org.basex.query.expr
Class FLWOR

java.lang.Object
  org.basex.query.ExprInfo
      org.basex.query.expr.Expr
          org.basex.query.expr.FLWOR

Direct Known Subclasses:

FLWR

public class FLWOR
extends Expr

FLWOR Clause.

Author:

Workgroup DBIS, University of Konstanz 2005-09, ISC License, Christian Gruen

Constructor Summary

FLWOR(ForLet[] f, Expr w, Order o, Expr r)
Constructor.

Method Summary

java.lang.String	color() Returns a string description of the expression.
Expr	comp(QueryContext ctx) Optimizes and compiles the expression.
Iter	iter(QueryContext ctx) Evaluates the expression and returns an iterator on the resulting items.
void	plan(Serializer ser) Recursively sends the abstract syntax of this expression to the specified serializer.
boolean	removable(Var v, QueryContext ctx) Checks if the specified variable is removable.
Expr	remove(Var v) Removes the specified variable in a sub expression.
Return	returned(QueryContext ctx) Indicates the return type of an expression.
java.lang.String	toString()
boolean	uses(Expr.Use use, QueryContext ctx) Indicates if an expression uses the specified type.

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

addText, atomic, checkCtx, checkDbl, checkItr, duplicates, e, ebv, i, indexAccessible, indexEquivalent, sameAs, size, test

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

FLWOR

public FLWOR(ForLet[] f,
             Expr w,
             Order o,
             Expr r)

Constructor.

Parameters:

f - variable inputs

w - where clause

o - order expressions

r - return expression

Method Detail

comp

public Expr comp(QueryContext ctx)
          throws QueryException

Description copied from class: Expr

Optimizes and compiles the expression.

Specified by:

comp in class Expr

Parameters:

ctx - query context

Returns:

optimized Expression

Throws:

QueryException - evaluation exception

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 - evaluation exception

uses

public boolean uses(Expr.Use use,
                    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 Expr

Parameters:

use - use type to be checked

ctx - query context

Returns:

result of check

removable

public boolean removable(Var v,
                         QueryContext ctx)

Description copied from class: Expr

Checks if the specified variable is removable.

Overrides:

removable in class Expr

Parameters:

v - variable to be removed

ctx - query context

Returns:

result of check

remove

public Expr remove(Var v)

Description copied from class: Expr

Removes the specified variable in a sub expression.

Overrides:

remove in class Expr

Parameters:

v - variable to be removed

Returns:

expression with removed variable

returned

public Return returned(QueryContext ctx)

Description copied from class: Expr

Indicates the return type of an expression. Called by the compiler to check if expressions can be reformulated. null is returned by default.

Overrides:

returned in class Expr

Parameters:

ctx - query context

Returns:

result of check

color

public final java.lang.String color()

Description copied from class: ExprInfo

Returns a string description of the expression. Contrary to the ExprInfo.toString() method, the current expressions aren't included in the output.

Overrides:

color in class ExprInfo

Returns:

result of check

plan

public final void plan(Serializer ser)
                throws java.io.IOException

Description copied from class: ExprInfo

Recursively sends the abstract syntax of this expression to the specified serializer.

Specified by:

plan in class ExprInfo

Parameters:

ser - serializer

Throws:

java.io.IOException - exception

toString

public final java.lang.String toString()

Specified by:

toString in class ExprInfo