org.basex.query.expr
Class Context

java.lang.Object
  org.basex.query.ExprInfo
      org.basex.query.expr.Expr
          org.basex.query.expr.Simple
              org.basex.query.expr.Context

public final class Context
extends Simple

Context item.

Author:

Workgroup DBIS, University of Konstanz 2005-10, ISC License, Christian Gruen

Nested Class Summary

Nested classes/interfaces inherited from class org.basex.query.expr.Expr

Expr.Use

Constructor Summary

Context()

Method Summary

Expr	addText(QueryContext ctx) Optionally adds a text node to an expression for potential index rewriting.
Iter	iter(QueryContext ctx) Evaluates the expression and returns an iterator on the resulting items.
boolean	sameAs(Expr cmp) Checks the current and specified expression for equality.
String	toString()
boolean	uses(Expr.Use u, QueryContext ctx) Indicates if an expression uses the specified type.

Methods inherited from class org.basex.query.expr.Simple

color, comp, plan

Methods inherited from class org.basex.query.expr.Expr

atomic, checkCtx, checkDbl, checkItr, duplicates, e, ebv, i, indexAccessible, indexEquivalent, removable, remove, returned, size, test, v

Methods inherited from class org.basex.query.ExprInfo

info, name

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Context

public Context()

Method Detail

iter

public Iter iter(QueryContext ctx)
          throws QueryException

Description copied from class: Expr

Evaluates the expression and returns an iterator on the resulting items. If this method is not overwritten, Expr.atomic(org.basex.query.QueryContext) must be implemented.

Overrides:

iter in class Expr

Parameters:

ctx - query context

Returns:

resulting item

Throws:

QueryException - query exception

addText

public Expr addText(QueryContext ctx)

Description copied from class: Expr

Optionally adds a text node to an expression for potential index rewriting.

Overrides:

addText in class Expr

Parameters:

ctx - query context

Returns:

expression

uses

public boolean uses(Expr.Use u,
                    QueryContext ctx)

Description copied from class: Expr

Indicates if an expression uses the specified type. Called by the compiler to perform certain optimizations. true is returned by default and thus assumed as "worst-case".

Overrides:

uses in class Simple

Parameters:

u - use type to be checked

ctx - query context

Returns:

result of check

sameAs

public boolean sameAs(Expr cmp)

Description copied from class: Expr

Checks the current and specified expression for equality.

Overrides:

sameAs in class Expr

Parameters:

cmp - expression to be compared

Returns:

result of check

toString

public String toString()

Specified by:

toString in class ExprInfo