com.saxonica.xsltextn.instruct

Class Assign

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.instruct.Instruction

com.saxonica.xsltextn.instruct.Assign

All Implemented Interfaces:

SourceLocator, BindingReference, TailCallReturner, IdentityComparable, InstructionInfo

public class Assign
extends Instruction
implements BindingReference

Compiled instruction deriving from 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.expr.Expression

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

Constructor Summary

Constructors

Constructor and Description
Assign()

Method Summary

Methods

Modifier and Type	Method and Description
Expression	copy() Copy an expression.
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
void	fixup(Binding binding) Fix up this binding reference to a binding
ExpressionCompiler	getExpressionCompiler() Return the compiler of the Assign expression
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.
Iterable<Operand>	operands() Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.
TailCall	processLeavingTail(XPathContext context) ProcessLeavingTail: called to do the real work of this instruction.
Expression	promote(PromotionOffer offer, Expression parent) Offer promotion for this subexpression.
protected void	promoteInst(PromotionOffer offer) Handle promotion offers, that is, non-local tree rewrites.
void	setSelectExpression(Expression select)
void	setStaticType(SequenceType type, GroundedValue constantValue, int properties) Fix up the static type of this variable reference; optionally, supply a constant value for the variable.
Expression	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Perform type checking of an expression and its subexpressions.

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

assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, createsNewNodes, dynamicError, evaluateAsString, evaluateItem, getConstructType, getExpressionName, getImplementationMethod, getInstructionName, getItemType, getIteratorFromProcessMethod, getSourceLocator, isXSLT, iterate, process, toStreamingPattern

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

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getConfiguration, getContainer, getDependencies, getEvaluationMethod, getHostLanguage, getIntegerBounds, getLineNumber, getLocationId, getObjectName, getPosture, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getStreamingAdjunct, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isIdentical, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, makeStreamingAdjunct, markTailFunctionCalls, operandList, optimize, replaceOperand, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, setPostureAndSweep, simplify, staticTypeCheck, suppressValidation, toPattern, toShortString, toString, typeError, unordered

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

Constructor Detail

Assign

public Assign()

Method Detail

setStaticType

public void setStaticType(SequenceType type,
                 GroundedValue constantValue,
                 int properties)

Description copied from interface: BindingReference

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

Parameters:

type - The static type of the variable reference, typically either the declared type of the variable, or the static type of the expression to which the variable is bound

constantValue - if non-null, indicates that the value of the variable is known at compile time, and supplies the value

properties - static properties of the expression to which the variable is bound

setSelectExpression

public void setSelectExpression(Expression select)

fixup

public void fixup(Binding binding)

Description copied from interface: BindingReference

Fix up this binding reference to a binding

Specified by:

fixup in interface BindingReference

Parameters:

binding - the Binding to which the variable refers

getIntrinsicDependencies

public int getIntrinsicDependencies()

Description copied from class: Expression

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 class Expression

Returns:

a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

typeCheck

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

Perform type checking of an expression and its subexpressions. This is the second phase of static optimization.

Overrides:

typeCheck in class Expression

Parameters:

visitor - an expression visitor

contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

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

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Returns:

the copy of the original expression

operands

public Iterable<Operand> operands()

Description copied from class: Expression

Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation works off the results of iterateSubExpressions()

If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

Overrides:

operands in class Expression

Returns:

an iterator containing the sub-expressions of this expression

promote

public Expression promote(PromotionOffer offer,
                 Expression parent)
                   throws XPathException

Offer promotion for this subexpression. This needs careful handling in the case of saxon:assign

Overrides:

promote in class 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

parent - the parent expression of the expression to be promoted

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

promoteInst

protected void promoteInst(PromotionOffer offer)
                    throws XPathException

Handle promotion offers, that is, non-local tree rewrites.

Overrides:

promoteInst in class Instruction

Parameters:

offer - The type of rewrite being offered

Throws:

XPathException - if an error occurs

getInstructionNameCode

public int getInstructionNameCode()

Get the name of this instruction for diagnostic and tracing purposes

Overrides:

getInstructionNameCode in class Instruction

Returns:

a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace

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

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()

Return the compiler of the Assign expression

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler

explain

public void explain(ExpressionPresenter out)

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