Class ExpressionHelper

Supports the calculations of expressions and summaries on an IEnumerable object. See the InitSummaryLibrary and InitFunctionLibrary methods to see the code for adding support for specific summaries and functions. Summaries are aggregation calculations applied to IEnumerable lists (e.g, StdDev), and functions are calculation applied to singular objects, usually members of an IEnumerable list (e.g, Cos).

Inheritance

System.Object

ExpressionHelper

Inherited Members

System.Object.ToString()

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

Namespace: Syncfusion.Olap.Engine.CalculationColumn

Assembly: Syncfusion.Olap.Base.dll

Syntax

public class ExpressionHelper

Constructors

ExpressionHelper()

Declaration

public ExpressionHelper()

Properties

CaseSensitive

Gets or sets a value indicating whether the case is considered while parsing formulas.

Declaration

public bool CaseSensitive { get; set; }

Property Value

Type	Description
System.Boolean

Error

Gets the error result from the most recent calculation.

Declaration

public ExpressionError Error { get; }

Property Value

Type	Description
ExpressionError

ErrorString

Gets the description of the most recent calculation.

Declaration

public string ErrorString { get; }

Property Value

Type	Description
System.String

ListSeparator

Gets or sets the list separator.

Declaration

public static char ListSeparator { get; set; }

Property Value

Type	Description
System.Char	The list separator.

QuoteMark

Gets or sets the quote mark.

Declaration

public static char QuoteMark { get; set; }

Property Value

Type	Description
System.Char	The quote mark.

Methods

AddExpression(String, String)

Adds a visible expression column displaying the passed-in expression.

Declaration

public bool AddExpression(string name, string expression)

Parameters

Type	Name	Description
System.String	name	The mapping name for the added column.
System.String	expression	The expression.

Returns

Type	Description
System.Boolean	True if a column was added.

AddExpression(String, String, Boolean)

Adds an expression.

Declaration

public bool AddExpression(string name, string expression, bool showInGrid)

Parameters

Type	Name	Description
System.String	name	The name of the expression.
System.String	expression	The expression.
System.Boolean	showInGrid	Indicates whether a visible column should be added to the underlying grid.

Returns

Type	Description
System.Boolean	True if expression was added.

AddFunction(String, LambdaExpression)

Adds a function calculation.

Declaration

public bool AddFunction(string name, LambdaExpression exp)

Parameters

Type	Name	Description
System.String	name	The name of the function.
System.Linq.Expressions.LambdaExpression	exp	The expression defining the function.

Returns

Type	Description
System.Boolean	True if the function is added.

AddNamedConstant(String, Object)

Adds the named constant.

Declaration

public void AddNamedConstant(string name, object value)

Parameters

Type	Name	Description
System.String	name	The name.
System.Object	value	The value.

AddSummary(String, LambdaExpression)

Adds a summary calculation to the SummaryLibrary.

Declaration

public bool AddSummary(string name, LambdaExpression exp)

Parameters

Type	Name	Description
System.String	name	The name of the summary calculation.
System.Linq.Expressions.LambdaExpression	exp	LambdaExpression defining the summary calculation.

Returns

Type	Description
System.Boolean	True if the summary was added.

ChangeExpression(String, String)

Changes an expression.

Declaration

public bool ChangeExpression(string name, string expression)

Parameters

Type	Name	Description
System.String	name	The name of the expression to be changed.
System.String	expression	The expression.

Returns

Type	Description
System.Boolean	True if the change was done.

ChangeNamedConstant(String, Object)

Changes the named constant.

Declaration

public void ChangeNamedConstant(string name, object newValue)

Parameters

Type	Name	Description
System.String	name	The name.
System.Object	newValue	The new value.

Clear()

Clears all expressions.

Declaration

public bool Clear()

Returns

Type	Description
System.Boolean	True if all the expressions are removed.

ClearNamedConstants()

Clears the named constants.

Declaration

public void ClearNamedConstants()

ComputeCount(IEnumerable)

Returns the number of items in a given list.

Declaration

public static int ComputeCount(IEnumerable list)

Parameters

Type	Name	Description
System.Collections.IEnumerable	list	A list of items.

Returns

Type	Description
System.Int32	The number of items in the list.

ComputeMaximum(IEnumerable)

Computes the maximum value in the given list.

Declaration

public static double ComputeMaximum(IEnumerable list)

Parameters

Type	Name	Description
System.Collections.IEnumerable	list	A list containing numeric values.

Returns

Type	Description
System.Double	The maximum value.

ComputeMinimum(IEnumerable)

Computes the minimum value for a given list.

Declaration

public static double ComputeMinimum(IEnumerable list)

Parameters

Type	Name	Description
System.Collections.IEnumerable	list	A list of numeric values.

Returns

Type	Description
System.Double	The minimum value.

ComputeStdDev(IEnumerable)

Returns the sample standard deviation of a list of values.

Declaration

public static double ComputeStdDev(IEnumerable list)

Parameters

Type	Name	Description
System.Collections.IEnumerable	list	The list of numeric values.

Returns

Type	Description
System.Double	The standard deviation of the list of numbers.

ComputeSum(IEnumerable)

Computes the sum of the values in a given list.

Declaration

public static double ComputeSum(IEnumerable list)

Parameters

Type	Name	Description
System.Collections.IEnumerable	list	A list of numeric values.

Returns

Type	Description
System.Double	The sum.

ComputeSummary(String, IEnumerable)

Computes a summary calculation.

Declaration

public object ComputeSummary(string summaryFormula, IEnumerable dataSource)

Parameters

Type	Name	Description
System.String	summaryFormula	The summary formula.
System.Collections.IEnumerable	dataSource	The data source.

Returns

Type	Description
System.Object

GetComputedValue(ExpressionHelper, String, Object)

Gets the value of an expression for the given item.

Declaration

public static object GetComputedValue(ExpressionHelper helper, string expressionName, object item)

Parameters

Type	Name	Description
ExpressionHelper	helper	The expression helper.
System.String	expressionName	The name of the expression.
System.Object	item	The item for which the expression is to be evaluated.

Returns

Type	Description
System.Object	The computed expression.

InitFunctionLibrary()

Initializes the default function library.

Declaration

public virtual void InitFunctionLibrary()

InitSummaryLibrary()

Initializes the default summary library.

Declaration

public virtual void InitSummaryLibrary()

IsExpressionName(String)

Gets a value indicating whether the specified string is the name of an expression.

Declaration

public bool IsExpressionName(string expressionName)

Parameters

Type	Name	Description
System.String	expressionName	The name of the expression.

Returns

Type	Description
System.Boolean	True if there is an expression with this name.

IsNamedConstant(String)

Determines whether the specified name is named constant.

Declaration

public bool IsNamedConstant(string name)

Parameters

Type	Name	Description
System.String	name	The name.

Returns

Type	Description
System.Boolean

RemoveExpression(String)

Removes an expression.

Declaration

public bool RemoveExpression(string name)

Parameters

Type	Name	Description
System.String	name	The name of the expression to be removed.

Returns

Type	Description
System.Boolean	True if the expression was removed.

RemoveFunction(String, LambdaExpression)

Removes a function calculation.

Declaration

public bool RemoveFunction(string name, LambdaExpression exp)

Parameters

Type	Name	Description
System.String	name	The name of the function.
System.Linq.Expressions.LambdaExpression	exp	The expression defining the function.

Returns

Type	Description
System.Boolean	True if the function is removed.

RemoveNamedConstant(String, Object)

Removes the named constant.

Declaration

public void RemoveNamedConstant(string name, object value)

Parameters

Type	Name	Description
System.String	name	The name.
System.Object	value	The value.

RemoveSummary(String, LambdaExpression)

Removes a summary from the summary library.

Declaration

public bool RemoveSummary(string name, LambdaExpression exp)

Parameters

Type	Name	Description
System.String	name	The name of the expression to be removed.
System.Linq.Expressions.LambdaExpression	exp	The expression to be removed.

Returns

Type	Description
System.Boolean	True if the removal was done.