net.sf.saxon.instruct

Class Assign

Implemented Interfaces:
Binding, BindingReference, SourceLocator, EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator, TailCallReturner

public class Assign
extends GeneralVariable
implements BindingReference

saxon:assign element in stylesheet. The saxon:assign element has mandatory attribute name and optional attribute expr. It also allows xsl:extension-element-prefixes etc.

Field Summary

Fields inherited from class net.sf.saxon.instruct.GeneralVariable

evaluationMode, referenceCount, slotNumber, variableQName

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD, locationId, staticProperties

Constructor Summary

Assign()
Create a general variable

Method Summary

ValueRepresentation
evaluateVariable(XPathContext context)
Evaluate the variable (method exists only to satisfy the interface)
void
explain(ExpressionPresenter out)
Diagnostic print of expression structure.
void
fixup(Binding binding)
Fix up this binding reference to a binding
int
getInstructionNameCode()
Get the name of this instruction for diagnostic and tracing purposes
int
getIntrinsicDependencies()
Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
TailCall
processLeavingTail(XPathContext context)
ProcessLeavingTail: called to do the real work of this instruction.
Expression
promote(PromotionOffer offer)
Offer promotion for this subexpression.
void
setStaticType(SequenceType type, Value constantValue, int properties)
Fix up the static type of this variable reference; optionally, supply a constant value for the variable.

Methods inherited from class net.sf.saxon.instruct.GeneralVariable

copy, evaluateItem, explain, getCardinality, getEvaluationMode, getInstructionNameCode, getItemType, getLocalSlotNumber, getRequiredType, getSelectExpression, getSelectValue, getSlotNumber, getVariableQName, init, isAssignable, isGlobal, isImplicitlyRequiredParam, isRequiredParam, isTunnelParam, iterate, iterateSubExpressions, optimize, promoteInst, replaceSubExpression, setAssignable, setImplicitlyRequiredParam, setReferenceCount, setRequiredParam, setRequiredType, setSelectExpression, setSlotNumber, setTunnel, setVariableQName, simplify, typeCheck

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

assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, createsNewNodes, dynamicError, evaluateAsString, evaluateItem, getImplementationMethod, getInstructionInfo, getInstructionNameCode, getItemType, getSourceLocator, isXSLT, iterate, process, processLeavingTail, promote, promoteInst, simplify

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

addToPathMap, adoptChildExpression, checkPermittedContents, computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, copy, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, explain, findParentOf, getCardinality, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getItemType, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterate, iterateEvents, iterateSubExpressions, markTailFunctionCalls, optimize, process, promote, replaceSubExpression, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, simplify, staticTypeCheck, suppressValidation, toString, typeCheck, typeError

Constructor Details

Assign

public Assign()
Create a general variable

Method Details

evaluateVariable

public ValueRepresentation evaluateVariable(XPathContext context)
            throws XPathException
Evaluate the variable (method exists only to satisfy the interface)
Specified by:
evaluateVariable in interface Binding

explain

public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
Overrides:
explain in interface GeneralVariable

fixup

public void fixup(Binding binding)
Fix up this binding reference to a binding
Specified by:
fixup in interface BindingReference

getInstructionNameCode

public int getInstructionNameCode()
Get the name of this instruction for diagnostic and tracing purposes
Overrides:
getInstructionNameCode in interface GeneralVariable

getIntrinsicDependencies

public int getIntrinsicDependencies()
Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions. For example, position() has an intrinsic dependency on the context position, while (position()+1) does not. The default implementation of the method returns 0, indicating "no dependencies".
Overrides:
getIntrinsicDependencies in interface Expression
Returns:
a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
            throws XPathException
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 interface 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.

promote

public Expression promote(PromotionOffer offer)
            throws XPathException
Offer promotion for this subexpression. This needs careful handling in the case of saxon:assign
Overrides:
promote in interface Instruction
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
Returns:
if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression
Throws:
XPathException - if any error is detected

setStaticType

public void setStaticType(SequenceType type,
                          Value constantValue,
                          int properties)
Fix up the static type of this variable reference; optionally, supply a constant value for the variable. Also supplies other static properties of the expression to which the variable is bound, for example whether it is an ordered node-set.
Specified by:
setStaticType in interface BindingReference