org.teiid.query.sql.lang

Class OrderBy

java.lang.Object

org.teiid.query.sql.lang.OrderBy

All Implemented Interfaces:

Cloneable, LanguageObject

public class OrderBy
extends Object
implements LanguageObject

Represents the ORDER BY clause of a query. The ORDER BY clause states what order the rows of a result should be returned in. Each element in the ORDER BY represents a sort that is completed in the order listed. The optional keywords ASC and DESC can be put after each element to specify whether the sort is ascending or descending.

Nested Class Summary

Nested classes/interfaces inherited from interface org.teiid.query.sql.LanguageObject

LanguageObject.Util

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	ASC Constant for the ascending value
static boolean	DESC Constant for the descending value

Constructor Summary

Constructors

Constructor and Description
OrderBy() Constructs a default instance of this class.
OrderBy(List<? extends Expression> parameters) Constructs an instance of this class from an ordered list of elements.
OrderBy(List<? extends Expression> parameters, List<Boolean> types) Constructs an instance of this class from an ordered set of elements.

Method Summary

Modifier and Type	Method and Description
void	acceptVisitor(LanguageVisitor visitor) Method for accepting a visitor.
OrderByItem	addVariable(Expression element) Adds a new variable to the list of order by elements.
OrderByItem	addVariable(Expression element, boolean type) Adds a new variable to the list of order by elements with the specified sort order
OrderBy	clone() Return deep copy of this ORDER BY clause.
boolean	equals(Object obj) Compare two OrderBys for equality.
int	getExpressionPosition(int orderIndex)
List<OrderByItem>	getOrderByItems()
Boolean	getOrderType(int index) Returns the sort order at the specified index
List<Expression>	getSortKeys() Get the list or sort key symbols.
List<Boolean>	getTypes()
Expression	getVariable(int index) Returns the ORDER BY element at the specified index.
int	getVariableCount() Returns the number of elements in ORDER BY.
int	hashCode() Get hashcode for OrderBy.
boolean	hasUnrelated()
boolean	isUserOrdering()
void	removeOrderByItem(int index)
void	setExpressionPosition(int orderIndex, int selectIndex)
void	setUserOrdering(boolean userOrdering)
String	toString() Returns a string representation of an instance of this class.

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

ASC

public static final boolean ASC

Constant for the ascending value

See Also:

Constant Field Values

DESC

public static final boolean DESC

Constant for the descending value

See Also:

Constant Field Values

Constructor Detail

OrderBy

public OrderBy()

Constructs a default instance of this class.

OrderBy

public OrderBy(List<? extends Expression> parameters)

Constructs an instance of this class from an ordered list of elements.

Parameters:

parameters - The ordered list of SingleElementSymbol

OrderBy

public OrderBy(List<? extends Expression> parameters,
               List<Boolean> types)

Constructs an instance of this class from an ordered set of elements.

Parameters:

parameters - The ordered list of SingleElementSymbol

types - The list of directions by which the results are ordered (Boolean, true=ascending)

Method Detail

getVariableCount

public int getVariableCount()

Returns the number of elements in ORDER BY.

Returns:

Number of variables in ORDER BY

getOrderByItems

public List<OrderByItem> getOrderByItems()

getVariable

public Expression getVariable(int index)

Returns the ORDER BY element at the specified index.

Parameters:

index - Index to get

Returns:

The element at the index

getOrderType

public Boolean getOrderType(int index)

Returns the sort order at the specified index

Parameters:

index - Index to get

Returns:

The sort order at the index

addVariable

public OrderByItem addVariable(Expression element)

Adds a new variable to the list of order by elements.

Parameters:

element - Element to add

addVariable

public OrderByItem addVariable(Expression element,
                               boolean type)

Adds a new variable to the list of order by elements with the specified sort order

Parameters:

element - Element to add

type - True for ascending, false for descending

acceptVisitor

public void acceptVisitor(LanguageVisitor visitor)

Description copied from interface: LanguageObject

Method for accepting a visitor. It is the responsibility of the language object to call back on the visitor.

Specified by:

acceptVisitor in interface LanguageObject

Parameters:

visitor - Visitor being used

clone

public OrderBy clone()

Return deep copy of this ORDER BY clause.

Specified by:

clone in interface LanguageObject

Overrides:

clone in class Object

Returns:

Deep clone of this object

equals

public boolean equals(Object obj)

Compare two OrderBys for equality. Order is important in the order by, so that is considered in the comparison. Also, the sort orders are considered.

Overrides:

equals in class Object

Parameters:

obj - Other object

Returns:

True if equal

hashCode

public int hashCode()

Get hashcode for OrderBy. WARNING: The hash code relies on the variables in the select, so changing the variables will change the hash code, causing a select to be lost in a hash structure. Do not hash a OrderBy if you plan to change it.

Overrides:

hashCode in class Object

Returns:

Hash code

toString

public String toString()

Returns a string representation of an instance of this class.

Overrides:

toString in class Object

Returns:

String representation of object

setExpressionPosition

public void setExpressionPosition(int orderIndex,
                                  int selectIndex)

getExpressionPosition

public int getExpressionPosition(int orderIndex)

removeOrderByItem

public void removeOrderByItem(int index)

hasUnrelated

public boolean hasUnrelated()

getSortKeys

public List<Expression> getSortKeys()

Get the list or sort key symbols. Modifications to this list will not add or remove OrderByItems.

Returns:

getTypes

public List<Boolean> getTypes()

setUserOrdering

public void setUserOrdering(boolean userOrdering)

isUserOrdering

public boolean isUserOrdering()