org.basex.query.expr
Class Grp

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

public final class Grp
extends Expr

Single group expression.

Author:
Workgroup DBIS, University of Konstanz 2005-10, ISC License, Michael Seiferle

Nested Class Summary
 
Nested classes/interfaces inherited from class org.basex.query.expr.Expr
Expr.Use
 
Constructor Summary
Grp(Expr e)
          Constructor.
 
Method Summary
 Expr comp(QueryContext ctx)
          Optimizes and compiles the expression.
 void plan(Serializer ser)
          Recursively sends the abstract syntax of this expression to the specified serializer.
 Grp remove(Var v)
          Removes the specified variable in a sub expression.
 Return returned(QueryContext ctx)
          Indicates the return type of an expression.
 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, iter, removable, sameAs, size, test, v
 
Methods inherited from class org.basex.query.ExprInfo
color, info, name
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

Grp

public Grp(Expr e)
Constructor.

Parameters:
e - 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 - query 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".

Specified by:
uses in class Expr
Parameters:
use - use type to be checked
ctx - query context
Returns:
result of check

remove

public Grp 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

plan

public void plan(Serializer ser)
          throws 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:
IOException - I/O exception

toString

public String toString()
Specified by:
toString in class ExprInfo