net.sf.saxon.instruct
Class CallTemplate

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.instruct.Instruction
          extended by 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


Copyright (C) Michael H. Kay. All rights reserved.