net.sf.saxon.pattern

Class LocationPathPattern

java.lang.Object

net.sf.saxon.pattern.Pattern

net.sf.saxon.pattern.LocationPathPattern

All Implemented Interfaces:

Serializable, SourceLocator, Container, PatternFinder

public final class LocationPathPattern
extends Pattern

A LocationPathPattern represents a path, for example of the form A/B/C... The components are represented as a linked list, each component pointing to its predecessor

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected Expression	equivalentExpr
protected Expression[]	filters
protected boolean	firstElementPattern
protected boolean	lastElementPattern
NodeTest	nodeTest
protected boolean	specialFilter

Constructor Summary

Constructors

Constructor and Description
LocationPathPattern() Create a LocationPathPattern

Method Summary

Modifier and Type	Method and Description
void	addFilter(Expression filter) Add a filter to the pattern (while under construction)
int	allocateSlots(StaticContext env, SlotManager slotManager, int nextFree) Allocate slots to any variables used within the pattern
Pattern	analyze(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Type-check the pattern, performing any type-dependent optimizations.
boolean	equals(Object other) Determine whether this pattern is the same as another pattern
int	getDependencies() Get the dependencies of the pattern.
Expression[]	getFilters() Get the filters assocated with the last step in the pattern
int	getFingerprint() Determine the fingerprint of nodes to which this pattern applies.
ItemType	getItemType() Get a NodeTest that all the nodes matching this pattern must satisfy
int	getNodeKind() Determine the types of nodes to which this pattern applies.
Pattern	getUpperPattern() Get the pattern applying to the parent node, if there is one
byte	getUpwardsAxis() Get the upwards axis, that is, the axis by which the upper pattern is reached.
int	hashCode() hashcode supporting equals()
protected boolean	internalMatches(NodeInfo node, NodeInfo anchor, XPathContext context) Test whether the pattern matches, but without changing the current() node
boolean	isPositional(TypeHierarchy th) Determine if the pattern uses positional filters
Iterator	iterateSubExpressions() Iterate over the subexpressions within this pattern
boolean	matches(Item item, XPathContext context) Determine whether the pattern matches a 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.
void	promote(PromotionOffer offer, Expression parent) Offer promotion for subexpressions within this pattern.
boolean	replaceSubExpression(Expression original, Expression replacement) Replace one subexpression by a replacement subexpression
void	resolveCurrent(LetExpression let, PromotionOffer offer, boolean topLevel) If the pattern contains any calls on current(), this method is called to modify such calls to become variable references to a variable declared in a specially-allocated local variable
boolean	selectsOutwards() Test whether any predicate within the pattern contains a prohibited selection, that is, use of an axis such as child, descendant, following-sibling
void	setExecutable(Executable executable) Set the executable containing this pattern
void	setLineNumber(int lineNumber) Set the line number where the pattern occurred
void	setNodeTest(NodeTest test) Set the NodeTest
void	setSystemId(String systemId) Set the system ID where the pattern occurred
void	setUpperPattern(byte axis, Pattern upper) Set the superior pattern (matching a parent or ancestor node
void	setVariableBindingExpression(Expression exp) Set an expression used to bind the variable that represents the value of the current() function
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, getHostLanguage, getLineNumber, getLocationProvider, getPublicId, getSystemId, make, selectNodes, setOriginalText, toString

Methods inherited from class java.lang.Object

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

Field Detail

nodeTest

public NodeTest nodeTest

filters

protected Expression[] filters

equivalentExpr

protected Expression equivalentExpr

firstElementPattern

protected boolean firstElementPattern

lastElementPattern

protected boolean lastElementPattern

specialFilter

protected boolean specialFilter

Constructor Detail

LocationPathPattern

public LocationPathPattern()

Create a LocationPathPattern

Method Detail

setNodeTest

public void setNodeTest(NodeTest test)

Set the NodeTest

Parameters:

test - the NodeTest

setUpperPattern

public void setUpperPattern(byte axis,
                            Pattern upper)

Set the superior pattern (matching a parent or ancestor node

Parameters:

axis - the axis (parent or ancestor) connecting to the upper pattern

upper - the pattern that a parent or ancestor must match

addFilter

public void addFilter(Expression filter)

Add a filter to the pattern (while under construction)

Parameters:

filter - The predicate (a boolean expression or numeric expression) to be added

setLineNumber

public void setLineNumber(int lineNumber)

Description copied from class: Pattern

Set the line number where the pattern occurred

Overrides:

setLineNumber in class Pattern

Parameters:

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

setSystemId

public void setSystemId(String systemId)

Description copied from class: Pattern

Set the system ID where the pattern occurred

Overrides:

setSystemId in class Pattern

Parameters:

systemId - the URI of the module containing the pattern

setExecutable

public void setExecutable(Executable executable)

Set the executable containing this pattern

Overrides:

setExecutable in class Pattern

Parameters:

executable - the executable

setVariableBindingExpression

public void setVariableBindingExpression(Expression exp)

Set an expression used to bind the variable that represents the value of the current() function

Overrides:

setVariableBindingExpression in class Pattern

Parameters:

exp - the expression that binds the variable

getFilters

public Expression[] getFilters()

Get the filters assocated with the last step in the pattern

Returns:

an array of expression holding the filter predicates in order

getUpperPattern

public Pattern getUpperPattern()

Get the pattern applying to the parent node, if there is one

Returns:

the parent pattern, for example if the pattern is a/b[1]/c then the parent pattern is a/b[1]

getUpwardsAxis

public byte getUpwardsAxis()

Get the upwards axis, that is, the axis by which the upper pattern is reached. Typically Axis.PARENT or Axis.ANCESTOR

selectsOutwards

public boolean selectsOutwards()

Test whether any predicate within the pattern contains a prohibited selection, that is, use of an axis such as child, descendant, following-sibling

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 - if a static error is discovered

analyze

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

Type-check the pattern, performing any type-dependent optimizations.

Overrides:

analyze in class Pattern

Parameters:

visitor - an expression visitor

contextItemType - the type of the context item at the point where the pattern appears

Returns:

the optimised Pattern

Throws:

XPathException - if a static error is discovered

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 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

replaceSubExpression

public boolean replaceSubExpression(Expression original,
                                    Expression replacement)

Replace one subexpression by a replacement subexpression

Overrides:

replaceSubExpression in class Pattern

Parameters:

original - the original subexpression

replacement - the replacement subexpression

Returns:

true if the original subexpression is found

allocateSlots

public int allocateSlots(StaticContext env,
                         SlotManager slotManager,
                         int nextFree)

Allocate slots to any variables used within the pattern

Overrides:

allocateSlots in class Pattern

Parameters:

env - the static context in the XSLT stylesheet

slotManager -

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

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

matches

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

Determine whether the pattern matches a given item.

Specified by:

matches in class Pattern

Parameters:

item - the item to be tested

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 pattern matches, else false

Throws:

XPathException - if a dynamic error occurs during pattern matching

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 a dynamic error occurs during pattern matching

internalMatches

protected boolean internalMatches(NodeInfo node,
                                  NodeInfo anchor,
                                  XPathContext context)
                           throws XPathException

Test whether the pattern matches, but without changing the current() node

Overrides:

internalMatches 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(). @return true if the node matches the Pattern, false otherwise

Returns:

true if the pattern matches the supplied node

Throws:

XPathException - if a dynamic error occurs during pattern matching

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

getFingerprint

public int getFingerprint()

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

Overrides:

getFingerprint in class Pattern

Returns:

the fingerprint of nodes matched by this pattern.

getItemType

public ItemType getItemType()

Get a NodeTest that all the nodes matching this pattern must satisfy

Specified by:

getItemType in class Pattern

Returns:

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

isPositional

public boolean isPositional(TypeHierarchy th)

Determine if the pattern uses positional filters

Parameters:

th - the type hierarchy cache

Returns:

true if there is a numeric filter in the pattern, or one that uses the position() or last() functions

resolveCurrent

public void resolveCurrent(LetExpression let,
                           PromotionOffer offer,
                           boolean topLevel)
                    throws XPathException

If the pattern contains any calls on current(), this method is called to modify such calls to become variable references to a variable declared in a specially-allocated local variable

Overrides:

resolveCurrent in class Pattern

Parameters:

let - the expression that assigns the local variable. This returns a dummy result, and is executed just before evaluating the pattern, to get the value of the context item into the variable.

offer - A PromotionOffer used to process the expressions and change the call on current() into a variable reference

topLevel -

Throws:

XPathException

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