org.basex.query.func

Class FNDb

java.lang.Object

org.basex.data.ExprInfo

org.basex.query.expr.Expr

org.basex.query.expr.ParseExpr

org.basex.query.expr.Arr

org.basex.query.func.StandardFunc

org.basex.query.func.FNDb

public final class FNDb
extends StandardFunc

Database functions.

Author:

BaseX Team 2005-12, BSD License, Christian Gruen, Dimitar Popov

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.Arr

expr

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

input, size, type

Constructor Summary

Constructors

Constructor and Description
FNDb(InputInfo ii, Function f, Expr... e) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	isVacuous() Tests if this is a vacuous expression (empty sequence or error function).
Item	item(QueryContext ctx, InputInfo ii) Evaluates the expression and returns the resulting item or a null reference, if the expression yields an empty sequence.
Iter	iter(QueryContext ctx) Evaluates the expression and returns an iterator on the resulting items.
boolean	iterable() Returns true if the expression is iterable, i.e., if it does not contain any duplicates and if all results are sorted.
boolean	uses(Expr.Use u) Indicates if an expression uses the specified type or operation.
Value	value(QueryContext ctx) Evaluates the expression and returns the resulting value.

Methods inherited from class org.basex.query.func.StandardFunc

atom, comp, description, isFunction, plan, toString

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

allAreValues, count, indexEquivalent, removable, remove, toString

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

checkBln, checkColl, checkCreate, checkCtx, checkDbl, checkDBNode, checkEStr, checkEStr, checkIO, checkItem, checkItr, checkItr, checkMap, checkNode, checkNoEmpty, checkStr, checkType, checkUp, checkUp, checkWrite, compBln, ebv, optPre, preEval, size, test, type

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

addText, compEbv, hasFreeVars, indexAccessible, isEmpty, isItem, isValue, markTailCalls, sameAs

Methods inherited from class org.basex.data.ExprInfo

info

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

FNDb

public FNDb(InputInfo ii,
    Function f,
    Expr... e)

Constructor.

Parameters:

ii - input info

f - function definition

e - arguments

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.item(org.basex.query.QueryContext, org.basex.util.InputInfo) must be implemented by an expression, as it may be called by this method.

Overrides:

iter in class ParseExpr

Parameters:

ctx - query context

Returns:

resulting item

Throws:

QueryException - query exception

value

public Value value(QueryContext ctx)
            throws QueryException

Description copied from class: Expr

Evaluates the expression and returns the resulting value.

Overrides:

value in class ParseExpr

Parameters:

ctx - query context

Returns:

iterator

Throws:

QueryException - query exception

item

public Item item(QueryContext ctx,
        InputInfo ii)
          throws QueryException

Description copied from class: Expr

Evaluates the expression and returns the resulting item or a null reference, if the expression yields an empty sequence. If this method is not overwritten, Expr.iter(org.basex.query.QueryContext) must be implemented by an expression, as it may be called by this method.

Overrides:

item in class ParseExpr

Parameters:

ctx - query context

ii - input info

Returns:

iterator

Throws:

QueryException - query exception

isVacuous

public boolean isVacuous()

Description copied from class: Expr

Tests if this is a vacuous expression (empty sequence or error function). This check is needed for updating queries.

Overrides:

isVacuous in class Expr

Returns:

result of check

uses

public boolean uses(Expr.Use u)

Description copied from class: Expr

Indicates if an expression uses the specified type or operation. This method is called by numerous Expr.comp(org.basex.query.QueryContext) methods to test the properties of sub-expressions. It will return true as soon as at least one test is successful.

Overrides:

uses in class Arr

Parameters:

u - type/operation to be found

Returns:

result of check

iterable

public boolean iterable()

Description copied from class: Expr

Returns true if the expression is iterable, i.e., if it does not contain any duplicates and if all results are sorted. This method is called e.g. by AxisPath.

Overrides:

iterable in class Expr

Returns:

result of check