mondrian.calc.impl
Class ConstantCalc

java.lang.Object
  mondrian.calc.impl.AbstractCalc
      mondrian.calc.impl.GenericCalc
          mondrian.calc.impl.ConstantCalc

All Implemented Interfaces:

BooleanCalc, Calc, DateTimeCalc, DimensionCalc, DoubleCalc, HierarchyCalc, IntegerCalc, LevelCalc, MemberCalc, StringCalc, TupleCalc, VoidCalc

public class ConstantCalc
extends GenericCalc

Calculator which always returns the same value.

Since:

Sep 27, 2005

Author:

jhyde

Field Summary

Fields inherited from class mondrian.calc.impl.AbstractCalc

exp, type

Constructor Summary

ConstantCalc(Type type, Object o)

Method Summary

void	collectArguments(Map<String,Object> arguments) Collects any other arguments to this calc.
static BooleanCalc	constantBoolean(boolean b) Creates an expression which evaluates to a given boolean.
static Calc	constantDimension(Dimension dimension) Creates an expression which evaluates to a given dimension.
static DoubleCalc	constantDouble(double v) Creates an expression which evaluates to a given double.
static Calc	constantHierarchy(Hierarchy hierarchy) Creates an expression which evaluates to a given hierarchy.
static ConstantCalc	constantInteger(int i) Creates an expression which evaluates to a given integer.
static Calc	constantLevel(Level level) Creates an expression which evaluates to a given level.
static Calc	constantMember(Member member) Creates an expression which evaluates to a given member.
static ConstantCalc	constantNull(Type type) Creates an expression which evaluates to null.
static StringCalc	constantString(String s) Creates an expression which evaluates to a given string.
boolean	dependsOn(Hierarchy hierarchy) Returns whether this expression depends upon a given hierarchy.
Object	evaluate(Evaluator evaluator) Evaluates this expression.
double	evaluateDouble(Evaluator evaluator) Evaluates this expression to yield a double value.
int	evaluateInteger(Evaluator evaluator) Evaluates this expression to yield an int value.
Calc[]	getCalcs() Returns this expression's child expressions.
protected String	getName() Returns the name of this expression type, used when serializing an expression to a string.
ResultStyle	getResultStyle() Returns style in which the result of evaluating this expression is returned.

Methods inherited from class mondrian.calc.impl.GenericCalc

evaluateBoolean, evaluateDateTime, evaluateDimension, evaluateHierarchy, evaluateLevel, evaluateMember, evaluateString, evaluateTuple, evaluateVoid, numberToDouble

Methods inherited from class mondrian.calc.impl.AbstractCalc

accept, anyDepends, anyDependsButFirst, butDepends, getArguments, getType, isWrapperFor, simplifyEvaluator, unwrap

Methods inherited from class java.lang.Object

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

Methods inherited from interface mondrian.calc.Calc

accept, getType, isWrapperFor, unwrap

Constructor Detail

ConstantCalc

public ConstantCalc(Type type,
                    Object o)

Method Detail

getName

protected String getName()

Description copied from class: AbstractCalc

Returns the name of this expression type, used when serializing an expression to a string.

The default implementation tries to extract a name from a function call, if any, then prints the last part of the class name.

Overrides:

getName in class AbstractCalc

getResultStyle

public ResultStyle getResultStyle()

Description copied from interface: Calc

Returns style in which the result of evaluating this expression is returned.

One application of this method is for the compiler to figure out whether the compiled expression is returning a mutable list. If a mutable list is required, the compiler can create a mutable copy.

Specified by:

getResultStyle in interface Calc

Overrides:

getResultStyle in class AbstractCalc

See Also:

ExpCompiler.compileList(mondrian.olap.Exp, boolean)

collectArguments

public void collectArguments(Map<String,Object> arguments)

Description copied from class: AbstractCalc

Collects any other arguments to this calc.

The default implementation returns name, class, type, resultStyle. A subclass must call super, but may add other arguments.

Overrides:

collectArguments in class AbstractCalc

Parameters:

arguments - Collection of name/value pairs, represented as a map

evaluate

public Object evaluate(Evaluator evaluator)

Description copied from interface: Calc

Evaluates this expression.

Parameters:

evaluator - Provides dimensional context in which to evaluate this expression

Returns:

Result of expression evaluation

evaluateInteger

public int evaluateInteger(Evaluator evaluator)

Description copied from interface: IntegerCalc

Evaluates this expression to yield an int value. If the result is null, returns the special FunUtil.IntegerNull value.

Specified by:

evaluateInteger in interface IntegerCalc

Overrides:

evaluateInteger in class GenericCalc

Parameters:

evaluator - Evaluation context

Returns:

evaluation result

evaluateDouble

public double evaluateDouble(Evaluator evaluator)

Description copied from interface: DoubleCalc

Evaluates this expression to yield a double value. If the result is null, returns the special FunUtil.DoubleNull value.

Specified by:

evaluateDouble in interface DoubleCalc

Overrides:

evaluateDouble in class GenericCalc

Parameters:

evaluator - Evaluation context

Returns:

evaluation result

dependsOn

public boolean dependsOn(Hierarchy hierarchy)

Description copied from interface: Calc

Returns whether this expression depends upon a given hierarchy.

If it does not depend on the hierarchy, then re-evaluating the expression with a different member of this context must produce the same answer.

Some examples:

• The expression

  [Measures].[Unit Sales]

  depends on all dimensions except [Measures].
• The boolean expression

  ([Measures].[Unit Sales], [Time].[1997]) > 1000

  depends on all hierarchies except [Measures] and [Time].
• The list expression

  Filter([Store].[USA].Children, [Measures].[Unit Sales] < 50)

  depends upon all hierarchies except [Store] and [Measures]. How so? Normally the scalar expression would depend upon all hierarchies except [Measures], but the Filter function sets the [Store] context before evaluating the scalar expression, so it is not inherited from the surrounding context.

Specified by:

dependsOn in interface Calc

Overrides:

dependsOn in class AbstractCalc

Parameters:

hierarchy - Hierarchy

Returns:

Whether this expression's result depends upon the current member of the hierarchy

getCalcs

public Calc[] getCalcs()

Description copied from class: AbstractCalc

Returns this expression's child expressions.

Overrides:

getCalcs in class AbstractCalc

constantInteger

public static ConstantCalc constantInteger(int i)

Creates an expression which evaluates to a given integer.

Parameters:

i - Integer value

Returns:

Constant integer expression

constantDouble

public static DoubleCalc constantDouble(double v)

Creates an expression which evaluates to a given double.

Parameters:

v - Double value

Returns:

Constant double expression

constantString

public static StringCalc constantString(String s)

Creates an expression which evaluates to a given string.

Parameters:

s - String value

Returns:

Constant string expression

constantBoolean

public static BooleanCalc constantBoolean(boolean b)

Creates an expression which evaluates to a given boolean.

Parameters:

b - Boolean value

Returns:

Constant boolean expression

constantNull

public static ConstantCalc constantNull(Type type)

Creates an expression which evaluates to null.

Parameters:

type - Type

Returns:

Constant null expression

constantMember

public static Calc constantMember(Member member)

Creates an expression which evaluates to a given member.

Parameters:

member - Member

Returns:

Constant member expression

constantLevel

public static Calc constantLevel(Level level)

Creates an expression which evaluates to a given level.

Parameters:

level - Level

Returns:

Constant level expression

constantHierarchy

public static Calc constantHierarchy(Hierarchy hierarchy)

Creates an expression which evaluates to a given hierarchy.

Parameters:

hierarchy - Hierarchy

Returns:

Constant hierarchy expression

constantDimension

public static Calc constantDimension(Dimension dimension)

Creates an expression which evaluates to a given dimension.

Parameters:

dimension - Dimension

Returns:

Constant dimension expression