getHostLanguage, getLineNumber, getLocationProvider, getPublicId, getSystemId, make, matchesBeneathAnchor, replaceCurrent, replaceSubExpression, selectNodes, setExecutable, setLineNumber, setOriginalText, setSystemId, simplify, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

PatternWithPredicate

public PatternWithPredicate(Pattern basePattern,
                    Expression predicate)

Method Detail

bindCurrent

public void bindCurrent(Binding binding)

Replace any calls on current() by a variable reference bound to the supplied binding

Overrides:

bindCurrent in class Pattern

promote

public void promote(PromotionOffer offer,
           Expression parent)
             throws XPathException

Offer promotion for subexpressions within this pattern. The offer will be accepted if the subexpression is not dependent on the factors (e.g. the context item) identified in the PromotionOffer. By default the offer is not accepted - this is appropriate in the case of simple expressions such as constant values and variable references where promotion would give no performance advantage. This method is always called at compile time.

Unlike the corresponding method on Expression, this method does not return anything: it can make internal changes to the pattern, but cannot return a different pattern. Only certain kinds of promotion are applicable within a pattern: specifically, promotions affecting local variable references within the pattern.

Overrides:

promote in class Pattern

Parameters:

offer - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression

parent -

Throws:

XPathException - if any error is detected

allocateSlots

public int allocateSlots(SlotManager slotManager,
                int nextFree)

Allocate slots to any variables used within the pattern

Overrides:

allocateSlots in class Pattern

Parameters:

slotManager - holds details of the allocated slots

nextFree - the next slot that is free to be allocated @return the next slot that is free to be allocated

Returns:

the next slot that is free to be allocated

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

matches

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

Determine whether this Pattern matches the given Node.

Specified by:

matches in class Pattern

Parameters:

item - The NodeInfo representing the Element or other node 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 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)

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

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

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

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

isMotionless

public boolean isMotionless(boolean allowExtensions)

Description copied from class: Pattern

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