Package net.sf.saxon.pattern
Class NodeSetPattern
- java.lang.Object
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- net.sf.saxon.pattern.Pattern
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- net.sf.saxon.pattern.NodeSetPattern
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,Container
,PatternFinder
public class NodeSetPattern extends Pattern
A NodeSetPattern is a pattern based on an expression that is evaluated to return a set of nodes; a node matches the pattern if it is a member of this node-set.In XSLT 2.0 there are two forms of NodeSetPattern allowed, represented by calls on the id() and key() functions. In XSLT 3.0, additional forms are allowed, for example a variable reference, and a call to the doc() function. This class provides the general capability to use any expression at the head of a pattern. This is used also to support streaming, where streaming XPath expressions are mapped to patterns.
- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description protected Expression
expression
protected ItemType
itemType
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Constructor Summary
Constructors Constructor Description NodeSetPattern(Expression exp, Configuration config)
Create a node-set pattern.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
allocateSlots(StaticContext env, SlotManager slotManager, int nextFree)
Allocate slots to any variables used within the patternPattern
analyze(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)
Type-check the pattern.boolean
equals(java.lang.Object other)
Determine whether this pattern is the same as another patternint
getDependencies()
Get the dependencies of the pattern.ItemType
getItemType()
Get a NodeTest that all the nodes matching this pattern must satisfyint
getNodeKind()
Determine the type of nodes to which this pattern applies.int
hashCode()
Hashcode supporting equals()java.util.Iterator
iterateSubExpressions()
Iterate over the subexpressions within this patternboolean
matches(Item item, XPathContext context)
Determine whether this Pattern matches the given Nodevoid
promote(PromotionOffer offer, Expression parent)
Offer promotion for subexpressions within this pattern.boolean
replaceSubExpression(Expression original, Expression replacement)
Replace a subexpression by a replacement subexpression-
Methods inherited from class net.sf.saxon.pattern.Pattern
getColumnNumber, getContainerGranularity, getDefaultPriority, getExecutable, getFingerprint, getHostLanguage, getLineNumber, getLocationProvider, getPublicId, getSystemId, internalMatches, make, matchesBeneathAnchor, resolveCurrent, selectNodes, setExecutable, setLineNumber, setOriginalText, setSystemId, setVariableBindingExpression, simplify, toString
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Field Detail
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expression
protected Expression expression
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itemType
protected ItemType itemType
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Constructor Detail
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NodeSetPattern
public NodeSetPattern(Expression exp, Configuration config)
Create a node-set pattern.- Parameters:
exp
- an expression that can be evaluated to return a node-set; a node matches the pattern if it is present in this node-set. The expression must not depend on the focus, though it can depend on other aspects of the dynamic context such as local or global variables.
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Method Detail
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analyze
public Pattern analyze(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
Type-check the pattern. Default implementation does nothing. This is only needed for patterns that contain variable references or function calls.- Overrides:
analyze
in classPattern
- Parameters:
visitor
- the expression visitorcontextItemType
- 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 a static error is discovered
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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 classPattern
- Returns:
- the dependencies, as a bit-significant mask
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iterateSubExpressions
public java.util.Iterator iterateSubExpressions()
Iterate over the subexpressions within this pattern- Overrides:
iterateSubExpressions
in classPattern
- Returns:
- an iterator over the subexpressions. Default implementation returns an empty sequence
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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 classPattern
- 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 expressionparent
-- Throws:
XPathException
- if any error is detected
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replaceSubExpression
public boolean replaceSubExpression(Expression original, Expression replacement)
Replace a subexpression by a replacement subexpression- Overrides:
replaceSubExpression
in classPattern
- Parameters:
original
- the expression to be replacedreplacement
- the new expression to be inserted in its place- Returns:
- true if the replacement was carried out
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allocateSlots
public int allocateSlots(StaticContext env, SlotManager slotManager, int nextFree)
Allocate slots to any variables used within the pattern- Overrides:
allocateSlots
in classPattern
- Parameters:
env
- the static context in the XSLT stylesheetslotManager
- the slot manager representing the stack frame for local variablesnextFree
- 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
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matches
public boolean matches(Item item, XPathContext context) throws XPathException
Determine whether this Pattern matches the given Node- Specified by:
matches
in classPattern
- Parameters:
item
- The NodeInfo representing the Element or other node to be tested against the Patterncontext
- 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
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getNodeKind
public int getNodeKind()
Determine the type of nodes to which this pattern applies.- Overrides:
getNodeKind
in classPattern
- Returns:
- Type.NODE (may be overridden in subclasses)
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getItemType
public ItemType getItemType()
Get a NodeTest that all the nodes matching this pattern must satisfy- Specified by:
getItemType
in classPattern
- Returns:
- an ItemType, as specific as possible, which all the matching items satisfy
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equals
public boolean equals(java.lang.Object other)
Determine whether this pattern is the same as another pattern- Overrides:
equals
in classjava.lang.Object
- Parameters:
other
- the other object
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hashCode
public int hashCode()
Hashcode supporting equals()- Overrides:
hashCode
in classjava.lang.Object
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