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## 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:
  java.io.Serializable, javax.xml.transform.SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, TailCallReturner, InstructionInfo, org.xml.sax.Locator

    public class CallTemplate

extends Instruction

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

See Also:
  Serialized Form

Nested Class Summary
`static class` | `CallTemplate.CallTemplatePackage` A CallTemplatePackage is an object that encapsulates the name of a template to be called, the parameters to be supplied, and the execution context.

Field Summary

Fields inherited from class net.sf.saxon.expr.Expression
`EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties`

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.
`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
`StructuredQName` | `getObjectName()` Get a name identifying the object of the expression, for example a function name, template name, variable name, key name, element name, etc.
`Template` | `getTargetTemplate(XPathContext context)` Get the template, in the case where it is specified dynamically.
`java.util.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.
`protected void` | `promoteInst(PromotionOffer offer)` Handle promotion offers, that is, non-local tree rewrites.
`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
`assembleParams, assembleTunnelParams, computeSpecialProperties, dynamicError, evaluateAsString, evaluateItem, getConstructType, getImplementationMethod, getSourceLocator, isXSLT, iterate, promote`

Methods inherited from class net.sf.saxon.expr.Expression
`addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterateEvents, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString, typeError`

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

### 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

### 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 java.util.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

### 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`

### 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

### getObjectName

    public StructuredQName getObjectName()

  Description copied from interface: `InstructionInfo`
  Get a name identifying the object of the expression, for example a function name, template name, variable name, key name, element name, etc. This is used only where the name is known statically.

  Specified by:
    `getObjectName` in interface `InstructionInfo`
  Overrides:
    `getObjectName` in class `Expression`
  Returns:
    the QName of the object declared or manipulated by this instruction or expression

### 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

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