Re-enable std.typecons.Nullable and NullableRef

std/typecons.d

@@ -1109,11 +1109,9 @@ unittest
     assert(y == 5);
 }
 
-/+
-
 /**
 Defines a value paired with a distinctive "null" state that denotes
-the absence of a valud value. If default constructed, a $(D
+the absence of a value. If default constructed, a $(D
 Nullable!T) object starts in the null state. Assigning it renders it
 non-null. Calling $(D nullify) can nullify it again.
 
@@ -1145,7 +1143,7 @@ Constructor initializing $(D this) with $(D value).
 /**
 Returns $(D true) if and only if $(D this) is in the null state.
  */
-    bool isNull()
+    @property bool isNull() const
     {
         return _isNull;
     }
@@ -1155,8 +1153,7 @@ Forces $(D this) to the null state.
  */
     void nullify()
     {
-        // destroy
-        //static if (is(typeof(_value.__dtor()))) _value.__dtor();
+        clear(_value);
         _isNull = true;
     }
 
@@ -1175,7 +1172,14 @@ Gets the value. Throws an exception if $(D this) is in the null
 state. This function is also called for the implicit conversion to $(D
 T).
  */
-    ref T get()
+    @property ref T get()
+    {
+        enforce(!isNull);
+        return _value;
+    }
+    //@@@BUG3748@@@: inout does not work properly.
+    //               need to define a separate 'const' version
+    @property ref const(T) get() const
     {
         enforce(!isNull);
         return _value;
@@ -1192,9 +1196,55 @@ unittest
 {
     Nullable!int a;
     assert(a.isNull);
+    assertThrown(a.get);
     a = 5;
     assert(!a.isNull);
     assert(a == 5);
+    //@@@BUG5188@@@
+    //assert(a != 3);
+    assert(a.get != 3);
+    a.nullify();
+    assert(a.isNull);
+    a = 3;
+    assert(a == 3);
+    a *= 6;
+    assert(a == 18);
+    a.nullify();
+    assertThrown(a += 2);
+}
+unittest
+{
+    auto k = Nullable!int(74);
+    assert(k == 74);
+    k.nullify();
+    assert(k.isNull);
+}
+unittest
+{
+    static int f(in Nullable!int x) {
+        return x.isNull ? 42 : x.get;
+    }
+    Nullable!int a;
+    assert(f(a) == 42);
+    a = 8;
+    assert(f(a) == 8);
+    a.nullify();
+    assert(f(a) == 42);
+}
+unittest
+{
+    static struct S { int x; }
+    Nullable!S s;
+    assert(s.isNull);
+    s = S(6);
+    assert(s == S(6));
+    //@@@BUG5188@@@
+    //assert(s != S(0));
+    assert(s.get != S(0));
+    s.x = 9190;
+    assert(s.x == 9190);
+    s.nullify();
+    assertThrown(s.x = 9441);
 }
 
 /**
@@ -1219,7 +1269,7 @@ Constructor initializing $(D this) with $(D value).
 /**
 Returns $(D true) if and only if $(D this) is in the null state.
  */
-    bool isNull()
+    @property bool isNull() const
     {
         return _value == nullValue;
     }
@@ -1246,7 +1296,13 @@ Gets the value. Throws an exception if $(D this) is in the null
 state. This function is also called for the implicit conversion to $(D
 T).
  */
-    ref T get()
+    @property ref T get()
+    {
+        enforce(!isNull);
+        return _value;
+    }
+    //@@@BUG3748@@@
+    @property ref const(T) get() const
     {
         enforce(!isNull);
         return _value;
@@ -1263,9 +1319,30 @@ unittest
 {
     Nullable!(int, int.min) a;
     assert(a.isNull);
+    assertThrown(a.get);
     a = 5;
     assert(!a.isNull);
     assert(a == 5);
+    static assert(a.sizeof == int.sizeof);
+}
+unittest
+{
+    auto a = Nullable!(int, int.min)(8);
+    assert(a == 8);
+    a.nullify();
+    assert(a.isNull);
+}
+unittest
+{
+    static int f(in Nullable!(int, int.min) x) {
+        return x.isNull ? 42 : x.get;
+    }
+    Nullable!(int, int.min) a;
+    assert(f(a) == 42);
+    a = 8;
+    assert(f(a) == 8);
+    a.nullify();
+    assert(f(a) == 42);
 }
 
 /**
@@ -1297,7 +1374,7 @@ Binds the internal state to $(D value).
 /**
 Returns $(D true) if and only if $(D this) is in the null state.
  */
-    bool isNull()
+    @property bool isNull() const
     {
         return _value is null;
     }
@@ -1324,7 +1401,13 @@ Gets the value. Throws an exception if $(D this) is in the null
 state. This function is also called for the implicit conversion to $(D
 T).
  */
-    ref T get()
+    @property ref T get()
+    {
+        enforce(!isNull);
+        return *_value;
+    }
+    //@@@BUG3748@@@
+    @property ref const(T) get() const
     {
         enforce(!isNull);
         return *_value;
@@ -1339,17 +1422,36 @@ the null state.
 
 unittest
 {
-    int x = 5;
+    int x = 5, y = 7;
     auto a = NullableRef!(int)(&x);
     assert(!a.isNull);
     assert(a == 5);
+    assert(x == 5);
     a = 42;
+    assert(x == 42);
     assert(!a.isNull);
     assert(a == 42);
+    a.nullify();
+    assert(x == 42);
+    assert(a.isNull);
+    assertThrown(a.get);
+    assertThrown(a = 71);
+    a.bind(&y);
+    assert(a == 7);
+    y = 135;
+    assert(a == 135);
+}
+unittest
+{
+    static int f(in NullableRef!int x) {
+        return x.isNull ? 42 : x.get;
+    }
+    int x = 5;
+    auto a = NullableRef!int(&x);
+    assert(f(a) == 5);
+    a.nullify();
+    assert(f(a) == 42);
 }
-
-+/
-
 
 /**
 $(D BlackHole!Base) is a subclass of $(D Base) which automatically implements