org.basex.query.expr

Class Pos

java.lang.Object

org.basex.data.ExprInfo

org.basex.query.expr.Expr

org.basex.query.expr.ParseExpr

org.basex.query.expr.Simple

org.basex.query.expr.Pos

public final class Pos
extends Simple

Pos expression.

Author:

BaseX Team 2005-12, BSD 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.ParseExpr

input, size, type

Method Summary

Methods

Modifier and Type	Method and Description
static Expr	get(CmpV.OpV cmp, Expr a, Expr o, InputInfo ii) Returns an instance of this class, if possible, and the input expression otherwise.
static Expr	get(long mn, long mx, InputInfo ii) Returns a position expression, or an optimized boolean item.
Bln	item(QueryContext ctx, InputInfo ii) Evaluates the expression and returns the resulting item or a null reference, if the expression yields an empty sequence.
void	plan(Serializer ser) Serializes the expression tree.
boolean	sameAs(Expr cmp) Compares the current and specified expression for equality.
boolean	skip(QueryContext ctx) Returns false if no more results can be expected.
java.lang.String	toString()
boolean	uses(Expr.Use u) Indicates if an expression uses the specified type or operation.

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

comp, count, removable, remove

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, iter, optPre, preEval, size, test, type, value

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

addText, compEbv, hasFreeVars, indexAccessible, indexEquivalent, isEmpty, isFunction, isItem, isVacuous, isValue, iterable, markTailCalls

Methods inherited from class org.basex.data.ExprInfo

description, info

Methods inherited from class java.lang.Object

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

Method Detail

get

public static Expr get(long mn,
       long mx,
       InputInfo ii)

Returns a position expression, or an optimized boolean item.

Parameters:

mn - minimum value

mx - minimum value

ii - input info

Returns:

expression

get

public static Expr get(CmpV.OpV cmp,
       Expr a,
       Expr o,
       InputInfo ii)
                throws QueryException

Returns an instance of this class, if possible, and the input expression otherwise.

Parameters:

cmp - comparator

a - argument

o - original expression

ii - input info

Returns:

resulting expression, or null

Throws:

QueryException - query exception

item

public Bln 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

skip

public boolean skip(QueryContext ctx)

Returns false if no more results can be expected.

Parameters:

ctx - query context

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 Simple

Parameters:

u - type/operation to be found

Returns:

result of check

sameAs

public boolean sameAs(Expr cmp)

Description copied from class: Expr

Compares the current and specified expression for equality.

Overrides:

sameAs in class Expr

Parameters:

cmp - expression to be compared

Returns:

result of check

plan

public void plan(Serializer ser)
          throws java.io.IOException

Description copied from class: ExprInfo

Serializes the expression tree.

Overrides:

plan in class Simple

Parameters:

ser - serializer

Throws:

java.io.IOException - I/O exception

toString

public java.lang.String toString()

Specified by:

toString in class ExprInfo