net.sf.saxon.instruct
Class CallTemplate

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.instruct.Instruction
          net.sf.saxon.instruct.CallTemplate

All Implemented Interfaces:

Serializable, SourceLocator, EvaluableItem, SequenceIterable, TailCallReturner, InstructionInfoProvider

public class CallTemplate
extends Instruction

Instruction representing an xsl:call-template element in the stylesheet.

See Also:

Serialized Form

Field Summary

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

CallTemplate(Template template, boolean useTailRecursion, Expression calledTemplateExpression, NamespaceResolver nsContext)
Construct a CallTemplate instruction.

Method Summary

int	computeCardinality() Get the cardinality of the sequence returned by evaluating this instruction
Expression	copy() Copy an expression.
boolean	createsNewNodes() Determine whether this instruction creates new nodes.
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
InstructionInfo	getInstructionInfo() Set additional trace properties appropriate to the kind of instruction.
int	getInstructionNameCode() Return the name of this instruction.
int	getIntrinsicDependencies() Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
ItemType	getItemType(TypeHierarchy th) Get the item type of the items returned by evaluating this instruction
Template	getTargetTemplate(XPathContext context) Get the template, in the case where it is specified dynamically.
Iterator	iterateSubExpressions() Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)
Expression	optimize(ExpressionVisitor visitor, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.
void	process(XPathContext context) Process this instruction, without leaving any tail calls.
TailCall	processLeavingTail(XPathContext context) Process this instruction.
boolean	replaceSubExpression(Expression original, Expression replacement) Replace one subexpression by a replacement subexpression
void	setActualParameters(WithParam[] actualParams, WithParam[] tunnelParams) Set the actual parameters on the call
Expression	simplify(ExpressionVisitor visitor) Simplify an expression.
Expression	typeCheck(ExpressionVisitor visitor, ItemType contextItemType) Perform type checking of an expression and its subexpressions.

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

computeSpecialProperties, evaluateAsString, evaluateItem, getImplementationMethod, getSourceLocator, isXSLT, iterate, promote

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

addToPathMap, adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, effectiveBooleanValue, explain, findParentOf, getCardinality, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterateEvents, markTailFunctionCalls, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface javax.xml.transform.SourceLocator

getColumnNumber, getLineNumber, getPublicId, getSystemId

Constructor Detail

CallTemplate

public CallTemplate(Template template,
                    boolean useTailRecursion,
                    Expression calledTemplateExpression,
                    NamespaceResolver nsContext)

Construct a CallTemplate instruction.

Parameters:

template - the Template object identifying the template to be called, in the normal case where this is known statically

useTailRecursion - true if the call is potentially tail recursive

calledTemplateExpression - expression to calculate the name of the template to be called at run-time, this supports the saxon:allow-avt option

nsContext - the static namespace context of the instruction, needed only in the case where the name of the called template is to be calculated dynamically

Method Detail

setActualParameters

public void setActualParameters(WithParam[] actualParams,
                                WithParam[] tunnelParams)

Set the actual parameters on the call

Parameters:

actualParams - the parameters that are not tunnel parameters

tunnelParams - the tunnel parameters

getInstructionNameCode

public int getInstructionNameCode()

Return the name of this instruction.

Overrides:

getInstructionNameCode in class Instruction

Returns:

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

getInstructionInfo

public InstructionInfo getInstructionInfo()

Set additional trace properties appropriate to the kind of instruction. This implementation adds the template property, which identities the template to be called

Specified by:

getInstructionInfo in interface InstructionInfoProvider

Overrides:

getInstructionInfo in class Instruction

simplify

public Expression simplify(ExpressionVisitor visitor)
                    throws XPathException

Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression).

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

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                            ItemType contextItemType)
                     throws XPathException

Description copied from class: Expression

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

This checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared.

If the implementation returns a value other than "this", then it is required to ensure that the parent pointer and location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.

Overrides:

typeCheck in class Expression

Parameters:

visitor - an expression visitor

contextItemType - 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 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)

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ItemType contextItemType)
                    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 Expression

Parameters:

visitor - an expression visitor

contextItemType - 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)

computeCardinality

public int computeCardinality()

Get the cardinality of the sequence returned by evaluating this instruction

Overrides:

computeCardinality in class Instruction

Returns:

the static cardinality

getItemType

public ItemType getItemType(TypeHierarchy th)

Get the item type of the items returned by evaluating this instruction

Overrides:

getItemType in class Instruction

Parameters:

th - the type hierarchy cache

Returns:

the static item type of the instruction

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

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

createsNewNodes

public final boolean createsNewNodes()

Determine whether this instruction creates new nodes. This implementation currently returns true unconditionally.

Overrides:

createsNewNodes in class Instruction

Returns:

true if the instruction creates new nodes (or if it can't be proved that it doesn't)

iterateSubExpressions

public Iterator iterateSubExpressions()

Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)

Overrides:

iterateSubExpressions in class Expression

Returns:

an iterator containing the sub-expressions of this expression

replaceSubExpression

public boolean replaceSubExpression(Expression original,
                                    Expression replacement)

Replace one subexpression by a replacement subexpression

Overrides:

replaceSubExpression in class Expression

Parameters:

original - the original subexpression

replacement - the replacement subexpression

Returns:

true if the original subexpression is found

process

public void process(XPathContext context)
             throws XPathException

Process this instruction, without leaving any tail calls.

Overrides:

process in class Instruction

Parameters:

context - the dynamic context for this transformation

Throws:

XPathException - if a dynamic error occurs

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws XPathException

Process this instruction. If the called template contains a tail call (which may be an xsl:call-template of xsl:apply-templates instruction) then the tail call will not actually be evaluated, but will be returned in a TailCall object for the caller to execute.

Specified by:

processLeavingTail in interface TailCallReturner

Specified by:

processLeavingTail in class Instruction

Parameters:

context - the dynamic context for this transformation

Returns:

an object containing information about the tail call to be executed by the caller. Returns null if there is no tail call.

Throws:

XPathException

getTargetTemplate

public Template getTargetTemplate(XPathContext context)
                           throws XPathException

Get the template, in the case where it is specified dynamically.

Parameters:

context - The dynamic context of the transformation

Returns:

The template to be called

Throws:

XPathException - if a dynamic error occurs: specifically, if the template name is computed at run-time (Saxon extension) and the name is invalid or does not reference a known template

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