com.saxonica.expr
Class BreakInstr

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.expr.instruct.Instruction
          extended by com.saxonica.expr.BreakInstr
All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, TailCallReturner, SequenceIterable, InstructionInfo, Locator

public class BreakInstr
extends Instruction

A compiled xsl:break instruction. The effect of executing this instruction is to register with the dynamic context that a tail call on a pseudo-function break() has been made; the enclosing xsl:iterate loop detects this tail call request and uses it as a signal to terminate execution of the loop.

See Also:
Serialized Form

Field Summary
static StructuredQName SAXON_BREAK
           
 
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_METHOD
 
Constructor Summary
BreakInstr()
          Create the instruction
 
Method Summary
 Expression copy()
          Copy an expression.
 boolean createsNewNodes()
          Determine whether this instruction creates new nodes.
 void explain(ExpressionPresenter out)
          Diagnostic print of expression structure.
 TailCall processLeavingTail(XPathContext context)
          ProcessLeavingTail: called to do the real work of this instruction.
 Expression simplify(ExpressionVisitor visitor)
          Simplify an expression.
 
Methods inherited from class net.sf.saxon.expr.instruct.Instruction
assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, dynamicError, evaluateAsString, evaluateItem, getConstructType, getExpressionName, getImplementationMethod, getInstructionName, getInstructionNameCode, getItemType, getIteratorFromProcessMethod, getSourceLocator, isXSLT, iterate, process, promote, promoteInst
 
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSameFocusSubExpressions, iterateSubExpressions, markTailFunctionCalls, optimize, replaceSubExpression, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString, typeCheck, typeError
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface javax.xml.transform.SourceLocator
getColumnNumber, getLineNumber, getPublicId, getSystemId
 

Field Detail

SAXON_BREAK

public static final StructuredQName SAXON_BREAK
Constructor Detail

BreakInstr

public BreakInstr()
Create the instruction

Method Detail

simplify

public Expression simplify(ExpressionVisitor visitor)
                    throws XPathException
Description copied from class: Instruction
Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.

Specified by:
simplify in class Instruction
Parameters:
visitor - an expression visitor
Returns:
the simplified expression
Throws:
XPathException - if an error is discovered during expression rewriting

copy

public Expression copy()
Description copied from class: Expression
Copy an expression. This makes a deep copy.

Specified by:
copy in class Expression
Returns:
the copy of the original expression

createsNewNodes

public boolean createsNewNodes()
Description copied from class: Instruction
Determine whether this instruction creates new nodes. This implementation returns a default value of false

Overrides:
createsNewNodes in class Instruction
Returns:
true if the instruction creates new nodes (or if it can't be proved that it doesn't)

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws XPathException
Description copied from class: Instruction
ProcessLeavingTail: called to do the real work of this instruction. This method must be implemented in each subclass. The results of the instruction are written to the current Receiver, which can be obtained via the Controller.

Specified by:
processLeavingTail in interface TailCallReturner
Specified by:
processLeavingTail in class Instruction
Parameters:
context - The dynamic context of the transformation, giving access to the current node, the current variables, etc.
Returns:
null if the instruction has completed execution; or a TailCall indicating a function call or template call that is delegated to the caller, to be made after the stack has been unwound so as to save stack space.
Throws:
XPathException

explain

public void explain(ExpressionPresenter out)
Description copied from class: Expression
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:
explain in class Expression
Parameters:
out - the expression presenter used to display the structure


Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.