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## net.sf.saxon.expr
Class AtomicSequenceConverter

    java.lang.Object
      net.sf.saxon.expr.ComputedExpression
          net.sf.saxon.expr.UnaryExpression
              net.sf.saxon.expr.AtomicSequenceConverter

All Implemented Interfaces:
  Container, Expression, InstructionInfoProvider, MappingFunction, java.io.Serializable, javax.xml.transform.SourceLocator

public final class AtomicSequenceConverter
extends UnaryExpression
implements MappingFunction

An AtomicSequenceConverter is an expression that performs a cast on each member of a supplied sequence

See Also:
  Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.UnaryExpression
`operand`

Fields inherited from class net.sf.saxon.expr.ComputedExpression
`locationId, staticProperties`

Fields inherited from interface net.sf.saxon.expr.Expression
`EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD`

Constructor Summary
`AtomicSequenceConverter(Expression sequence, AtomicType requiredItemType)` Constructor

Method Summary
`int` | `computeCardinality()` Determine the static cardinality of the expression
`int` | `computeSpecialProperties()` Determine the special properties of this expression
`protected java.lang.String` | `displayOperator(NamePool pool)` Give a string representation of the operator for use in diagnostics
`boolean` | `equals(java.lang.Object other)` Is this expression the same as another expression?
`Item` | `evaluateItem(XPathContext context)` Evaluate as an Item.
`ItemType` | `getItemType(TypeHierarchy th)` Determine the data type of the items returned by the expression, if possible
`SequenceIterator` | `iterate(XPathContext context)` Iterate over the sequence of values
`java.lang.Object` | `map(Item item, XPathContext context)` Implement the mapping function
`Expression` | `simplify(StaticContext env)` Simplify an expression
`Expression` | `typeCheck(StaticContext env, ItemType contextItemType)` Type-check the expression

Methods inherited from class net.sf.saxon.expr.UnaryExpression
`display, getBaseExpression, hashCode, iterateSubExpressions, optimize, promote`

Methods inherited from class net.sf.saxon.expr.ComputedExpression
`adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, suppressValidation, typeError, typeError`

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

Constructor Detail

### AtomicSequenceConverter

    public AtomicSequenceConverter(Expression sequence,
                                   AtomicType requiredItemType)

  Constructor

Parameters:
  `sequence` - this must be a sequence of atomic values. This is not checked; a ClassCastException will occur if the precondition is not satisfied.
  `requiredItemType` - the item type to which all items in the sequence should be converted, using the rules for "cast as".

Method Detail

### simplify

    public Expression simplify(StaticContext env)
                        throws XPathException

  Simplify an expression

  Specified by:
    `simplify` in interface `Expression`
  Overrides:
    `simplify` in class `UnaryExpression`
  Returns:
    the simplified expression
  Throws:
    `XPathException`

### typeCheck

    public Expression typeCheck(StaticContext env,
                                ItemType contextItemType)
                         throws XPathException

  Type-check the expression

  Specified by:
    `typeCheck` in interface `Expression`
  Overrides:
    `typeCheck` in class `UnaryExpression`
  Throws:
    `XPathException`

### computeSpecialProperties

    public int computeSpecialProperties()

  Determine the special properties of this expression

  Overrides:
    `computeSpecialProperties` in class `UnaryExpression`
  Returns:
    `StaticProperty.NON_CREATIVE`.

### iterate

    public SequenceIterator iterate(XPathContext context)
                             throws XPathException

  Iterate over the sequence of values

  Specified by:
    `iterate` in interface `Expression`
  Overrides:
    `iterate` in class `ComputedExpression`
  Parameters:
    `context` - supplies the context for evaluation
  Returns:
    a SequenceIterator that can be used to iterate over the result of the expression
  Throws:
    `XPathException` - if any dynamic error occurs evaluating the expression

### evaluateItem

    public Item evaluateItem(XPathContext context)
                      throws XPathException

  Evaluate as an Item. This should only be called if the AtomicSequenceConverter has cardinality zero-or-one

  Specified by:
    `evaluateItem` in interface `Expression`
  Overrides:
    `evaluateItem` in class `ComputedExpression`
  Parameters:
    `context` - 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

### map

    public java.lang.Object map(Item item,
                                XPathContext context)
                         throws XPathException

  Implement the mapping function

  Specified by:
    `map` in interface `MappingFunction`
  Parameters:
    `item` - The item to be mapped. If context is supplied, this must be the same as context.currentItem().
    `context` - The processing context. Some mapping functions use this because they require context information. Some mapping functions modify the context by maintaining the context item and position. In other cases, the context may be null.
  Returns:
    either (a) a SequenceIterator over the sequence of items that the supplied input item maps to, or (b) an Item if it maps to a single item, or (c) null if it maps to an empty sequence.
  Throws:
    `XPathException`

### getItemType

    public ItemType getItemType(TypeHierarchy th)

  Determine the data type of the items returned by the expression, if possible

  Specified by:
    `getItemType` in interface `Expression`
  Overrides:
    `getItemType` in class `UnaryExpression`
  Parameters:
    `th` -
  Returns:
    a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known in advance)

### computeCardinality

    public int computeCardinality()

  Determine the static cardinality of the expression

  Overrides:
    `computeCardinality` in class `UnaryExpression`

### equals

    public boolean equals(java.lang.Object other)

  Is this expression the same as another expression?

  Overrides:
    `equals` in class `UnaryExpression`

### displayOperator

    protected java.lang.String displayOperator(NamePool pool)

  Give a string representation of the operator for use in diagnostics

  Specified by:
    `displayOperator` in class `UnaryExpression`
  Returns:
    the operator, as a string

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