net.sf.saxon.pattern

Class PatternThatSetsCurrent

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.PseudoExpression

net.sf.saxon.pattern.Pattern

net.sf.saxon.pattern.PatternThatSetsCurrent

All Implemented Interfaces:

ExportAgent, Locatable, IdentityComparable

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()

Field Summary

Fields inherited from class net.sf.saxon.expr.Expression

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
PatternThatSetsCurrent(Pattern wrappedPattern)
PatternThatSetsCurrent(Pattern wrappedPattern, LocalVariableBinding binding)

Method Summary

Modifier and Type	Method and Description
int	allocateSlots(SlotManager slotManager, int nextFree) Allocate slots to any variables used within the pattern
Pattern	convertToTypedPattern(java.lang.String val) Convert the pattern to a typed pattern, in which an element name is treated as schema-element(N)
Pattern	copy(RebindingMap rebindings) Copy a pattern.
void	export(ExpressionPresenter presenter) Diagnostic print of expression structure.
LocalBinding	getCurrentBinding() Get the binding of the item being matched by the pattern, that is, the binding that represents the value of the current() function
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
UType	getUType() Get a UType indicating which kinds of items this Pattern can match.
Pattern	getWrappedPattern()
boolean	hasVariableBinding(Binding binding) Ask whether this expression is, or contains, the binding of a given variable
boolean	isMotionless() Test whether a pattern is motionless, that is, whether it can be evaluated against a node without repositioning the input stream.
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.
java.lang.Iterable<Operand>	operands() Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.
Pattern	simplify() Simplify the pattern by applying any context-independent optimisations.
java.lang.String	toString() Get the original pattern text
Pattern	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) Type-check the pattern.

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

bindCurrent, effectiveBooleanValue, getDefaultPriority, getDependencies, handleDynamicError, isLiftable, isRecoverable, make, matchesCurrentGroup, optimize, patternContainsVariable, replaceCurrent, selectNodes, setOriginalText, setPriority, setRecoverable, toShortString

Methods inherited from class net.sf.saxon.expr.PseudoExpression

computeCardinality, evaluateAsString, evaluateItem, getImplementationMethod, iterate, process

Methods inherited from class net.sf.saxon.expr.Expression

addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeHashCode, computeSpecialProperties, computeStaticProperties, dynamicError, equals, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getEvaluationMethod, getExpressionName, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, getStreamerName, hasCompatibleStaticContext, hashCode, hasSpecialProperty, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, typeCheckChildren, typeError, unordered, verifyParentPointers

Methods inherited from class java.lang.Object

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

Constructor Detail

PatternThatSetsCurrent

public PatternThatSetsCurrent(Pattern wrappedPattern)

PatternThatSetsCurrent

public PatternThatSetsCurrent(Pattern wrappedPattern,
                              LocalVariableBinding binding)

Method Detail

operands

public java.lang.Iterable<Operand> operands()

Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation works off the results of iterateSubExpressions()

If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

Overrides:

operands in class Expression

Returns:

an iterator containing the sub-expressions of this expression

getCurrentBinding

public LocalBinding 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

hasVariableBinding

public boolean hasVariableBinding(Binding binding)

Ask whether this expression is, or contains, the binding of a given variable

Overrides:

hasVariableBinding in class Expression

Parameters:

binding - the variable binding

Returns:

true if this expression is the variable binding (for example a ForExpression or LetExpression) or if it is a FLWOR expression that binds the variable in one of its clauses.

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

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()
                 throws XPathException

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

Overrides:

simplify in class Pattern

Returns:

the simplified expression (or the original if unchanged, or if modified in-situ)

Throws:

XPathException - if an error is discovered during expression rewriting

typeCheck

public Pattern typeCheck(ExpressionVisitor visitor,
                         ContextItemStaticInfo contextItemType)
                  throws XPathException

Type-check the pattern.

Overrides:

typeCheck 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 - if an error is discovered during this phase (typically a type error)

getUType

public UType getUType()

Get a UType indicating which kinds of items this Pattern can match.

Specified by:

getUType in class Pattern

Returns:

a UType indicating all the primitive types of item that the pattern can match.

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

toString

public java.lang.String toString()

Get the original pattern text

Overrides:

toString in class Pattern

Returns:

a representation of the expression as a string

getHostLanguage

public int getHostLanguage()

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

Overrides:

getHostLanguage in class Pattern

Returns:

typically Configuration.XSLT or Configuration.XQUERY

isMotionless

public boolean isMotionless()

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

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)

convertToTypedPattern

public Pattern convertToTypedPattern(java.lang.String val)
                              throws XPathException

Convert the pattern to a typed pattern, in which an element name is treated as schema-element(N)

Overrides:

convertToTypedPattern in class Pattern

Parameters:

val - either "strict" or "lax" depending on the value of xsl:mode/@typed

Returns:

either the original pattern unchanged, or a new pattern as the result of the conversion

Throws:

XPathException - if the pattern cannot be converted

copy

public Pattern copy(RebindingMap rebindings)

Copy a pattern. This makes a deep copy.

Specified by:

copy in class Pattern

Parameters:

rebindings - variables that need to be re-bound

Returns:

the copy of the original pattern

export

public void export(ExpressionPresenter presenter)
            throws XPathException

Description copied from class: Expression

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:

export in interface ExportAgent

Specified by:

export in class Pattern

Parameters:

presenter - the expression presenter used to display the structure

Throws:

XPathException - if the export fails, for example if an expression is found that won't work in the target environment.

getWrappedPattern

public Pattern getWrappedPattern()