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## net.sf.saxon.expr
Class SuppliedParameterReference

    java.lang.Object
      net.sf.saxon.expr.Expression
          net.sf.saxon.expr.SuppliedParameterReference

All Implemented Interfaces:
  java.io.Serializable, javax.xml.transform.SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, InstructionInfo, org.xml.sax.Locator

    public class SuppliedParameterReference

extends Expression

Supplied parameter reference: this is an internal expression used to refer to the value of the n'th parameter supplied on a template call (apply-templates). It is used within a type-checking expression designed to check the consistency of the supplied value with the required type. This type checking is all done at run-time, because the binding of apply-templates to actual template rules is entirely dynamic.

See Also:
  Serialized Form

Field Summary

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

Constructor Summary
`SuppliedParameterReference(int slot)` Constructor

Method Summary
`int` | `computeCardinality()` Get the static cardinality
`Expression` | `copy()` Copy an expression.
`boolean` | `equals(java.lang.Object other)` Test if this expression is the same as another expression.
`Item` | `evaluateItem(XPathContext c)` Evaluate an expression as a single item.
`void` | `explain(ExpressionPresenter destination)` Diagnostic print of expression structure.
`ItemType` | `getItemType(TypeHierarchy th)` Determine the data type of the expression, if possible.
`SequenceIterator` | `iterate(XPathContext c)` Get the value of this expression in a given context.
`Expression` | `optimize(ExpressionVisitor visitor, ItemType contextItemType)` Perform optimisation of an expression and its subexpressions.
`Expression` | `typeCheck(ExpressionVisitor visitor, ItemType contextItemType)` Perform type checking of an expression and its subexpressions.

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

Methods inherited from class java.lang.Object
`clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

### SuppliedParameterReference

    public SuppliedParameterReference(int slot)

  Constructor

  Parameters:
    `slot` - identifies this parameter

Method Detail

### 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)

### getItemType

    public ItemType getItemType(TypeHierarchy th)

  Determine the data type of the expression, if possible.

  Specified by:
    `getItemType` in class `Expression`
  Parameters:
    `th` - the type hierarchy cache
  Returns:
    Type.ITEM, because we don't know the type of the supplied value in advance.

### computeCardinality

    public int computeCardinality()

  Get the static cardinality

  Specified by:
    `computeCardinality` in class `Expression`
  Returns:
    ZERO_OR_MORE, because we don't know the type of the supplied value in advance.

### 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

### equals

    public boolean equals(java.lang.Object other)

  Test if this expression is the same as another expression. (Note, we only compare expressions that have the same static and dynamic context).

  Overrides:
    `equals` in class `java.lang.Object`

### iterate

    public SequenceIterator iterate(XPathContext c)
                             throws XPathException

  Get the value of this expression in a given context.

  Specified by:
    `iterate` in interface `SequenceIterable`
  Overrides:
    `iterate` in class `Expression`
  Parameters:
    `c` - the XPathContext which contains the relevant variable bindings
  Returns:
    the value of the variable, if it is defined
  Throws:
    `XPathException` - if the variable is undefined

### evaluateItem

    public Item evaluateItem(XPathContext c)
                      throws XPathException

  Description copied from class: `Expression`
  Evaluate an expression as a single item. This always returns either a single Item or null (denoting the empty sequence). No conversion is done. This method should not be used unless the static type of the expression is a subtype of "item" or "item?": that is, it should not be called if the expression may return a sequence. There is no guarantee that this condition will be detected.

  Specified by:
    `evaluateItem` in interface `EvaluableItem`
  Overrides:
    `evaluateItem` in class `Expression`
  Parameters:
    `c` - The context in which the expression is to be evaluated
  Returns:
    the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
  Throws:
    `XPathException` - if any dynamic error occurs evaluating the expression

### explain

    public void explain(ExpressionPresenter destination)

  Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

  Specified by:
    `explain` in class `Expression`
  Parameters:
    `destination` - the expression presenter used to display the structure

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