From ec87df07ffb41d5fc27ee153fd1136224570b719 Mon Sep 17 00:00:00 2001 From: samirhappy Date: Fri, 25 Sep 2026 18:38:55 +0300 Subject: [PATCH 1/7] Implement part 1 snowflake --- src/part1/constants.py | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/src/part1/constants.py b/src/part1/constants.py index 9abfbba2..2cc5954b 100644 --- a/src/part1/constants.py +++ b/src/part1/constants.py @@ -19,20 +19,22 @@ # 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). +NODE_ID_SHIFT: Final[int] = SEQUENCE_ID_BITS +TIMESTAMP_SHIFT: Final[int] = NODE_ID_BITS + SEQUENCE_ID_BITS From eb01c003631cec1484d420d7b4f873b7906b43f7 Mon Sep 17 00:00:00 2001 From: samirhappy Date: Fri, 25 Sep 2026 22:51:58 +0300 Subject: [PATCH 2/7] Implement snowflake generator --- src/part1/snowflake.py | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index d3abf050..0bb11774 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -13,14 +13,16 @@ :func:`decode_node_id` and :func:`decode_sequence_id`. """ -import time # noqa: F401 +from time import time -from .constants import ( # noqa: F401 +from .constants import ( EPOCH_MS_DEFAULT, NODE_ID_DEFAULT, NODE_ID_MAX, + NODE_ID_SHIFT, SEQUENCE_ID_MAX, TIMESTAMP_MS_MAX, + TIMESTAMP_SHIFT, ) @@ -34,8 +36,7 @@ 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() * 1000 - epoch_ms) def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int: @@ -50,8 +51,7 @@ def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> The absolute Unix time in milliseconds at which the identifier was generated. """ - # TODO: реализуйте функцию - return 0 + return (snowflake_id >> TIMESTAMP_SHIFT) + epoch_ms def decode_node_id(snowflake_id: int) -> int: @@ -64,8 +64,7 @@ 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 + return (snowflake_id >> NODE_ID_SHIFT) & NODE_ID_MAX def decode_sequence_id(snowflake_id: int) -> int: @@ -78,8 +77,7 @@ 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 + return snowflake_id & SEQUENCE_ID_MAX def generate_snowflake_id( @@ -110,5 +108,17 @@ 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 not (0 <= node_id <= NODE_ID_MAX): + print(f"node_id must be in [0, {NODE_ID_MAX}], got {node_id}") + return None + + if not (0 <= 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("overflows") + return None + + return (elapsed_ms << TIMESTAMP_SHIFT) | (node_id << NODE_ID_SHIFT) | sequence_id From 0a156f653ad9e40b77144fb2e1114c8afbc58511 Mon Sep 17 00:00:00 2001 From: samirhappy Date: Fri, 9 Oct 2026 20:02:59 +0300 Subject: [PATCH 3/7] Solved task 3 --- src/part2/cart.py | 70 ++++++++++++++++++++++++++++++++------- src/part2/crud.py | 53 +++++++++++++++++++++-------- src/part2/storage.py | 10 +++--- src/part2/utils.py | 10 +++--- src/part3/crud.py | 73 ++++++++++++++++++++++++++++++++-------- src/part3/run_admin.py | 75 ++++++++++++++++++++++++++++++++++++------ src/part3/storage.py | 11 +++---- src/part3/utils.py | 40 ++++++++++++++++------ 8 files changed, 267 insertions(+), 75 deletions(-) diff --git a/src/part2/cart.py b/src/part2/cart.py index 063f9aea..1d3f7f43 100644 --- a/src/part2/cart.py +++ b/src/part2/cart.py @@ -11,11 +11,8 @@ from typing import Final -from .crud import read_product, update_product # noqa: F401 -from .storage import ( # noqa: F401 - NAME_INDEX, - PRICE_INDEX, - QUANTITY_INDEX, +from .crud import read_product, update_product +from .storage import ( Product, ) @@ -23,8 +20,8 @@ type CartLine = tuple[int, int] # TODO: задайте позиции полей внутри кортежа CartLine -LINE_PRODUCT_ID_INDEX: Final = 0 -LINE_QUANTITY_INDEX: Final = 0 +LINE_PRODUCT_ID_INDEX: Final[int] = 0 +LINE_QUANTITY_INDEX: Final[int] = 1 def add_to_cart( @@ -53,8 +50,30 @@ 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 not product: + return None + + _, name, price, stock_quantity = product + if stock_quantity < quantity: + print( + f"Not enough stock for product {product_id}: " + f"{stock_quantity} available, {quantity} requested" + ) + return None + + update_product(storage, product_id, (name, price, stock_quantity - quantity)) + + for i in range(len(cart)): + if cart[i][LINE_PRODUCT_ID_INDEX] == product_id: + cart_quantity = cart[i][LINE_QUANTITY_INDEX] + new_line = (product_id, cart_quantity + quantity) + cart[i] = new_line + return new_line + + new_line = (product_id, quantity) + cart.append(new_line) + return new_line def remove_from_cart( @@ -85,5 +104,34 @@ 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) + for i in range(len(cart)): + if cart[i][LINE_PRODUCT_ID_INDEX] == product_id: + cart_quantity = cart[i][LINE_QUANTITY_INDEX] + if quantity > cart_quantity: + print( + f"Cart holds only {cart_quantity} units of product {product_id}, " + f"cannot remove {quantity}" + ) + return None + + product = read_product(storage, product_id) + if not product: + return None + + _, name, price, stock_quantity = product + update_product( + storage, + product_id, + (name, price, stock_quantity + quantity), + ) + + remaining_quantity = cart_quantity - quantity + if remaining_quantity == 0: + del cart[i] + return (product_id, 0) + + cart[i] = (product_id, remaining_quantity) + return cart[i] + + print(f"Product {product_id} is not in the cart") + return None diff --git a/src/part2/crud.py b/src/part2/crud.py index d026cbcb..0bfe0959 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 +34,14 @@ 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 + + max_id = 0 + for product in storage: + current_id = int(product[PRODUCT_ID_INDEX]) + max_id = max(current_id, max_id) + return max_id + 1 def create_product( @@ -56,8 +62,16 @@ def create_product( ``storage`` is left unchanged and a message naming the clashing 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 + + new_id = generate_product_id(storage) + normalized_price = normalize_price(price) + storage.append((new_id, name, normalized_price, quantity)) + return new_id def read_product(storage: list[Product], product_id: int) -> Product | None: @@ -65,15 +79,17 @@ def read_product(storage: list[Product], product_id: int) -> Product | None: Args: storage: The product store to search. - product_id: The identifier to look up. Returns: The matching ``(product_id, name, price, quantity)`` record, or ``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 +115,15 @@ 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) + name, price, quantity = fields + normalized_price = normalize_price(price) + for i in range(len(storage)): + if storage[i][PRODUCT_ID_INDEX] == product_id: + updated_product = (product_id, name, normalized_price, quantity) + storage[i] = 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: @@ -116,5 +139,9 @@ 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 i in range(len(storage)): + if storage[i][PRODUCT_ID_INDEX] == product_id: + del storage[i] + 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..73cc4464 100644 --- a/src/part2/storage.py +++ b/src/part2/storage.py @@ -25,10 +25,10 @@ type Product = tuple[int, str, Decimal, int] # TODO: задайте позиции полей внутри кортежа Product -PRODUCT_ID_INDEX: Final = 0 -NAME_INDEX: Final = 0 -PRICE_INDEX: Final = 0 -QUANTITY_INDEX: Final = 0 +PRODUCT_ID_INDEX: Final[int] = 0 +NAME_INDEX: Final[int] = 1 +PRICE_INDEX: Final[int] = 2 +QUANTITY_INDEX: Final[int] = 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..528429ef 100644 --- a/src/part2/utils.py +++ b/src/part2/utils.py @@ -1,4 +1,4 @@ -"""Standalone helpers shared by the part2 storage and CRUD modules. +"""Standalone helpers shared by the hw4 storage and CRUD modules. For now this is limited to money handling: :func:`normalize_price` rounds a raw :class:`~decimal.Decimal` amount to the fixed number of fractional @@ -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] = 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) diff --git a/src/part3/crud.py b/src/part3/crud.py index 68811d7e..17f3fbad 100644 --- a/src/part3/crud.py +++ b/src/part3/crud.py @@ -20,13 +20,13 @@ 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, normalize_product_name # noqa: F401 +from .utils import normalize_price, normalize_product_name def generate_product_id(storage: list[Product]) -> int: @@ -37,11 +37,17 @@ def generate_product_id(storage: list[Product]) -> int: Returns: One past the greatest identifier currently held in ``storage``, or - :data:`~src.part3.storage.PRODUCT_ID_MIN` when ``storage`` is + :data:`~src.part2.storage.PRODUCT_ID_MIN` when ``storage`` is empty. """ - # TODO: реализуйте функцию (используйте своё решение части 2) - return 0 + if not storage: + return PRODUCT_ID_MIN + + max_id = 0 + for product in storage: + current_id = int(product[PRODUCT_ID_INDEX]) + max_id = max(current_id, max_id) + return max_id + 1 def create_product( @@ -64,8 +70,20 @@ def create_product( normalised name already exists. In the ``None`` case ``storage`` is left unchanged and an explanatory message is printed. """ - # TODO: реализуйте функцию - return 0 + name, price, quantity = fields + name = normalize_product_name(name) + if not name: + print("product name must not be blank") + return None + for product in storage: + if product[NAME_INDEX] == name: + print(f"product name '{name}' is already taken") + return None + + new_id = generate_product_id(storage) + normalized_price = normalize_price(price) + storage.append((new_id, name, normalized_price, quantity)) + return new_id def read_product(storage: list[Product], product_id: int) -> Product | None: @@ -73,15 +91,17 @@ def read_product(storage: list[Product], product_id: int) -> Product | None: Args: storage: The product store to search. - product_id: The identifier to look up. Returns: The matching ``(product_id, name, price, quantity)`` record, or ``None`` when no product carries that identifier (a message is printed in that case). """ - # TODO: реализуйте функцию (используйте своё решение части 2) - 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( @@ -110,8 +130,29 @@ def update_product( unchanged and an explanatory message is printed. Renaming a product to its own current name is allowed. """ - # TODO: реализуйте функцию - return (0, "", Decimal(0), 0) + name, price, quantity = fields + name = normalize_product_name(name) + normalized_price = normalize_price(price) + if not name: + print("product name must not be blank") + return None + flag = False + index_of_needed_id = 0 + for i in range(len(storage)): + if storage[i][PRODUCT_ID_INDEX] == product_id: + flag = True + index_of_needed_id = i + break + if not flag: + print(f"no product with id {product_id}") + return None + for i in range(len(storage)): + if i != index_of_needed_id and storage[i][NAME_INDEX] == name: + print(f"product name '{name}' is already taken") + return None + updated = (product_id, name, normalized_price, quantity) + storage[index_of_needed_id] = updated + return storage[index_of_needed_id] def delete_product(storage: list[Product], product_id: int) -> int | None: @@ -127,5 +168,9 @@ 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 (используйте своё решение части 2) - return 0 + for i in range(len(storage)): + if storage[i][PRODUCT_ID_INDEX] == product_id: + del storage[i] + return product_id + print(f"no product with id {product_id}") + return None diff --git a/src/part3/run_admin.py b/src/part3/run_admin.py index c5feeb0b..83df2d51 100644 --- a/src/part3/run_admin.py +++ b/src/part3/run_admin.py @@ -29,22 +29,33 @@ it. """ -from decimal import Decimal, InvalidOperation # noqa: F401 +from decimal import Decimal, InvalidOperation from typing import Final -from .crud import ( # noqa: F401 +from .crud import ( create_product, delete_product, read_product, update_product, ) from .storage import Product -from .utils import get_storage_str_representation # noqa: F401 +from .utils import get_storage_str_representation -# TODO: задайте приглашение и текст справки -PROMPT: Final[str] = "" -HELP_TEXT: Final[str] = "" +PROMPT: Final[str] = "admin> " + +HELP_TEXT: Final[str] = """Available commands: + help show this message + exit leave the console + show print the whole store as a table + create add a product, print its new id + read print the product with that id + update overwrite that product's fields + delete remove the product with that id + +For create and update the price and quantity are the last two words of the +line; everything before them is the product name, so it may contain spaces +(for example "Gibson SG Junior") and needs no quoting.""" def show_help() -> None: @@ -54,7 +65,7 @@ def show_help() -> None: is: a heading, one line per command with a short description, and a note on how multi-word names are parsed. """ - # TODO: реализуйте функцию + print(HELP_TEXT) def print_result(result: object) -> None: @@ -65,7 +76,8 @@ def print_result(result: object) -> None: operation already reported its own failure, so nothing is printed in that case. """ - # TODO: реализуйте функцию + if result is not None: + print(result) def run_command(storage: list[Product], line: str) -> bool: @@ -88,8 +100,51 @@ def run_command(storage: list[Product], line: str) -> bool: decimal.InvalidOperation: If the price argument of ``create`` or ``update`` does not parse as a decimal number. """ - # TODO: реализуйте функцию - return False + words = line.split() + if not words: + print(f"'{line}' is not a command") + return True + + command = words[0] + + if command == "exit" and len(words) == 1: + return False + + if command == "help" and len(words) == 1: + show_help() + return True + + if command == "show" and len(words) == 1: + print(get_storage_str_representation(storage)) + return True + + if command == "read" and len(words) == 2: + product_id = int(words[1]) + print_result(read_product(storage, product_id)) + return True + + if command == "delete" and len(words) == 2: + product_id = int(words[1]) + print_result(delete_product(storage, product_id)) + return True + + if command == "create" and len(words) >= 4: + name = " ".join(words[1:-2]) + price = Decimal(words[-2]) + quantity = int(words[-1]) + print_result(create_product(storage, (name, price, quantity))) + return True + + if command == "update" and len(words) >= 5: + product_id = int(words[1]) + name = " ".join(words[2:-2]) + price = Decimal(words[-2]) + quantity = int(words[-1]) + print_result(update_product(storage, product_id, (name, price, quantity))) + return True + + print(f"'{line}' is not a command") + return True def main() -> None: diff --git a/src/part3/storage.py b/src/part3/storage.py index c5e34be5..c516645b 100644 --- a/src/part3/storage.py +++ b/src/part3/storage.py @@ -24,12 +24,9 @@ type Product = tuple[int, str, Decimal, int] -# TODO: задайте позиции полей внутри кортежа Product (используйте своё решение -# части 2) 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/part3/utils.py b/src/part3/utils.py index 318ded0b..dcd354e6 100644 --- a/src/part3/utils.py +++ b/src/part3/utils.py @@ -18,7 +18,7 @@ the longest value it holds in that particular call. """ -from decimal import ROUND_HALF_UP, Decimal # noqa: F401 +from decimal import ROUND_HALF_UP, Decimal from typing import Final from .storage import Product @@ -28,14 +28,14 @@ # Quantisation step derived from PRICE_PRECISION, e.g. Decimal("0.01"). # TODO: задайте число знаков после запятой и шаг квантования (используйте своё # решение части 2) -PRICE_PRECISION: Final[int] = 0 -PRICE_STEP: Final = Decimal(0) +PRICE_PRECISION: Final[int] = 2 +PRICE_STEP: Final[Decimal] = Decimal(1).scaleb(-PRICE_PRECISION) # Column headers of the table produced by get_storage_str_representation, # left to right. The width of each column is not fixed here -- it is # measured per call from the data (see the function). # TODO: задайте заголовки столбцов таблицы -TABLE_HEADERS: Final[tuple[str, ...]] = () +TABLE_HEADERS: Final[tuple[str, ...]] = ("ID", "name", "price", "quantity") def normalize_price(price: Decimal) -> Decimal: @@ -48,8 +48,7 @@ def normalize_price(price: Decimal) -> Decimal: ``price`` quantised to :data:`PRICE_PRECISION` fractional digits, with halves rounded up. """ - # TODO: реализуйте функцию (используйте своё решение части 2) - return Decimal(0) + return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP) def normalize_product_name(name: str) -> str: @@ -66,8 +65,10 @@ def normalize_product_name(name: str) -> str: The result is an empty string when ``name`` holds nothing but whitespace. """ - # TODO: реализуйте функцию - return "" + list_of_words = name.split() + name = " ".join(list_of_words) + name = name.lower() + return name # TODO: при необходимости добавьте свои вспомогательные функции @@ -91,5 +92,24 @@ def get_storage_str_representation(storage: list[Product]) -> str: is empty only the header and separator rows are returned, sized to the header labels. """ - # TODO: реализуйте функцию - return "" + mxlen1 = len(TABLE_HEADERS[0]) + mxlen2 = len(TABLE_HEADERS[1]) + mxlen3 = len(TABLE_HEADERS[2]) + mxlen4 = len(TABLE_HEADERS[3]) + for product in storage: + item_id = str(product[0]) + name = str(product[1]) + price = str(product[2]) + quantity = str(product[3]) + mxlen1 = max(mxlen1, len(item_id)) + mxlen2 = max(mxlen2, len(name)) + mxlen3 = max(mxlen3, len(price)) + mxlen4 = max(mxlen4, len(quantity)) + s1 = f"| {TABLE_HEADERS[0].ljust(mxlen1)} | {TABLE_HEADERS[1].ljust(mxlen2)} | {TABLE_HEADERS[2].ljust(mxlen3)} | {TABLE_HEADERS[3].ljust(mxlen4)} |" + s2 = f"|{'-' * (mxlen1 + 2)}|{'-' * (mxlen2 + 2)}|{'-' * (mxlen3 + 2)}|{'-' * (mxlen4 + 2)}|" + snext = [ + f"| {str(product[0]).ljust(mxlen1)} | {str(product[1]).ljust(mxlen2)} | {str(product[2]).ljust(mxlen3)} | {str(product[3]).ljust(mxlen4)} |" + for product in storage + ] + rows = [s1, s2, *snext] + return "\n".join(rows) From 23443f344209e8225f68296948e2762d28ed5013 Mon Sep 17 00:00:00 2001 From: SimencaSs <74181505+SimencaSs@users.noreply.github.com> Date: Thu, 15 Oct 2026 08:46:46 +0300 Subject: [PATCH 4/7] =?UTF-8?q?=D0=BF=D0=B5=D1=80=D0=B5=D0=B4=D0=B5=D0=BB?= =?UTF-8?q?=D0=B0=D0=BB=20=D0=B8=D0=BC=D0=BF=D0=BE=D1=80=D1=82?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- conftest.py | 0 src/part1/__init__.py | 1 - src/part1/constants.py | 29 +------------- src/part1/snowflake.py | 85 +++--------------------------------------- 4 files changed, 6 insertions(+), 109 deletions(-) create mode 100644 conftest.py diff --git a/conftest.py b/conftest.py new file mode 100644 index 00000000..e69de29b diff --git a/src/part1/__init__.py b/src/part1/__init__.py index 242b07ce..e69de29b 100644 --- a/src/part1/__init__.py +++ b/src/part1/__init__.py @@ -1 +0,0 @@ -"""Homework 3: a Twitter Snowflake identifier generator and its bit layout.""" diff --git a/src/part1/constants.py b/src/part1/constants.py index 2cc5954b..09033e11 100644 --- a/src/part1/constants.py +++ b/src/part1/constants.py @@ -1,40 +1,13 @@ -"""Bit layout and default epoch for the Twitter Snowflake ID generator. - -A Snowflake identifier is a 63-bit positive integer packed as follows, from -the most significant bit downwards: - - 1 bit unused sign bit, always zero - 41 bits milliseconds elapsed since a custom epoch - 10 bits node identifier - 12 bits per-millisecond sequence counter - -The shift and mask constants should be derived from the bit widths so that -changing a width keeps everything else consistent. -""" - from typing import Final -# 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] = 1288834974657 - -# Node identifier used when the caller does not supply one. NODE_ID_DEFAULT: Final[int] = 1 - -# Width of each field, in bits. 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] = 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). NODE_ID_SHIFT: Final[int] = SEQUENCE_ID_BITS -TIMESTAMP_SHIFT: Final[int] = NODE_ID_BITS + 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 0bb11774..bed5f406 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -1,19 +1,4 @@ -"""Twitter Snowflake identifier generator. - -Snowflake produces roughly time-ordered 64-bit integer identifiers without -coordination between nodes. Each identifier packs the milliseconds elapsed -since a custom epoch, a node identifier and a per-millisecond sequence counter -into a single 63-bit positive integer (see ``constants`` for the layout). - -The public entry point is :func:`generate_snowflake_id`. It is stateless: the -caller passes the sequence counter on every call and is responsible for -advancing it within a millisecond and resetting it when the clock ticks over. - -Each packed field can be read back on its own with :func:`decode_timestamp_ms`, -:func:`decode_node_id` and :func:`decode_sequence_id`. -""" - -from time import time +import time from .constants import ( EPOCH_MS_DEFAULT, @@ -27,56 +12,19 @@ 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. - - Returns: - The count of whole milliseconds between ``epoch_ms`` and now. May be - negative if ``epoch_ms`` lies in the future. - """ - return int(time() * 1000 - epoch_ms) + return time.time_ns() // 1000000 - epoch_ms 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). - - Returns: - The absolute Unix time in milliseconds at which the identifier was - generated. - """ - return (snowflake_id >> TIMESTAMP_SHIFT) + epoch_ms + stored_ms = snowflake_id >> TIMESTAMP_SHIFT + return stored_ms + epoch_ms def decode_node_id(snowflake_id: int) -> int: - """Read the node identifier field out of a Snowflake identifier. - - Args: - snowflake_id: An identifier produced by :func:`generate_snowflake_id`. - - Returns: - The node identifier packed into ``snowflake_id``, in the range - ``[0, NODE_ID_MAX]``. - """ return (snowflake_id >> NODE_ID_SHIFT) & NODE_ID_MAX def decode_sequence_id(snowflake_id: int) -> int: - """Read the sequence counter field out of a Snowflake identifier. - - Args: - snowflake_id: An identifier produced by :func:`generate_snowflake_id`. - - Returns: - The per-millisecond sequence counter packed into ``snowflake_id``, in - the range ``[0, SEQUENCE_ID_MAX]``. - """ return snowflake_id & SEQUENCE_ID_MAX @@ -85,29 +33,6 @@ def generate_snowflake_id( node_id: int = NODE_ID_DEFAULT, epoch_ms: int = EPOCH_MS_DEFAULT, ) -> int | None: - """Build and return a Snowflake identifier for the current millisecond. - - The function is stateless: the caller passes the per-millisecond sequence - counter explicitly. It is the caller's responsibility to increment - ``sequence_id`` for identifiers minted within the same millisecond and to - reset it once the clock advances. - - Args: - sequence_id: The per-millisecond sequence counter, in the range - ``[0, SEQUENCE_ID_MAX]``. - node_id: The identifier of this node, in the range ``[0, NODE_ID_MAX]``. - Optional; defaults to ``NODE_ID_DEFAULT``. - epoch_ms: The start of the epoch as Unix milliseconds. Optional; - defaults to the original Twitter epoch (2010-11-04 01:42:54.657 - UTC). - - Returns: - The Snowflake identifier as a positive 63-bit integer, or ``None`` if - ``node_id`` is outside ``[0, NODE_ID_MAX]``, ``sequence_id`` is outside - ``[0, SEQUENCE_ID_MAX]``, or the elapsed time no longer fits in the - timestamp field (roughly 69 years after ``epoch_ms``). In each of those - cases an explanatory message is printed to stdout first. - """ if not (0 <= node_id <= NODE_ID_MAX): print(f"node_id must be in [0, {NODE_ID_MAX}], got {node_id}") return None @@ -118,7 +43,7 @@ def generate_snowflake_id( elapsed_ms = read_current_millis(epoch_ms) if elapsed_ms > TIMESTAMP_MS_MAX: - print("overflows") + print(f"timestamp overflows: {elapsed_ms} > {TIMESTAMP_MS_MAX}") return None return (elapsed_ms << TIMESTAMP_SHIFT) | (node_id << NODE_ID_SHIFT) | sequence_id From 4e04d1b01026b4a698296c301eff1234b2721e07 Mon Sep 17 00:00:00 2001 From: SimencaSs <74181505+SimencaSs@users.noreply.github.com> Date: Thu, 15 Oct 2026 14:16:23 +0300 Subject: [PATCH 5/7] =?UTF-8?q?=D0=A1=D0=BB=D0=BE=D0=BC=D0=B0=D0=BB=D1=81?= =?UTF-8?q?=D1=8F=20=D0=BF=D1=83=D1=88?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- src/part1/TASK.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/part1/TASK.md b/src/part1/TASK.md index ef8e0faf..8838ed72 100644 --- a/src/part1/TASK.md +++ b/src/part1/TASK.md @@ -7,7 +7,7 @@ Начнём с фундамента: у каждой записи должен быть уникальный идентификатор. Казалось бы, можно просто нумеровать записи 1, 2, 3, … Пока хранилище живёт на -одной машине, так и происходит. Но реальные системы почти всегда распределены: +одной машине, так и происходит. Но реальные системы почти всегда распределены: записи создаются на десятках серверов одновременно. Тогда возникают проблемы: - единый счётчик становится «бутылочным горлышком»: каждому серверу приходится From 568f27548f17782e21a365afe933af54715c86d7 Mon Sep 17 00:00:00 2001 From: SimencaSs <74181505+SimencaSs@users.noreply.github.com> Date: Fri, 23 Oct 2026 12:03:12 +0300 Subject: [PATCH 6/7] =?UTF-8?q?2=20=D0=B7=D0=B0=D0=B4=D0=B0=D0=BD=D0=B8?= =?UTF-8?q?=D0=B5=20=D0=B8=D0=B7=D0=BC=D0=B5=D0=BD=D1=91=D0=BD=D0=BD=D1=8B?= =?UTF-8?q?=D0=B5=20=D0=B8=D0=BC=D0=BF=D0=BE=D1=80=D1=82=D1=8B?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- src/part1/snowflake.py | 2 +- src/part2/cart.py | 160 ++++++++++++++++++++--------------------- src/part2/crud.py | 65 ----------------- src/part2/utils.py | 11 --- src/part3/TASK.md | 16 ++--- src/part3/crud.py | 146 +++++++------------------------------ src/part3/run_admin.py | 120 ++++++++----------------------- src/part3/storage.py | 20 ------ src/part3/utils.py | 114 +++++------------------------ 9 files changed, 159 insertions(+), 495 deletions(-) diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index bed5f406..deb039bf 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -12,7 +12,7 @@ def read_current_millis(epoch_ms: int) -> int: - return time.time_ns() // 1000000 - epoch_ms + return time.time_ns() // 1_000_000 - epoch_ms def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int: diff --git a/src/part2/cart.py b/src/part2/cart.py index 1d3f7f43..6e042567 100644 --- a/src/part2/cart.py +++ b/src/part2/cart.py @@ -9,67 +9,72 @@ an explanatory message to stdout and returns ``None``. """ -from typing import Final +from decimal import Decimal +from typing import Final, cast from .crud import read_product, update_product from .storage import ( + NAME_INDEX, + PRICE_INDEX, + PRODUCT_ID_INDEX, + QUANTITY_INDEX, Product, ) type CartLine = tuple[int, int] -# TODO: задайте позиции полей внутри кортежа CartLine LINE_PRODUCT_ID_INDEX: Final[int] = 0 LINE_QUANTITY_INDEX: Final[int] = 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], cart: list[CartLine], product_id: int, quantity: int, ) -> CartLine | None: - """Move ``quantity`` units of ``product_id`` from the store into ``cart``. - - The product is looked up in ``storage``. If it is missing, a message is - printed (by :func:`~src.part2.crud.read_product`) and nothing - changes. If the store holds fewer units than requested, an explanatory - message is printed and nothing changes. Otherwise the store record is - decremented by ``quantity`` and the cart line for ``product_id`` gains - ``quantity`` units -- a new line is created when the cart had none. - - Args: - storage: The product store to draw stock from; modified in place on - success. - cart: The cart to add the units to; modified in place on success. - product_id: The identifier of the product to add. - quantity: Number of units to move into the cart. - - Returns: - The cart line for ``product_id`` after the addition, or ``None`` - when the product is unknown or the store cannot cover the request. - """ product = read_product(storage, product_id) - if not product: + if product is None: + return None + + stored_id = cast(int, product[PRODUCT_ID_INDEX]) + if stored_id != product_id: + print(f"storage returned a wrong record for product {product_id}") return None - _, name, price, stock_quantity = product - if stock_quantity < quantity: + name = cast(str, product[NAME_INDEX]) + price = cast(Decimal, product[PRICE_INDEX]) + available = cast(int, product[QUANTITY_INDEX]) + + if available < quantity: print( - f"Not enough stock for product {product_id}: " - f"{stock_quantity} available, {quantity} requested" + f"not enough stock for product {product_id}: " + f"{available} available, {quantity} requested" ) return None - update_product(storage, product_id, (name, price, stock_quantity - quantity)) + update_product( + storage, + product_id, + (name, price, available - quantity), + ) - for i in range(len(cart)): - if cart[i][LINE_PRODUCT_ID_INDEX] == product_id: - cart_quantity = cart[i][LINE_QUANTITY_INDEX] - new_line = (product_id, cart_quantity + quantity) - cart[i] = new_line - return new_line + for index, line in enumerate(cart): + if line[LINE_PRODUCT_ID_INDEX] == product_id: + updated = ( + product_id, + line[LINE_QUANTITY_INDEX] + quantity, + ) + cart[index] = updated + return updated new_line = (product_id, quantity) cart.append(new_line) @@ -82,56 +87,45 @@ def remove_from_cart( product_id: int, quantity: int, ) -> CartLine | None: - """Move ``quantity`` units of ``product_id`` from ``cart`` back to the store. - - The cart line for ``product_id`` is looked up. If there is none, a - message is printed and nothing changes. If the line holds fewer units - than requested, an explanatory message is printed and nothing changes. - Otherwise the cart line loses ``quantity`` units -- the line is dropped - when it reaches zero -- and the store record gains ``quantity`` units - back. - - Args: - storage: The product store to return stock to; modified in place on - success. - cart: The cart to take the units from; modified in place on - success. - product_id: The identifier of the product to remove. - quantity: Number of units to move back into the store. - - Returns: - The cart line for ``product_id`` after the removal (a quantity of - zero means the line was dropped), or ``None`` when the cart has no - line for the product or holds too few units. - """ - for i in range(len(cart)): - if cart[i][LINE_PRODUCT_ID_INDEX] == product_id: - cart_quantity = cart[i][LINE_QUANTITY_INDEX] - if quantity > cart_quantity: - print( - f"Cart holds only {cart_quantity} units of product {product_id}, " - f"cannot remove {quantity}" - ) - return None - - product = read_product(storage, product_id) - if not product: - return None - - _, name, price, stock_quantity = product - update_product( - storage, - product_id, - (name, price, stock_quantity + quantity), - ) + line = find_cart_line(cart, product_id) + if line is None: + print(f"product {product_id} is not in the cart") + return None - remaining_quantity = cart_quantity - quantity - if remaining_quantity == 0: - del cart[i] - return (product_id, 0) + cart_qty = line[LINE_QUANTITY_INDEX] + if cart_qty < quantity: + print( + f"cart holds only {cart_qty} unit(s) of product {product_id}, " + f"cannot remove {quantity}" + ) + return None - cart[i] = (product_id, remaining_quantity) - return cart[i] + product = read_product(storage, product_id) + if product is None: + return None - print(f"Product {product_id} is not in the cart") + stored_id = cast(int, product[PRODUCT_ID_INDEX]) + if stored_id != product_id: + print(f"storage returned a wrong record for product {product_id}") + return None + + name = cast(str, product[NAME_INDEX]) + price = cast(Decimal, product[PRICE_INDEX]) + stock_quantity = cast(int, product[QUANTITY_INDEX]) + + update_product( + storage, + product_id, + (name, price, stock_quantity + quantity), + ) + + for index, cart_line in enumerate(cart): + if cart_line[LINE_PRODUCT_ID_INDEX] == product_id: + remaining = cart_qty - quantity + if remaining == 0: + del cart[index] + return (product_id, 0) + updated = (product_id, remaining) + cart[index] = updated + return updated return None diff --git a/src/part2/crud.py b/src/part2/crud.py index 0bfe0959..cd509e05 100644 --- a/src/part2/crud.py +++ b/src/part2/crud.py @@ -24,16 +24,6 @@ def generate_product_id(storage: list[Product]) -> int: - """Choose the identifier for the next product added to ``storage``. - - Args: - storage: The product store to inspect. - - Returns: - One past the greatest identifier currently held in ``storage``, or - :data:`~src.part2.storage.PRODUCT_ID_MIN` when ``storage`` is - empty. - """ if not storage: return PRODUCT_ID_MIN @@ -47,21 +37,6 @@ def generate_product_id(storage: list[Product]) -> int: def create_product( storage: list[Product], fields: tuple[str, Decimal, int] ) -> int | None: - """Append a new product to ``storage`` and return its new identifier. - - Args: - storage: The product store to append to; modified in place on - success. - fields: A ``(name, price, quantity)`` tuple describing the product. - ``price`` is a :class:`~decimal.Decimal` amount and is rounded - to the stored money precision before it is saved. - - Returns: - The identifier generated for the new product, or ``None`` when a - product with the same name already exists. In the ``None`` case - ``storage`` is left unchanged and a message naming the clashing - name is printed. - """ name, price, quantity = fields for product in storage: if product[NAME_INDEX] == name: @@ -75,16 +50,6 @@ def create_product( def read_product(storage: list[Product], product_id: int) -> Product | None: - """Return the product stored under ``product_id``. - - Args: - storage: The product store to search. - - Returns: - The matching ``(product_id, name, price, quantity)`` record, or - ``None`` when no product carries that identifier (a message is - printed in that case). - """ for product in storage: if product[PRODUCT_ID_INDEX] == product_id: return product @@ -97,24 +62,6 @@ def update_product( product_id: int, fields: tuple[str, Decimal, int], ) -> Product | None: - """Overwrite the fields of the product stored under ``product_id``. - - The identifier itself is preserved; only ``name``, ``price`` and - ``quantity`` are replaced. - - Args: - storage: The product store to modify; the matching record is - replaced in place on success. - product_id: The identifier of the product to change. - fields: A ``(name, price, quantity)`` tuple with the new values. - ``price`` is a :class:`~decimal.Decimal` amount and is rounded - to the stored money precision before it is saved. - - Returns: - The updated ``(product_id, name, price, quantity)`` record, or - ``None`` when no product carries that identifier (``storage`` is - left unchanged and a message is printed). - """ name, price, quantity = fields normalized_price = normalize_price(price) for i in range(len(storage)): @@ -127,18 +74,6 @@ def update_product( def delete_product(storage: list[Product], product_id: int) -> int | None: - """Remove the product stored under ``product_id`` from ``storage``. - - Args: - storage: The product store to remove from; modified in place on - success. - product_id: The identifier of the product to remove. - - Returns: - ``product_id`` when a product was removed, or ``None`` when no - product carried that identifier (``storage`` is left unchanged and - a message is printed). - """ for i in range(len(storage)): if storage[i][PRODUCT_ID_INDEX] == product_id: del storage[i] diff --git a/src/part2/utils.py b/src/part2/utils.py index 528429ef..f18a7eb6 100644 --- a/src/part2/utils.py +++ b/src/part2/utils.py @@ -10,20 +10,9 @@ from typing import Final -# TODO: задайте число знаков после запятой и шаг квантования PRICE_PRECISION: Final[int] = 2 PRICE_STEP: Final[Decimal] = Decimal(1).scaleb(-PRICE_PRECISION) def normalize_price(price: Decimal) -> Decimal: - """Round a price to the precision every stored record uses. - - Args: - price: The raw price amount. - - Returns: - ``price`` quantised to :data:`PRICE_PRECISION` fractional digits, - with halves rounded up. - """ - # TODO: реализуйте функцию return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP) diff --git a/src/part3/TASK.md b/src/part3/TASK.md index e48ecdac..f229ae2f 100644 --- a/src/part3/TASK.md +++ b/src/part3/TASK.md @@ -204,7 +204,7 @@ storage: list[Product] = [] first_id = create_product(storage, (" Cordless Drill ", Decimal("89.999"), 12)) second_id = create_product(storage, ("Claw Hammer", Decimal("9.9"), 40)) -print(first_id) # 1 +print(first_id) # 1 print(second_id) # 2 print(storage) # [(1, 'cordless drill', Decimal('90.00'), 12), @@ -220,7 +220,7 @@ create_product(storage, ("cordless drill", Decimal("50"), 3)) result = create_product(storage, (" CORDLESS DRILL ", Decimal("75"), 1)) # печатает: product name 'cordless drill' is already taken -print(result) # None +print(result) # None print(storage) # [(1, 'cordless drill', Decimal('50.00'), 3)] ``` @@ -232,7 +232,7 @@ storage: list[Product] = [] result = create_product(storage, (" ", Decimal("10"), 5)) # печатает: product name must not be blank -print(result) # None +print(result) # None print(storage) # [] ``` @@ -271,7 +271,7 @@ storage: list[Product] = [ ```python result = update_product(storage, 2, (" Rubber Mallet ", Decimal("7.505"), 25)) -print(result) # (2, 'rubber mallet', Decimal('7.51'), 25) +print(result) # (2, 'rubber mallet', Decimal('7.51'), 25) print(storage) # [(1, 'cordless drill', Decimal('90.00'), 12), # (2, 'rubber mallet', Decimal('7.51'), 25)] @@ -283,7 +283,7 @@ print(storage) ```python result = update_product(storage, 1, ("CORDLESS Drill", Decimal("85"), 10)) -print(result) # (1, 'cordless drill', Decimal('85.00'), 10) +print(result) # (1, 'cordless drill', Decimal('85.00'), 10) ``` Имя уже занято другим товаром, хранилище не меняется: @@ -292,7 +292,7 @@ print(result) # (1, 'cordless drill', Decimal('85.00'), 10) result = update_product(storage, 1, (" Claw Hammer ", Decimal("85"), 10)) # печатает: product name 'claw hammer' is already taken -print(result) # None +print(result) # None print(storage) # [(1, 'cordless drill', Decimal('90.00'), 12), # (2, 'claw hammer', Decimal('9.90'), 40)] @@ -304,11 +304,11 @@ print(storage) ```python result = update_product(storage, 99, ("saw", Decimal("20"), 5)) # печатает: no product with id 99 -print(result) # None +print(result) # None result = update_product(storage, 99, (" ", Decimal("20"), 5)) # печатает: product name must not be blank (а не no product with id 99) -print(result) # None +print(result) # None ``` --- diff --git a/src/part3/crud.py b/src/part3/crud.py index 17f3fbad..11de16ed 100644 --- a/src/part3/crud.py +++ b/src/part3/crud.py @@ -1,23 +1,3 @@ -"""Create/read/update/delete operations over the in-memory product store. - -Every operation takes the store -- a list of -:data:`~src.part3.storage.Product` tuples -- as its first argument and -works on it in place. The failure path never raises: the operation prints -an explanatory message to stdout and returns ``None``. - -The identifier of a new product is derived from the store itself -(:func:`generate_product_id`): one past the greatest identifier in use, or -:data:`~src.part3.storage.PRODUCT_ID_MIN` when the store is empty. - -Every product name that reaches the store is passed through -:func:`~src.part3.utils.normalize_product_name` first. A name that -normalises to an empty string is rejected -- the operation prints a -message and changes nothing. Names are also kept unique -- -:func:`create_product` refuses a normalised name that is already taken, -and :func:`update_product` refuses one that is already taken by another -product. -""" - from decimal import Decimal from .storage import ( @@ -30,76 +10,32 @@ def generate_product_id(storage: list[Product]) -> int: - """Choose the identifier for the next product added to ``storage``. - - Args: - storage: The product store to inspect. - - Returns: - One past the greatest identifier currently held in ``storage``, or - :data:`~src.part2.storage.PRODUCT_ID_MIN` when ``storage`` is - empty. - """ if not storage: return PRODUCT_ID_MIN - - max_id = 0 - for product in storage: - current_id = int(product[PRODUCT_ID_INDEX]) - max_id = max(current_id, max_id) - return max_id + 1 + return max(p[PRODUCT_ID_INDEX] for p in storage) + 1 def create_product( storage: list[Product], fields: tuple[str, Decimal, int] ) -> int | None: - """Append a new product to ``storage`` and return its new identifier. - - Args: - storage: The product store to append to; modified in place on - success. - fields: A ``(name, price, quantity)`` tuple describing the product. - ``name`` is normalised (surrounding whitespace stripped, - lower-cased) before it is stored or compared. ``price`` is a - :class:`~decimal.Decimal` amount and is rounded to the stored - money precision before it is saved. - - Returns: - The identifier generated for the new product, or ``None`` when - ``name`` is blank once normalised or a product with the same - normalised name already exists. In the ``None`` case ``storage`` - is left unchanged and an explanatory message is printed. - """ name, price, quantity = fields name = normalize_product_name(name) if not name: print("product name must not be blank") return None - for product in storage: - if product[NAME_INDEX] == name: - print(f"product name '{name}' is already taken") - return None - - new_id = generate_product_id(storage) - normalized_price = normalize_price(price) - storage.append((new_id, name, normalized_price, quantity)) - return new_id + if any(p[NAME_INDEX] == name for p in storage): + print(f"product name '{name}' is already taken") + return None + product_id = generate_product_id(storage) + storage.append((product_id, name, normalize_price(price), quantity)) + return product_id def read_product(storage: list[Product], product_id: int) -> Product | None: - """Return the product stored under ``product_id``. - - Args: - storage: The product store to search. - - Returns: - The matching ``(product_id, name, price, quantity)`` record, or - ``None`` when no product carries that identifier (a message is - printed in that case). - """ for product in storage: if product[PRODUCT_ID_INDEX] == product_id: return product + print(f"no product with id {product_id}") return None @@ -109,68 +45,36 @@ def update_product( product_id: int, fields: tuple[str, Decimal, int], ) -> Product | None: - """Overwrite the fields of the product stored under ``product_id``. - - The identifier itself is preserved; only ``name``, ``price`` and - ``quantity`` are replaced. - - Args: - storage: The product store to modify; the matching record is - replaced in place on success. - product_id: The identifier of the product to change. - fields: A ``(name, price, quantity)`` tuple with the new values. - ``price`` is a :class:`~decimal.Decimal` amount and is rounded - to the stored money precision before it is saved. - - Returns: - The updated ``(product_id, name, price, quantity)`` record, or - ``None`` when ``name`` is blank once normalised, no product - carries that identifier, or the normalised name is already taken - by another product. In every ``None`` case ``storage`` is left - unchanged and an explanatory message is printed. Renaming a - product to its own current name is allowed. - """ name, price, quantity = fields name = normalize_product_name(name) - normalized_price = normalize_price(price) if not name: print("product name must not be blank") return None - flag = False - index_of_needed_id = 0 - for i in range(len(storage)): - if storage[i][PRODUCT_ID_INDEX] == product_id: - flag = True - index_of_needed_id = i + + index = None + for i, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + index = i break - if not flag: + + if index is None: print(f"no product with id {product_id}") return None - for i in range(len(storage)): - if i != index_of_needed_id and storage[i][NAME_INDEX] == name: + + for product in storage: + if product[NAME_INDEX] == name and product[PRODUCT_ID_INDEX] != product_id: print(f"product name '{name}' is already taken") return None - updated = (product_id, name, normalized_price, quantity) - storage[index_of_needed_id] = updated - return storage[index_of_needed_id] + updated = (product_id, name, normalize_price(price), quantity) + storage[index] = updated + return updated def delete_product(storage: list[Product], product_id: int) -> int | None: - """Remove the product stored under ``product_id`` from ``storage``. - - Args: - storage: The product store to remove from; modified in place on - success. - product_id: The identifier of the product to remove. - - Returns: - ``product_id`` when a product was removed, or ``None`` when no - product carried that identifier (``storage`` is left unchanged and - a message is printed). - """ - for i in range(len(storage)): - if storage[i][PRODUCT_ID_INDEX] == product_id: - del storage[i] + for index, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + del storage[index] return product_id + print(f"no product with id {product_id}") return None diff --git a/src/part3/run_admin.py b/src/part3/run_admin.py index 83df2d51..5608f2e3 100644 --- a/src/part3/run_admin.py +++ b/src/part3/run_admin.py @@ -1,34 +1,3 @@ -"""Interactive admin console for the part3 in-memory product store. - -Running this module starts a read-eval-print loop over a single product -store that lives in memory for the lifetime of the process. Every line -typed at the prompt is stripped of surrounding whitespace and matched -against the set of known commands: - -* ``help`` -- print the list of commands and what each one does; -* ``exit`` -- leave the loop and end the program; -* ``show`` -- print the whole store as a text table; -* ``create `` -- add a product; -* ``read `` -- print one product; -* ``update `` -- overwrite a product; -* ``delete `` -- remove a product. - -For ``create`` and ``update`` the price and quantity are always the last -two words of the line; everything between the verb (and, for ``update``, -the id) and those two words is joined with single spaces into the -product name, so a multi-word name such as ``Gibson SG Junior`` needs no -quoting. - -The four CRUD commands forward to :mod:`src.part3.crud`; whatever -that call returns is printed unless it is ``None``. A line whose first -word is not a known verb, or that carries the wrong number of arguments -for its verb, prints an "is not a command" notice. A line that names a -command correctly but whose id, price or quantity argument will not -parse prints a distinct "arguments are invalid" notice. Either way the -store is left untouched and the loop keeps running; only ``exit`` stops -it. -""" - from decimal import Decimal, InvalidOperation from typing import Final @@ -43,7 +12,6 @@ PROMPT: Final[str] = "admin> " - HELP_TEXT: Final[str] = """Available commands: help show this message exit leave the console @@ -59,83 +27,54 @@ def show_help() -> None: - """Print the command reference to stdout. - - The text is the module-level :data:`HELP_TEXT` constant, printed as - is: a heading, one line per command with a short description, and a - note on how multi-word names are parsed. - """ print(HELP_TEXT) def print_result(result: object) -> None: - """Print a CRUD result to stdout unless it is ``None``. - - Args: - result: The value returned by a CRUD operation. ``None`` means the - operation already reported its own failure, so nothing is - printed in that case. - """ if result is not None: print(result) def run_command(storage: list[Product], line: str) -> bool: - """Parse one console line and carry out the command it names. - - Args: - storage: The product store shared across the session; mutated in - place by the ``create``, ``update`` and ``delete`` commands. - line: One line of console input, already stripped of surrounding - whitespace. - - Returns: - ``True`` to keep the read-eval-print loop running, or ``False`` - once the ``exit`` command has been seen. A line that is not a - known command prints a notice and still returns ``True``. - - Raises: - ValueError: If an id or quantity argument of a CRUD command does - not parse as a base-10 integer. - decimal.InvalidOperation: If the price argument of ``create`` or - ``update`` does not parse as a decimal number. - """ words = line.split() if not words: - print(f"'{line}' is not a command") return True command = words[0] - if command == "exit" and len(words) == 1: - return False - if command == "help" and len(words) == 1: show_help() return True - if command == "show" and len(words) == 1: - print(get_storage_str_representation(storage)) - return True - - if command == "read" and len(words) == 2: - product_id = int(words[1]) - print_result(read_product(storage, product_id)) - return True + if command == "exit" and len(words) == 1: + return False - if command == "delete" and len(words) == 2: - product_id = int(words[1]) - print_result(delete_product(storage, product_id)) + if command == "show" and len(words) == 1: + print_result(get_storage_str_representation(storage)) return True - if command == "create" and len(words) >= 4: + if command == "create": + if len(words) < 4: + print(f"{line!r} is not a command") + return True name = " ".join(words[1:-2]) price = Decimal(words[-2]) quantity = int(words[-1]) print_result(create_product(storage, (name, price, quantity))) return True - if command == "update" and len(words) >= 5: + if command == "read": + if len(words) != 2: + print(f"{line!r} is not a command") + return True + product_id = int(words[1]) + print_result(read_product(storage, product_id)) + return True + + if command == "update": + if len(words) < 5: + print(f"{line!r} is not a command") + return True product_id = int(words[1]) name = " ".join(words[2:-2]) price = Decimal(words[-2]) @@ -143,20 +82,19 @@ def run_command(storage: list[Product], line: str) -> bool: print_result(update_product(storage, product_id, (name, price, quantity))) return True - print(f"'{line}' is not a command") + if command == "delete": + if len(words) != 2: + print(f"{line!r} is not a command") + return True + product_id = int(words[1]) + print_result(delete_product(storage, product_id)) + return True + + print(f"{line!r} is not a command") return True def main() -> None: - """Run the admin console until the ``exit`` command is entered. - - A single product store is created empty and kept in memory for the - whole session. Each iteration reads one line from stdin, strips its - surrounding whitespace and hands it to :func:`run_command`. A line - that names a command but whose id, price or quantity argument does - not parse is caught here and reported without stopping the loop; only - ``exit`` ends it. - """ storage: list[Product] = [] running = True diff --git a/src/part3/storage.py b/src/part3/storage.py index c516645b..81651a75 100644 --- a/src/part3/storage.py +++ b/src/part3/storage.py @@ -1,23 +1,3 @@ -"""In-memory product store for the shop CRUD exercise. - -The store is deliberately primitive: a plain list of tuples, with no -persistence, no indexing and no schema enforcement. Each element is a -:data:`Product` record -- a ``(product_id, name, price, quantity)`` tuple -where: - -* ``product_id`` -- unique positive integer key, assigned by the create - operation in :mod:`src.part3.crud`; -* ``name`` -- human-readable product name, unique across the store; -* ``price`` -- price of a single unit, held as a :class:`~decimal.Decimal` - amount rounded to a fixed number of decimal places (see - :func:`src.part3.utils.normalize_price`) so that money is never - subject to binary floating-point error; -* ``quantity`` -- number of units currently in stock. - -Field positions are exposed as ``*_INDEX`` constants so callers never -hard-code tuple offsets. -""" - from decimal import Decimal from typing import Final diff --git a/src/part3/utils.py b/src/part3/utils.py index dcd354e6..9b2b1a72 100644 --- a/src/part3/utils.py +++ b/src/part3/utils.py @@ -1,115 +1,39 @@ -"""Standalone helpers shared by the part3 storage and CRUD modules. - -Normalisation: - -* :func:`normalize_price` rounds a raw :class:`~decimal.Decimal` amount to - the fixed number of fractional digits (:data:`PRICE_PRECISION`) that - every stored price uses, keeping currency values free of binary - floating-point error. -* :func:`normalize_product_name` strips surrounding whitespace from a - product name, collapses every internal run of whitespace to a single - space and lower-cases it, giving every stored name a single canonical - form. - -Presentation: - -* :func:`get_storage_str_representation` renders the whole store as a - text table meant to be printed to a terminal; each column is sized to - the longest value it holds in that particular call. -""" - from decimal import ROUND_HALF_UP, Decimal from typing import Final from .storage import Product -# Number of fractional digits every stored price is rounded to. -# Quantisation step derived from PRICE_PRECISION, e.g. Decimal("0.01"). -# TODO: задайте число знаков после запятой и шаг квантования (используйте своё -# решение части 2) PRICE_PRECISION: Final[int] = 2 PRICE_STEP: Final[Decimal] = Decimal(1).scaleb(-PRICE_PRECISION) - -# Column headers of the table produced by get_storage_str_representation, -# left to right. The width of each column is not fixed here -- it is -# measured per call from the data (see the function). -# TODO: задайте заголовки столбцов таблицы -TABLE_HEADERS: Final[tuple[str, ...]] = ("ID", "name", "price", "quantity") +TABLE_HEADERS: Final[tuple[str, str, str, str]] = ("ID", "name", "price", "quantity") def normalize_price(price: Decimal) -> Decimal: - """Round a price to the precision every stored record uses. - - Args: - price: The raw price amount. - - Returns: - ``price`` quantised to :data:`PRICE_PRECISION` fractional digits, - with halves rounded up. - """ return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP) def normalize_product_name(name: str) -> str: - """Reduce a product name to the canonical form the store keeps. - - Args: - name: The raw product name. - - Returns: - ``name`` with every leading and trailing whitespace character - removed, every internal run of whitespace (spaces, tabs and the - like) collapsed to a single space, and the rest lower-cased. For - example ``"abc def\tghi\tjkl"`` becomes ``"abc def ghi jkl"``. - The result is an empty string when ``name`` holds nothing but - whitespace. - """ - list_of_words = name.split() - name = " ".join(list_of_words) - name = name.lower() - return name - - -# TODO: при необходимости добавьте свои вспомогательные функции + return " ".join(name.split()).lower() def get_storage_str_representation(storage: list[Product]) -> str: - """Render the product store as a text table with data-sized columns. - - The table has the columns named by :data:`TABLE_HEADERS` -- id, name, - price and quantity. Each column is made exactly as wide as the longest - value it carries in this call (its header counted), so the columns - line up when the string is printed to a terminal and no value is ever - truncated. - - Args: - storage: The product store to render. - - Returns: - A multi-line string: a header row, a dashed separator row, then - one row per product in ``storage`` in list order. When ``storage`` - is empty only the header and separator rows are returned, sized to - the header labels. - """ - mxlen1 = len(TABLE_HEADERS[0]) - mxlen2 = len(TABLE_HEADERS[1]) - mxlen3 = len(TABLE_HEADERS[2]) - mxlen4 = len(TABLE_HEADERS[3]) - for product in storage: - item_id = str(product[0]) - name = str(product[1]) - price = str(product[2]) - quantity = str(product[3]) - mxlen1 = max(mxlen1, len(item_id)) - mxlen2 = max(mxlen2, len(name)) - mxlen3 = max(mxlen3, len(price)) - mxlen4 = max(mxlen4, len(quantity)) - s1 = f"| {TABLE_HEADERS[0].ljust(mxlen1)} | {TABLE_HEADERS[1].ljust(mxlen2)} | {TABLE_HEADERS[2].ljust(mxlen3)} | {TABLE_HEADERS[3].ljust(mxlen4)} |" - s2 = f"|{'-' * (mxlen1 + 2)}|{'-' * (mxlen2 + 2)}|{'-' * (mxlen3 + 2)}|{'-' * (mxlen4 + 2)}|" - snext = [ - f"| {str(product[0]).ljust(mxlen1)} | {str(product[1]).ljust(mxlen2)} | {str(product[2]).ljust(mxlen3)} | {str(product[3]).ljust(mxlen4)} |" + rows: list[tuple[str, str, str, str]] = [ + (str(product[0]), product[1], str(product[2]), str(product[3])) for product in storage ] - rows = [s1, s2, *snext] - return "\n".join(rows) + widths: list[int] = [ + max(len(header), *(len(row[i]) for row in rows)) if rows else len(header) + for i, header in enumerate(TABLE_HEADERS) + ] + header_line = ( + "|" + + "|".join(f" {cell:<{width}} " for cell, width in zip(TABLE_HEADERS, widths)) + + "|" + ) + dop_line = "|" + "|".join("-" * (width + 2) for width in widths) + "|" + data_lines = [ + "|" + "|".join(f" {cell:<{width}} " for cell, width in zip(row, widths)) + "|" + for row in rows + ] + return "\n".join([header_line, dop_line, *data_lines]) From 6fa5006ea4877d1b6d198e57ac3d125bd5711f11 Mon Sep 17 00:00:00 2001 From: SimencaSs <74181505+SimencaSs@users.noreply.github.com> Date: Fri, 30 Oct 2026 11:21:38 +0300 Subject: [PATCH 7/7] 4 task --- src/part4/TASK.md | 411 +++++++++++++++++++++++++++++++++++++++++ src/part4/__init__.py | 0 src/part4/cart.py | 63 +++++++ src/part4/crud.py | 98 ++++++++++ src/part4/run_admin.py | 128 +++++++++++++ src/part4/storage.py | 8 + src/part4/utils.py | 49 +++++ 7 files changed, 757 insertions(+) create mode 100644 src/part4/TASK.md create mode 100644 src/part4/__init__.py create mode 100644 src/part4/cart.py create mode 100644 src/part4/crud.py create mode 100644 src/part4/run_admin.py create mode 100644 src/part4/storage.py create mode 100644 src/part4/utils.py diff --git a/src/part4/TASK.md b/src/part4/TASK.md new file mode 100644 index 00000000..6857ed0c --- /dev/null +++ b/src/part4/TASK.md @@ -0,0 +1,411 @@ +# Задача: хранилище-словарь, UUID-идентификаторы, индекс имён и корзина-словарь + +## Легенда + +Наше хранилище товаров уже умеет немало: CRUD-операции, нормализацию имён и +цен, красивую таблицу и консоль администратора. Но устроено оно по-прежнему +«на коленке» — как список кортежей, — и пока каталог маленький, этого хватает. +Но когда в каталоге появляются тысячи товаров, начинают проявляться проблемы: + +- чтобы найти товар по идентификатору или проверить, не занято ли имя, надо + пройти весь список целиком, и чем больше каталог, тем медленнее работает + каждая операция; +- идентификатор вычисляется по содержимому хранилища («максимальный плюс + один»): его нельзя выдать независимо от остальных товаров, а два хранилища + (например, на разных серверах) легко выдадут одинаковые номера; +- поля кортежа различаются только позицией, поэтому в коде появляются + «магические» индексы, а чтобы поменять одно поле, приходится пересобирать + запись целиком. + +Обычные решения этих проблем знакомы любой базе данных. Записи хранят как +«ключ → значение» в хеш-таблице, где поиск по ключу не зависит от размера +хранилища. Рядом держат индекс — в СУБД это, например, уникальный индекс по +имени. А идентификаторы генерируют так, чтобы каждый узел мог выдавать их сам, +не согласовывая номера с остальными: в части 1 вы уже писали для этого +Snowflake, а UUID — самый распространённый стандартный вариант. + +Именно это мы и напишем: переведём хранилище на словари, заведём +UUID-идентификаторы и отдельный индекс имён, научим `update_product` +менять только нужные поля и оформим корзину покупателя тоже в виде словаря. +Получившееся хранилище станет основой, на которую опирается дальнейшая работа над магазином. + +## Контекст + +Часть 4 продолжает [часть 3](../part3/TASK.md): тот же интернет-магазин, те же +CRUD-операции, та же нормализация имён и цен, та же отрисовка таблицей и та же +консоль администратора. То, что в этой части не меняется, берите из своего +решения части 3. Меняется устройство данных: + +- хранилище — уже не список кортежей, а **словарь** «идентификатор → запись», + а сама запись — словарь с именованными полями; +- идентификатор товара — **строка с UUID**, а не порядковое целое число; +- рядом с хранилищем передаётся **индекс имён** — множество нормализованных + имён, которые сейчас есть в хранилище. Проверка уникальности имени идёт по + нему, без перебора всех записей; +- `update_product` может менять **любую часть** полей, а не все три сразу; +- корзина — тоже словарь «идентификатор товара → количество»; модуль `cart.py` + из [части 2](../part2/TASK.md), который в части 3 не использовался, снова + входит в задание. + +Модули: + +- `storage.py` — новая форма записи и новые константы; +- `utils.py` — логика **без изменений относительно части 3** + (`PRICE_PRECISION`, `PRICE_STEP`, `TABLE_HEADERS`, `normalize_price`, + `normalize_product_name`, `get_storage_str_representation`) — используйте своё + решение части 3; меняется только тип хранилища (см. ниже); +- `crud.py` — все функции дорабатываются под новое хранилище и индекс имён; +- `cart.py` — корзина из части 2, переделанная под словари; +- `run_admin.py` — консоль из части 3, переделанная под новые сигнатуры. + +Если поведение не менялось, оно здесь не расписывается: реализуйте его так, как +в своём решении части 3 (для корзины — части 2), см. +[описание части 3](../part3/TASK.md) и [описание части 2](../part2/TASK.md). + +Как и раньше, при неудаче функции `crud.py` и `cart.py` печатают сообщение в +stdout, возвращают `None` и ничего не меняют. + +--- + +## Формат данных + +### Хранилище + +`storage: dict[str, Product]` — словарь, где ключ — идентификатор товара (строка +с UUID, например `"3f2c…-…"`), а значение — запись `Product`. Идентификатор +хранится **только в ключе**, внутри записи его нет. + +Запись `Product` — словарь ровно с тремя ключами: + +| Ключ | Тип | Что хранит | +| ------------ | --------- | -------------------------------------------------------------------- | +| `"name"` | `str` | имя товара в нормализованной форме, уникальное в пределах хранилища | +| `"price"` | `Decimal` | цена за единицу, округлённая через `normalize_price` | +| `"quantity"` | `int` | сколько единиц товара на складе | + +### Индекс имён + +`product_names: set[str]` — множество нормализованных имён всех товаров, +которые сейчас лежат в хранилище. Индекс всегда должен совпадать с набором +имён в `storage`. Каждая функция, которая меняет хранилище, получает индекс +вторым аргументом и после каждого успешного вызова поддерживает его в +актуальном виде. Хранилище и индекс передаются двумя отдельными аргументами, +в один объект их не объединяют. + +### Корзина + +`cart: dict[str, int]` — словарь «идентификатор товара → количество единиц в +корзине». Товары с нулевым количеством в корзине не хранятся: если количество +падает до нуля, ключ удаляется. + +--- + +## Модуль `storage.py` + +- `Product` — псевдоним типа `dict[str, Any]`. +- `NAME_KEY`, `PRICE_KEY`, `QUANTITY_KEY` — имена полей записи: `"name"`, + `"price"`, `"quantity"`. Каждая константа аннотирована `typing.Final`. Код + обращается к полям записи только через эти константы, а не через строковые + литералы. + +По сравнению с частью 3 константы `PRODUCT_ID_INDEX`, `NAME_INDEX`, +`PRICE_INDEX`, `QUANTITY_INDEX` и `PRODUCT_ID_MIN` больше не нужны — не +определяйте их. + +--- + +## Модуль `utils.py` + +Поведение всех функций прежнее. Меняется только тип хранилища в +`get_storage_str_representation(storage: dict[str, Product]) -> str`: + +- в столбец `ID` попадает ключ словаря (строка UUID, выводится как есть); + столбцы `name`, `price`, `quantity` берутся из соответствующих полей записи + (`price` и `quantity` — через `str(...)`); +- строки товаров идут **в порядке вставки** в словарь; +- формат таблицы, расчёт ширины столбцов и вид пустой таблицы — как в части 3. + +--- + +## Модуль `crud.py` + +### `generate_product_id() -> str` + +- **Вход:** ничего. Хранилище больше не передаётся. +- **Выход:** новый случайный UUID в виде строки. Результат можно разобрать + через `uuid.UUID(...)`, а два вызова дают разные значения. Идентификатор + не зависит ни от порядка вставки, ни от уже занятых идентификаторов. + +> **Подсказка.** Не придумывайте генерацию сами: в стандартной библиотеке +> есть модуль `uuid`, а в нём функция `uuid4()`, которая возвращает случайный +> UUID. Не забудьте превратить результат в строку. + +**Примеры.** Сами значения случайны, поэтому в комментариях указаны не они, а +свойства результата: + +```python +product_id = generate_product_id() + +print(product_id) # например: 3f2c9a4e-8b1d-4c7a-9e55-0d6a1b7c2f10 +print(type(product_id)) # +print(len(product_id)) # 36 +print(uuid.UUID(product_id).version) # 4 (строка разбирается как UUID) +``` + +Два вызова подряд дают разные идентификаторы: + +```python +first_id = generate_product_id() +second_id = generate_product_id() + +print(first_id == second_id) # False +``` + +### `create_product(storage: dict[str, Product], product_names: set[str], fields: dict[str, Any]) -> str | None` + +- **Вход:** хранилище, индекс имён и `fields` — словарь, где **обязательно** + есть все три ключа: `NAME_KEY`, `PRICE_KEY` (`Decimal`) и `QUANTITY_KEY` + (`int`). +- **Выход:** идентификатор нового товара или `None`. + +Шаги выполняются в таком порядке. Шаги 2 и 3 — проверки: если любая из них не +проходит, хранилище и индекс не меняются. + +1. Имя пропускается через `normalize_product_name`. +2. Если нормализованное имя пустое, печатается `product name must not be blank` + и возвращается `None`. +3. Если нормализованное имя уже есть в `product_names`, печатается + `product name '<имя>' is already taken` и возвращается `None`. Имена + сравниваются по нормализованной форме, поэтому `" Cordless Drill "` + конфликтует с `"cordless drill"`. +4. Иначе через `generate_product_id()` создаётся новый идентификатор, и под ним + в `storage` кладётся запись `{name: нормализованное имя, price: + normalize_price(цена), quantity: количество}`. Нормализованное имя + добавляется в `product_names`, функция возвращает идентификатор. + +**Примеры.** Каждый пример — отдельный фрагмент скрипта, который начинается с +пустого хранилища и пустого индекса. Идентификатор случаен, поэтому у вас +в выводе будет другой UUID — это нормально. + +Успешное создание: имя нормализуется, цена округляется, имя попадает в индекс: + +```python +storage: dict[str, Product] = {} +product_names: set[str] = set() + +product_id = create_product( + storage, + product_names, + {NAME_KEY: " Cordless Drill ", PRICE_KEY: Decimal("89.999"), QUANTITY_KEY: 12}, +) + +print(product_id) # 3f2c9a4e-8b1d-4c7a-9e55-0d6a1b7c2f10 +print(storage) +# { +# '3f2c9a4e-8b1d-4c7a-9e55-0d6a1b7c2f10': { +# 'name': 'cordless drill', +# 'price': Decimal('90.00'), +# 'quantity': 12 +# } +# } +print(product_names) # {'cordless drill'} +``` + +Имя уже есть в индексе (сравнение идёт по нормализованной форме), хранилище и +индекс не меняются: + +```python +storage: dict[str, Product] = {} +product_names: set[str] = set() + +create_product( + storage, + product_names, + {NAME_KEY: "cordless drill", PRICE_KEY: Decimal("50"), QUANTITY_KEY: 3}, +) +result = create_product( + storage, + product_names, + {NAME_KEY: " CORDLESS DRILL ", PRICE_KEY: Decimal("75"), QUANTITY_KEY: 1}, +) +# печатает: product name 'cordless drill' is already taken + +print(result) # None +print(len(storage)) # 1 +print(product_names) # {'cordless drill'} +``` + +### `read_product(storage: dict[str, Product], product_id: str) -> Product | None` + +- **Вход:** хранилище и идентификатор (строка). +- **Выход:** запись, которая лежит под этим ключом. Если такого ключа нет, + печатается `no product with id ` и возвращается `None`. + +### `update_product(storage: dict[str, Product], product_names: set[str], product_id: str, fields: dict[str, Any]) -> Product | None` + +**Частичное обновление:** в `fields` может быть любое подмножество ключей +`NAME_KEY`, `PRICE_KEY` и `QUANTITY_KEY`. Поля без ключа в `fields` сохраняют +текущее значение, поэтому, например, можно поменять одно количество, не +передавая имя и цену. Идентификатор (ключ в `storage`) не меняется. + +Шаги выполняются в таком порядке. Шаги 1 и 2 содержат проверки: если любая из +них не проходит, хранилище и индекс не меняются. **Порядок изменился по +сравнению с частью 3:** сначала проверяется, есть ли товар с таким +идентификатором. + +1. Если ключа `product_id` в `storage` нет, печатается + `no product with id ` и возвращается `None`. +2. Если в `fields` есть имя, оно нормализуется через `normalize_product_name`. + - Если нормализованное имя пустое, печатается + `product name must not be blank` и возвращается `None`. + - Если нормализованное имя отличается от текущего имени товара и уже есть + в `product_names`, печатается `product name '<имя>' is already taken` и + возвращается `None`. Переименование товара в его же текущее имя + конфликтом не считается. +3. Если в `fields` есть цена, она округляется через `normalize_price`. +4. Поля из `fields` записываются в запись товара. Если имя изменилось, старое + имя удаляется из `product_names`, а новое добавляется. Обновление без + переименования индекс не меняет. +5. Возвращается обновлённая запись, то есть тот же объект, который лежит в + `storage[product_id]`. + +Побочный эффект: переданный словарь `fields` меняется на месте. Имя и цена в +нём заменяются нормализованными значениями. + +**Пример.** Сначала меняется одно количество, затем товар переименовывается +вместе с новой ценой. Идентификатор случаен, поэтому у вас в выводе будет +другой UUID — это нормально: + +```python +storage: dict[str, Product] = {} +product_names: set[str] = set() + +product_id = create_product( + storage, + product_names, + {NAME_KEY: "Cordless Drill", PRICE_KEY: Decimal("89.99"), QUANTITY_KEY: 12}, +) +print(product_id) # 3f2c9a4e-8b1d-4c7a-9e55-0d6a1b7c2f10 + +# Частичное обновление: меняется только количество, индекс имён остаётся прежним +print(update_product(storage, product_names, product_id, {QUANTITY_KEY: 7})) +# { +# 'name': 'cordless drill', +# 'price': Decimal('89.99'), +# 'quantity': 7 +# } +print(product_names) # {'cordless drill'} + +# Переименование: имя и цена нормализуются, в индексе старое имя заменяется новым +print( + update_product( + storage, + product_names, + product_id, + {NAME_KEY: " Hammer Drill ", PRICE_KEY: Decimal("109.999")}, + ) +) +# { +# 'name': 'hammer drill', +# 'price': Decimal('110.00'), +# 'quantity': 7 +# } +print(product_names) # {'hammer drill'} +``` + +### `delete_product(storage: dict[str, Product], product_names: set[str], product_id: str) -> str | None` + +- **Вход:** хранилище, индекс имён, идентификатор. +- **Выход:** `product_id`, если товар был удалён. В этом случае его имя + убирается из `product_names`. Если ключа нет, печатается + `no product with id ` и возвращается `None`; хранилище и индекс не + меняются. + +--- + +## Модуль `cart.py` + +По сравнению с частью 2 здесь нет типа `CartLine` и констант `LINE_*_INDEX`: +корзина — обычный словарь `dict[str, int]` (см. «Формат данных»). Вспомогательные +функции можно добавлять на своё усмотрение. Обе функции возвращают теперь не +строку корзины, а **количество** единиц товара в корзине после операции. Обе +принимают индекс имён вместе с хранилищем. Сам индекс при этом не меняется: +при изменении одного количества имя товара не меняется. + +### `add_to_cart(storage: dict[str, Product], product_names: set[str], cart: dict[str, int], product_id: str, quantity: int) -> int | None` + +Переносит `quantity` единиц товара со склада в корзину. Проверки идут в таком +порядке (если какая-то не проходит, склад и корзина не меняются): + +1. Если товара с таким идентификатором нет в хранилище, печатается + `no product with id ` и возвращается `None`. +2. Если на складе **строго меньше** `quantity` единиц, печатается + `not enough stock for product : <на складе> available, requested` + и возвращается `None`. Можно запросить ровно столько, сколько есть на + складе: тогда остаток станет `0`, но запись останется в хранилище. + +Если обе проверки пройдены, количество товара на складе уменьшается на +`quantity`, остальные поля записи не меняются. В корзине количество этого +товара увеличивается на `quantity`; если товара в корзине не было, для него +появляется ключ. Возвращается новое количество товара в корзине. + +### `remove_from_cart(storage: dict[str, Product], product_names: set[str], cart: dict[str, int], product_id: str, quantity: int) -> int | None` + +Переносит `quantity` единиц товара из корзины обратно на склад. Проверки идут +в таком порядке (если какая-то не проходит, склад и корзина не меняются): + +1. Если `product_id` нет в корзине, печатается + `product is not in the cart` и возвращается `None`. +2. Если в корзине **строго меньше** `quantity` единиц, печатается + `cart holds only <в корзине> unit(s) of product , cannot remove ` + и возвращается `None`. +3. Если товара с таким идентификатором нет в хранилище, печатается + `no product with id ` и возвращается `None`. + +Если все три проверки пройдены, количество товара на складе увеличивается на +`quantity`, остальные поля записи не меняются, а в корзине количество +уменьшается на `quantity`. Если в корзине осталось `0`, ключ удаляется. +Возвращается оставшееся в корзине количество; `0` значит, что товар из корзины +убран. + +--- + +## Модуль `run_admin.py` + +Набор команд, формат ввода, константы `PROMPT` и `HELP_TEXT`, функции +`show_help` и `print_result`, сообщения `'<строка>' is not a command` и +`'<строка>' names a command but its arguments are invalid`, а также обработка +`ValueError` и `decimal.InvalidOperation` такие же, как в части 3. Отличия: + +- `run_command(storage: dict[str, Product], product_names: set[str], line: str) -> bool` + дополнительно принимает индекс имён и передаёт его в `create_product`, + `update_product` и `delete_product`. +- `` в командах `read`, `update` и `delete` **не приводится к `int`**, а + передаётся строкой как есть. Поэтому неверный идентификатор уже не вызывает + исключение: `crud.py` просто печатает `no product with id `. +- Для `create` и `update` аргументы собираются в словарь + `{NAME_KEY: имя, PRICE_KEY: Decimal(цена), QUANTITY_KEY: int(количество)}`. + Консольный `update` всегда передаёт все три поля. +- `main()` создаёт пустое хранилище `{}` и пустой индекс `set()`, держит их в + памяти всю сессию и передаёт в каждый вызов `run_command`. Остальное + поведение цикла такое же, как в части 3. + +--- + +## Инварианты + +- `product_names` всегда равно множеству `{запись["name"] for запись in + storage.values()}`: каждый успешный `create_product`, `update_product` с + переименованием и `delete_product` поддерживает это равенство, а неуспешный + вызов не меняет ни хранилище, ни индекс. +- Все сохранённые имена нормализованы и уникальны с точностью до нормализации. +- Все сохранённые цены прошли через `normalize_price`. +- Для успешно созданного товара `read_product(storage, id)` возвращает + `{"name": normalize_product_name(name), "price": normalize_price(price), + "quantity": quantity}`. +- После `delete_product(storage, product_names, id)` вызов + `read_product(storage, id)` возвращает `None`. +- Количество сохраняется: после успешного `add_to_cart` или `remove_from_cart` + сумма «на складе + в корзине» для этого товара не меняется. Если после + `add_to_cart` вызвать `remove_from_cart` с тем же `quantity`, склад и + корзина вернутся в исходное состояние. diff --git a/src/part4/__init__.py b/src/part4/__init__.py new file mode 100644 index 00000000..e69de29b diff --git a/src/part4/cart.py b/src/part4/cart.py new file mode 100644 index 00000000..7e9665eb --- /dev/null +++ b/src/part4/cart.py @@ -0,0 +1,63 @@ +from .storage import ( + QUANTITY_KEY, + Product, +) + + +def add_to_cart( + storage: dict[str, Product], + product_names: set[str], + cart: dict[str, int], + product_id: str, + quantity: int, +) -> int | None: + if product_id not in storage: + print(f"no product with id {product_id}") + return None + + product = storage[product_id] + available = product[QUANTITY_KEY] + if available < quantity: + print( + f"not enough stock for product {product_id}: " + f"{available} available, {quantity} requested" + ) + return None + + product[QUANTITY_KEY] = available - quantity + cart[product_id] = cart.get(product_id, 0) + quantity + return cart[product_id] + + +def remove_from_cart( + storage: dict[str, Product], + product_names: set[str], + cart: dict[str, int], + product_id: str, + quantity: int, +) -> int | None: + if product_id not in cart: + print(f"product {product_id} is not in the cart") + return None + + in_cart = cart[product_id] + if in_cart < quantity: + print( + f"cart holds only {in_cart} unit(s) of product {product_id}, " + f"cannot remove {quantity}" + ) + return None + + if product_id not in storage: + print(f"no product with id {product_id}") + return None + + product = storage[product_id] + product[QUANTITY_KEY] = product[QUANTITY_KEY] + quantity + + remaining = in_cart - quantity + if remaining == 0: + del cart[product_id] + else: + cart[product_id] = remaining + return remaining diff --git a/src/part4/crud.py b/src/part4/crud.py new file mode 100644 index 00000000..30494a2a --- /dev/null +++ b/src/part4/crud.py @@ -0,0 +1,98 @@ +from typing import Any +from uuid import uuid4 + +from .storage import ( + NAME_KEY, + PRICE_KEY, + QUANTITY_KEY, + Product, +) +from .utils import normalize_price, normalize_product_name + + +def generate_product_id() -> str: + return str(uuid4()) + + +def create_product( + storage: dict[str, Product], + product_names: set[str], + fields: dict[str, Any], +) -> str | None: + name = normalize_product_name(fields[NAME_KEY]) + if not name: + print("product name must not be blank") + return None + if name in product_names: + print(f"product name '{name}' is already taken") + return None + product_id = generate_product_id() + storage[product_id] = { + NAME_KEY: name, + PRICE_KEY: normalize_price(fields[PRICE_KEY]), + QUANTITY_KEY: fields[QUANTITY_KEY], + } + product_names.add(name) + return product_id + + +def read_product(storage: dict[str, Product], product_id: str) -> Product | None: + product = storage.get(product_id) + if product is not None: + return product + + print(f"no product with id {product_id}") + return None + + +def update_product( + storage: dict[str, Product], + product_names: set[str], + product_id: str, + fields: dict[str, Any], +) -> Product | None: + if product_id not in storage: + print(f"no product with id {product_id}") + return None + + product = storage[product_id] + old_name = product[NAME_KEY] + new_name: str | None = None + + if NAME_KEY in fields: + name = normalize_product_name(fields[NAME_KEY]) + if not name: + print("product name must not be blank") + return None + if name != old_name and name in product_names: + print(f"product name '{name}' is already taken") + return None + new_name = name + fields[NAME_KEY] = name + + if PRICE_KEY in fields: + fields[PRICE_KEY] = normalize_price(fields[PRICE_KEY]) + + for key in (NAME_KEY, PRICE_KEY, QUANTITY_KEY): + if key in fields: + product[key] = fields[key] + + if new_name is not None and new_name != old_name: + product_names.discard(old_name) + product_names.add(new_name) + + return product + + +def delete_product( + storage: dict[str, Product], + product_names: set[str], + product_id: str, +) -> str | None: + if product_id in storage: + product_names.discard(storage[product_id][NAME_KEY]) + del storage[product_id] + return product_id + + print(f"no product with id {product_id}") + return None diff --git a/src/part4/run_admin.py b/src/part4/run_admin.py new file mode 100644 index 00000000..cd70759a --- /dev/null +++ b/src/part4/run_admin.py @@ -0,0 +1,128 @@ +from decimal import Decimal, InvalidOperation +from typing import Final + +from .crud import ( + create_product, + delete_product, + read_product, + update_product, +) +from .storage import NAME_KEY, PRICE_KEY, QUANTITY_KEY, Product +from .utils import get_storage_str_representation + + +PROMPT: Final[str] = "admin> " +HELP_TEXT: Final[str] = """Available commands: + help show this message + exit leave the console + show print the whole store as a table + create add a product, print its new id + read print the product with that id + update overwrite that product's fields + delete remove the product with that id + +For create and update the price and quantity are the last two words of the +line; everything before them is the product name, so it may contain spaces +(for example "Gibson SG Junior") and needs no quoting.""" + + +def show_help() -> None: + print(HELP_TEXT) + + +def print_result(result: object) -> None: + if result is not None: + print(result) + + +def run_command( + storage: dict[str, Product], product_names: set[str], line: str +) -> bool: + words = line.split() + if not words: + return True + + command = words[0] + + if command == "help" and len(words) == 1: + show_help() + return True + + if command == "exit" and len(words) == 1: + return False + + if command == "show" and len(words) == 1: + print_result(get_storage_str_representation(storage)) + return True + + if command == "create": + if len(words) < 4: + print(f"{line!r} is not a command") + return True + name = " ".join(words[1:-2]) + price = Decimal(words[-2]) + quantity = int(words[-1]) + print_result( + create_product( + storage, + product_names, + {NAME_KEY: name, PRICE_KEY: price, QUANTITY_KEY: quantity}, + ) + ) + return True + + if command == "read": + if len(words) != 2: + print(f"{line!r} is not a command") + return True + product_id = words[1] + print_result(read_product(storage, product_id)) + return True + + if command == "update": + if len(words) < 5: + print(f"{line!r} is not a command") + return True + product_id = words[1] + name = " ".join(words[2:-2]) + price = Decimal(words[-2]) + quantity = int(words[-1]) + print_result( + update_product( + storage, + product_names, + product_id, + {NAME_KEY: name, PRICE_KEY: price, QUANTITY_KEY: quantity}, + ) + ) + return True + + if command == "delete": + if len(words) != 2: + print(f"{line!r} is not a command") + return True + product_id = words[1] + print_result(delete_product(storage, product_names, product_id)) + return True + + print(f"{line!r} is not a command") + return True + + +def main() -> None: + storage: dict[str, Product] = {} + product_names: set[str] = set() + running = True + + while running: + line = input(PROMPT).strip() + + try: + running = run_command(storage, product_names, line) + + except (ValueError, InvalidOperation): + print(f"{line!r} names a command but its arguments are invalid") + + +if __name__ == "__main__": + main() diff --git a/src/part4/storage.py b/src/part4/storage.py new file mode 100644 index 00000000..048ce1b6 --- /dev/null +++ b/src/part4/storage.py @@ -0,0 +1,8 @@ +from typing import Any, Final + + +type Product = dict[str, Any] + +NAME_KEY: Final[str] = "name" +PRICE_KEY: Final[str] = "price" +QUANTITY_KEY: Final[str] = "quantity" diff --git a/src/part4/utils.py b/src/part4/utils.py new file mode 100644 index 00000000..f2a104ff --- /dev/null +++ b/src/part4/utils.py @@ -0,0 +1,49 @@ +from decimal import ROUND_HALF_UP, Decimal +from typing import Final + +from .storage import ( + NAME_KEY, + PRICE_KEY, + QUANTITY_KEY, + Product, +) + + +PRICE_PRECISION: Final[int] = 2 +PRICE_STEP: Final[Decimal] = Decimal(1).scaleb(-PRICE_PRECISION) +TABLE_HEADERS: Final[tuple[str, str, str, str]] = ("ID", "name", "price", "quantity") + + +def normalize_price(price: Decimal) -> Decimal: + return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP) + + +def normalize_product_name(name: str) -> str: + return " ".join(name.split()).lower() + + +def get_storage_str_representation(storage: dict[str, Product]) -> str: + rows: list[tuple[str, str, str, str]] = [ + ( + product_id, + product[NAME_KEY], + str(product[PRICE_KEY]), + str(product[QUANTITY_KEY]), + ) + for product_id, product in storage.items() + ] + widths: list[int] = [ + max(len(header), *(len(row[i]) for row in rows)) if rows else len(header) + for i, header in enumerate(TABLE_HEADERS) + ] + header_line = ( + "|" + + "|".join(f" {cell:<{width}} " for cell, width in zip(TABLE_HEADERS, widths)) + + "|" + ) + dop_line = "|" + "|".join("-" * (width + 2) for width in widths) + "|" + data_lines = [ + "|" + "|".join(f" {cell:<{width}} " for cell, width in zip(row, widths)) + "|" + for row in rows + ] + return "\n".join([header_line, dop_line, *data_lines])