Add generic isnull, unsafe_get methods

Author: davidagold

base/exports.jl

@@ -1324,6 +1324,7 @@ export
 
 # nullable types
     isnull,
+    unsafe_get,
 
 # Macros
     # parser internal

base/nullable.jl

@@ -61,7 +61,11 @@ end
 
 get(x::Nullable) = x.isnull ? throw(NullException()) : x.value
 
+unsafe_get(x::Nullable) = x.value
+unsafe_get(x) = x
+
 isnull(x::Nullable) = x.isnull
+isnull(x) = false
 
 
 ## Operators

test/nullable.jl

@@ -161,6 +161,33 @@ for T in types
     @test get(x3, zero(T)) === one(T)
 end
 
+# unsafe_get(x::Nullable)
+for T in types
+    x1 = Nullable{T}()
+    x2 = Nullable(zero(T))
+    x3 = Nullable(one(T))
+    a = rand(T)
+    x4 = Nullable(a)
+
+    @test isa(unsafe_get(x1), T)
+    @test unsafe_get(x2) === zero(T)
+    @test unsafe_get(x3) === one(T)
+    @test unsafe_get(x4) === a
+end
+
+@test_throws UndefRefError unsafe_get(Nullable())
+
+# unsafe_get(x)
+for T in types
+    x2 = zero(T)
+    x3 = one(T)
+    x4 = rand(T)
+
+    @test unsafe_get(x2) === zero(T)
+    @test unsafe_get(x3) === one(T)
+    @test unsafe_get(x4) === x4
+end
+
 # isnull(x::Nullable)
 for T in types
     x1 = Nullable{T}()
@@ -174,6 +201,17 @@ end
 
 @test isnull(Nullable())
 
+# isnull(x)
+for T in types
+    x1 = zero(T)
+    x2 = one(T)
+    x3 = rand(T)
+
+    @test isnull(x1) === false
+    @test isnull(x2) === false
+    @test isnull(x3) === false
+end
+
 # function =={S, T}(x::Nullable{S}, y::Nullable{T})
 for T in types
     x0 = Nullable()