diff --git a/src/part1/constants.py b/src/part1/constants.py index 9abfbba2..f07ba214 100644 --- a/src/part1/constants.py +++ b/src/part1/constants.py @@ -16,23 +16,22 @@ # TODO: замените заглушки (0) на корректные значения, см. TASK.md. -# 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] = 2**TIMESTAMP_BITS - 1 +NODE_ID_MAX: Final[int] = 2**NODE_ID_BITS - 1 +SEQUENCE_ID_MAX: Final[int] = 2**SEQUENCE_ID_BITS - 1 # Здесь можно добавить собственные вспомогательные константы # (например, сдвиги полей при сборке идентификатора). diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index d3abf050..970866cc 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -13,45 +13,35 @@ :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_BITS, NODE_ID_DEFAULT, NODE_ID_MAX, + SEQUENCE_ID_BITS, SEQUENCE_ID_MAX, TIMESTAMP_MS_MAX, ) def read_current_millis(epoch_ms: int) -> int: - """Read the number of milliseconds elapsed since the custom epoch. - Args: - epoch_ms: The custom epoch expressed as Unix milliseconds. + user_time = int(time.time() * 1000) - Returns: - 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 + differnse_time = user_time - epoch_ms + + return differnse_time def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int: - """Read the timestamp field out of a Snowflake identifier. - Args: - snowflake_id: An identifier produced against the same epoch. - epoch_ms: The epoch the identifier was generated against. Defaults to - the original Twitter epoch (2010-11-04 01:42:54.657 UTC). + user_mc = snowflake_id >> (NODE_ID_BITS + SEQUENCE_ID_BITS) - Returns: - The absolute Unix time in milliseconds at which the identifier was - generated. - """ - # TODO: реализуйте функцию - return 0 + absolut_time = user_mc + epoch_ms + + return absolut_time def decode_node_id(snowflake_id: int) -> int: @@ -64,8 +54,8 @@ def decode_node_id(snowflake_id: int) -> int: The node identifier packed into ``snowflake_id``, in the range ``[0, NODE_ID_MAX]``. """ - # TODO: реализуйте функцию - return 0 + identifier_id = (snowflake_id >> SEQUENCE_ID_BITS) & NODE_ID_MAX + return identifier_id def decode_sequence_id(snowflake_id: int) -> int: @@ -78,8 +68,8 @@ def decode_sequence_id(snowflake_id: int) -> int: The per-millisecond sequence counter packed into ``snowflake_id``, in 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( @@ -110,5 +100,19 @@ def generate_snowflake_id( timestamp field (roughly 69 years after ``epoch_ms``). In each of those cases an explanatory message is printed to stdout first. """ - # TODO: реализуйте функцию - return 0 + if node_id < 0 or node_id > NODE_ID_MAX: + print(f"node_id must be in [0, {NODE_ID_MAX}], got {node_id}") + return None + if sequence_id < 0 or sequence_id > SEQUENCE_ID_MAX: + print(f"sequence_id must be in [0, {SEQUENCE_ID_MAX}], got {sequence_id}") + return None + elapsed_ms = read_current_millis(epoch_ms) + if elapsed_ms > TIMESTAMP_MS_MAX: + print(f"timestamp overflows: {elapsed_ms} > {TIMESTAMP_MS_MAX}") + return None + snowflake_id = ( + (elapsed_ms << (NODE_ID_BITS + SEQUENCE_ID_BITS)) + | (node_id << SEQUENCE_ID_BITS) + | sequence_id + ) + return snowflake_id diff --git a/src/part2/cart.py b/src/part2/cart.py index 063f9aea..e116a8a4 100644 --- a/src/part2/cart.py +++ b/src/part2/cart.py @@ -11,10 +11,11 @@ from typing import Final -from .crud import read_product, update_product # noqa: F401 -from .storage import ( # noqa: F401 +from .crud import read_product +from .storage import ( NAME_INDEX, PRICE_INDEX, + PRODUCT_ID_INDEX, QUANTITY_INDEX, Product, ) @@ -24,7 +25,25 @@ # 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: + """Return the cart line stored under ``product_id``. + + Args: + cart: The store of cart line. + product_id: The identifier to look up. + + Returns: + The matching ``(product_id, line_quantity)`` record, + ``None`` when no cart line carries that identifier (a message is + printed in that case). + """ + for cart_line in cart: + if cart_line[LINE_PRODUCT_ID_INDEX] == product_id: + return cart_line + return None def add_to_cart( @@ -53,8 +72,40 @@ def add_to_cart( The cart line for ``product_id`` after the addition, or ``None`` 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 is None: + return None + if product[QUANTITY_INDEX] < quantity: + print( + f"not enough stock for product {product_id}: " + f"{product[QUANTITY_INDEX]} available, {quantity} requested" + ) + return None + + for index_product, cell in enumerate(storage): + if cell[PRODUCT_ID_INDEX] == product_id: + storage[index_product] = ( + cell[PRODUCT_ID_INDEX], + cell[NAME_INDEX], + cell[PRICE_INDEX], + cell[QUANTITY_INDEX] - quantity, + ) + break + else: + return None + + for index_line, purchase in enumerate(cart): + if purchase[LINE_PRODUCT_ID_INDEX] == product_id: + new_line: CartLine = ( + purchase[LINE_PRODUCT_ID_INDEX], + purchase[LINE_QUANTITY_INDEX] + quantity, + ) + cart[index_line] = new_line + return new_line + + new_line = (product_id, quantity) + cart.append(new_line) + return new_line def remove_from_cart( @@ -85,5 +136,41 @@ def remove_from_cart( zero means the line was dropped), or ``None`` when the cart has no line for the product or holds too few units. """ - # TODO: реализуйте функцию - return (0, 0) + our_line = find_cart_line(cart, product_id) + if our_line is None: + print(f"product {product_id} is not in the cart") + return None + if our_line[LINE_QUANTITY_INDEX] < quantity: + print( + f"cart holds only {our_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 + + for index_product, stored_product in enumerate(storage): + if stored_product[PRODUCT_ID_INDEX] == product_id: + storage[index_product] = ( + stored_product[PRODUCT_ID_INDEX], + stored_product[NAME_INDEX], + stored_product[PRICE_INDEX], + stored_product[QUANTITY_INDEX] + quantity, + ) + break + else: + return None + + for index_cart_line, cart_line in enumerate(cart): + if cart_line[LINE_PRODUCT_ID_INDEX] == product_id: + new_quantity = cart_line[LINE_QUANTITY_INDEX] - quantity + if new_quantity == 0: + del cart[index_cart_line] + return (product_id, 0) + updated_line: CartLine = (product_id, new_quantity) + cart[index_cart_line] = updated_line + return updated_line + + return None diff --git a/src/part2/crud.py b/src/part2/crud.py index d026cbcb..6578b837 100644 --- a/src/part2/crud.py +++ b/src/part2/crud.py @@ -14,13 +14,13 @@ from decimal import Decimal -from .storage import ( # noqa: F401 +from .storage import ( NAME_INDEX, PRODUCT_ID_INDEX, PRODUCT_ID_MIN, Product, ) -from .utils import normalize_price # noqa: F401 +from .utils import normalize_price def generate_product_id(storage: list[Product]) -> int: @@ -34,8 +34,10 @@ def generate_product_id(storage: list[Product]) -> int: :data:`~src.part2.storage.PRODUCT_ID_MIN` when ``storage`` is empty. """ - # TODO: реализуйте функцию - return 0 + if not storage: + return PRODUCT_ID_MIN + product_id = max(product[PRODUCT_ID_INDEX] for product in storage) + 1 + return product_id def create_product( @@ -56,8 +58,15 @@ def create_product( ``storage`` is left unchanged and a message naming the clashing name is printed. """ - # TODO: реализуйте функцию - return 0 + + for product in storage: + if product[NAME_INDEX] == fields[0]: + print(f"Product name {product[NAME_INDEX]} is already taken.") + return None + new_product_id = generate_product_id(storage) + new_product = (new_product_id, fields[0], normalize_price(fields[1]), fields[2]) + storage.append(new_product) + return new_product_id def read_product(storage: list[Product], product_id: int) -> Product | None: @@ -72,8 +81,11 @@ def read_product(storage: list[Product], product_id: int) -> Product | None: ``None`` when no product carries that identifier (a message is 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( @@ -99,8 +111,19 @@ def update_product( ``None`` when no product carries that identifier (``storage`` is left unchanged and a message is printed). """ - # TODO: реализуйте функцию - return (0, "", Decimal(0), 0) + norm_price = normalize_price(fields[1]) + for index_old_product, old_product in enumerate(storage): + if old_product[PRODUCT_ID_INDEX] == product_id: + updation_product: Product = ( + old_product[PRODUCT_ID_INDEX], + fields[0], + norm_price, + fields[2], + ) + storage[index_old_product] = updation_product + return updation_product + print(f"no product with id {product_id}") + return None def delete_product(storage: list[Product], product_id: int) -> int | None: @@ -116,5 +139,10 @@ def delete_product(storage: list[Product], product_id: int) -> int | None: product carried that identifier (``storage`` is left unchanged and 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 ec0348d3..25df1db7 100644 --- a/src/part2/utils.py +++ b/src/part2/utils.py @@ -6,13 +6,13 @@ currency values free of binary floating-point error. """ -from decimal import ROUND_HALF_UP, Decimal # noqa: F401 +from decimal import ROUND_HALF_UP, Decimal from typing import Final # 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: @@ -25,5 +25,7 @@ def normalize_price(price: Decimal) -> Decimal: ``price`` quantised to :data:`PRICE_PRECISION` fractional digits, with halves rounded up. """ - # TODO: реализуйте функцию - return Decimal(0) + ratio = price / PRICE_STEP + steps = ratio.quantize(Decimal("1."), rounding=ROUND_HALF_UP) + real_price = steps * PRICE_STEP + return real_price