com.saxonica.ee.optim

Class MultithreadedForEach

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.instruct.Instruction

net.sf.saxon.expr.instruct.ForEach

com.saxonica.ee.optim.MultithreadedForEach

All Implemented Interfaces:

ContextMappingFunction<Item<?>>, ContextOriginator, ContextSwitchingExpression, ExportAgent, TailCallReturner, Locatable, IdentityComparable

public class MultithreadedForEach
extends ForEach

This instruction represents an xsl:for-each instruction using more than one thread

Field Summary

Fields inherited from class net.sf.saxon.expr.instruct.ForEach

actionOp, containsTailCall, isInstruction, selectOp, threadsOp

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

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

Constructor Summary

Constructors

Constructor and Description
MultithreadedForEach(Expression select, Expression action, boolean containsTailCall, Expression threads)

Method Summary

Modifier and Type	Method and Description
Expression	copy(RebindingMap rebindings) Copy an expression.
protected void	explainThreads(ExpressionPresenter out) Add the value of the saxon:threads attribute to the explain output
java.lang.String	getExpressionName() Get a name identifying the kind of expression, in terms meaningful to a user.
int	getImplementationMethod() An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
boolean	isMultiThreaded(Configuration config) Ask whether the expression is multithreaded (that is, whether its operands are evaluated in parallel)
SequenceIterator<?>	iterate(XPathContext context) Return an Iterator to iterate over the values of the sequence.
Expression	optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Perform optimisation of an expression and its subexpressions.
TailCall	processLeavingTail(XPathContext context) ProcessLeavingTail: called to do the real work of this instruction.

Methods inherited from class net.sf.saxon.expr.instruct.ForEach

addToPathMap, alwaysCreatesNewNodes, checkForUpdatingSubexpressions, checkPermittedContents, computeSpecialProperties, evaluatePendingUpdates, export, getAction, getActionExpression, getInstructionNameCode, getItemType, getNumberOfThreadsExpression, getSelect, getSelectExpression, getStaticUType, getStreamerName, getThreads, isInstruction, isUpdatingExpression, map, mayCreateNewNodes, operands, setAction, setActionExpression, setInstruction, setSelect, setSelectExpression, setThreads, toShortString, toString, typeCheck, unordered

Methods inherited from class net.sf.saxon.expr.instruct.Instruction

assembleParams, assembleTunnelParams, computeCardinality, dynamicError, evaluateAsString, evaluateItem, getConstructType, getNetCost, getSourceLocator, isXSLT, process, someOperandCreatesNewNodes

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

adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, computeDependencies, computeHashCode, computeStaticProperties, dynamicError, effectiveBooleanValue, equals, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isLiftable, isStaticPropertiesKnown, isSubtreeExpression, isVacuousExpression, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, typeCheckChildren, typeError, verifyParentPointers

Methods inherited from class java.lang.Object

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

Constructor Detail

MultithreadedForEach

public MultithreadedForEach(Expression select,
                            Expression action,
                            boolean containsTailCall,
                            Expression threads)

Method Detail

isMultiThreaded

public boolean isMultiThreaded(Configuration config)

Description copied from class: Expression

Ask whether the expression is multithreaded (that is, whether its operands are evaluated in parallel)

Overrides:

isMultiThreaded in class Expression

Parameters:

config - the Saxon configuration

Returns:

true if execution will be multithreaded

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ContextItemStaticInfo contextInfo)
                    throws XPathException

Description copied from class: Expression

Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

Overrides:

optimize in class ForEach

Parameters:

visitor - an expression visitor

contextInfo - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE

Returns:

the original expression, rewritten if appropriate to optimize execution

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

copy

public Expression copy(RebindingMap rebindings)

Description copied from class: ForEach

Copy an expression. This makes a deep copy.

Overrides:

copy in class ForEach

Parameters:

rebindings - variables that need to be re-bound

Returns:

the copy of the original expression

getImplementationMethod

public int getImplementationMethod()

An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is provided. This implementation provides only the process() method natively.

Overrides:

getImplementationMethod in class ForEach

Returns:

the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

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

Overrides:

processLeavingTail in class ForEach

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 - if a dynamic error occurs during the evaluation of the instruction

iterate

public SequenceIterator<?> iterate(XPathContext context)
                            throws XPathException

Return an Iterator to iterate over the values of the sequence.

Overrides:

iterate in class ForEach

Parameters:

context - supplies the context for evaluation

Returns:

a SequenceIterator that can be used to iterate over the result of the expression

Throws:

XPathException - if any dynamic error occurs evaluating the expression

getExpressionName

public java.lang.String getExpressionName()

Get a name identifying the kind of expression, in terms meaningful to a user.

Overrides:

getExpressionName in class ForEach

Returns:

a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.

explainThreads

protected void explainThreads(ExpressionPresenter out)
                       throws XPathException

Add the value of the saxon:threads attribute to the explain output

Overrides:

explainThreads in class ForEach

Parameters:

out - the destination for explain output

Throws:

XPathException