Implement PEP 238 in its (almost) full glory.

This introduces:

- A new operator // that means floor division (the kind of division
  where 1/2 is 0).

- The "future division" statement ("from __future__ import division)
  which changes the meaning of the / operator to implement "true
  division" (where 1/2 is 0.5).

- New overloadable operators __truediv__ and __floordiv__.

- New slots in the PyNumberMethods struct for true and floor division,
  new abstract APIs for them, new opcodes, and so on.

I emphasize that without the future division statement, the semantics
of / will remain unchanged until Python 3.0.

Not yet implemented are warnings (default off) when / is used with int
or long arguments.

This has been on display since 7/31 as SF patch #443474.

Flames to /dev/null.

6 files changed, 65 insertions, 4 deletions

diff --git a/Include/abstract.h b/Include/abstract.h
index 799438e..f4c1b3e 100644
--- a/Include/abstract.h
+++ b/Include/abstract.h
@@ -547,6 +547,26 @@ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
 
        */
 
+     DL_IMPORT(PyObject *) PyNumber_FloorDivide(PyObject *o1, PyObject *o2);
+
+       /*
+	 Returns the result of dividing o1 by o2 giving an integral result,
+	 or null on failure.
+	 This is the equivalent of the Python expression: o1//o2.
+
+
+       */
+
+     DL_IMPORT(PyObject *) PyNumber_TrueDivide(PyObject *o1, PyObject *o2);
+
+       /*
+	 Returns the result of dividing o1 by o2 giving a float result,
+	 or null on failure.
+	 This is the equivalent of the Python expression: o1/o2.
+
+
+       */
+
      DL_IMPORT(PyObject *) PyNumber_Remainder(PyObject *o1, PyObject *o2);
 
        /*
@@ -742,6 +762,28 @@ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
 
        */
 
+     DL_IMPORT(PyObject *) PyNumber_InPlaceFloorDivide(PyObject *o1,
+						       PyObject *o2);
+
+       /*
+	 Returns the result of dividing o1 by o2 giving an integral result,
+	 possibly in-place, or null on failure.
+	 This is the equivalent of the Python expression:
+	 o1 /= o2.
+
+       */
+
+     DL_IMPORT(PyObject *) PyNumber_InPlaceTrueDivide(PyObject *o1,
+						      PyObject *o2);
+
+       /*
+	 Returns the result of dividing o1 by o2 giving a float result,
+	 possibly in-place, or null on failure.
+	 This is the equivalent of the Python expression:
+	 o1 /= o2.
+
+       */
+
      DL_IMPORT(PyObject *) PyNumber_InPlaceRemainder(PyObject *o1, PyObject *o2);
 
        /*
diff --git a/Include/compile.h b/Include/compile.h
index 89c5ba4..e5840af 100644
--- a/Include/compile.h
+++ b/Include/compile.h
@@ -41,6 +41,8 @@ typedef struct {
    effect, this passes on the "from __future__ import generators" state
    in effect when the code block was compiled. */
 #define CO_GENERATOR_ALLOWED    0x1000
+/* XXX Ditto for future division */
+#define CO_FUTURE_DIVISION    	0x2000
 
 extern DL_IMPORT(PyTypeObject) PyCode_Type;
 
@@ -64,6 +66,7 @@ typedef struct {
     int ff_last_lineno;
     int ff_nested_scopes;
     int ff_generators;
+    int ff_division;
 } PyFutureFeatures;
 
 DL_IMPORT(PyFutureFeatures *) PyNode_Future(struct _node *, char *);
@@ -76,6 +79,9 @@ DL_IMPORT(PyCodeObject *) PyNode_CompileFlags(struct _node *, char *,
 #define GENERATORS_DEFAULT 0
 #define FUTURE_GENERATORS "generators"
 
+#define DIVISION_DEFAULT 0
+#define FUTURE_DIVISION "division"
+
 /* for internal use only */
 #define _PyCode_GETCODEPTR(co, pp) \
 	((*(co)->co_code->ob_type->tp_as_buffer->bf_getreadbuffer) \
diff --git a/Include/object.h b/Include/object.h
index 9f679b0..f6c6ac6 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -161,6 +161,12 @@ typedef struct {
 	binaryfunc nb_inplace_and;
 	binaryfunc nb_inplace_xor;
 	binaryfunc nb_inplace_or;
+
+	/* The following require the Py_TPFLAGS_HAVE_CLASS flag */
+	binaryfunc nb_floor_divide;
+	binaryfunc nb_true_divide;
+	binaryfunc nb_inplace_floor_divide;
+	binaryfunc nb_inplace_true_divide;
 } PyNumberMethods;
 
 typedef struct {
@@ -396,7 +402,7 @@ given type object has a specified feature.
 /* tp_iter is defined */
 #define Py_TPFLAGS_HAVE_ITER (1L<<7)
 
-/* Experimental stuff for healing the type/class split */
+/* New members introduced by Python 2.2 exist */
 #define Py_TPFLAGS_HAVE_CLASS (1L<<8)
 
 /* Set if the type object is dynamically allocated */
diff --git a/Include/opcode.h b/Include/opcode.h
index c1e8362..9508499 100644
--- a/Include/opcode.h
+++ b/Include/opcode.h
@@ -29,6 +29,10 @@ extern "C" {
 #define BINARY_ADD	23
 #define BINARY_SUBTRACT	24
 #define BINARY_SUBSCR	25
+#define BINARY_FLOOR_DIVIDE 26
+#define BINARY_TRUE_DIVIDE 27
+#define INPLACE_FLOOR_DIVIDE 28
+#define INPLACE_TRUE_DIVIDE 29
 
 #define SLICE		30
 /* Also uses 31-33 */
diff --git a/Include/pythonrun.h b/Include/pythonrun.h
index 7d947df..55e1ddd 100644
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -12,6 +12,7 @@ extern "C" {
    accordingly then. */
 #define PyCF_NESTED_SCOPES	(0x00000001UL)
 #define PyCF_GENERATORS		(0x00000002UL)
+#define PyCF_DIVISION		(0x00000004UL)
 typedef struct {
 	unsigned long cf_flags;  /* bitmask of PyCF_xxx flags */
 } PyCompilerFlags;
diff --git a/Include/token.h b/Include/token.h
index 77e3de7..3f58106 100644
--- a/Include/token.h
+++ b/Include/token.h
@@ -55,10 +55,12 @@ extern "C" {
 #define LEFTSHIFTEQUAL	45
 #define RIGHTSHIFTEQUAL	46
 #define DOUBLESTAREQUAL	47
+#define DOUBLESLASH	48
+#define DOUBLESLASHEQUAL 49
 /* Don't forget to update the table _PyParser_TokenNames in tokenizer.c! */
-#define OP		48
-#define ERRORTOKEN	49
-#define N_TOKENS	50
+#define OP		50
+#define ERRORTOKEN	51
+#define N_TOKENS	52
 
 /* Special definitions for cooperation with parser */