net.sf.saxon.expr
Class ForExpression

java.lang.Object
  |
  +--net.sf.saxon.expr.ComputedExpression
        |
        +--net.sf.saxon.expr.Assignation
              |
              +--net.sf.saxon.expr.ForExpression
All Implemented Interfaces:
Binding, Expression, Instr, Locatable, java.io.Serializable

public class ForExpression
extends Assignation
implements Instr

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 process(XPathContext context)
          Process this expression as an instruction, writing results to the current outputter
 TailCall processLeavingTail(XPathContext context)
          Process the instruction, optionally returning an uncompleted tail call to be invoked by the caller
 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, getSourceLocator, getSpecialProperties, markTailFunctionCalls, setLineNumber, typeError
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface net.sf.saxon.instruct.Locatable
getSourceLocator
 

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

Specified by:
analyze in interface 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
XPathException

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

process

public void process(XPathContext context)
             throws javax.xml.transform.TransformerException
Process this expression as an instruction, writing results to the current outputter

Specified by:
process in interface Instr
Parameters:
context - The dynamic context, giving access to the current node, the current variables, etc.
javax.xml.transform.TransformerException

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws javax.xml.transform.TransformerException
Process the instruction, optionally returning an uncompleted tail call to be invoked by the caller

Specified by:
processLeavingTail in interface Instr
Parameters:
context - The dynamic context, giving access to the current node, the current variables, etc.
javax.xml.transform.TransformerException

getItemType

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

Specified by:
getItemType in interface Expression
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

Specified by:
display in interface Expression
Parameters:
level - indentation level for this expression