feat: add TimeRanges iterator for time window operations

src/SpaceDataModel.jl

@@ -33,5 +33,6 @@ const getdim = dim
 
 include("times.jl");        using .Times
 include("timeseries.jl");   using .TimeSeriesAPI
+include("timerange.jl");    export TimeRanges
 
 end

src/timerange.jl

@@ -0,0 +1,21 @@
+abstract type AbstractTimeRanges end
+
+# https://docs.sunpy.org/en/stable/generated/api/sunpy.time.TimeRange.html#sunpy.time.TimeRange.window
+"""An iterator over a series of time ranges that are window long, with a cadence of cadence."""
+struct TimeRanges{T, P1, P2} <: AbstractTimeRanges
+    start::T
+    stop::T
+    cadence::P1
+    window::P2
+end
+
+TimeRanges(t0, t1, cadence = t1 - t0) = TimeRanges(t0, t1, cadence, cadence)
+
+Base.length(iter::TimeRanges) = cld(iter.stop - iter.start, iter.cadence)
+
+function Base.iterate(iter::TimeRanges, current=iter.start)
+    current > iter.stop && return nothing
+    tstop = current + iter.window
+    next_start = current + iter.cadence
+    return (current, tstop), next_start
+end

test/timerange.jl

@@ -0,0 +1,19 @@
+@testitem "TimeRanges" begin
+    using Dates
+    using SpaceDataModel: TimeRanges
+
+    start = DateTime("2010-03-04T00:10:00")
+    stop = DateTime("2010-03-04T01:20:00")
+
+    tranges = TimeRanges(start, stop, Hour(1), Second(12))
+    fragments = collect(tranges)
+
+    @test length(tranges) == 2
+    @test length(fragments) == 2
+
+    @test first(tranges) == fragments[1] == (DateTime("2010-03-04T00:10:00"), DateTime("2010-03-04T00:10:12"))
+    @test fragments[2] == (DateTime("2010-03-04T01:10:00"), DateTime("2010-03-04T01:10:12"))
+
+    tranges = TimeRanges(start, stop)
+    @test length(tranges) == 1
+end