py: Add enum helper code

This makes it much easier to implement enums, and the printing code is
shared.  We might want to convert other enums to this in the future.

py/enum.c

@@ -0,0 +1,52 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * SPDX-FileCopyrightText: Copyright (c) 2020 Jeff Epler for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/enum.h"
+#include "py/runtime.h"
+
+mp_obj_t cp_enum_find(const mp_obj_type_t *type, int value) {
+    const mp_obj_dict_t *dict = type->locals_dict;
+    for (size_t i=0; i<dict->map.used; i++) {
+        const cp_enum_obj_t *v = dict->map.table[i].value;
+        if (v->value == value) {
+            return (mp_obj_t)v;
+        }
+    }
+    return mp_const_none;
+}
+
+int cp_enum_value(const mp_obj_type_t *type, mp_obj_t *obj) {
+    if (!MP_OBJ_IS_TYPE(obj, type)) {
+        mp_raise_TypeError_varg(translate("Expected a %q"), type->name);
+    }
+    return ((cp_enum_obj_t*)MP_OBJ_TO_PTR(obj))->value;
+}
+
+void cp_enum_obj_print_helper(uint16_t module, const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    (void) kind;
+    cp_enum_obj_t *self = self_in;
+    mp_printf(print, "%q.%q.%q", module, self->base.type->name, self->name);
+}

py/enum.h

@@ -0,0 +1,65 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * SPDX-FileCopyrightText: Copyright (c) 2020 Jeff Epler for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#pragma once
+
+#include "py/obj.h"
+
+typedef struct {
+    mp_obj_base_t base;
+    int16_t value;
+    int16_t name;
+} cp_enum_obj_t;
+
+#define MAKE_ENUM_VALUE(type, prefix, name, value) \
+    STATIC const cp_enum_obj_t prefix ## _ ## name ## _obj = { \
+        { &type }, value, MP_QSTR_ ## name, \
+    }
+
+#define MAKE_ENUM_MAP(name) \
+    STATIC const mp_rom_map_elem_t name ## _locals_table[] =
+
+#define MAKE_ENUM_MAP_ENTRY(prefix, name) \
+    { MP_ROM_QSTR(MP_QSTR_ ## name), MP_ROM_PTR(&prefix ## _ ## name ## _obj) }
+
+#define MAKE_PRINTER(module, typename) \
+    STATIC void typename ## _ ## print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) { \
+        cp_enum_obj_print_helper(MP_QSTR_ ## module, print, self_in, kind); \
+    }
+
+#define MAKE_ENUM_TYPE(module, type, typename) \
+    const mp_obj_type_t typename ## _type = { \
+        { &mp_type_type }, \
+        .name = MP_QSTR_ ## type, \
+        .print = typename ## _print, \
+        .locals_dict = (mp_obj_t)&typename ## _locals_dict, \
+    }
+
+
+
+mp_obj_t cp_enum_find(const mp_obj_type_t *type, int value);
+int cp_enum_value(const mp_obj_type_t *type, mp_obj_t *obj);
+void cp_enum_obj_print_helper(uint16_t module, const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind);

py/py.mk

@@ -181,6 +181,7 @@ PY_CORE_O_BASENAME = $(addprefix py/,\
 	argcheck.o \
 	warning.o \
 	map.o \
+	enum.o \
 	obj.o \
 	objarray.o \
 	objattrtuple.o \