LiveAggregate Method

LiveAggregate<TSource>(View<TSource>, Expression<Func<TSource, TSource, TSource>>, Expression<Func<TSource, TSource, TSource>>, Expression<Func<TSource, TSource, bool>>)

Applies an accumulator function over a view.

Declaration

public static AggregationView<TSource, TSource> LiveAggregate<TSource>(this View<TSource> source, Expression<Func<TSource, TSource, TSource>> funcAdd, Expression<Func<TSource, TSource, TSource>> funcRemove, Expression<Func<TSource, TSource, bool>> funcRemoveDefined)

Public Shared Function LiveAggregate(Of TSource)(source As View(Of TSource), funcAdd As Expression(Of Func(Of TSource, TSource, TSource)), funcRemove As Expression(Of Func(Of TSource, TSource, TSource)), funcRemoveDefined As Expression(Of Func(Of TSource, TSource, Boolean))) As AggregationView(Of TSource, TSource)

Parameters

Type	Name	Description
View<TSource>	source	A view to aggregate over.
Expression<Func<TSource, TSource, TSource>>	funcAdd	An accumulator function to be invoked on each element that is added to the source view.
Expression<Func<TSource, TSource, TSource>>	funcRemove	A function to be applied to the accumulated value and to an element to obtain the changed accumulated value, when an element is removed from the source view.
Expression<Func<TSource, TSource, bool>>	funcRemoveDefined	A function used to determine whether funcRemove must be applied when an element is removed from the source view, or the accumulated value is not affected by its removal.

Returns

Type	Description
AggregationView<TSource, TSource>	A view representing the final accumulator value.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

It is possible to use standard LINQ query operator Aggregate instead of LiveAggregate. Both are "live" in the sense that they are recomputed automatically when any change occurs in the source. The difference is that Aggregate will every time loop through the entire source collection and aggregate it from scratch, whereas LiveAggregate will use a more performant algorithm, will maintain its value incrementally, processing only those source items that actually changed.

LiveAggregate<TSource, TAccumulate>(View<TSource>, TAccumulate, Expression<Func<TAccumulate, TSource, TAccumulate>>, Expression<Func<TAccumulate, TSource, TAccumulate>>, Expression<Func<TAccumulate, TSource, bool>>)

Applies an accumulator function over a view. The specified seed value is used as the initial accumulator value.

Declaration

public static AggregationView<TSource, TAccumulate> LiveAggregate<TSource, TAccumulate>(this View<TSource> source, TAccumulate seed, Expression<Func<TAccumulate, TSource, TAccumulate>> funcAdd, Expression<Func<TAccumulate, TSource, TAccumulate>> funcRemove, Expression<Func<TAccumulate, TSource, bool>> funcRemoveDefined)

Public Shared Function LiveAggregate(Of TSource, TAccumulate)(source As View(Of TSource), seed As TAccumulate, funcAdd As Expression(Of Func(Of TAccumulate, TSource, TAccumulate)), funcRemove As Expression(Of Func(Of TAccumulate, TSource, TAccumulate)), funcRemoveDefined As Expression(Of Func(Of TAccumulate, TSource, Boolean))) As AggregationView(Of TSource, TAccumulate)

Parameters

Type	Name	Description
View<TSource>	source	A view to aggregate over.
TAccumulate	seed	The initial accumulator value.
Expression<Func<TAccumulate, TSource, TAccumulate>>	funcAdd	An accumulator function to be invoked on each element that is added to the source view.
Expression<Func<TAccumulate, TSource, TAccumulate>>	funcRemove	A function to be applied to the accumulated value and to an element to obtain the changed accumulated value, when an element is removed from the source view.
Expression<Func<TAccumulate, TSource, bool>>	funcRemoveDefined	A function used to determine whether funcRemove must be applied when an element is removed from the source view, or the accumulated value is not affected by its removal.

Returns

Type	Description
AggregationView<TSource, TAccumulate>	A view representing the final accumulator value.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TAccumulate	The type of the accumulator value.

Remarks

LiveAggregate<TSource, TAccumulate, TResult>(View<TSource>, TAccumulate, Expression<Func<TAccumulate, TSource, TAccumulate>>, Expression<Func<TAccumulate, TSource, TAccumulate>>, Expression<Func<TAccumulate, TSource, bool>>, Expression<Func<TAccumulate, TResult>>)

Applies an accumulator function over a view. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value.

Declaration

public static AggregationView<TSource, TResult> LiveAggregate<TSource, TAccumulate, TResult>(this View<TSource> source, TAccumulate seed, Expression<Func<TAccumulate, TSource, TAccumulate>> funcAdd, Expression<Func<TAccumulate, TSource, TAccumulate>> funcRemove, Expression<Func<TAccumulate, TSource, bool>> funcRemoveDefined, Expression<Func<TAccumulate, TResult>> resultSelector)

Public Shared Function LiveAggregate(Of TSource, TAccumulate, TResult)(source As View(Of TSource), seed As TAccumulate, funcAdd As Expression(Of Func(Of TAccumulate, TSource, TAccumulate)), funcRemove As Expression(Of Func(Of TAccumulate, TSource, TAccumulate)), funcRemoveDefined As Expression(Of Func(Of TAccumulate, TSource, Boolean)), resultSelector As Expression(Of Func(Of TAccumulate, TResult))) As AggregationView(Of TSource, TResult)

Parameters

Type	Name	Description
View<TSource>	source	A view to aggregate over.
TAccumulate	seed	The initial accumulator value.
Expression<Func<TAccumulate, TSource, TAccumulate>>	funcAdd	An accumulator function to be invoked on each element that is added to the source view.
Expression<Func<TAccumulate, TSource, TAccumulate>>	funcRemove	A function to be applied to the accumulated value and to an element to obtain the changed accumulated value, when an element is removed from the source view.
Expression<Func<TAccumulate, TSource, bool>>	funcRemoveDefined	A function used to determine whether funcRemove must be applied when an element is removed from the source view, or the accumulated value is not affected by its removal.
Expression<Func<TAccumulate, TResult>>	resultSelector	A function to transform the final accumulator value into the result value.

Returns

Type	Description
AggregationView<TSource, TResult>	A view representing the final accumulator value.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TAccumulate	The type of the accumulator value.
TResult	The type of the resulting value.