Package net.sf.saxon.expr

Class Operand

java.lang.Object

net.sf.saxon.expr.Operand

All Implemented Interfaces:

java.lang.Iterable<Operand>, ExpressionOwner

public final class Operand
extends java.lang.Object
implements java.lang.Iterable<Operand>, ExpressionOwner

Information about a sub-expression and its relationship to the parent expression

Constructor Summary

Constructors

Constructor	Description
Operand(Expression parentExpression, Expression childExpression, OperandRole role)	Create an operand object

Method Summary

Modifier and Type	Method	Description
void	detachChild()
Expression	getChildExpression()	Get the expression used as the actual operand
OperandRole	getOperandRole()	Get the operand role
Expression	getParentExpression()	Get the parent expression of this operand
SequenceType	getRequiredType()	Get the required type of the operand
OperandUsage	getUsage()	Get the usage of the operand
boolean	hasSameFocus()	Ask whether the child expression is evaluated with the same focus as its parent expression
boolean	hasSpecialFocusRules()
boolean	isEvaluatedRepeatedly()	Ask whether the operand is is evaluated repeatedly during a single evaluation of the parent expression.
boolean	isHigherOrder()	Ask whether the operand is a higher-order operand,: typically this means that the child expression is evaluated repeatedly during a single evaluation of the parent expression (but there are some cases like xsl:for-each select=".." where the operand is higher-order despite not being evaluated repeatedly).
boolean	isInChoiceGroup()	Ask whether the operand is a member of a choice group
java.util.Iterator<Operand>	iterator()	Get a singleton iterator that returns this operand only
void	optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo)
void	setChildExpression(Expression childExpression)	Change the child expression used for this operand.
void	setOperandRole(OperandRole role)	Set the operand role
boolean	setsNewFocus()	Ask whether the child expression sets a new focus for evaluation of other operands
void	setUsage(OperandUsage usage)	Set the usage of the operand
void	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo)
static OperandUsage	typeDeterminedUsage(ItemType type)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

Operand

public Operand(Expression parentExpression,
               Expression childExpression,
               OperandRole role)

Create an operand object

Parameters:

parentExpression - the expression of which this is an operand

childExpression - the actual expression used as the operand

role - information about the role this operand plays within the parent expression

Method Detail

getParentExpression

public Expression getParentExpression()

Get the parent expression of this operand

Returns:

the parent expression

getChildExpression

public Expression getChildExpression()

Get the expression used as the actual operand

Specified by:

getChildExpression in interface ExpressionOwner

Returns:

the child expression

setChildExpression

public void setChildExpression(Expression childExpression)

Change the child expression used for this operand. This is the only approved way of making structural changes to the expression tree, and the implementation of this method is responsible for maintaining the consistency of the tree

Specified by:

setChildExpression in interface ExpressionOwner

Parameters:

childExpression - the new child expression

detachChild

public void detachChild()

getOperandRole

public OperandRole getOperandRole()

Get the operand role

Returns:

the operand role

setOperandRole

public void setOperandRole(OperandRole role)

Set the operand role

Parameters:

role - the operand role

setsNewFocus

public boolean setsNewFocus()

Ask whether the child expression sets a new focus for evaluation of other operands

Returns:

true if the child expression is evaluated with the same focus as its parent expression

hasSpecialFocusRules

public boolean hasSpecialFocusRules()

hasSameFocus

public boolean hasSameFocus()

Ask whether the child expression is evaluated with the same focus as its parent expression

Returns:

true if the child expression is evaluated with the same focus as its parent expression

isHigherOrder

public boolean isHigherOrder()

Ask whether the operand is a higher-order operand,: typically this means that the child expression is evaluated repeatedly during a single evaluation of the parent expression (but there are some cases like xsl:for-each select=".." where the operand is higher-order despite not being evaluated repeatedly).

Returns:

true if the operand is higher-order

isEvaluatedRepeatedly

public boolean isEvaluatedRepeatedly()

Ask whether the operand is is evaluated repeatedly during a single evaluation of the parent expression. This is true if the operand is higher-order and the operand does not have the OperandRole.SINGLETON property.

Returns:

true if the operand is higher-order

getUsage

public OperandUsage getUsage()

Get the usage of the operand

Returns:

the usage

setUsage

public void setUsage(OperandUsage usage)

Set the usage of the operand

Parameters:

usage - the operand usage

getRequiredType

public SequenceType getRequiredType()

Get the required type of the operand

Returns:

the required type

isInChoiceGroup

public boolean isInChoiceGroup()

Ask whether the operand is a member of a choice group

Returns:

true if the operand is in a choice group

iterator

public java.util.Iterator<Operand> iterator()

Get a singleton iterator that returns this operand only

Specified by:

iterator in interface java.lang.Iterable<Operand>

Returns:

a singleton iterator

typeCheck

public void typeCheck(ExpressionVisitor visitor,
                      ContextItemStaticInfo contextInfo)
               throws XPathException

Throws:

XPathException

optimize

public void optimize(ExpressionVisitor visitor,
                     ContextItemStaticInfo contextInfo)
              throws XPathException

Throws:

XPathException

typeDeterminedUsage

public static OperandUsage typeDeterminedUsage(ItemType type)