bpo-43753: Add Py_Is() and Py_IsNone() functions (GH-25227)

Add the Py_Is(x, y) function to test if the 'x' object is the 'y'
object, the same as "x is y" in Python. Add also the Py_IsNone(),
Py_IsTrue(), Py_IsFalse() functions to test if an object is,
respectively, the None singleton, the True singleton or the False
singleton.

1 files changed, 9 insertions, 0 deletions

diff --git a/Include/object.h b/Include/object.h
index 3138db0..695f015 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -122,6 +122,11 @@ typedef struct {
 #define _PyVarObject_CAST_CONST(op) ((const PyVarObject*)(op))
 
 
+// Test if the 'x' object is the 'y' object, the same as "x is y" in Python.
+PyAPI_FUNC(int) Py_Is(PyObject *x, PyObject *y);
+#define Py_Is(x, y) ((x) == (y))
+
+
 static inline Py_ssize_t _Py_REFCNT(const PyObject *ob) {
     return ob->ob_refcnt;
 }
@@ -586,6 +591,10 @@ Don't forget to apply Py_INCREF() when returning this value!!!
 PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */
 #define Py_None (&_Py_NoneStruct)
 
+// Test if an object is the None singleton, the same as "x is None" in Python.
+PyAPI_FUNC(int) Py_IsNone(PyObject *x);
+#define Py_IsNone(x) Py_Is((x), Py_None)
+
 /* Macro for returning Py_None from a function */
 #define Py_RETURN_NONE return Py_NewRef(Py_None)