"""

A counter of type `T` that increments by one each time it is called.

Optionally, a `min_count` value can be specified from when onwards

this operation changes into the "valid" state. This is useful if

other operations need to first be called multiple times before downstream

operations can start processing, so this operation can be used to signal when

these operations are deemed ready and further processing can begin.

"""

mutable struct Counter{T} <: StreamOperation

counter::T

const min_count::T

Counter(start::T=0; min_count::T=0) where{T} = new{T}(start, min_count)

Counter{T}(; min_count::T=0) where{T} = new{T}(zero(T), min_count)

end

@inline function(op::Counter{T})(args...) where {T}

op.counter += one(T)

nothing

end

@inline is_valid(op::Counter) = op.counter >= op.min_count

@inline function get_state(op::Counter{T})::T where {T}

op.counter

end

@inline function reset!(op::Counter{T}) where {T}

op.counter = zero(T)

nothing

end