preliminary support for native float subclasses in float constructor

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/BuiltinConstructors.java

@@ -60,6 +60,7 @@
 import com.oracle.graal.python.builtins.CoreFunctions;
 import com.oracle.graal.python.builtins.PythonBuiltinClassType;
 import com.oracle.graal.python.builtins.PythonBuiltins;
+import com.oracle.graal.python.builtins.modules.BuiltinConstructorsFactory.FloatNodeFactory;
 import com.oracle.graal.python.builtins.objects.PEllipsis;
 import com.oracle.graal.python.builtins.objects.PNone;
 import com.oracle.graal.python.builtins.objects.PNotImplemented;
@@ -68,6 +69,10 @@
 import com.oracle.graal.python.builtins.objects.bytes.PBytes;
 import com.oracle.graal.python.builtins.objects.bytes.PIBytesLike;
 import com.oracle.graal.python.builtins.objects.cell.PCell;
+import com.oracle.graal.python.builtins.objects.cext.CExtNodes.FromNativeSubclassNode;
+import com.oracle.graal.python.builtins.objects.cext.NativeCAPISymbols;
+import com.oracle.graal.python.builtins.objects.cext.PythonNativeClass;
+import com.oracle.graal.python.builtins.objects.cext.PythonNativeObject;
 import com.oracle.graal.python.builtins.objects.common.HashingStorage.DictEntry;
 import com.oracle.graal.python.builtins.objects.common.HashingStorageNodes;
 import com.oracle.graal.python.builtins.objects.complex.PComplex;
@@ -478,6 +483,21 @@ Object doPythonObject(PythonClass cls, PythonObject obj,
             }
         }
 
+        protected static FromNativeSubclassNode cacheGetFloat() {
+            return FromNativeSubclassNode.create(PythonBuiltinClassType.PFloat, NativeCAPISymbols.FUN_PY_FLOAT_AS_DOUBLE);
+        }
+
+        @Specialization
+        Object doNativeFloat(PythonNativeClass cls, PythonNativeObject possibleBase,
+                        @Cached("cacheGetFloat()") FromNativeSubclassNode getFloat) {
+            Object convertedFloat = getFloat.execute(possibleBase);
+            if (convertedFloat instanceof Double) {
+                return possibleBase; // TODO (tfel): we really need to call back into C
+            } else {
+                throw raise(TypeError, "must be real number, not %p", possibleBase);
+            }
+        }
+
         @Fallback
         @TruffleBoundary
         public Object floatFromObject(@SuppressWarnings("unused") Object cls, Object arg) {