net.sf.saxon.pattern

Class BooleanExpressionPattern

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.PseudoExpression

net.sf.saxon.pattern.Pattern

net.sf.saxon.pattern.BooleanExpressionPattern

All Implemented Interfaces:

ExportAgent, Locatable, IdentityComparable, PatternWithPredicate

public class BooleanExpressionPattern
extends Pattern
implements PatternWithPredicate

A BooleanExpressionPattern is a pattern of the form .[ Expr ] introduced in XSLT 3.0. It matches an item if the expression has an effective boolean value of true() when evaluated with that item as the singleton focus.

Author:

Michael H. Kay

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
BooleanExpressionPattern(Expression expression) Create a BooleanExpressionPattern

Method Summary

Modifier and Type	Method and Description
int	allocateSlots(SlotManager slotManager, int nextFree) Allocate slots to any variables used within the pattern
int	computeHashCode() Hashcode supporting equals()
Pattern	copy(RebindingMap rebindings) Copy a pattern.
boolean	equals(java.lang.Object other) Determine whether this pattern is the same as another pattern
void	export(ExpressionPresenter presenter) Diagnostic print of expression structure.
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
Expression	getPredicate()
UType	getUType() Get a UType indicating which kinds of items this Pattern can match.
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.
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	optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Perform optimisation of an expression and its subexpressions.
java.lang.String	toString() Display the pattern for diagnostics
Pattern	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) Type-check the pattern.

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

bindCurrent, convertToTypedPattern, effectiveBooleanValue, getDefaultPriority, getDependencies, getHostLanguage, handleDynamicError, isLiftable, isRecoverable, make, matchesBeneathAnchor, matchesCurrentGroup, patternContainsVariable, replaceCurrent, selectNodes, setOriginalText, setPriority, setRecoverable, simplify, 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, computeSpecialProperties, computeStaticProperties, dynamicError, 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, hasVariableBinding, 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

BooleanExpressionPattern

public BooleanExpressionPattern(Expression expression)

Create a BooleanExpressionPattern

Parameters:

expression - the expression to be evaluated (the expression in the predicate)

Method Detail

getPredicate

public Expression getPredicate()

Specified by:

getPredicate in interface PatternWithPredicate

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

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.

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

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)

optimize

public Pattern optimize(ExpressionVisitor visitor,
                        ContextItemStaticInfo contextInfo)
                 throws XPathException

Description copied from class: Pattern

Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

Overrides:

optimize in class Pattern

Parameters:

visitor - an expression visitor

contextInfo - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE

Returns:

the original expression, rewritten if appropriate to optimize execution

Throws:

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

isMotionless

public boolean isMotionless()

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

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

matches

public boolean matches(Item<?> item,
                       XPathContext context)

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 context in which the match is to take place. 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

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

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

toString

public java.lang.String toString()

Display the pattern for diagnostics

Overrides:

toString in class Pattern

Returns:

a representation of the expression as a string

equals

public boolean equals(java.lang.Object other)

Determine whether this pattern is the same as another pattern

Overrides:

equals in class Expression

Parameters:

other - the other object

Returns:

true if the other operand is an expression and if it can be determined that the two expressions are equivalent, in the sense that they will always return the same result.

computeHashCode

public int computeHashCode()

Hashcode supporting equals()

Overrides:

computeHashCode in class Expression

Returns:

a computed hash code

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.