org.basex.query.item
Class Seq

java.lang.Object
  org.basex.query.ExprInfo
      org.basex.query.expr.Expr
          org.basex.query.item.Item
              org.basex.query.item.Seq

public class Seq
extends Item

Item sequence.

Author:

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

Field Summary

static Seq

EMPTY Empty sequence.

Fields inherited from class org.basex.query.item.Item

type

Method Summary

Item	atomic(QueryContext ctx) Evaluates the expression and returns the resulting item or a null reference.
int	diff(Item it) Returns the difference between the current and the specified item.
boolean	duplicates(QueryContext ctx) Returns true if the expression might yield duplicates and unsorted results.
Item	ebv(QueryContext ctx) Checks if the iterator can be dissolved into an effective boolean value.
boolean	eq(Item it) Checks the items for equality.
static Item	get(Item[] v, int s) Constructor.
boolean	i() Checks if this is an item.
Iter	iter() Returns an item iterator.
void	plan(Serializer ser) Recursively sends the abstract syntax of this expression to the specified serializer.
Return	returned(QueryContext ctx) Indicates the return type of an expression.
void	serialize(Serializer ser) Serializes the item.
long	size(QueryContext ctx) Returns the sequence size or 1.
Item	test(QueryContext ctx) Performs a predicate test and returns the item if test was successful.
java.lang.String	toString()

Methods inherited from class org.basex.query.item.Item

bool, castErr, comp, d, dbl, dec, flt, hash, iter, itr, java, n, name, node, removable, s, score, score, str, u, uses

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

addText, checkCtx, checkDbl, checkItr, e, indexAccessible, indexEquivalent, remove, sameAs

Methods inherited from class org.basex.query.ExprInfo

color, info

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final Seq EMPTY

Empty sequence.

Method Detail

get

public static Item get(Item[] v,
                       int s)

Constructor.

Parameters:

v - value

s - size

Returns:

resulting item or sequence

i

public final boolean i()

Description copied from class: Expr

Checks if this is an item.

Overrides:

i in class Item

Returns:

result of check

size

public long size(QueryContext ctx)

Description copied from class: Expr

Returns the sequence size or 1.

Overrides:

size in class Expr

Parameters:

ctx - query context

Returns:

result of check

iter

public Iter iter()

Description copied from class: Item

Returns an item iterator.

Overrides:

iter in class Item

Returns:

iterator

atomic

public Item atomic(QueryContext ctx)
            throws QueryException

Description copied from class: Expr

Evaluates the expression and returns the resulting item or a null reference. If this method is not overwritten, Expr.iter(org.basex.query.QueryContext) must be implemented.

Overrides:

atomic in class Item

Parameters:

ctx - query context

Returns:

iterator

Throws:

QueryException - query exception

ebv

public Item ebv(QueryContext ctx)
         throws QueryException

Description copied from class: Expr

Checks if the iterator can be dissolved into an effective boolean value. If not, returns an error. If yes, returns the first value - which can be also be e.g. an integer, which is later evaluated as position predicate.

Overrides:

ebv in class Item

Parameters:

ctx - query context

Returns:

item

Throws:

QueryException - query exception

test

public Item test(QueryContext ctx)
          throws QueryException

Description copied from class: Expr

Performs a predicate test and returns the item if test was successful.

Overrides:

test in class Item

Parameters:

ctx - query context

Returns:

item

Throws:

QueryException - evaluation exception

eq

public boolean eq(Item it)
           throws QueryException

Description copied from class: Item

Checks the items for equality.

Specified by:

eq in class Item

Parameters:

it - item to be compared.

Returns:

result of check

Throws:

QueryException - evaluation exception

diff

public int diff(Item it)

Description copied from class: Item

Returns the difference between the current and the specified item.

Overrides:

diff in class Item

Parameters:

it - item to be compared.

Returns:

difference

serialize

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

Description copied from class: Item

Serializes the item.

Overrides:

serialize in class Item

Parameters:

ser - serializer

Throws:

java.io.IOException - exception

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 Item

Parameters:

ctx - query context

Returns:

result of check

duplicates

public boolean duplicates(QueryContext ctx)

Description copied from class: Expr

Returns true if the expression might yield duplicates and unsorted results.

Overrides:

duplicates in class Item

Parameters:

ctx - query context

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.

Overrides:

plan in class Item

Parameters:

ser - serializer

Throws:

java.io.IOException - exception

toString

public java.lang.String toString()

Overrides:

toString in class Item