net.sf.saxon.pattern

Class VennPattern

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.PseudoExpression

net.sf.saxon.pattern.Pattern

net.sf.saxon.pattern.VennPattern

All Implemented Interfaces:

ExportAgent, Locatable, IdentityComparable

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

Field Summary

Fields

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

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
VennPattern(Pattern p1, Pattern p2) Constructor

Method Summary

Modifier and Type	Method and Description
int	allocateSlots(SlotManager slotManager, int nextFree) Allocate slots to any variables used within the pattern
void	bindCurrent(LocalBinding binding) Replace any calls on current() by a variable reference bound to the supplied binding
int	computeHashCode() Hashcode supporting equals()
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.
void	gatherComponentPatterns(java.util.Set<Pattern> set) Gather the component (non-Venn) patterns of this Venn pattern
int	getDependencies() Get the dependencies of the pattern.
Pattern	getLHS() Get the LHS of the union
protected abstract java.lang.String	getOperatorName() Get the relevant operator: "union", "intersect", or "except"
Pattern	getRHS() Get the RHS of the union
boolean	isMotionless() Test whether a pattern is motionless, that is, whether it can be evaluated against a node without repositioning the input stream.
boolean	matchesCurrentGroup() Ask whether the pattern is anchored on a call on current-group()
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: perform 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

convertToTypedPattern, copy, effectiveBooleanValue, getDefaultPriority, getFingerprint, getHostLanguage, getItemType, getUType, handleDynamicError, isLiftable, isRecoverable, make, matches, matchesBeneathAnchor, 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, 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

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

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

simplify

public Pattern simplify()
                 throws XPathException

Simplify the pattern: perform any context-independent optimisations

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. This is only needed for patterns that contain variable references or function calls.

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)

bindCurrent

public void bindCurrent(LocalBinding binding)

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

Overrides:

bindCurrent in class Pattern

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

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(java.util.Set<Pattern> set)

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

Parameters:

set - the set into which the components will be added

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

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

matchesCurrentGroup

public boolean matchesCurrentGroup()

Ask whether the pattern is anchored on a call on current-group()

Overrides:

matchesCurrentGroup in class Pattern

Returns:

true if calls on matchesBeneathAnchor should test with all nodes in the current group as anchor nodes. If false, only the first node in a group is treated as the anchor node

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

getOperatorName

protected abstract java.lang.String getOperatorName()

Get the relevant operator: "union", "intersect", or "except"

Returns:

the operator, as a string

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

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.