Special case maximum/minimum for cached fill vectors (#147)

Project.toml

@@ -1,6 +1,6 @@
 name = "LazyArrays"
 uuid = "5078a376-72f3-5289-bfd5-ec5146d43c02"
-version = "0.19.2"
+version = "0.19.3"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/cache.jl

@@ -363,3 +363,26 @@ copy(a::CachedArray) = CachedArray(copy(a.data), a.array, a.datasize)
 copy(a::Adjoint{<:Any,<:CachedArray}) = copy(parent(a))'
 copy(a::Transpose{<:Any,<:CachedArray}) = transpose(copy(parent(a)))
 
+###
+# special maximum/minimum
+# TODO: when view returns a Fill this can be generalised
+###
+
+
+function maximum(a::CachedVector{<:Any,<:Any,<:AbstractFill})
+    data = cacheddata(a)
+    if length(data) < length(a)
+        max(maximum(data), getindex_value(a.array))
+    else
+        maximum(data)
+    end
+end
+
+function minimum(a::CachedVector{<:Any,<:Any,<:AbstractFill})
+    data = cacheddata(a)
+    if length(data) < length(a)
+        min(minimum(data), getindex_value(a.array))
+    else
+        minimum(data)
+    end
+end

test/cachetests.jl

@@ -317,4 +317,18 @@ import LazyArrays: CachedArray, CachedMatrix, CachedVector, PaddedLayout, Cached
         @test zero!(a) ≡ a
         @test a.datasize == (0,)
     end
+
+    @testset "minimum/maximum" begin
+        c = cache(Fill(2,4));
+        c[1] = 1;
+        @test maximum(c) == 2
+        @test minimum(c) == 1
+        c[1] = 3;
+        @test maximum(c) == 3
+        @test minimum(c) == 2
+        c[1:4] .= 1;
+        @test maximum(c) == 1
+        c[1:4] .= 3;
+        @test minimum(c) == 3
+    end
 end