org.basex.query.expr
Class Pred

java.lang.Object
  org.basex.query.ExprInfo
      org.basex.query.expr.Expr
          org.basex.query.expr.Preds
              org.basex.query.expr.Pred

Direct Known Subclasses:

IterPred

public class Pred
extends Preds

Predicate expression.

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

Field Summary

Fields inherited from class org.basex.query.expr.Preds

pred

Constructor Summary

Pred(Expr r, Expr... p)
Constructor.

Method Summary

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.
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.Preds

color

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

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

Pred

public Pred(Expr r,
            Expr... p)

Constructor.

Parameters:

r - expression

p - predicates

Method Detail

comp

public final Expr comp(QueryContext ctx)
                throws QueryException

Description copied from class: Expr

Optimizes and compiles the expression.

Overrides:

comp in class Preds

Parameters:

ctx - query context

Returns:

optimized Expression

Throws:

QueryException - query 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 - query exception

uses

public final 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 Preds

Parameters:

u - use type to be checked

ctx - query context

Returns:

result of check

removable

public final boolean removable(Var v,
                               QueryContext ctx)

Description copied from class: Expr

Checks if the specified variable is removable.

Overrides:

removable in class Preds

Parameters:

v - variable to be removed

ctx - query context

Returns:

result of check

remove

public final Expr remove(Var v)

Description copied from class: Expr

Removes the specified variable in a sub expression.

Overrides:

remove in class Preds

Parameters:

v - variable to be removed

Returns:

expression with removed variable

plan

public final void plan(Serializer ser)
                throws IOException

Description copied from class: ExprInfo

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

Overrides:

plan in class Preds

Parameters:

ser - serializer

Throws:

IOException - I/O exception

toString

public final String toString()

Overrides:

toString in class Preds