org.basex.query.ft
Class FTExpr

java.lang.Object
  org.basex.query.ExprInfo
      org.basex.query.expr.Expr
          org.basex.query.ft.FTExpr

Direct Known Subclasses:

FTAnd, FTIndex, FTMildNot, FTMildNotIndex, FTNot, FTNotIndex, FTOptions, FTOr, FTPos, FTPosIndex, FTWords

public abstract class FTExpr
extends Expr

This class defines is an abstract class for full-text expressions.

Author:

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

Field Summary

FTExpr[]

expr Expression list.

Method Summary

java.lang.String	color() Returns a string description of the expression.
FTExpr	comp(QueryContext ctx) Optimizes and compiles the expression.
FTExpr	indexEquivalent(QueryContext ctx, IndexContext ic) Returns an equivalent expression which accesses an index structure.
abstract FTNodeIter	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.
FTExpr	remove(Var v) Removes the specified variable in a sub expression.
Return	returned(QueryContext ctx) Indicates the return type of an expression.
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, removable, sameAs, size, test

Methods inherited from class org.basex.query.ExprInfo

info, name, toString

Methods inherited from class java.lang.Object

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

Field Detail

expr

public FTExpr[] expr

Expression list.

Method Detail

comp

public FTExpr 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 abstract FTNodeIter 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

remove

public final FTExpr 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

indexEquivalent

public FTExpr indexEquivalent(QueryContext ctx,
                              IndexContext ic)
                       throws QueryException

Description copied from class: Expr

Returns an equivalent expression which accesses an index structure. Must be called if Expr.indexAccessible(org.basex.query.QueryContext, org.basex.query.IndexContext) is implemented for an expression.

Overrides:

indexEquivalent in class Expr

Parameters:

ctx - query context

ic - index context

Returns:

Equivalent index-expression or null

Throws:

QueryException - Exception

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 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