circuitpython/py/objdict.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013, 2014 Damien P. George
 * Copyright (c) 2014-2017 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 <assert.h>

#include "py/runtime.h"
#include "py/builtin.h"
#include "py/objtype.h"
#include "py/objstr.h"

bool mp_obj_is_dict_or_ordereddict(mp_obj_t o) {
    return mp_obj_is_obj(o) && MP_OBJ_TYPE_GET_SLOT_OR_NULL(((mp_obj_base_t *)MP_OBJ_TO_PTR(o))->type, make_new) == mp_obj_dict_make_new;
}

const mp_obj_dict_t mp_const_empty_dict_obj = {
    .base = { .type = &mp_type_dict },
    .map = {
        .all_keys_are_qstrs = 0,
        .is_fixed = 1,
        .is_ordered = 1,
        .used = 0,
        .alloc = 0,
        .table = NULL,
    }
};

STATIC mp_obj_t dict_update(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs);

// This is a helper function to iterate through a dictionary.  The state of
// the iteration is held in *cur and should be initialised with zero for the
// first call.  Will return NULL when no more elements are available.
STATIC mp_map_elem_t *dict_iter_next(mp_obj_dict_t *dict, size_t *cur) {
    size_t max = dict->map.alloc;
    mp_map_t *map = &dict->map;

    size_t i = *cur;
    for (; i < max; i++) {
        if (mp_map_slot_is_filled(map, i)) {
            *cur = i + 1;
            return &(map->table[i]);
        }
    }

    assert(map->used == 0 || i == max);
    return NULL;
}

STATIC void dict_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
    bool first = true;
    const char *item_separator = ", ";
    const char *key_separator = ": ";
    if (!(MICROPY_PY_UJSON && kind == PRINT_JSON)) {
        kind = PRINT_REPR;
    } else {
        #if MICROPY_PY_UJSON_SEPARATORS
        item_separator = MP_PRINT_GET_EXT(print)->item_separator;
        key_separator = MP_PRINT_GET_EXT(print)->key_separator;
        #endif
    }
    if (MICROPY_PY_COLLECTIONS_ORDEREDDICT && self->base.type != &mp_type_dict && kind != PRINT_JSON) {
        mp_printf(print, "%q(", self->base.type->name);
    }
    mp_print_str(print, "{");
    size_t cur = 0;
    mp_map_elem_t *next = NULL;
    while ((next = dict_iter_next(self, &cur)) != NULL) {
        if (!first) {
            mp_print_str(print, item_separator);
        }
        first = false;
        bool add_quote = MICROPY_PY_UJSON && kind == PRINT_JSON && !mp_obj_is_str_or_bytes(next->key);
        if (add_quote) {
            mp_print_str(print, "\"");
        }
        mp_obj_print_helper(print, next->key, kind);
        if (add_quote) {
            mp_print_str(print, "\"");
        }
        mp_print_str(print, key_separator);
        mp_obj_print_helper(print, next->value, kind);
    }
    mp_print_str(print, "}");
    if (MICROPY_PY_COLLECTIONS_ORDEREDDICT && self->base.type != &mp_type_dict && kind != PRINT_JSON) {
        mp_print_str(print, ")");
    }
}

// This is a helper function to initialize an empty, but typed dictionary with
// a given number of slots.
STATIC mp_obj_t dict_new_typed(const mp_obj_type_t *type, const size_t n) {
    mp_obj_t dict_out = mp_obj_new_dict(n);
    mp_obj_dict_t *dict = MP_OBJ_TO_PTR(dict_out);
    dict->base.type = type;
    #if MICROPY_PY_COLLECTIONS_ORDEREDDICT
    if (type == &mp_type_ordereddict) {
        dict->map.is_ordered = 1;
    }
    #endif
    return dict_out;
}

mp_obj_t mp_obj_dict_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
    mp_obj_t dict_out = mp_obj_new_dict(0);
    mp_obj_dict_t *dict = MP_OBJ_TO_PTR(dict_out);
    dict->base.type = type;
    #if MICROPY_PY_COLLECTIONS_ORDEREDDICT
    if (type == &mp_type_ordereddict) {
        dict->map.is_ordered = 1;
    }
    #endif
    if (n_args > 0 || n_kw > 0) {
        mp_obj_t args2[2] = {dict_out, args[0]}; // args[0] is always valid, even if it's not a positional arg
        mp_map_t kwargs;
        mp_map_init_fixed_table(&kwargs, n_kw, args + n_args);
        dict_update(n_args + 1, args2, &kwargs); // dict_update will check that n_args + 1 == 1 or 2
    }
    return dict_out;
}

STATIC mp_obj_t dict_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
    switch (op) {
        case MP_UNARY_OP_BOOL:
            return mp_obj_new_bool(self->map.used != 0);
        case MP_UNARY_OP_LEN:
            return MP_OBJ_NEW_SMALL_INT(self->map.used);
        #if MICROPY_PY_SYS_GETSIZEOF
        case MP_UNARY_OP_SIZEOF: {
            size_t sz = sizeof(*self) + sizeof(*self->map.table) * self->map.alloc;
            return MP_OBJ_NEW_SMALL_INT(sz);
        }
        #endif
        default:
            return MP_OBJ_NULL;      // op not supported
    }
}

STATIC mp_obj_t dict_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
    mp_obj_dict_t *o = MP_OBJ_TO_PTR(lhs_in);
    switch (op) {
        case MP_BINARY_OP_CONTAINS: {
            mp_map_elem_t *elem = mp_map_lookup(&o->map, rhs_in, MP_MAP_LOOKUP);
            return mp_obj_new_bool(elem != NULL);
        }
        case MP_BINARY_OP_EQUAL: {
            #if MICROPY_PY_COLLECTIONS_ORDEREDDICT
            if (MP_UNLIKELY(mp_obj_is_type(lhs_in, &mp_type_ordereddict) && mp_obj_is_type(rhs_in, &mp_type_ordereddict))) {
                // Iterate through both dictionaries simultaneously and compare keys and values.
                mp_obj_dict_t *rhs = MP_OBJ_TO_PTR(rhs_in);
                size_t c1 = 0, c2 = 0;
                mp_map_elem_t *e1 = dict_iter_next(o, &c1), *e2 = dict_iter_next(rhs, &c2);
                for (; e1 != NULL && e2 != NULL; e1 = dict_iter_next(o, &c1), e2 = dict_iter_next(rhs, &c2)) {
                    if (!mp_obj_equal(e1->key, e2->key) || !mp_obj_equal(e1->value, e2->value)) {
                        return mp_const_false;
                    }
                }
                return e1 == NULL && e2 == NULL ? mp_const_true : mp_const_false;
            }
            #endif

            if (mp_obj_is_type(rhs_in, &mp_type_dict)) {
                mp_obj_dict_t *rhs = MP_OBJ_TO_PTR(rhs_in);
                if (o->map.used != rhs->map.used) {
                    return mp_const_false;
                }

                size_t cur = 0;
                mp_map_elem_t *next = NULL;
                while ((next = dict_iter_next(o, &cur)) != NULL) {
                    mp_map_elem_t *elem = mp_map_lookup(&rhs->map, next->key, MP_MAP_LOOKUP);
                    if (elem == NULL || !mp_obj_equal(next->value, elem->value)) {
                        return mp_const_false;
                    }
                }
                return mp_const_true;
            } else {
                // dict is not equal to instance of any other type
                return mp_const_false;
            }
        }
        #if MICROPY_CPYTHON_COMPAT
        case MP_BINARY_OP_INPLACE_OR:
        case MP_BINARY_OP_OR: {
            if (op == MP_BINARY_OP_OR) {
                lhs_in = mp_obj_dict_copy(lhs_in);
            }
            mp_obj_t dicts[2] = {lhs_in, rhs_in};
            dict_update(2, dicts, (mp_map_t *)&mp_const_empty_map);
            return lhs_in;
        }
        #endif
        default:
            // op not supported
            return MP_OBJ_NULL;
    }
}

// Note: Make sure this is inlined in load part of dict_subscr() below.
mp_obj_t mp_obj_dict_get(mp_obj_t self_in, mp_obj_t index) {
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
    mp_map_elem_t *elem = mp_map_lookup(&self->map, index, MP_MAP_LOOKUP);
    if (elem == NULL) {
        mp_raise_type_arg(&mp_type_KeyError, index);
    } else {
        return elem->value;
    }
}

STATIC mp_obj_t dict_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
    if (value == MP_OBJ_NULL) {
        // delete
        mp_obj_dict_delete(self_in, index);
        return mp_const_none;
    } else if (value == MP_OBJ_SENTINEL) {
        // load
        mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
        mp_map_elem_t *elem = mp_map_lookup(&self->map, index, MP_MAP_LOOKUP);
        if (elem == NULL) {
            mp_raise_type_arg(&mp_type_KeyError, index);
        } else {
            return elem->value;
        }
    } else {
        // store
        mp_obj_dict_store(self_in, index, value);
        return mp_const_none;
    }
}

/******************************************************************************/
/* dict methods                                                               */

STATIC void PLACE_IN_ITCM(mp_ensure_not_fixed)(const mp_obj_dict_t * dict) {
    if (dict->map.is_fixed) {
        mp_raise_TypeError(NULL);
    }
}

STATIC mp_obj_t dict_clear(mp_obj_t self_in) {
    mp_check_self(mp_obj_is_dict_or_ordereddict(self_in));
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
    mp_ensure_not_fixed(self);

    mp_map_clear(&self->map);

    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(dict_clear_obj, dict_clear);

mp_obj_t mp_obj_dict_copy(mp_obj_t self_in) {
    mp_check_self(mp_obj_is_dict_or_ordereddict(self_in));
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
    mp_obj_t other_out = mp_obj_new_dict(self->map.alloc);
    mp_obj_dict_t *other = MP_OBJ_TO_PTR(other_out);
    other->base.type = self->base.type;
    other->map.used = self->map.used;
    other->map.all_keys_are_qstrs = self->map.all_keys_are_qstrs;
    other->map.is_fixed = 0;
    other->map.is_ordered = self->map.is_ordered;
    memcpy(other->map.table, self->map.table, self->map.alloc * sizeof(mp_map_elem_t));
    return other_out;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(dict_copy_obj, mp_obj_dict_copy);

#if MICROPY_PY_BUILTINS_DICT_FROMKEYS
// this is a classmethod
STATIC mp_obj_t dict_fromkeys(size_t n_args, const mp_obj_t *args) {
    mp_obj_type_t *type = MP_OBJ_TO_PTR(args[0]);
    mp_obj_t iter = mp_getiter(args[1], NULL);
    mp_obj_t value = mp_const_none;
    mp_obj_t next = MP_OBJ_NULL;

    if (n_args > 2) {
        value = args[2];
    }

    // optimisation to allocate result based on len of argument
    mp_obj_t self_out;
    mp_obj_t len = mp_obj_len_maybe(args[1]);
    if (len == MP_OBJ_NULL) {
        /* object's type doesn't have a __len__ slot */
        self_out = dict_new_typed(type, 0);
    } else {
        self_out = dict_new_typed(type, MP_OBJ_SMALL_INT_VALUE(len));
    }

    mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_out);
    while ((next = mp_iternext(iter)) != MP_OBJ_STOP_ITERATION) {
        mp_map_lookup(&self->map, next, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = value;
    }

    return self_out;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(dict_fromkeys_fun_obj, 2, 3, dict_fromkeys);
STATIC MP_DEFINE_CONST_CLASSMETHOD_OBJ(dict_fromkeys_obj, MP_ROM_PTR(&dict_fromkeys_fun_obj));
#endif

STATIC mp_obj_t dict_get_helper(size_t n_args, const mp_obj_t *args, mp_map_lookup_kind_t lookup_kind) {
    mp_check_self(mp_obj_is_dict_or_ordereddict(args[0]));
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(args[0]);
    if (lookup_kind != MP_MAP_LOOKUP) {
        mp_ensure_not_fixed(self);
    }
    mp_map_elem_t *elem = mp_map_lookup(&self->map, args[1], lookup_kind);
    mp_obj_t value;
    if (elem == NULL || elem->value == MP_OBJ_NULL) {
        if (n_args == 2) {
            if (lookup_kind == MP_MAP_LOOKUP_REMOVE_IF_FOUND) {
                mp_raise_type_arg(&mp_type_KeyError, args[1]);
            } else {
                value = mp_const_none;
            }
        } else {
            value = args[2];
        }
        if (lookup_kind == MP_MAP_LOOKUP_ADD_IF_NOT_FOUND) {
            elem->value = value;
        }
    } else {
        value = elem->value;
        if (lookup_kind == MP_MAP_LOOKUP_REMOVE_IF_FOUND) {
            elem->value = MP_OBJ_NULL; // so that GC can collect the deleted value
        }
    }
    return value;
}

STATIC mp_obj_t dict_get(size_t n_args, const mp_obj_t *args) {
    return dict_get_helper(n_args, args, MP_MAP_LOOKUP);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(dict_get_obj, 2, 3, dict_get);

STATIC mp_obj_t dict_pop(size_t n_args, const mp_obj_t *args) {
    return dict_get_helper(n_args, args, MP_MAP_LOOKUP_REMOVE_IF_FOUND);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(dict_pop_obj, 2, 3, dict_pop);

STATIC mp_obj_t dict_setdefault(size_t n_args, const mp_obj_t *args) {
    return dict_get_helper(n_args, args, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(dict_setdefault_obj, 2, 3, dict_setdefault);

STATIC mp_obj_t dict_popitem(mp_obj_t self_in) {
    mp_check_self(mp_obj_is_dict_or_ordereddict(self_in));
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
    mp_ensure_not_fixed(self);
    if (self->map.used == 0) {
        mp_raise_msg_varg(&mp_type_KeyError, MP_ERROR_TEXT("pop from empty %q"), MP_QSTR_dict);
    }
    size_t cur = 0;
    #if MICROPY_PY_COLLECTIONS_ORDEREDDICT
    if (self->map.is_ordered) {
        cur = self->map.used - 1;
    }
    #endif
    mp_map_elem_t *next = dict_iter_next(self, &cur);
    assert(next);
    self->map.used--;
    mp_obj_t items[] = {next->key, next->value};
    next->key = MP_OBJ_SENTINEL; // must mark key as sentinel to indicate that it was deleted
    next->value = MP_OBJ_NULL;
    mp_obj_t tuple = mp_obj_new_tuple(2, items);

    return tuple;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(dict_popitem_obj, dict_popitem);

STATIC mp_obj_t dict_update(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
    mp_check_self(mp_obj_is_dict_or_ordereddict(args[0]));
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(args[0]);
    mp_ensure_not_fixed(self);

    mp_arg_check_num(n_args, kwargs->used, 1, 2, true);

    if (n_args == 2) {
        // given a positional argument

        if (mp_obj_is_dict_or_ordereddict(args[1])) {
            // update from other dictionary (make sure other is not self)
            if (args[1] != args[0]) {
                size_t cur = 0;
                mp_map_elem_t *elem = NULL;
                while ((elem = dict_iter_next((mp_obj_dict_t *)MP_OBJ_TO_PTR(args[1]), &cur)) != NULL) {
                    mp_map_lookup(&self->map, elem->key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = elem->value;
                }
            }
        } else {
            // update from a generic iterable of pairs
            mp_obj_t iter = mp_getiter(args[1], NULL);
            mp_obj_t next = MP_OBJ_NULL;
            while ((next = mp_iternext(iter)) != MP_OBJ_STOP_ITERATION) {
                mp_obj_t inneriter = mp_getiter(next, NULL);
                mp_obj_t key = mp_iternext(inneriter);
                mp_obj_t value = mp_iternext(inneriter);
                mp_obj_t stop = mp_iternext(inneriter);
                if (key == MP_OBJ_STOP_ITERATION
                    || value == MP_OBJ_STOP_ITERATION
                    || stop != MP_OBJ_STOP_ITERATION) {
                    mp_raise_ValueError(MP_ERROR_TEXT("dict update sequence has wrong length"));
                } else {
                    mp_map_lookup(&self->map, key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = value;
                }
            }
        }
    }

    // update the dict with any keyword args
    for (size_t i = 0; i < kwargs->alloc; i++) {
        if (mp_map_slot_is_filled(kwargs, i)) {
            mp_map_lookup(&self->map, kwargs->table[i].key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = kwargs->table[i].value;
        }
    }

    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_KW(dict_update_obj, 1, dict_update);

#if MICROPY_PY_COLLECTIONS_ORDEREDDICT
STATIC mp_obj_t dict_move_to_end(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(pos_args[0]);
    mp_arg_validate_type(self, &mp_type_ordereddict, MP_QSTR_self);

    // parse args
    enum { ARG_key, ARG_last };
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_key, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE } },
        { MP_QSTR_last, MP_ARG_BOOL, {.u_bool = true } }
    };
    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    mp_obj_t *key = args[ARG_key].u_obj;
    bool last = args[ARG_last].u_bool;

    mp_map_elem_t *elem = mp_map_lookup(&self->map, key, MP_MAP_LOOKUP);
    if (!elem) {
        mp_raise_type_arg(&mp_type_KeyError, key);
    }

    mp_map_elem_t tmp = *elem;
    mp_map_elem_t *table = self->map.table;
    mp_map_elem_t *dest, *move_begin, *move_dest;
    size_t move_count;

    if (last) {
        mp_map_elem_t *top = &table[self->map.used];
        dest = top - 1;
        move_begin = elem + 1;
        move_dest = elem;
        move_count = top - move_begin;
    } else {
        dest = &table[0];
        move_begin = table;
        move_dest = table + 1;
        move_count = elem - table;
    }
    memmove(move_dest, move_begin, move_count * sizeof(*elem));
    *dest = tmp;

    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_KW(dict_move_to_end_obj, 1, dict_move_to_end);
#endif

/******************************************************************************/
/* dict views                                                                 */

STATIC const mp_obj_type_t mp_type_dict_view;
STATIC const mp_obj_type_t mp_type_dict_view_it;

typedef enum _mp_dict_view_kind_t {
    MP_DICT_VIEW_ITEMS,
    MP_DICT_VIEW_KEYS,
    MP_DICT_VIEW_VALUES,
} mp_dict_view_kind_t;

STATIC const char *const mp_dict_view_names[] = {"dict_items", "dict_keys", "dict_values"};

typedef struct _mp_obj_dict_view_it_t {
    mp_obj_base_t base;
    mp_dict_view_kind_t kind;
    mp_obj_t dict;
    size_t cur;
} mp_obj_dict_view_it_t;

typedef struct _mp_obj_dict_view_t {
    mp_obj_base_t base;
    mp_obj_t dict;
    mp_dict_view_kind_t kind;
} mp_obj_dict_view_t;

STATIC mp_obj_t dict_view_it_iternext(mp_obj_t self_in) {
    mp_check_self(mp_obj_is_type(self_in, &mp_type_dict_view_it));
    mp_obj_dict_view_it_t *self = MP_OBJ_TO_PTR(self_in);
    mp_map_elem_t *next = dict_iter_next(MP_OBJ_TO_PTR(self->dict), &self->cur);

    if (next == NULL) {
        return MP_OBJ_STOP_ITERATION;
    } else {
        switch (self->kind) {
            case MP_DICT_VIEW_ITEMS:
            default: {
                mp_obj_t items[] = {next->key, next->value};
                return mp_obj_new_tuple(2, items);
            }
            case MP_DICT_VIEW_KEYS:
                return next->key;
            case MP_DICT_VIEW_VALUES:
                return next->value;
        }
    }
}

STATIC MP_DEFINE_CONST_OBJ_TYPE(
    mp_type_dict_view_it,
    MP_QSTR_iterator,
    MP_TYPE_FLAG_ITER_IS_ITERNEXT,
    iter, dict_view_it_iternext
    );

STATIC mp_obj_t dict_view_getiter(mp_obj_t view_in, mp_obj_iter_buf_t *iter_buf) {
    assert(sizeof(mp_obj_dict_view_it_t) <= sizeof(mp_obj_iter_buf_t));
    mp_check_self(mp_obj_is_type(view_in, &mp_type_dict_view));
    mp_obj_dict_view_t *view = MP_OBJ_TO_PTR(view_in);
    mp_obj_dict_view_it_t *o = (mp_obj_dict_view_it_t *)iter_buf;
    o->base.type = &mp_type_dict_view_it;
    o->kind = view->kind;
    o->dict = view->dict;
    o->cur = 0;
    return MP_OBJ_FROM_PTR(o);
}

STATIC void dict_view_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
    (void)kind;
    mp_check_self(mp_obj_is_type(self_in, &mp_type_dict_view));
    mp_obj_dict_view_t *self = MP_OBJ_TO_PTR(self_in);
    bool first = true;
    mp_print_str(print, mp_dict_view_names[self->kind]);
    mp_print_str(print, "([");
    mp_obj_iter_buf_t iter_buf;
    mp_obj_t self_iter = dict_view_getiter(self_in, &iter_buf);
    mp_obj_t next = MP_OBJ_NULL;
    while ((next = dict_view_it_iternext(self_iter)) != MP_OBJ_STOP_ITERATION) {
        if (!first) {
            mp_print_str(print, ", ");
        }
        first = false;
        mp_obj_print_helper(print, next, PRINT_REPR);
    }
    mp_print_str(print, "])");
}

STATIC mp_obj_t dict_view_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
    // only supported for the 'keys' kind until sets and dicts are refactored
    mp_obj_dict_view_t *o = MP_OBJ_TO_PTR(lhs_in);
    if (o->kind != MP_DICT_VIEW_KEYS) {
        return MP_OBJ_NULL; // op not supported
    }
    if (op != MP_BINARY_OP_CONTAINS) {
        return MP_OBJ_NULL; // op not supported
    }
    return dict_binary_op(op, o->dict, rhs_in);
}

STATIC MP_DEFINE_CONST_OBJ_TYPE(
    mp_type_dict_view,
    MP_QSTR_dict_view,
    MP_TYPE_FLAG_ITER_IS_GETITER,
    print, dict_view_print,
    binary_op, dict_view_binary_op,
    iter, dict_view_getiter
    );

STATIC mp_obj_t mp_obj_new_dict_view(mp_obj_t dict, mp_dict_view_kind_t kind) {
    mp_obj_dict_view_t *o = mp_obj_malloc(mp_obj_dict_view_t, &mp_type_dict_view);
    o->dict = dict;
    o->kind = kind;
    return MP_OBJ_FROM_PTR(o);
}

STATIC mp_obj_t dict_view(mp_obj_t self_in, mp_dict_view_kind_t kind) {
    mp_check_self(mp_obj_is_dict_or_ordereddict(self_in));
    return mp_obj_new_dict_view(self_in, kind);
}

STATIC mp_obj_t dict_items(mp_obj_t self_in) {
    return dict_view(self_in, MP_DICT_VIEW_ITEMS);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(dict_items_obj, dict_items);

STATIC mp_obj_t dict_keys(mp_obj_t self_in) {
    return dict_view(self_in, MP_DICT_VIEW_KEYS);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(dict_keys_obj, dict_keys);

STATIC mp_obj_t dict_values(mp_obj_t self_in) {
    return dict_view(self_in, MP_DICT_VIEW_VALUES);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(dict_values_obj, dict_values);

/******************************************************************************/
/* dict iterator                                                              */

STATIC mp_obj_t dict_getiter(mp_obj_t self_in, mp_obj_iter_buf_t *iter_buf) {
    assert(sizeof(mp_obj_dict_view_it_t) <= sizeof(mp_obj_iter_buf_t));
    mp_check_self(mp_obj_is_dict_or_ordereddict(self_in));
    mp_obj_dict_view_it_t *o = (mp_obj_dict_view_it_t *)iter_buf;
    o->base.type = &mp_type_dict_view_it;
    o->kind = MP_DICT_VIEW_KEYS;
    o->dict = self_in;
    o->cur = 0;
    return MP_OBJ_FROM_PTR(o);
}

/******************************************************************************/
/* dict constructors & public C API                                           */

STATIC const mp_rom_map_elem_t dict_locals_dict_table[] = {
    { MP_ROM_QSTR(MP_QSTR_clear), MP_ROM_PTR(&dict_clear_obj) },
    { MP_ROM_QSTR(MP_QSTR_copy), MP_ROM_PTR(&dict_copy_obj) },
    #if MICROPY_PY_BUILTINS_DICT_FROMKEYS
    { MP_ROM_QSTR(MP_QSTR_fromkeys), MP_ROM_PTR(&dict_fromkeys_obj) },
    #endif
    { MP_ROM_QSTR(MP_QSTR_get), MP_ROM_PTR(&dict_get_obj) },
    { MP_ROM_QSTR(MP_QSTR_items), MP_ROM_PTR(&dict_items_obj) },
    { MP_ROM_QSTR(MP_QSTR_keys), MP_ROM_PTR(&dict_keys_obj) },
    #if MICROPY_PY_COLLECTIONS_ORDEREDDICT
    { MP_ROM_QSTR(MP_QSTR_move_to_end), MP_ROM_PTR(&dict_move_to_end_obj) },
    #endif
    { MP_ROM_QSTR(MP_QSTR_pop), MP_ROM_PTR(&dict_pop_obj) },
    { MP_ROM_QSTR(MP_QSTR_popitem), MP_ROM_PTR(&dict_popitem_obj) },
    { MP_ROM_QSTR(MP_QSTR_setdefault), MP_ROM_PTR(&dict_setdefault_obj) },
    { MP_ROM_QSTR(MP_QSTR_update), MP_ROM_PTR(&dict_update_obj) },
    { MP_ROM_QSTR(MP_QSTR_values), MP_ROM_PTR(&dict_values_obj) },
    { MP_ROM_QSTR(MP_QSTR___getitem__), MP_ROM_PTR(&mp_op_getitem_obj) },
    { MP_ROM_QSTR(MP_QSTR___setitem__), MP_ROM_PTR(&mp_op_setitem_obj) },
    { MP_ROM_QSTR(MP_QSTR___delitem__), MP_ROM_PTR(&mp_op_delitem_obj) },
};

STATIC MP_DEFINE_CONST_DICT(dict_locals_dict, dict_locals_dict_table);

MP_DEFINE_CONST_OBJ_TYPE(
    mp_type_dict,
    MP_QSTR_dict,
    MP_TYPE_FLAG_ITER_IS_GETITER,
    make_new, mp_obj_dict_make_new,
    print, dict_print,
    unary_op, dict_unary_op,
    binary_op, dict_binary_op,
    subscr, dict_subscr,
    iter, dict_getiter,
    locals_dict, &dict_locals_dict
    );

#if MICROPY_PY_COLLECTIONS_ORDEREDDICT
MP_DEFINE_CONST_OBJ_TYPE(
    mp_type_ordereddict,
    MP_QSTR_OrderedDict,
    MP_TYPE_FLAG_ITER_IS_GETITER,
    make_new, mp_obj_dict_make_new,
    print, dict_print,
    unary_op, dict_unary_op,
    binary_op, dict_binary_op,
    subscr, dict_subscr,
    iter, dict_getiter,
    parent, &mp_type_dict,
    locals_dict, &dict_locals_dict
    );
#endif

void mp_obj_dict_init(mp_obj_dict_t *dict, size_t n_args) {
    dict->base.type = &mp_type_dict;
    mp_map_init(&dict->map, n_args);
}

mp_obj_t mp_obj_new_dict(size_t n_args) {
    mp_obj_dict_t *o = m_new_obj(mp_obj_dict_t);
    mp_obj_dict_init(o, n_args);
    return MP_OBJ_FROM_PTR(o);
}

size_t mp_obj_dict_len(mp_obj_t self_in) {
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
    return self->map.used;
}

mp_obj_t mp_obj_dict_store(mp_obj_t self_in, mp_obj_t key, mp_obj_t value) {
    mp_check_self(mp_obj_is_dict_or_ordereddict(self_in));
    mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
    mp_ensure_not_fixed(self);
    mp_map_lookup(&self->map, key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = value;
    return self_in;
}

mp_obj_t mp_obj_dict_delete(mp_obj_t self_in, mp_obj_t key) {
    mp_obj_t args[2] = {self_in, key};
    dict_get_helper(2, args, MP_MAP_LOOKUP_REMOVE_IF_FOUND);
    return self_in;
}