Support comparison operators (pythonnet#1347)

christabella · web-flow · commit e44aa467e21c · 2021-01-12T09:33:00.000-08:00
diff --git a/src/embed_tests/TestOperator.cs b/src/embed_tests/TestOperator.cs
@@ -25,6 +25,17 @@ public class OperableObject
         {
             public int Num { get; set; }
 
+            public override int GetHashCode()
+            {
+                return unchecked(159832395 + Num.GetHashCode());
+            }
+
+            public override bool Equals(object obj)
+            {
+                return obj is OperableObject @object &&
+                       Num == @object.Num;
+            }
+
             public OperableObject(int num)
             {
                 Num = num;
@@ -149,6 +160,103 @@ public OperableObject(int num)
                 return new OperableObject(a.Num ^ b);
             }
 
+            public static bool operator ==(int a, OperableObject b)
+            {
+                return (a == b.Num);
+            }
+            public static bool operator ==(OperableObject a, OperableObject b)
+            {
+                return (a.Num == b.Num);
+            }
+            public static bool operator ==(OperableObject a, int b)
+            {
+                return (a.Num == b);
+            }
+
+            public static bool operator !=(int a, OperableObject b)
+            {
+                return (a != b.Num);
+            }
+            public static bool operator !=(OperableObject a, OperableObject b)
+            {
+                return (a.Num != b.Num);
+            }
+            public static bool operator !=(OperableObject a, int b)
+            {
+                return (a.Num != b);
+            }
+
+            public static bool operator <=(int a, OperableObject b)
+            {
+                return (a <= b.Num);
+            }
+            public static bool operator <=(OperableObject a, OperableObject b)
+            {
+                return (a.Num <= b.Num);
+            }
+            public static bool operator <=(OperableObject a, int b)
+            {
+                return (a.Num <= b);
+            }
+
+            public static bool operator >=(int a, OperableObject b)
+            {
+                return (a >= b.Num);
+            }
+            public static bool operator >=(OperableObject a, OperableObject b)
+            {
+                return (a.Num >= b.Num);
+            }
+            public static bool operator >=(OperableObject a, int b)
+            {
+                return (a.Num >= b);
+            }
+
+            public static bool operator >=(OperableObject a, PyObject b)
+            {
+                using (Py.GIL())
+                {
+                    // Assuming b is a tuple, take the first element.
+                    int bNum = b[0].As<int>();
+                    return a.Num >= bNum;
+                }
+            }
+            public static bool operator <=(OperableObject a, PyObject b)
+            {
+                using (Py.GIL())
+                {
+                    // Assuming b is a tuple, take the first element.
+                    int bNum = b[0].As<int>();
+                    return a.Num <= bNum;
+                }
+            }
+
+            public static bool operator <(int a, OperableObject b)
+            {
+                return (a < b.Num);
+            }
+            public static bool operator <(OperableObject a, OperableObject b)
+            {
+                return (a.Num < b.Num);
+            }
+            public static bool operator <(OperableObject a, int b)
+            {
+                return (a.Num < b);
+            }
+
+            public static bool operator >(int a, OperableObject b)
+            {
+                return (a > b.Num);
+            }
+            public static bool operator >(OperableObject a, OperableObject b)
+            {
+                return (a.Num > b.Num);
+            }
+            public static bool operator >(OperableObject a, int b)
+            {
+                return (a.Num > b);
+            }
+
             public static OperableObject operator <<(OperableObject a, int offset)
             {
                 return new OperableObject(a.Num << offset);
@@ -161,7 +269,7 @@ public OperableObject(int num)
         }
 
         [Test]
-        public void OperatorOverloads()
+        public void SymmetricalOperatorOverloads()
         {
             string name = string.Format("{0}.{1}",
                 typeof(OperableObject).DeclaringType.Name,
@@ -206,6 +314,24 @@ public void OperatorOverloads()
 
 c = a ^ b
 assert c.Num == a.Num ^ b.Num
+
+c = a == b
+assert c == (a.Num == b.Num)
+
+c = a != b
+assert c == (a.Num != b.Num)
+
+c = a <= b
+assert c == (a.Num <= b.Num)
+
+c = a >= b
+assert c == (a.Num >= b.Num)
+
+c = a < b
+assert c == (a.Num < b.Num)
+
+c = a > b
+assert c == (a.Num > b.Num)
 ");
         }
 
@@ -263,6 +389,51 @@ public void ForwardOperatorOverloads()
 
 c = a ^ b
 assert c.Num == a.Num ^ b
+
+c = a == b
+assert c == (a.Num == b)
+
+c = a != b
+assert c == (a.Num != b)
+
+c = a <= b
+assert c == (a.Num <= b)
+
+c = a >= b
+assert c == (a.Num >= b)
+
+c = a < b
+assert c == (a.Num < b)
+
+c = a > b
+assert c == (a.Num > b)
+");
+        }
+
+        [Test]
+        public void TupleComparisonOperatorOverloads()
+        {
+                string name = string.Format("{0}.{1}",
+                typeof(OperableObject).DeclaringType.Name,
+                typeof(OperableObject).Name);
+            string module = MethodBase.GetCurrentMethod().DeclaringType.Namespace;
+                PythonEngine.Exec($@"
+from {module} import *
+cls = {name}
+a = cls(2)
+b = (1, 2)
+
+c = a >= b
+assert c == (a.Num >= b[0])
+
+c = a <= b
+assert c == (a.Num <= b[0])
+
+c = b >= a
+assert c == (b[0] >= a.Num)
+
+c = b <= a
+assert c == (b[0] <= a.Num)
 ");
         }
 
@@ -304,6 +475,24 @@ public void ReverseOperatorOverloads()
 
 c = a ^ b
 assert c.Num == a ^ b.Num
+
+c = a == b
+assert c == (a == b.Num)
+
+c = a != b
+assert c == (a != b.Num)
+
+c = a <= b
+assert c == (a <= b.Num)
+
+c = a >= b
+assert c == (a >= b.Num)
+
+c = a < b
+assert c == (a < b.Num)
+
+c = a > b
+assert c == (a > b.Num)
 ");
 
         }
diff --git a/src/runtime/classbase.cs b/src/runtime/classbase.cs
@@ -21,6 +21,7 @@ internal class ClassBase : ManagedType
         [NonSerialized]
         internal List<string> dotNetMembers;
         internal Indexer indexer;
+        internal Dictionary<int, MethodObject> richcompare;
         internal MaybeType type;
 
         internal ClassBase(Type tp)
@@ -35,6 +36,15 @@ internal virtual bool CanSubclass()
             return !type.Value.IsEnum;
         }
 
+        public readonly static Dictionary<string, int> CilToPyOpMap = new Dictionary<string, int>
+        {
+            ["op_Equality"] = Runtime.Py_EQ,
+            ["op_Inequality"] = Runtime.Py_NE,
+            ["op_LessThanOrEqual"] = Runtime.Py_LE,
+            ["op_GreaterThanOrEqual"] = Runtime.Py_GE,
+            ["op_LessThan"] = Runtime.Py_LT,
+            ["op_GreaterThan"] = Runtime.Py_GT,
+        };
 
         /// <summary>
         /// Default implementation of [] semantics for reflected types.
@@ -72,6 +82,30 @@ public static IntPtr tp_richcompare(IntPtr ob, IntPtr other, int op)
         {
             CLRObject co1;
             CLRObject co2;
+            IntPtr tp = Runtime.PyObject_TYPE(ob);
+            var cls = (ClassBase)GetManagedObject(tp);
+            // C# operator methods take precedence over IComparable.
+            // We first check if there's a comparison operator by looking up the richcompare table,
+            // otherwise fallback to checking if an IComparable interface is handled.
+            if (cls.richcompare.TryGetValue(op, out var methodObject))
+            {
+                // Wrap the `other` argument of a binary comparison operator in a PyTuple.
+                IntPtr args = Runtime.PyTuple_New(1);
+                Runtime.XIncref(other);
+                Runtime.PyTuple_SetItem(args, 0, other);
+
+                IntPtr value;
+                try
+                {
+                    value = methodObject.Invoke(ob, args, IntPtr.Zero);
+                }
+                finally
+                {
+                    Runtime.XDecref(args);  // Free args pytuple
+                }
+                return value;
+            }
+
             switch (op)
             {
                 case Runtime.Py_EQ:
diff --git a/src/runtime/classmanager.cs b/src/runtime/classmanager.cs
@@ -259,6 +259,7 @@ private static void InitClassBase(Type type, ClassBase impl)
             ClassInfo info = GetClassInfo(type);
 
             impl.indexer = info.indexer;
+            impl.richcompare = new Dictionary<int, MethodObject>();
 
             // Now we allocate the Python type object to reflect the given
             // managed type, filling the Python type slots with thunks that
@@ -284,6 +285,9 @@ private static void InitClassBase(Type type, ClassBase impl)
                 Runtime.PyDict_SetItemString(dict, name, item.pyHandle);
                 // Decref the item now that it's been used.
                 item.DecrRefCount();
+                if (ClassBase.CilToPyOpMap.TryGetValue(name, out var pyOp)) {
+                    impl.richcompare.Add(pyOp, (MethodObject)item);
+                }
             }
 
             // If class has constructors, generate an __doc__ attribute.
@@ -553,8 +557,7 @@ private static ClassInfo GetClassInfo(Type type)
                 {
                     string pyName = OperatorMethod.GetPyMethodName(name);
                     string pyNameReverse = OperatorMethod.ReversePyMethodName(pyName);
-                    MethodInfo[] forwardMethods, reverseMethods;
-                    OperatorMethod.FilterMethods(mlist, out forwardMethods, out reverseMethods);
+                    OperatorMethod.FilterMethods(mlist, out var forwardMethods, out var reverseMethods);
                     // Only methods where the left operand is the declaring type.
                     if (forwardMethods.Length > 0)
                         ci.members[pyName] = new MethodObject(type, name, forwardMethods);
diff --git a/src/runtime/methodbinder.cs b/src/runtime/methodbinder.cs
@@ -354,16 +354,17 @@ internal Binding Bind(IntPtr inst, IntPtr args, IntPtr kw, MethodBase info, Meth
                 int kwargsMatched;
                 int defaultsNeeded;
                 bool isOperator = OperatorMethod.IsOperatorMethod(mi);
-                int clrnargs = pi.Length;
                 // Binary operator methods will have 2 CLR args but only one Python arg
                 // (unary operators will have 1 less each), since Python operator methods are bound.
-                isOperator = isOperator && pynargs == clrnargs - 1;
+                isOperator = isOperator && pynargs == pi.Length - 1;
+                bool isReverse = isOperator && OperatorMethod.IsReverse((MethodInfo)mi);  // Only cast if isOperator.
+                if (isReverse && OperatorMethod.IsComparisonOp((MethodInfo)mi))
+                    continue;  // Comparison operators in Python have no reverse mode.
                 if (!MatchesArgumentCount(pynargs, pi, kwargDict, out paramsArray, out defaultArgList, out kwargsMatched, out defaultsNeeded) && !isOperator)
                 {
                     continue;
                 }
                 // Preprocessing pi to remove either the first or second argument.
-                bool isReverse = isOperator && OperatorMethod.IsReverse((MethodInfo)mi);  // Only cast if isOperator.
                 if (isOperator && !isReverse) {
                     // The first Python arg is the right operand, while the bound instance is the left.
                     // We need to skip the first (left operand) CLR argument.
diff --git a/src/runtime/operatormethod.cs b/src/runtime/operatormethod.cs
