net.sf.saxon.pattern

Class SimplePositionalPattern

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.PseudoExpression

net.sf.saxon.pattern.Pattern

net.sf.saxon.pattern.SimplePositionalPattern

All Implemented Interfaces:

ExportAgent, IdentityComparable

public final class SimplePositionalPattern
extends Pattern

A SimplePositionalPattern is a pattern of the form A[N] where A is an axis expression using the child axis and P is a numeric literal.

Field Summary

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

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

Constructor Summary

Constructors

Constructor and Description
SimplePositionalPattern(NodeTest nodeTest, int position) Create a SimplePositionalPattern

Method Summary

Modifier and Type	Method and Description
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 fingerprint of nodes to which this pattern applies.
ItemType	getItemType() Get an ItemType that all the nodes matching this pattern must satisfy
NodeTest	getNodeTest() Get the node test
int	getPosition() Get the required position
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 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.
java.lang.String	toString() Get the original pattern text

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

allocateSlots, bindCurrent, convertToTypedPattern, effectiveBooleanValue, getDefaultPriority, getDependencies, getHostLanguage, handleDynamicError, isLiftable, isRecoverable, make, matchesCurrentGroup, optimize, patternContainsVariable, replaceCurrent, selectNodes, setOriginalText, setPriority, setRecoverable, simplify, toShortString, typeCheck

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, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isCallOnSystemFunction, isIdentical, isInstruction, isMultiThreaded, isSameExpression, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operands, operandSparseList, optimizeChildren, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, typeCheckChildren, typeError, unordered, verifyParentPointers, verifyParentPointers

Methods inherited from class java.lang.Object

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

Constructor Detail

SimplePositionalPattern

public SimplePositionalPattern(NodeTest nodeTest,
                               int position)

Create a SimplePositionalPattern

Parameters:

nodeTest - the test that the node must satisfy

position - the required position of the node

Method Detail

getPosition

public int getPosition()

Get the required position

Returns:

the integer appearing as the filter predicate

getNodeTest

public NodeTest getNodeTest()

Get the node test

Returns:

the node test used

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.

Returns:

true if the pattern matches, else false

Throws:

XPathException - if an error occurs while matching the pattern (the caller will usually treat this the same as a false result)

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 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 an ItemType 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

equals

public boolean equals(java.lang.Object other)

Determine whether this pattern is the same as another pattern

Overrides:

equals in class java.lang.Object

Parameters:

other - the other object

computeHashCode

public int computeHashCode()

hashcode supporting equals()

Overrides:

computeHashCode in class Expression

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)

copy

public Pattern copy(RebindingMap rebindings)

Copy a pattern. This makes a deep copy.

Specified by:

copy in class Pattern

Parameters:

rebindings -

Returns:

the copy of the original pattern

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.