net.sf.saxon.pattern
Class KeyPattern

java.lang.Object
  net.sf.saxon.pattern.Pattern
      net.sf.saxon.pattern.KeyPattern

All Implemented Interfaces:

Serializable, SourceLocator, Container, PatternFinder

public final class KeyPattern
extends Pattern

A KeyPattern is a pattern of the form key(keyname, keyvalue)

See Also:

Serialized Form

Constructor Summary

KeyPattern(StructuredQName keyName, Expression key)
Constructor

Method Summary

Pattern	analyze(ExpressionVisitor visitor, ItemType contextItemType) Type-check the pattern.
int	getDependencies() Get the dependencies of the pattern.
NodeTest	getNodeTest() Get a NodeTest that all the nodes matching this pattern must satisfy
Iterator	iterateSubExpressions() Iterate over the subexpressions within this pattern
boolean	matches(NodeInfo e, XPathContext context) Determine whether this Pattern matches the given Node.
void	promote(PromotionOffer offer) Offer promotion for subexpressions within this pattern.

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

getColumnNumber, getDefaultPriority, getExecutable, getFingerprint, getHostLanguage, getLineNumber, getLocationProvider, getNodeKind, getPublicId, getSystemId, make, makeSearchExpression, replaceSubExpression, selectNodes, setExecutable, setLineNumber, setOriginalText, setSystemId, simplify, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

KeyPattern

public KeyPattern(StructuredQName keyName,
                  Expression key)

Constructor

Parameters:

keyName - the name of the key

key - the value of the key: either a StringValue or a VariableReference

Method Detail

analyze

public Pattern analyze(ExpressionVisitor visitor,
                       ItemType contextItemType)
                throws XPathException

Type-check the pattern. This is needed for patterns that contain variable references or function calls.

Overrides:

analyze in class Pattern

Parameters:

visitor - the expression visitor

contextItemType - the type of the context item, if known, at the point where the pattern is defined

Returns:

the optimised Pattern

Throws:

XPathException

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

iterateSubExpressions

public Iterator iterateSubExpressions()

Iterate over the subexpressions within this pattern

Overrides:

iterateSubExpressions in class Pattern

Returns:

an iterator over the subexpressions. Default implementation returns an empty sequence

promote

public void promote(PromotionOffer offer)
             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 class Pattern

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 expression

Throws:

XPathException - if any error is detected

matches

public boolean matches(NodeInfo e,
                       XPathContext context)
                throws XPathException

Determine whether this Pattern matches the given Node.

Specified by:

matches in class Pattern

Parameters:

e - The NodeInfo representing the Element or other node 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 node matches the Pattern, false otherwise

Throws:

XPathException

getNodeTest

public NodeTest getNodeTest()

Get a NodeTest that all the nodes matching this pattern must satisfy

Specified by:

getNodeTest in class Pattern

Returns:

a NodeTest, as specific as possible, which all the matching nodes satisfy