org.basex.query.item

Class Item

java.lang.Object

org.basex.data.ExprInfo

org.basex.query.expr.Expr

org.basex.query.item.Value

org.basex.query.item.Item

All Implemented Interfaces:

java.lang.Iterable<Item>

Direct Known Subclasses:

ANode, Bin, Bln, Date, Dbl, Dec, Dur, FItem, Flt, Int, Jav, QNm, Str, StrStream

public abstract class Item
extends Value

Abstract item.

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

Modifier and Type	Field and Description
static int	UNDEF Undefined item.

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

type

Method Summary

Methods

Modifier and Type	Method and Description
boolean	bool(InputInfo ii) Returns a boolean representation of the value.
boolean	comparable(Item it) Checks if the items can be compared.
double	dbl(InputInfo ii) Returns a double representation of the value.
java.math.BigDecimal	dec(InputInfo ii) Returns a decimal representation of the value.
int	diff(InputInfo ii, Item it) Returns the difference between the current and the specified item.
Item	ebv(QueryContext ctx, InputInfo ii) Checks if the iterator can be dissolved into an effective boolean value.
abstract boolean	eq(InputInfo ii, Item it) Checks the items for equality.
boolean	equiv(InputInfo ii, Item it) Checks the items for equivalence.
float	flt(InputInfo ii) Returns a float representation of the value.
int	hash(InputInfo ii) Returns a hash code for this value.
boolean	homogenous() Checks if all items of this value share the same type.
java.io.InputStream	input(InputInfo ii) Returns an input stream.
boolean	isItem() Tests if this is an item.
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.
Item	itemAt(long pos) Gets the item at the given position in the value.
ValueIter	iter() Returns an iterator.
boolean	iterable() Returns true if the expression is iterable, i.e., if it does not contain any duplicates and if all results are sorted.
long	itr(InputInfo ii) Returns an integer (long) representation of the value.
void	plan(Serializer ser) Serializes the expression tree.
double	score() Returns a score value.
void	score(double s) Sets a new score value.
void	serialize(Serializer ser) Serializes the item.
long	size() Returns the sequence size or 1.
abstract byte[]	string(InputInfo ii) Returns a string representation of the value.
Item	test(QueryContext ctx, InputInfo ii) Performs a predicate test and returns the item if test was successful.
SeqType	type() Returns the sequence type of the evaluated value.
int	writeTo(Item[] arr, int start) Writes this value's items out to the given array.
byte[]	xdmInfo() Returns meta data on the current item.

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

cache, comp, count, data, description, info, isValue, iter, iterator, removable, remove, toJava, uses, value

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

addText, compEbv, hasFreeVars, indexAccessible, indexEquivalent, isEmpty, isFunction, isVacuous, markTailCalls, sameAs

Methods inherited from class org.basex.data.ExprInfo

toString

Methods inherited from class java.lang.Object

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

Field Detail

UNDEF

public static final int UNDEF

Undefined item.

See Also:

Constant Field Values

Method Detail

iter

public final ValueIter iter()

Description copied from class: Value

Returns an iterator.

Specified by:

iter in class Value

Returns:

iterator

item

public final Item item(QueryContext ctx,
        InputInfo ii)

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.

Specified by:

item in class Expr

Parameters:

ctx - query context

ii - input info

Returns:

iterator

itemAt

public final Item itemAt(long pos)

Description copied from class: Value

Gets the item at the given position in the value.

Specified by:

itemAt in class Value

Parameters:

pos - position

Returns:

item

ebv

public final Item ebv(QueryContext ctx,
       InputInfo ii)

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 numeric predicate.

Specified by:

ebv in class Expr

Parameters:

ctx - query context

ii - input info

Returns:

item

test

public final Item test(QueryContext ctx,
        InputInfo ii)
                throws QueryException

Description copied from class: Expr

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

Specified by:

test in class Expr

Parameters:

ctx - query context

ii - input info

Returns:

item

Throws:

QueryException - query exception

isItem

public final boolean isItem()

Description copied from class: Expr

Tests if this is an item.

Overrides:

isItem in class Expr

Returns:

result of check

string

public abstract byte[] string(InputInfo ii)
                       throws QueryException

Returns a string representation of the value.

Parameters:

ii - input info, use null if none is available

Returns:

string value

Throws:

QueryException - if the item can't be atomized

bool

public boolean bool(InputInfo ii)
             throws QueryException

Returns a boolean representation of the value.

Parameters:

ii - input info

Returns:

boolean value

Throws:

QueryException - query exception

dec

public java.math.BigDecimal dec(InputInfo ii)
                         throws QueryException

Returns a decimal representation of the value.

Parameters:

ii - input info

Returns:

decimal value

Throws:

QueryException - query exception

itr

public long itr(InputInfo ii)
         throws QueryException

Returns an integer (long) representation of the value.

Parameters:

ii - input info

Returns:

long value

Throws:

QueryException - query exception

flt

public float flt(InputInfo ii)
          throws QueryException

Returns a float representation of the value.

Parameters:

ii - input info

Returns:

float value

Throws:

QueryException - query exception

dbl

public double dbl(InputInfo ii)
           throws QueryException

Returns a double representation of the value.

Parameters:

ii - input info

Returns:

double value

Throws:

QueryException - query exception

comparable

public final boolean comparable(Item it)

Checks if the items can be compared.

Parameters:

it - item to be compared

Returns:

result of check

eq

public abstract boolean eq(InputInfo ii,
         Item it)
                    throws QueryException

Checks the items for equality.

Parameters:

ii - input info

it - item to be compared

Returns:

result of check

Throws:

QueryException - query exception

equiv

public final boolean equiv(InputInfo ii,
            Item it)
                    throws QueryException

Checks the items for equivalence.

Parameters:

ii - input info

it - item to be compared

Returns:

result of check

Throws:

QueryException - query exception

diff

public int diff(InputInfo ii,
       Item it)
         throws QueryException

Returns the difference between the current and the specified item.

Parameters:

ii - input info

it - item to be compared

Returns:

difference

Throws:

QueryException - query exception

input

public java.io.InputStream input(InputInfo ii)
                          throws QueryException

Returns an input stream.

Parameters:

ii - input info

Returns:

input stream

Throws:

QueryException - query exception

type

public final SeqType type()

Description copied from class: Expr

Returns the sequence type of the evaluated value. For simplicity, some types have been summarized. E.g., all numbers are treated as integers.

Specified by:

type in class Expr

Returns:

result of check

size

public final long size()

Description copied from class: Expr

Returns the sequence size or 1.

Specified by:

size in class Value

Returns:

result of check

iterable

public final 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

score

public double score()

Returns a score value.

Returns:

score value

score

public final void score(double s)

Sets a new score value.

Parameters:

s - score value

serialize

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

Serializes the item.

Parameters:

ser - serializer

Throws:

java.io.IOException - I/O exception

plan

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

Description copied from class: ExprInfo

Serializes the expression tree.

Specified by:

plan in class ExprInfo

Parameters:

ser - serializer

Throws:

java.io.IOException - I/O exception

hash

public int hash(InputInfo ii)
         throws QueryException

Description copied from class: Value

Returns a hash code for this value.

Specified by:

hash in class Value

Parameters:

ii - input info

Returns:

hash code

Throws:

QueryException - if atomization can't be applied (e.g. function item)

writeTo

public final int writeTo(Item[] arr,
          int start)

Description copied from class: Value

Writes this value's items out to the given array.

Specified by:

writeTo in class Value

Parameters:

arr - array to write to

start - start position

Returns:

number of written items

homogenous

public final boolean homogenous()

Description copied from class: Value

Checks if all items of this value share the same type.

Specified by:

homogenous in class Value

Returns:

result of check

xdmInfo

public byte[] xdmInfo()

Returns meta data on the current item.

Returns:

type string