net.sf.saxon.pattern
Class ConditionalPattern

java.lang.Object
  extended by net.sf.saxon.pattern.Pattern
      extended by net.sf.saxon.pattern.ConditionalPattern
All Implemented Interfaces:
Serializable, SourceLocator, Container, PatternFinder

public class ConditionalPattern
extends Pattern

A ConditionalPattern tests a node against one of a number of patterns depending on the value of a condition. This is used only as a streaming selection.

See Also:
Serialized Form

Constructor Summary
ConditionalPattern(Expression[] conditions, Pattern[] patterns)
           
 
Method Summary
 int allocateSlots(StaticContext env, SlotManager slotManager, int nextFree)
          Allocate slots to any variables used within the pattern
 Pattern analyze(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)
          Type-check the pattern.
 boolean equals(Object other)
          Determine whether this pattern is the same as another pattern
 int getDependencies()
          Get the dependencies of the pattern.
 ItemType getItemType()
          Get a NodeTest that all the nodes matching this pattern must satisfy
 int getNodeKind()
          Determine the types of nodes to which this pattern applies.
 int hashCode()
          Hashcode supporting equals()
 Iterator iterateSubExpressions()
          Iterate over the subexpressions within this pattern
 boolean matches(Item item, XPathContext context)
          Determine if the supplied node matches the pattern
 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.
 void 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
 void setExecutable(Executable executable)
          Set the executable containing this pattern
 void setLineNumber(int lineNumber)
          Override method to set the line number
 void setOriginalText(String pattern)
          Set the original text
 void setSystemId(String systemId)
          Override method to set the system ID
 Pattern simplify(ExpressionVisitor visitor)
          Simplify the pattern: perform any context-independent optimisations
 
Methods inherited from class net.sf.saxon.pattern.Pattern
getColumnNumber, getContainerGranularity, getDefaultPriority, getExecutable, getFingerprint, getHostLanguage, getLineNumber, getLocationProvider, getPublicId, getSystemId, internalMatches, make, resolveCurrent, selectNodes, toString
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

ConditionalPattern

public ConditionalPattern(Expression[] conditions,
                          Pattern[] patterns)
Method Detail

setExecutable

public void setExecutable(Executable executable)
Set the executable containing this pattern

Overrides:
setExecutable in class Pattern
Parameters:
executable - the executable

simplify

public Pattern simplify(ExpressionVisitor visitor)
                 throws XPathException
Simplify the pattern: perform any context-independent optimisations

Overrides:
simplify in class Pattern
Parameters:
visitor - an expression visitor
Returns:
the optimised Pattern
Throws:
XPathException

analyze

public Pattern analyze(ExpressionVisitor visitor,
                       ExpressionVisitor.ContextItemType contextItemType)
                throws XPathException
Type-check the pattern. This is only 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 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

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 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
parent -
Throws:
XPathException - if any error is detected

replaceSubExpression

public boolean replaceSubExpression(Expression original,
                                    Expression replacement)
Replace a subexpression by a replacement subexpression

Overrides:
replaceSubExpression in class Pattern
Parameters:
original - the expression to be replaced
replacement - the new expression to be inserted in its place
Returns:
true if the replacement was carried out

setOriginalText

public void setOriginalText(String pattern)
Set the original text

Overrides:
setOriginalText in class Pattern
Parameters:
pattern - the original text of the pattern

allocateSlots

public int allocateSlots(StaticContext env,
                         SlotManager slotManager,
                         int nextFree)
Allocate slots to any variables used within the pattern

Overrides:
allocateSlots in class Pattern
Parameters:
env - the static context in the XSLT stylesheet
slotManager -
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

matches

public boolean matches(Item item,
                       XPathContext context)
                throws XPathException
Determine if the supplied node matches the pattern

Specified by:
matches in class Pattern
Parameters:
item - the node to be compared
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 either of the operand patterns
Throws:
XPathException

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

getNodeKind

public int getNodeKind()
Determine the types of nodes to which this pattern applies. Used for optimisation. For patterns that match nodes of several types, return Type.NODE

Overrides:
getNodeKind in class Pattern
Returns:
the type of node matched by this pattern. e.g. Type.ELEMENT or Type.TEXT

getItemType

public ItemType getItemType()
Get a NodeTest 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

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.

setSystemId

public void setSystemId(String systemId)
Override method to set the system ID

Overrides:
setSystemId in class Pattern
Parameters:
systemId - the URI of the module containing the pattern

setLineNumber

public void setLineNumber(int lineNumber)
Override method to set the line number

Overrides:
setLineNumber in class Pattern
Parameters:
lineNumber - the line number of the pattern in the source module

equals

public boolean equals(Object other)
Determine whether this pattern is the same as another pattern

Overrides:
equals in class Object
Parameters:
other - the other object

hashCode

public int hashCode()
Hashcode supporting equals()

Overrides:
hashCode in class Object


Copyright (c) 2004-2011 Saxonica Limited. All rights reserved.