Add ==(::NullableArray, ::NullableArray) and ==(::NullableArray, ::Ab…

…stractArray)

Fixes JuliaStats#82.

src/primitives.jl

@@ -134,6 +134,59 @@ Returns the last entry of `X`.
 """ ->
 Base.endof(X::NullableArray) = endof(X.values) # -> Int
 
+@doc """
+`==(A::NullableArray, B::NullableArray)`
+`==(A::NullableArray, B::AbstractArray)`
+`==(A::AbstractArray, B::NullableArray)`
+
+Returns `Nullable(true)` if all array elements of the same rank
+are equal and none of the arrays contain missing values, `Nullable(false)`
+if two (non-missing) elements of the same rank differ, and `Nullable{Bool}()`
+otherwise.
+""" ->
+function Base.(:(==))(A::NullableArray, B::NullableArray)
+    if size(A) != size(B)
+        return Nullable(false)
+    end
+    anynull = false
+    for i in eachindex(A,B)
+        if A.isnull[i] || B.isnull[i]
+            anynull = true
+        elseif A.values[i] != B.values[i]
+            return Nullable(false)
+        end
+    end
+    if anynull
+        return Nullable{Bool}()
+    else
+        return Nullable(true)
+    end
+end
+
+function Base.(:(==))(A::NullableArray, B::AbstractArray)
+    if size(A) != size(B)
+        return Nullable(false)
+    end
+    if isa(B, Range)
+        return Nullable(false)
+    end
+    anynull = false
+    for i in eachindex(A,B)
+        if A.isnull[i]
+            anynull = true
+        elseif A.values[i] != B[i]
+            return Nullable(false)
+        end
+    end
+    if anynull
+        return Nullable{Bool}()
+    else
+        return Nullable(true)
+    end
+end
+
+Base.(:(==))(A::AbstractArray, B::NullableArray) = B == A
+
 @doc """
 
 """ ->

test/primitives.jl

@@ -149,6 +149,27 @@ module TestPrimitives
     @test endof(NullableArray(collect(1:10))) == 10
     @test endof(NullableArray([1, 2, nothing, 4, nothing])) == 5
 
+# ----- test Base.== ------------------------------------------------------#
+    x = collect(1:3)
+    xn = NullableArray(x)
+    y = [1.0, 2.0, 3.0]
+    yn = NullableArray(y, [false, false, true])
+    z = [1.1, 2.0, 3.0]
+    zn = NullableArray(z, [false, true, false])
+    @test get(x == NullableArray(x))
+    @test get(y == NullableArray(y))
+    @test get(x != NullableArray(z))
+    @test get(x != yn[1:2])
+    @test get(x != zn[1:2])
+
+    @test isnull(xn == yn)
+    @test get(xn == y)
+    @test isnull(x == yn)
+
+    @test get(xn != zn)
+    @test get(xn != z)
+    @test get(x != zn)
+
 # ----- test Base.find -------------------------------------------------------#
 
     z = NullableArray(rand(Bool, 10))