Package org.basex.query.func.fn

Class FnExists

java.lang.Object

org.basex.query.expr.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.fn.FnEmpty

org.basex.query.func.fn.FnExists

public final class FnExists
extends FnEmpty

Function implementation.

Author:

BaseX Team 2005-21, BSD License, Christian Gruen

Field Summary

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

definition, sc

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

exprs

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

exprType, info

Constructor Summary

Constructors

Constructor	Description
FnExists()

Method Summary

Modifier and Type	Method	Description
Bln	item(QueryContext qc, InputInfo ii)	Evaluates the expression and returns the resulting item, or Empty.VALUE if the expression yields an empty sequence.
Expr	mergeEbv(Expr expr, boolean or, CompileContext cc)	Tries to merge two expressions that are part of an EBV test.
protected Expr	opt(CompileContext cc)	Performs function specific optimizations.
Expr	simplifyFor(CompileContext.Simplify mode, CompileContext cc)	This function is called at compile time for expressions whose operands might be simplified.

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

checkAdmin, checkArity, checkArity, checkCreate, checkData, checkPath, checkPath, coerceFunc, compileData, copy, data, data, dataLock, dateTimeToMs, description, equals, has, optFirst, optFirst, optimize, plan, plan, serialize, simplifyArgs, toBaseUri, toBindings, toCollation, toDate, toDBNode, toEncodingOrNull, toNodeOrAtomItem, toOptions, toPath, toPath, toQuery, toQuery, vacuous

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

accept, allAreValues, args, checkUp, compile, copyAll, count, exprSize, flatten, inline, inline, inlineable, mayBePositional, simplifyAll

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

adoptType, atomValue, checkAllUp, checkNoEmpty, checkNoEmpty, checkNoneUp, checkNoUp, checkType, checkType, checkUp, copyType, ctxValue, ebv, iter, refineType, seqType, size, test, toArray, toArray, toAtomItem, toB64, toB64, toBin, toBin, toBoolean, toBoolean, toBytes, toBytes, toDouble, toDouble, toElem, toFloat, toFunc, toItem, toItem, toLong, toLong, toMap, toMap, toNode, toNode, toNodeOrNull, toNumber, toNumberOrNull, toQNm, toQNm, toToken, toToken, toTokenOrNull, toZeroToken, value

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

arg, atomItem, atomIter, ddo, funcType, hasFreeVars, indexAccessible, isSimple, markTailCalls, typeCheck, uses, visitAll

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

toErrorString, toString

Methods inherited from class java.lang.Object

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

Constructor Details

FnExists

public FnExists()

Method Details

item

public Bln item(QueryContext qc,
 InputInfo ii)
         throws QueryException

Description copied from class: Expr

Evaluates the expression and returns the resulting item, or Empty.VALUE if the expression yields an empty sequence. If this method is not implemented, Expr.value(QueryContext) must be implemented instead.

Overrides:

item in class FnEmpty

Parameters:

qc - query context

ii - input info (only required by Seq instances, which have no input info)

Returns:

item or Empty.VALUE

Throws:

QueryException - query exception

opt

protected Expr opt(CompileContext cc)
            throws QueryException

Description copied from class: StandardFunc

Performs function specific optimizations.

Overrides:

opt in class FnEmpty

Parameters:

cc - compilation context

Returns:

optimized or original expression

Throws:

QueryException - query exception

simplifyFor

public Expr simplifyFor(CompileContext.Simplify mode,
 CompileContext cc)
                 throws QueryException

Description copied from class: Expr

This function is called at compile time for expressions whose operands might be simplified.

Overrides:

simplifyFor in class Expr

Parameters:

mode - mode of simplification

cc - compilation context

Returns:

simplified or original expression

Throws:

QueryException - query exception

See Also:

• CompileContext.Simplify

mergeEbv

public Expr mergeEbv(Expr expr,
 boolean or,
 CompileContext cc)
              throws QueryException

Description copied from class: Expr

Tries to merge two expressions that are part of an EBV test. Called by And, Or), Step and Filter. Overwritten by CmpG, CmpIR, CmpR, CmpSR, ItrPos, Pos and others.

Overrides:

mergeEbv in class FnEmpty

Parameters:

expr - second expression

or - union or intersection

cc - compilation context

Returns:

optimized expression or null

Throws:

QueryException - query exception