net.sf.saxon.expr
Class Atomizer

java.lang.Object
  extended bynet.sf.saxon.expr.ComputedExpression
      extended bynet.sf.saxon.expr.UnaryExpression
          extended bynet.sf.saxon.expr.Atomizer
All Implemented Interfaces:
Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator

public final class Atomizer
extends UnaryExpression

An Atomizer is an expression corresponding essentially to the fn:data() function: it maps a sequence by replacing nodes with their typed values

See Also:
Serialized Form

Nested Class Summary
static class Atomizer.AtomizingFunction
          Implement the mapping function
 
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
Atomizer(Expression sequence, Configuration config)
          Constructor
 
Method Summary
 Expression analyze(StaticContext env, ItemType contextItemType)
          Type-check the expression
 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
 Item evaluateItem(XPathContext context)
          Evaluate as an Item.
 ItemType getItemType()
          Determine the data type of the items returned by the expression, if possible
 SequenceIterator iterate(XPathContext context)
          Iterate over the sequence of values
 Expression simplify(StaticContext env)
          Simplify an expression
 
Methods inherited from class net.sf.saxon.expr.UnaryExpression
display, equals, getBaseExpression, hashCode, iterateSubExpressions, promote
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getParentExpression, getPublicId, getSpecialProperties, getSystemId, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, typeError, typeError
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Atomizer

public Atomizer(Expression sequence,
                Configuration config)
Constructor

Parameters:
sequence - the sequence to be atomized
config - the Configuration. Used only for optimization, may be null. Atomization is faster if it is known in advance that all nodes will be untyped.
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

analyze

public Expression analyze(StaticContext env,
                          ItemType contextItemType)
                   throws XPathException
Type-check the expression

Specified by:
analyze in interface Expression
Overrides:
analyze 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 Atomizer has cardinality zero-or-one, which will only be the case if the underlying expression 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

getItemType

public ItemType getItemType()
Determine the data type of the items returned by the expression, if possible

Specified by:
getItemType in interface Expression
Overrides:
getItemType in class UnaryExpression
Returns:
a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER. For this class, the result is always an atomic type, but it might be more specific.

computeCardinality

public int computeCardinality()
Determine the static cardinality of the expression

Overrides:
computeCardinality 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