From b2a237d337b82085c5cd54da76d67f9fe5bf1489 Mon Sep 17 00:00:00 2001
From: "Peter D. Gray" <peter@conalgo.com>
Date: Fri, 6 Mar 2015 14:48:14 -0500
Subject: [PATCH] py: Add support for start/stop/step attributes of builtin
 range object.

---
 py/mpconfig.h                 |  6 ++++++
 py/objrange.c                 | 17 +++++++++++++++++
 py/qstrdefs.h                 |  5 +++++
 tests/basics/builtin_range.py |  5 +++++
 4 files changed, 33 insertions(+)

diff --git a/py/mpconfig.h b/py/mpconfig.h
index 26d228785..bfa412167 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -382,6 +382,12 @@ typedef double mp_float_t;
 #define MICROPY_PY_BUILTINS_PROPERTY (1)
 #endif
 
+// Whether to implement the start/stop/step attributes (readback) on
+// the "range" builtin type. Rarely used, and costs ~60 bytes (x86).
+#ifndef MICROPY_PY_BUILTINS_RANGE_ATTRS
+#define MICROPY_PY_BUILTINS_RANGE_ATTRS (1)
+#endif
+
 // Whether to support complete set of special methods
 // for user classes, otherwise only the most used
 #ifndef MICROPY_PY_ALL_SPECIAL_METHODS
diff --git a/py/objrange.c b/py/objrange.c
index cc3270159..ff62cc5b8 100644
--- a/py/objrange.c
+++ b/py/objrange.c
@@ -166,6 +166,20 @@ STATIC mp_obj_t range_getiter(mp_obj_t o_in) {
     return mp_obj_new_range_iterator(o->start, o->stop, o->step);
 }
 
+
+#if MICROPY_PY_BUILTINS_RANGE_ATTRS
+STATIC void range_load_attr(mp_obj_t o_in, qstr attr, mp_obj_t *dest) {
+    mp_obj_range_t *o = o_in;
+    if (attr == MP_QSTR_start) {
+        dest[0] = mp_obj_new_int(o->start);
+    } else if (attr == MP_QSTR_stop) {
+        dest[0] = mp_obj_new_int(o->stop);
+    } else if (attr == MP_QSTR_step) {
+        dest[0] = mp_obj_new_int(o->step);
+    }
+}
+#endif
+
 const mp_obj_type_t mp_type_range = {
     { &mp_type_type },
     .name = MP_QSTR_range,
@@ -174,4 +188,7 @@ const mp_obj_type_t mp_type_range = {
     .unary_op = range_unary_op,
     .subscr = range_subscr,
     .getiter = range_getiter,
+#if MICROPY_PY_BUILTINS_RANGE_ATTRS
+    .load_attr = range_load_attr,
+#endif
 };
diff --git a/py/qstrdefs.h b/py/qstrdefs.h
index 88c0d5a3e..63112e6c7 100644
--- a/py/qstrdefs.h
+++ b/py/qstrdefs.h
@@ -245,6 +245,11 @@ Q(single)
 Q(sep)
 Q(end)
 
+#if MICROPY_PY_BUILTINS_RANGE_ATTRS
+Q(step)
+Q(stop)
+#endif
+
 Q(clear)
 Q(copy)
 Q(fromkeys)
diff --git a/tests/basics/builtin_range.py b/tests/basics/builtin_range.py
index 0c0110c26..25f8b84fe 100644
--- a/tests/basics/builtin_range.py
+++ b/tests/basics/builtin_range.py
@@ -24,3 +24,8 @@ print(range(4)[1:2])
 print(range(4)[1:3])
 print(range(4)[1::2])
 print(range(4)[1:-2:2])
+
+# attrs
+print(range(1, 2, 3).start)
+print(range(1, 2, 3).stop)
+print(range(1, 2, 3).step)