net.sf.saxon.pattern

Class VennPattern

java.lang.Object

net.sf.saxon.pattern.Pattern

net.sf.saxon.pattern.VennPattern

All Implemented Interfaces:

Serializable, SourceLocator, Container, PatternFinder

Direct Known Subclasses:

ExceptPattern, IntersectPattern, UnionPattern

public abstract class VennPattern
extends Pattern

Abstract pattern formed as the union, intersection, or difference of two other patterns; concrete subclasses are used for the different operators

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected Pattern	p1
protected Pattern	p2

Constructor Summary

Constructors

Constructor and Description
VennPattern(Pattern p1, Pattern p2) Constructor

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
boolean	equals(Object other) Determine whether this pattern is the same as another pattern
void	gatherComponentPatterns(Set<Pattern> set) Gather the component (non-Venn) patterns of this Venn pattern
int	getDependencies() Get the dependencies of the pattern.
ItemType	getItemType() Get an ItemType that all the items matching this pattern must satisfy
Pattern	getLHS() Get the LHS of the union
int	getNodeKind() Determine the types of nodes to which this pattern applies.
Pattern	getRHS() Get the RHS of the union
int	hashCode() Hashcode supporting equals()
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
void	promote(PromotionOffer offer, Expression parent) Offer promotion for subexpressions within this pattern.
boolean	replaceSubExpression(Expression original, Expression replacement) Replace a subexpression by a replacement subexpression
void	setExecutable(Executable executable) Set the executable containing this pattern
void	setLineNumber(int lineNumber) Override method to set the system ID, so it's set on both halves
void	setOriginalText(String pattern) Set the original text
void	setSystemId(String systemId) Override method to set the system ID, so it's set on both halves
Pattern	simplify(ExpressionVisitor visitor) Simplify the pattern: perform any context-independent optimisations

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

getColumnNumber, getContainerGranularity, getDefaultPriority, getExecutable, getFingerprint, getHostLanguage, getLineNumber, getLocationProvider, getPublicId, getSystemId, make, matches, matchesBeneathAnchor, replaceCurrent, selectNodes, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

p1

protected Pattern p1

p2

protected Pattern p2

Constructor Detail

VennPattern

public VennPattern(Pattern p1,
           Pattern p2)

Constructor

Parameters:

p1 - the left-hand operand

p2 - the right-hand operand

Method Detail

setExecutable

public void setExecutable(Executable executable)

Set the executable containing this pattern

Overrides:

setExecutable in class Pattern

Parameters:

executable - the executable

simplify

public Pattern simplify(ExpressionVisitor visitor)
                 throws XPathException

Simplify the pattern: perform any context-independent optimisations

Overrides:

simplify in class Pattern

Parameters:

visitor - an expression visitor

Returns:

the optimised Pattern

Throws:

XPathException

analyze

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

Type-check the pattern. This is only needed for patterns that contain variable references or function calls.

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

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 - the parent expression

Throws:

XPathException - if any error is detected

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

setOriginalText

public void setOriginalText(String pattern)

Set the original text

Overrides:

setOriginalText in class Pattern

Parameters:

pattern - the original text of the pattern

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 - true if Saxon extensions are allowed

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

allocateSlots

public int allocateSlots(SlotManager slotManager,
                int nextFree)

Allocate slots to any variables used within the pattern

Overrides:

allocateSlots in class Pattern

Parameters:

slotManager - represents the stack frame on which slots are allocated

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

gatherComponentPatterns

public void gatherComponentPatterns(Set<Pattern> set)

Gather the component (non-Venn) patterns of this Venn pattern

Parameters:

set - the set into which the components will be added

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 Node.NODE

Overrides:

getNodeKind in class Pattern

Returns:

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

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

getDependencies

public int getDependencies()

Get the dependencies of the pattern. The only possible dependency for a pattern is on local variables. This is analyzed in those patterns where local variables may appear.

Overrides:

getDependencies in class Pattern

Returns:

the dependencies, as a bit-significant mask

iterateSubExpressions

public Iterator<Expression> iterateSubExpressions()

Iterate over the subexpressions within this pattern

Overrides:

iterateSubExpressions in class Pattern

Returns:

an iterator over the subexpressions.

getLHS

public Pattern getLHS()

Get the LHS of the union

Returns:

the first operand of the union

getRHS

public Pattern getRHS()

Get the RHS of the union

Returns:

the second operand of the union

setSystemId

public void setSystemId(String systemId)

Override method to set the system ID, so it's set on both halves

Overrides:

setSystemId in class Pattern

Parameters:

systemId - the URI of the module containing the pattern

setLineNumber

public void setLineNumber(int lineNumber)

Override method to set the system ID, so it's set on both halves

Overrides:

setLineNumber in class Pattern

Parameters:

lineNumber - the line number of the pattern in the source module

equals

public boolean equals(Object other)

Determine whether this pattern is the same as another pattern

Overrides:

equals in class Object

Parameters:

other - the other object

hashCode

public int hashCode()

Hashcode supporting equals()

Overrides:

hashCode in class Object