net.sf.saxon.expr
Class ForExpression

java.lang.Object
  extended by net.sf.saxon.expr.ComputedExpression
      extended by net.sf.saxon.expr.Assignation
          extended by net.sf.saxon.expr.ForExpression
All Implemented Interfaces:
Serializable, Binding, Expression

public class ForExpression
extends Assignation

A ForExpression maps an expression over a sequence. This version works with range variables, it doesn't change the context information

See Also:
Serialized Form

Field Summary
 
Fields inherited from class net.sf.saxon.expr.Assignation
action, declaration, sequence, slotNumber, variableName
 
Fields inherited from class net.sf.saxon.expr.ComputedExpression
lineNumber, NO_ARGUMENTS, staticProperties
 
Constructor Summary
ForExpression()
           
 
Method Summary
 Expression analyze(StaticContext env)
          Type-check the expression
 int computeCardinality()
          Determine the static cardinality of the expression
 void display(int level, NamePool pool)
          Diagnostic print of expression structure
 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
 void setAction(Expression action)
          Add the "return" or "satisfies" expression, and fix up all references to the range variable that occur within that expression
 void setPositionVariable(RangeVariableDeclaration decl)
          Set the reference to the position variable (XQuery only)
 
Methods inherited from class net.sf.saxon.expr.Assignation
evaluateVariable, getRequiredType, getSubExpressions, getVariableName, promote, setSequence, setSlotNumber, setVariableDeclaration, simplify
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
computeDependencies, computeSpecialProperties, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, getCardinality, getDependencies, getIntrinsicDependencies, getLineNumber, getSpecialProperties, markTailFunctionCalls, setLineNumber, typeError
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ForExpression

public ForExpression()
Method Detail

setPositionVariable

public void setPositionVariable(RangeVariableDeclaration decl)
Set the reference to the position variable (XQuery only)


setAction

public void setAction(Expression action)
Description copied from class: Assignation
Add the "return" or "satisfies" expression, and fix up all references to the range variable that occur within that expression

Overrides:
setAction in class Assignation
Parameters:
action - the expression that occurs after the "return" keyword of a "for" expression, the "satisfies" keyword of "some/every", or the ":=" operator of a "let" expression.

This method must be called after calling setVariableDeclaration()


analyze

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

Parameters:
env - the static context of the expression
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)

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

getItemType

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

Returns:
one of the values 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

Specified by:
computeCardinality in class ComputedExpression

display

public void display(int level,
                    NamePool pool)
Diagnostic print of expression structure

Parameters:
level - indentation level for this expression