py/objdeque: Implement ucollections.deque type with fixed size.

So far, implements just append() and popleft() methods, required for
a normal queue. Constructor doesn't accept an arbitarry sequence to
initialize from (am empty deque is always created), so an empty tuple
must be passed as such. Only fixed-size deques are supported, so 2nd
argument (size) is required.

There's also an extension to CPython - if True is passed as 3rd argument,
append(), instead of silently overwriting the oldest item on queue
overflow, will throw IndexError. This behavior is desired in many
cases, where queues should store information reliably, instead of
silently losing some items.

py/modcollections.c

@@ -30,6 +30,9 @@
 
 STATIC const mp_rom_map_elem_t mp_module_collections_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_ucollections) },
+    #if MICROPY_PY_COLLECTIONS_DEQUE
+    { MP_ROM_QSTR(MP_QSTR_deque), MP_ROM_PTR(&mp_type_deque) },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_namedtuple), MP_ROM_PTR(&mp_namedtuple_obj) },
     #if MICROPY_PY_COLLECTIONS_ORDEREDDICT
     { MP_ROM_QSTR(MP_QSTR_OrderedDict), MP_ROM_PTR(&mp_type_ordereddict) },

py/mpconfig.h

@@ -936,6 +936,11 @@ typedef double mp_float_t;
 #define MICROPY_PY_COLLECTIONS (1)
 #endif
 
+// Whether to provide "ucollections.deque" type
+#ifndef MICROPY_PY_COLLECTIONS_DEQUE
+#define MICROPY_PY_COLLECTIONS_DEQUE (0)
+#endif
+
 // Whether to provide "collections.OrderedDict" type
 #ifndef MICROPY_PY_COLLECTIONS_ORDEREDDICT
 #define MICROPY_PY_COLLECTIONS_ORDEREDDICT (0)

py/obj.h

@@ -553,6 +553,7 @@ extern const mp_obj_type_t mp_type_list;
 extern const mp_obj_type_t mp_type_map; // map (the python builtin, not the dict implementation detail)
 extern const mp_obj_type_t mp_type_enumerate;
 extern const mp_obj_type_t mp_type_filter;
+extern const mp_obj_type_t mp_type_deque;
 extern const mp_obj_type_t mp_type_dict;
 extern const mp_obj_type_t mp_type_ordereddict;
 extern const mp_obj_type_t mp_type_range;

py/objdeque.c

@@ -0,0 +1,159 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Paul Sokolovsky
+ *
+ * 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 <string.h>
+
+#include "py/mpconfig.h"
+#if MICROPY_PY_COLLECTIONS_DEQUE
+
+#include "py/runtime.h"
+
+typedef struct _mp_obj_deque_t {
+    mp_obj_base_t base;
+    size_t alloc;
+    size_t i_get;
+    size_t i_put;
+    mp_obj_t *items;
+    uint32_t flags;
+    #define FLAG_CHECK_OVERFLOW 1
+} mp_obj_deque_t;
+
+STATIC mp_obj_t deque_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    mp_arg_check_num(n_args, n_kw, 2, 3, false);
+
+    /* Initialization from existing sequence is not supported, so an empty
+       tuple must be passed as such. */
+    if (args[0] != mp_const_empty_tuple) {
+        mp_raise_ValueError(NULL);
+    }
+
+    mp_obj_deque_t *o = m_new_obj(mp_obj_deque_t);
+    o->base.type = type;
+    o->alloc = mp_obj_get_int(args[1]) + 1;
+    o->i_get = o->i_put = 0;
+    o->items = m_new(mp_obj_t, o->alloc);
+    mp_seq_clear(o->items, 0, o->alloc, sizeof(*o->items));
+
+    if (n_args > 2) {
+        o->flags = mp_obj_get_int(args[2]);
+    }
+
+    return MP_OBJ_FROM_PTR(o);
+}
+
+STATIC mp_obj_t deque_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
+    mp_obj_deque_t *self = MP_OBJ_TO_PTR(self_in);
+    switch (op) {
+        case MP_UNARY_OP_BOOL:
+            return mp_obj_new_bool(self->i_get != self->i_put);
+        case MP_UNARY_OP_LEN: {
+            mp_int_t len = self->i_put - self->i_get;
+            if (len < 0) {
+                len += self->alloc;
+            }
+            return MP_OBJ_NEW_SMALL_INT(len);
+        }
+        #if MICROPY_PY_SYS_GETSIZEOF
+        case MP_UNARY_OP_SIZEOF: {
+            size_t sz = sizeof(*self) + sizeof(mp_obj_t) * self->alloc;
+            return MP_OBJ_NEW_SMALL_INT(sz);
+        }
+        #endif
+        default:
+            return MP_OBJ_NULL; // op not supported
+    }
+}
+
+STATIC mp_obj_t mp_obj_deque_append(mp_obj_t self_in, mp_obj_t arg) {
+    mp_obj_deque_t *self = MP_OBJ_TO_PTR(self_in);
+
+    size_t new_i_put = self->i_put + 1;
+    if (new_i_put == self->alloc) {
+        new_i_put = 0;
+    }
+
+    if (self->flags & FLAG_CHECK_OVERFLOW && new_i_put == self->i_get) {
+        mp_raise_msg(&mp_type_IndexError, "full");
+    }
+
+    self->items[self->i_put] = arg;
+    self->i_put = new_i_put;
+
+    if (self->i_get == new_i_put) {
+        if (++self->i_get == self->alloc) {
+            self->i_get = 0;
+        }
+    }
+
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(deque_append_obj, mp_obj_deque_append);
+
+STATIC mp_obj_t deque_popleft(mp_obj_t self_in) {
+    mp_obj_deque_t *self = MP_OBJ_TO_PTR(self_in);
+
+    if (self->i_get == self->i_put) {
+        mp_raise_msg(&mp_type_IndexError, "empty");
+    }
+
+    mp_obj_t ret = self->items[self->i_get];
+    self->items[self->i_get] = MP_OBJ_NULL;
+
+    if (++self->i_get == self->alloc) {
+        self->i_get = 0;
+    }
+
+    return ret;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(deque_popleft_obj, deque_popleft);
+
+STATIC mp_obj_t deque_clear(mp_obj_t self_in) {
+    mp_obj_deque_t *self = MP_OBJ_TO_PTR(self_in);
+    self->i_get = self->i_put = 0;
+    mp_seq_clear(self->items, 0, self->alloc, sizeof(*self->items));
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(deque_clear_obj, deque_clear);
+
+STATIC const mp_rom_map_elem_t deque_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_append), MP_ROM_PTR(&deque_append_obj) },
+    #if 0
+    { MP_ROM_QSTR(MP_QSTR_clear), MP_ROM_PTR(&deque_clear_obj) },
+    #endif
+    { MP_ROM_QSTR(MP_QSTR_popleft), MP_ROM_PTR(&deque_popleft_obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(deque_locals_dict, deque_locals_dict_table);
+
+const mp_obj_type_t mp_type_deque = {
+    { &mp_type_type },
+    .name = MP_QSTR_deque,
+    .make_new = deque_make_new,
+    .unary_op = deque_unary_op,
+    .locals_dict = (mp_obj_dict_t*)&deque_locals_dict,
+};
+
+#endif // MICROPY_PY_COLLECTIONS_DEQUE

py/py.mk

@@ -158,6 +158,7 @@ PY_O_BASENAME = \
 	objcell.o \
 	objclosure.o \
 	objcomplex.o \
+	objdeque.o \
 	objdict.o \
 	objenumerate.o \
 	objexcept.o \