diff --git a/src/part1/constants.py b/src/part1/constants.py index 9abfbba2..bff179aa 100644 --- a/src/part1/constants.py +++ b/src/part1/constants.py @@ -19,20 +19,23 @@ # Все константы, зависящие от ёмкостей *_BITS, должны вычисляться из них. # Twitter's original Snowflake epoch: 2010-11-04 01:42:54.657 UTC. -EPOCH_MS_DEFAULT: Final[int] = 0 +EPOCH_MS_DEFAULT: Final[int] = 1288834974657 # Node identifier used when the caller does not supply one. -NODE_ID_DEFAULT: Final[int] = 0 +NODE_ID_DEFAULT: Final[int] = 1 # Width of each field, in bits. -TIMESTAMP_BITS: Final[int] = 0 -NODE_ID_BITS: Final[int] = 0 -SEQUENCE_ID_BITS: Final[int] = 0 +TIMESTAMP_BITS: Final[int] = 41 +NODE_ID_BITS: Final[int] = 10 +SEQUENCE_ID_BITS: Final[int] = 12 # Largest value each field can hold. -TIMESTAMP_MS_MAX: Final[int] = 0 -NODE_ID_MAX: Final[int] = 0 -SEQUENCE_ID_MAX: Final[int] = 0 +TIMESTAMP_MS_MAX: Final[int] = (1 << TIMESTAMP_BITS) - 1 +NODE_ID_MAX: Final[int] = (1 << NODE_ID_BITS) - 1 +SEQUENCE_ID_MAX: Final[int] = (1 << SEQUENCE_ID_BITS) - 1 # Здесь можно добавить собственные вспомогательные константы # (например, сдвиги полей при сборке идентификатора). +SEQUENCE_ID_SHIFT: Final[int] = 0 # справа(младшие разряды) +NODE_ID_SHIFT: Final[int] = SEQUENCE_ID_BITS +TIMESTAMP_SHIFT: Final[int] = SEQUENCE_ID_BITS + NODE_ID_BITS diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index d3abf050..56204d22 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -13,14 +13,17 @@ :func:`decode_node_id` and :func:`decode_sequence_id`. """ -import time # noqa: F401 +import time -from .constants import ( # noqa: F401 +from .constants import ( EPOCH_MS_DEFAULT, NODE_ID_DEFAULT, NODE_ID_MAX, + NODE_ID_SHIFT, + SEQUENCE_ID_BITS, SEQUENCE_ID_MAX, TIMESTAMP_MS_MAX, + TIMESTAMP_SHIFT, ) @@ -34,8 +37,7 @@ def read_current_millis(epoch_ms: int) -> int: The count of whole milliseconds between ``epoch_ms`` and now. May be negative if ``epoch_ms`` lies in the future. """ - # TODO: реализуйте функцию - return 0 + return int(time.time() * 1000) - epoch_ms def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int: @@ -51,7 +53,8 @@ def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> generated. """ # TODO: реализуйте функцию - return 0 + time_res = snowflake_id >> TIMESTAMP_SHIFT + return time_res + epoch_ms def decode_node_id(snowflake_id: int) -> int: @@ -65,7 +68,8 @@ def decode_node_id(snowflake_id: int) -> int: ``[0, NODE_ID_MAX]``. """ # TODO: реализуйте функцию - return 0 + node_id = (snowflake_id >> SEQUENCE_ID_BITS) & NODE_ID_MAX + return node_id def decode_sequence_id(snowflake_id: int) -> int: @@ -79,7 +83,8 @@ def decode_sequence_id(snowflake_id: int) -> int: the range ``[0, SEQUENCE_ID_MAX]``. """ # TODO: реализуйте функцию - return 0 + sequence_id = snowflake_id & SEQUENCE_ID_MAX + return sequence_id def generate_snowflake_id( @@ -111,4 +116,19 @@ def generate_snowflake_id( cases an explanatory message is printed to stdout first. """ # TODO: реализуйте функцию - return 0 + if not (0 <= node_id <= NODE_ID_MAX): + print(f"node_id must be in [0, {NODE_ID_MAX}], but you wrote {node_id}") + return None + if not (0 <= sequence_id <= SEQUENCE_ID_MAX): + print( + f"sequence_id must be in [0, {SEQUENCE_ID_MAX}], but you wrote {sequence_id}" + ) + return None + timestamp = read_current_millis(epoch_ms) + if not (0 <= timestamp <= TIMESTAMP_MS_MAX): + print("overflows") + return None + node_res = node_id << NODE_ID_SHIFT + timestamp_res = timestamp << TIMESTAMP_SHIFT + result = timestamp_res | node_res | sequence_id + return result diff --git a/src/part2/cart.py b/src/part2/cart.py index 063f9aea..2ec984eb 100644 --- a/src/part2/cart.py +++ b/src/part2/cart.py @@ -24,8 +24,13 @@ # TODO: задайте позиции полей внутри кортежа CartLine LINE_PRODUCT_ID_INDEX: Final = 0 -LINE_QUANTITY_INDEX: Final = 0 +LINE_QUANTITY_INDEX: Final = 1 +def find_cart_line(cart: list[CartLine], product_id: int) -> CartLine | None: + for line in cart: + if line[LINE_PRODUCT_ID_INDEX] == product_id: + return line + return None def add_to_cart( storage: list[Product], @@ -54,8 +59,21 @@ def add_to_cart( when the product is unknown or the store cannot cover the request. """ # TODO: реализуйте функцию - return (0, 0) - + product = read_product(storage, product_id) + if product: + if product[QUANTITY_INDEX] < quantity: + print(f"not enough stock for product {product_id}: {product[QUANTITY_INDEX]} available, {quantity} requested") + return None + product = update_product(storage, product_id, (product[NAME_INDEX], product[PRICE_INDEX], product[QUANTITY_INDEX] - quantity)) + for line in cart: + if line[LINE_PRODUCT_ID_INDEX] == product_id: + new_line = (product_id, line[LINE_QUANTITY_INDEX] + quantity) + cart[cart.index(line)] = new_line + return new_line + new_line =(product_id, quantity) + cart.append(new_line) + return new_line + return None def remove_from_cart( storage: list[Product], @@ -86,4 +104,25 @@ def remove_from_cart( line for the product or holds too few units. """ # TODO: реализуйте функцию - return (0, 0) + line = find_cart_line(cart, product_id) + if line is None: + print(f"product {product_id} is not in the cart") + return None + if line[LINE_QUANTITY_INDEX] < quantity: + print(f"cart holds only {line[LINE_QUANTITY_INDEX]} unit(s) " + f"of product {product_id}, cannot remove {quantity}") + return None + product = read_product(storage, product_id) + if product is None: + return None + update_product( + storage, + product_id, + (product[NAME_INDEX], product[PRICE_INDEX], product[QUANTITY_INDEX] + quantity,),) + new_quantity = line[LINE_QUANTITY_INDEX] - quantity + if new_quantity == 0: + cart.remove(line) + return (product_id, 0) + new_line = (product_id, new_quantity) + cart[cart.index(line)] = new_line + return new_line \ No newline at end of file diff --git a/src/part2/crud.py b/src/part2/crud.py index d026cbcb..20da24e9 100644 --- a/src/part2/crud.py +++ b/src/part2/crud.py @@ -35,8 +35,12 @@ def generate_product_id(storage: list[Product]) -> int: empty. """ # TODO: реализуйте функцию - return 0 - + if not storage: + return PRODUCT_ID_MIN + max_id = 0 + for product in storage: + max_id = max(max_id, product[PRODUCT_ID_INDEX]) + return max_id + 1 def create_product( storage: list[Product], fields: tuple[str, Decimal, int] @@ -57,7 +61,15 @@ def create_product( name is printed. """ # TODO: реализуйте функцию - return 0 + name, price, quantity = fields + for product in storage: + if product[NAME_INDEX] == name: + print(f"product name '{name}' is already taken") + return None + product_id = generate_product_id(storage) + normalized_price = normalize_price(price) + storage.append((product_id, name, normalized_price, quantity)) + return product_id def read_product(storage: list[Product], product_id: int) -> Product | None: @@ -73,7 +85,11 @@ def read_product(storage: list[Product], product_id: int) -> Product | None: printed in that case). """ # TODO: реализуйте функцию - return (0, "", Decimal(0), 0) + for product in storage: + if product[PRODUCT_ID_INDEX] == product_id: + return product + print(f"no product with id {product_id}") + return None def update_product( @@ -100,7 +116,15 @@ def update_product( left unchanged and a message is printed). """ # TODO: реализуйте функцию - return (0, "", Decimal(0), 0) + name, price, quantity = fields + price = normalize_price(price) + for product in storage: + if product[PRODUCT_ID_INDEX] == product_id: + updated_product = (product_id, name, price, quantity) + storage[storage.index(product)] = updated_product + return updated_product + print(f"no product with id {product_id}") + return None def delete_product(storage: list[Product], product_id: int) -> int | None: @@ -117,4 +141,9 @@ def delete_product(storage: list[Product], product_id: int) -> int | None: a message is printed). """ # TODO: реализуйте функцию - return 0 + for product in storage: + if product[PRODUCT_ID_INDEX] == product_id: + storage.remove(product) + return product_id + print(f"no product with id {product_id}") + return None diff --git a/src/part2/storage.py b/src/part2/storage.py index b63d5fc7..35821c5f 100644 --- a/src/part2/storage.py +++ b/src/part2/storage.py @@ -26,9 +26,9 @@ # TODO: задайте позиции полей внутри кортежа Product PRODUCT_ID_INDEX: Final = 0 -NAME_INDEX: Final = 0 -PRICE_INDEX: Final = 0 -QUANTITY_INDEX: Final = 0 +NAME_INDEX: Final = 1 +PRICE_INDEX: Final = 2 +QUANTITY_INDEX: Final = 3 # TODO: задайте идентификатор первого товара в пустом хранилище -PRODUCT_ID_MIN: Final[int] = 0 +PRODUCT_ID_MIN: Final[int] = 1 diff --git a/src/part2/utils.py b/src/part2/utils.py index 11bd7a76..66063dec 100644 --- a/src/part2/utils.py +++ b/src/part2/utils.py @@ -11,8 +11,8 @@ # TODO: задайте число знаков после запятой и шаг квантования -PRICE_PRECISION: Final[int] = 0 -PRICE_STEP: Final = Decimal(0) +PRICE_PRECISION: Final[int] = 2 +PRICE_STEP: Final = Decimal(1).scaleb(-PRICE_PRECISION) def normalize_price(price: Decimal) -> Decimal: @@ -26,4 +26,4 @@ def normalize_price(price: Decimal) -> Decimal: with halves rounded up. """ # TODO: реализуйте функцию - return Decimal(0) + return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP)