org.basex.query.expr
Class Context

java.lang.Object
  extended by org.basex.query.ExprInfo
      extended by org.basex.query.expr.Expr
          extended by org.basex.query.expr.Simple
              extended by 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