lux.xquery

Class Variable

java.lang.Object

lux.xpath.AbstractExpression

lux.xquery.Variable

All Implemented Interfaces:

Visitable

public class Variable
extends AbstractExpression

Nested Class Summary

Nested classes/interfaces inherited from class lux.xpath.AbstractExpression

AbstractExpression.Type

Field Summary

Fields inherited from class lux.xpath.AbstractExpression

subs, sup

Constructor Summary

Constructors

Constructor and Description
Variable(QName qname)
Variable(QName qname, String typeDesc)

Method Summary

Methods

Modifier and Type	Method and Description
AbstractExpression	accept(ExpressionVisitor visitor)
VariableContext	getBindingContext() If this expression depends "directly" on a variable, return that variable's binding context: a for or let clause, or a global variable definition.
AbstractExpression	getLastContextStep() This method is called by the optimizer in order to determine an element or attribute QName (or wildcard) against which some expression is being compared, in order to generate an appropriate text query.
int	getPrecedence()
QName	getQName()
AbstractExpression	getRoot()
AbstractExpression	getValue()
boolean	isDocumentOrdered()
void	setBindingContext(VariableContext context)
void	setValue(AbstractExpression value)
void	toString(StringBuilder buf) Each subclass must implement the toString(StringBuilder) method by appending itself as a syntatically valid XPath/XQuery expression in the given buffer.

Methods inherited from class lux.xpath.AbstractExpression

acceptSubs, appendSub, deepEquals, equivalent, geq, getHead, getSubs, getSuper, getTail, getType, isAbsolute, isRestrictive, matchDown, propEquals, propGreaterEqual, replaceRoot, setSubs, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

Variable

public Variable(QName qname)

Variable

public Variable(QName qname,
        String typeDesc)

Method Detail

accept

public AbstractExpression accept(ExpressionVisitor visitor)

toString

public void toString(StringBuilder buf)

Description copied from class: AbstractExpression

Each subclass must implement the toString(StringBuilder) method by appending itself as a syntatically valid XPath/XQuery expression in the given buffer.

Specified by:

toString in class AbstractExpression

Parameters:

buf - the buffer to append to

getQName

public QName getQName()

getPrecedence

public int getPrecedence()

Specified by:

getPrecedence in class AbstractExpression

Returns:

a number indicating the *outer* precedence of this expression. Expressions with lower precedence numbers have lower precedence, ie bind more loosely, than expressions with higher precedence. Expressions with no sub-expressions are assigned a high precedence. Complex expressions can be seen as having an inner and an outer precedence; for example function call expressions behave as a comma with regard to their sub-expressions, the arguments, and like parentheses to their enclosing expression.

isDocumentOrdered

public boolean isDocumentOrdered()

Overrides:

isDocumentOrdered in class AbstractExpression

Returns:

whether this expression is proven to return results in document order. This method returns true iff all its subs return true, or it has none. Warning: incorrect results may occur if document-ordering is falsely asserted.

setValue

public void setValue(AbstractExpression value)

getValue

public AbstractExpression getValue()

getRoot

public AbstractExpression getRoot()

Overrides:

getRoot in class AbstractExpression

Returns:

the root of this expression: this will either be a Root(/), a function returning document nodes, or null.

getLastContextStep

public AbstractExpression getLastContextStep()

Description copied from class: AbstractExpression

This method is called by the optimizer in order to determine an element or attribute QName (or wildcard) against which some expression is being compared, in order to generate an appropriate text query.

Overrides:

getLastContextStep in class AbstractExpression

Returns:

the last context step of the value expression.

getBindingContext

public VariableContext getBindingContext()

Description copied from class: AbstractExpression

If this expression depends "directly" on a variable, return that variable's binding context: a for or let clause, or a global variable definition. This recurses through variables, so if there are aliases it retrieves the ultimate context. We need to define directly dependent precisely; what it's used for is to determine with an order by expression is dependent on a for-variable, and ultimately whether an order by optimization can be applied.

Overrides:

getBindingContext in class AbstractExpression

Returns:

the binding context (for or let clause, or global definition) of this variable. Will be null if the variable represents a function argument.

setBindingContext

public void setBindingContext(VariableContext context)