Implement bounds and intervalbounds for Center locus with `Date…

…Time` (#846)

* fix intervalbounds for datetime

* fix and test Center DateTime

* cleanup

src/Lookups/lookup_arrays.jl

@@ -223,14 +223,20 @@ _bounds(::ReverseOrdered, ::Intervals, span::Explicit, ::AbstractSampled) =
     (val(span)[1, end], val(span)[2, 1])
 _bounds(::Intervals, span::Regular, lookup::AbstractSampled) =
     _bounds(locus(lookup), order(lookup), span, lookup)
-_bounds(::Start, ::ForwardOrdered, span, lookup) = first(lookup), last(lookup) + step(span)
-_bounds(::Start, ::ReverseOrdered, span, lookup) = last(lookup), first(lookup) - step(span)
-_bounds(::Center, ::ForwardOrdered, span, lookup) =
-    first(lookup) - step(span) / 2, last(lookup) + step(span) / 2
-_bounds(::Center, ::ReverseOrdered, span, lookup) =
-    last(lookup) + step(span) / 2, first(lookup) - step(span) / 2
-_bounds(::End, ::ForwardOrdered, span, lookup) = first(lookup) - step(span), last(lookup)
-_bounds(::End, ::ReverseOrdered, span, lookup) = last(lookup) + step(span), first(lookup)
+_bounds(::Start, ::ForwardOrdered, span::Regular, lookup) = first(lookup), last(lookup) + step(span)
+_bounds(::Start, ::ReverseOrdered, span::Regular, lookup) = last(lookup), first(lookup) - step(span)
+function _bounds(::Center, order::Ordered, span::Regular, lookup)
+    bounds = first(lookup) - step(span) / 2, last(lookup) + step(span) / 2
+    return _maybeflipbounds(order, bounds)
+end
+# DateTime handling
+function _bounds(::Center, order::Ordered, span::Regular, lookup::Lookup{<:Dates.AbstractTime})
+    f, l, s = first(lookup), last(lookup), step(span)
+    bounds = (f - (f - (f - s)) / 2, l - (l - (l + s)) / 2)
+    _maybeflipbounds(order, bounds)
+end
+_bounds(::End, ::ForwardOrdered, span::Regular, lookup) = first(lookup) - step(span), last(lookup)
+_bounds(::End, ::ReverseOrdered, span::Regular, lookup) = last(lookup) + step(span), first(lookup)
 
 
 const SAMPLED_ARGUMENTS_DOC = """
@@ -651,6 +657,11 @@ function intervalbounds(order::Ordered, locus::Center, span::Regular, l::Lookup,
     bounds = (x - halfstep, x + halfstep)
     return _maybeflipbounds(order, bounds)
 end
+function intervalbounds(order::Ordered, locus::Center, span::Regular, l::LookupArray{<:Dates.AbstractTime}, i::Int)
+    x = l[i]
+    bounds = (x - (x - step(span))) / 2 + x, (x - (x + step(span))) / 2 + x
+    return _maybeflipbounds(order, bounds)
+end
 # Irregular Center
 function intervalbounds(order::ForwardOrdered, locus::Center, span::Irregular, l::Lookup, i::Int)
     x = l[i]

test/lookup.jl

@@ -1,4 +1,5 @@
 using DimensionalData, Test, Unitful
+using Dates
 using DimensionalData.Lookups, DimensionalData.Dimensions
 using DimensionalData.Lookups: _slicespan, isrev, _bounds
 using DimensionalData.Dimensions: _slicedims
@@ -112,6 +113,18 @@ end
 @testset "bounds and intervalbounds" begin
     @testset "Intervals" begin
         @testset "Regular bounds are calculated from interval type and span value" begin
+            @testset "Forward Center DateTime" begin
+                ind = DateTime(2000):Month(1):DateTime(2000, 11)
+                dim = format(X(ind; sampling=Intervals(Center())))
+                @test bounds(dim) == (DateTime(1999, 12, 16, 12), DateTime(2000, 11, 16))
+                @test intervalbounds(dim, 3) == (DateTime(2000, 03, 15, 12), DateTime(2000, 02, 14, 12))
+            end
+            @testset "Reverse Center DateTime" begin
+                ind = DateTime(2000, 11):Month(-1):DateTime(2000, 1)
+                dim = format(X(ind; sampling=Intervals(Center())))
+                @test bounds(dim) == (DateTime(1999, 12, 16, 12), DateTime(2000, 11, 16))
+                @test intervalbounds(dim, 3) == (DateTime(2000, 09, 16, 12), DateTime(2000, 08, 17))
+            end
             @testset "forward ind" begin
                 ind = 10.0:10.0:50.0
                 dim = X(Sampled(ind, order=ForwardOrdered(), sampling=Intervals(Start()), span=Regular(10.0)))