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:

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