From 69261b6a6c2d948cbccab740199ae3bef1131797 Mon Sep 17 00:00:00 2001 From: spol Date: Wed, 23 Sep 2026 21:57:36 +0300 Subject: [PATCH 01/14] Calculate milliseconds since epoch in snowflake.py Implement current milliseconds calculation and update return value. --- src/part1/snowflake.py | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index d3abf050..58af1675 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -34,8 +34,9 @@ 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. """ + current_millis = time.time_ns() // 1_000_000 # TODO: реализуйте функцию - return 0 + return (current_millis - epoch_ms) def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int: @@ -87,6 +88,18 @@ def generate_snowflake_id( node_id: int = NODE_ID_DEFAULT, epoch_ms: int = EPOCH_MS_DEFAULT, ) -> int | None: + + if node_id < 0 or node_id > NODE_ID_MAX: + print(f"Invalid node_id: {node_id}, node_id must be in [0, {NODE_ID_MAX}].") + return None + if sequence_id < 0 or sequence_id > SEQUENCE_MAX: + print(f"Invalid sequence_id: {sequence_id}, sequence_id must be in [0, {SEQUENCE_MAX}].") + return None + if epoch_ms < 0 or epoch_ms > TIMESTAMP_MS_MAX: + print(f"Invalid epoch_ms: {epoch_ms}, epoch_ms must be in [0, {TIMESTAMP_MS_MAX}].") + return None + + """Build and return a Snowflake identifier for the current millisecond. The function is stateless: the caller passes the per-millisecond sequence From cd453798cf889882deca6ab95ce01436d33a15a9 Mon Sep 17 00:00:00 2001 From: spol Date: Wed, 23 Sep 2026 22:03:14 +0300 Subject: [PATCH 02/14] Define constants for Snowflake ID generator Updated constants for Twitter Snowflake ID generator, including default epoch and bit widths. --- src/part1/constants.py | 34 ++++++++-------------------------- 1 file changed, 8 insertions(+), 26 deletions(-) diff --git a/src/part1/constants.py b/src/part1/constants.py index 9abfbba2..0c933fbf 100644 --- a/src/part1/constants.py +++ b/src/part1/constants.py @@ -1,38 +1,20 @@ -"""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] = 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). From 16f067120d781ad9bc7613748765db5f02ae3edb Mon Sep 17 00:00:00 2001 From: spol Date: Wed, 23 Sep 2026 23:03:44 +0300 Subject: [PATCH 03/14] Update snowflake.py --- src/part1/snowflake.py | 47 ++++++++++-------------------------------- 1 file changed, 11 insertions(+), 36 deletions(-) diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index 58af1675..799f9173 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -25,34 +25,14 @@ 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. - """ - current_millis = time.time_ns() // 1_000_000 - # TODO: реализуйте функцию - return (current_millis - epoch_ms) + unix_epoch_time = time.time_ns() // 1_000_000_000 + return (unix_epoch_time - 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. - """ - # TODO: реализуйте функцию - return 0 + snowflake_binary = bin(snowflake_id)[2:] + snowflake_ms_binary = (snowflake_binary.zfill(63))[:41] + return (int(snowflake_ms_binary) + epoch_ms) def decode_node_id(snowflake_id: int) -> int: @@ -65,22 +45,17 @@ def decode_node_id(snowflake_id: int) -> int: The node identifier packed into ``snowflake_id``, in the range ``[0, NODE_ID_MAX]``. """ + snowflake_binary = bin(snowflake_id)[2:] + snowflake_node_id_binary = bin(snowflake_binary.zfill(63))[41:51]) # TODO: реализуйте функцию - return 0 + return int(snowflake_node_id_binary) 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]``. - """ + snowflake_binary = bin(snowflake_id)[2:] + snowflake_sequence_id_binary = bin(snowflake_binary.zfill(63))[51:]) # TODO: реализуйте функцию - return 0 + return int(snowflake_sequence_id_binary) def generate_snowflake_id( From aebb72d75d8939b0758672817c0e74f1c0ea222f Mon Sep 17 00:00:00 2001 From: spol Date: Fri, 25 Sep 2026 17:58:46 +0300 Subject: [PATCH 04/14] Refactor snowflake ID generation and decoding functions --- src/part1/snowflake.py | 74 +++++++++--------------------------------- 1 file changed, 16 insertions(+), 58 deletions(-) diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index 799f9173..de57e15e 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -25,78 +25,36 @@ def read_current_millis(epoch_ms: int) -> int: - unix_epoch_time = time.time_ns() // 1_000_000_000 + unix_epoch_time = time.time_ns() // 1_000_000 # get current time in milliseconds return (unix_epoch_time - epoch_ms) def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int: - snowflake_binary = bin(snowflake_id)[2:] - snowflake_ms_binary = (snowflake_binary.zfill(63))[:41] - return (int(snowflake_ms_binary) + epoch_ms) + return (snowflake_id >> (NODE_ID_BITS + SEQUENCE_ID_BITS)) + epoch_ms def decode_node_id(snowflake_id: int) -> int: - """Read the node identifier field out of a Snowflake identifier. + return (snowflake_id >> SEQUENCE_ID_BITS) & NODE_ID_MAX - 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]``. - """ - snowflake_binary = bin(snowflake_id)[2:] - snowflake_node_id_binary = bin(snowflake_binary.zfill(63))[41:51]) - # TODO: реализуйте функцию - return int(snowflake_node_id_binary) +def decode_sequence_id(snowflake_id: int) -> int: + return snowflake_id & SEQUENCE_ID_MAX +def generate_snowflake_id(sequence_id: int, node_id: int = NODE_ID_DEFAULT, epoch_ms: int = EPOCH_MS_DEFAULT) -> int | None: + timestamp_ms = read_current_millis(epoch_ms) -def decode_sequence_id(snowflake_id: int) -> int: - snowflake_binary = bin(snowflake_id)[2:] - snowflake_sequence_id_binary = bin(snowflake_binary.zfill(63))[51:]) - # TODO: реализуйте функцию - return int(snowflake_sequence_id_binary) - - -def generate_snowflake_id( - sequence_id: int, - node_id: int = NODE_ID_DEFAULT, - epoch_ms: int = EPOCH_MS_DEFAULT, -) -> int | None: - if node_id < 0 or node_id > NODE_ID_MAX: print(f"Invalid node_id: {node_id}, node_id must be in [0, {NODE_ID_MAX}].") return None - if sequence_id < 0 or sequence_id > SEQUENCE_MAX: - print(f"Invalid sequence_id: {sequence_id}, sequence_id must be in [0, {SEQUENCE_MAX}].") + if sequence_id < 0 or sequence_id > SEQUENCE_ID_MAX: + print(f"Invalid sequence_id: {sequence_id}, sequence_id must be in [0, {SEQUENCE_ID_MAX}].") return None - if epoch_ms < 0 or epoch_ms > TIMESTAMP_MS_MAX: - print(f"Invalid epoch_ms: {epoch_ms}, epoch_ms must be in [0, {TIMESTAMP_MS_MAX}].") + if timestamp_ms < 0 or timestamp_ms > TIMESTAMP_MS_MAX: + print("overflows") return 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. - """ - # TODO: реализуйте функцию - return 0 + return ( + (timestamp_ms << (NODE_ID_BITS + SEQUENCE_ID_BITS)) | + (node_id << SEQUENCE_ID_BITS) | + sequence_id + ) From 25bb0a9398067773f13d1640ebe8bb1460d62b4a Mon Sep 17 00:00:00 2001 From: spol Date: Fri, 25 Sep 2026 18:13:57 +0300 Subject: [PATCH 05/14] Solve task 1 (finished) From ae4b181d669278013e1ed1a15cef51a7488e174a Mon Sep 17 00:00:00 2001 From: spol Date: Fri, 25 Sep 2026 18:14:36 +0300 Subject: [PATCH 06/14] Solve task 1 (finished) --- src/part1/constants.py | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/part1/constants.py b/src/part1/constants.py index 0c933fbf..88c88241 100644 --- a/src/part1/constants.py +++ b/src/part1/constants.py @@ -17,4 +17,4 @@ SEQUENCE_ID_MAX: Final[int] = 2**SEQUENCE_ID_BITS - 1 # Здесь можно добавить собственные вспомогательные константы -# (например, сдвиги полей при сборке идентификатора). +# (например, сдвиги полей при сборке идентификатора) From 8c6c49b6546513d802a88fed3bb273f6808f6830 Mon Sep 17 00:00:00 2001 From: spol Date: Fri, 25 Sep 2026 18:15:02 +0300 Subject: [PATCH 07/14] Solve task 1 (finished) --- src/part1/snowflake.py | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index de57e15e..2ad44761 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -25,7 +25,7 @@ def read_current_millis(epoch_ms: int) -> int: - unix_epoch_time = time.time_ns() // 1_000_000 # get current time in milliseconds + unix_epoch_time = time.time_ns() // 1_000_000 #get current time in milliseconds return (unix_epoch_time - epoch_ms) From ae0fa3297f4d89261bc65c948454a27421b41a87 Mon Sep 17 00:00:00 2001 From: SpiridonovOleg Date: Fri, 25 Sep 2026 18:47:46 +0300 Subject: [PATCH 08/14] Solve task 1 --- src/part1/constants.py | 1 + src/part1/snowflake.py | 31 ++++++++++++++++++++----------- 2 files changed, 21 insertions(+), 11 deletions(-) diff --git a/src/part1/constants.py b/src/part1/constants.py index 88c88241..08d51bbc 100644 --- a/src/part1/constants.py +++ b/src/part1/constants.py @@ -1,5 +1,6 @@ from typing import Final + # Twitter's original Snowflake epoch: 2010-11-04 01:42:54.657 UTC. EPOCH_MS_DEFAULT: Final[int] = 1288834974657 diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index 2ad44761..965e604d 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -13,48 +13,57 @@ :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: - unix_epoch_time = time.time_ns() // 1_000_000 #get current time in milliseconds - return (unix_epoch_time - epoch_ms) + unix_epoch_time = time.time_ns() // 1_000_000 # get current time in milliseconds + return unix_epoch_time - epoch_ms def decode_timestamp_ms(snowflake_id: int, epoch_ms: int = EPOCH_MS_DEFAULT) -> int: - return (snowflake_id >> (NODE_ID_BITS + SEQUENCE_ID_BITS)) + epoch_ms + return (snowflake_id >> (NODE_ID_BITS + SEQUENCE_ID_BITS)) + epoch_ms def decode_node_id(snowflake_id: int) -> int: - return (snowflake_id >> SEQUENCE_ID_BITS) & NODE_ID_MAX + return (snowflake_id >> SEQUENCE_ID_BITS) & NODE_ID_MAX def decode_sequence_id(snowflake_id: int) -> int: return snowflake_id & SEQUENCE_ID_MAX -def generate_snowflake_id(sequence_id: int, node_id: int = NODE_ID_DEFAULT, epoch_ms: int = EPOCH_MS_DEFAULT) -> int | None: + +def generate_snowflake_id( + sequence_id: int, node_id: int = NODE_ID_DEFAULT, epoch_ms: int = EPOCH_MS_DEFAULT +) -> int | None: timestamp_ms = read_current_millis(epoch_ms) if node_id < 0 or node_id > NODE_ID_MAX: print(f"Invalid node_id: {node_id}, node_id must be in [0, {NODE_ID_MAX}].") return None if sequence_id < 0 or sequence_id > SEQUENCE_ID_MAX: - print(f"Invalid sequence_id: {sequence_id}, sequence_id must be in [0, {SEQUENCE_ID_MAX}].") + print( + f"Invalid sequence_id: {sequence_id}, sequence_id must be in [0, {SEQUENCE_ID_MAX}]." + ) return None if timestamp_ms < 0 or timestamp_ms > TIMESTAMP_MS_MAX: print("overflows") return None return ( - (timestamp_ms << (NODE_ID_BITS + SEQUENCE_ID_BITS)) | - (node_id << SEQUENCE_ID_BITS) | - sequence_id + (timestamp_ms << (NODE_ID_BITS + SEQUENCE_ID_BITS)) + | (node_id << SEQUENCE_ID_BITS) + | sequence_id ) + +print(decode_timestamp_ms(generate_snowflake_id(0,))) From 6269b68cc48e51df7d52945e41359ac8c0129d4d Mon Sep 17 00:00:00 2001 From: spol Date: Fri, 25 Sep 2026 18:50:34 +0300 Subject: [PATCH 09/14] Solve task 1 (finished) --- src/part1/snowflake.py | 1 - 1 file changed, 1 deletion(-) diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index 965e604d..f6b5b2c1 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -66,4 +66,3 @@ def generate_snowflake_id( | sequence_id ) -print(decode_timestamp_ms(generate_snowflake_id(0,))) From 3eddba0b8c58d91fe05ed8ce7f6e29bb73783f45 Mon Sep 17 00:00:00 2001 From: SpiridonovOleg Date: Fri, 25 Sep 2026 19:12:17 +0300 Subject: [PATCH 10/14] Format source files with Ruff --- src/part1/snowflake.py | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index 965e604d..094cab61 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -66,4 +66,11 @@ def generate_snowflake_id( | sequence_id ) -print(decode_timestamp_ms(generate_snowflake_id(0,))) + +print( + decode_timestamp_ms( + generate_snowflake_id( + 0, + ) + ) +) From e4bdd116e40d3491c75922348a650b85672340f1 Mon Sep 17 00:00:00 2001 From: SpiridonovOleg Date: Fri, 25 Sep 2026 19:13:21 +0300 Subject: [PATCH 11/14] Format source files with Ruff --- src/part1/snowflake.py | 9 --------- 1 file changed, 9 deletions(-) diff --git a/src/part1/snowflake.py b/src/part1/snowflake.py index 094cab61..f643237e 100644 --- a/src/part1/snowflake.py +++ b/src/part1/snowflake.py @@ -65,12 +65,3 @@ def generate_snowflake_id( | (node_id << SEQUENCE_ID_BITS) | sequence_id ) - - -print( - decode_timestamp_ms( - generate_snowflake_id( - 0, - ) - ) -) From e46602d83dbb0c06042a1751afba663d9b86e628 Mon Sep 17 00:00:00 2001 From: SpiridonovOleg Date: Fri, 2 Oct 2026 17:52:11 +0300 Subject: [PATCH 12/14] Solve task 2 --- src/part2/cart.py | 130 ++++++++++++++++++++++++++----------------- src/part2/crud.py | 109 +++++++++++------------------------- src/part2/storage.py | 10 ++-- src/part2/utils.py | 19 ++----- 4 files changed, 122 insertions(+), 146 deletions(-) diff --git a/src/part2/cart.py b/src/part2/cart.py index 063f9aea..f8e2d122 100644 --- a/src/part2/cart.py +++ b/src/part2/cart.py @@ -11,8 +11,8 @@ from typing import Final -from .crud import read_product, update_product # noqa: F401 -from .storage import ( # noqa: F401 +from .crud import read_product, update_product +from .storage import ( NAME_INDEX, PRICE_INDEX, QUANTITY_INDEX, @@ -22,9 +22,25 @@ type CartLine = tuple[int, int] -# TODO: задайте позиции полей внутри кортежа CartLine + LINE_PRODUCT_ID_INDEX: Final = 0 -LINE_QUANTITY_INDEX: Final = 0 +LINE_QUANTITY_INDEX: Final = 1 + + +def find_cart_line(cart: list[CartLine], product_id: int) -> CartLine | None: + for cartline in cart: + if cartline[LINE_PRODUCT_ID_INDEX] == product_id: + return cartline + return None + + +def change_cart_quantity( + cart: list[CartLine], cartline: CartLine, quantity: int +) -> None: + cart.append( + (cartline[LINE_PRODUCT_ID_INDEX], cartline[LINE_QUANTITY_INDEX] + quantity) + ) + cart.remove(cartline) def add_to_cart( @@ -33,28 +49,31 @@ def add_to_cart( 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. - """ - # TODO: реализуйте функцию - return (0, 0) + requested_product = read_product(storage, product_id) + if requested_product is None: + return None + product_name = requested_product[NAME_INDEX] + product_price = requested_product[PRICE_INDEX] + product_amount = requested_product[QUANTITY_INDEX] + + if product_amount < quantity: + print( + f"not enough stock for product {product_id}: {product_amount} available, {quantity} requested" + ) + return None + + update_product( + storage, product_id, (product_name, product_price, product_amount - quantity) + ) + + old_cartline = find_cart_line(cart, product_id) + + if old_cartline is not None: + change_cart_quantity(cart, old_cartline, quantity) + else: + cart.append((product_id, quantity)) + + return find_cart_line(cart, product_id) def remove_from_cart( @@ -63,27 +82,38 @@ 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. - """ - # TODO: реализуйте функцию - return (0, 0) + changable_cartline = find_cart_line(cart, product_id) + + if changable_cartline is None: + print(f"product {product_id} is not in the cart") + return None + if changable_cartline[LINE_QUANTITY_INDEX] < quantity: + print( + f"cart holds only {changable_cartline[LINE_QUANTITY_INDEX]} unit(s) of product {product_id}, cannot remove {quantity}" + ) + return None + + storage_product = read_product(storage, product_id) + if storage_product is None: + return None + + update_product( + storage, + product_id, + ( + storage_product[NAME_INDEX], + storage_product[PRICE_INDEX], + storage_product[QUANTITY_INDEX] + quantity, + ), + ) + change_cart_quantity(cart, changable_cartline, -quantity) + updated_cartline = find_cart_line(cart, product_id) + + if updated_cartline is None: # проверка, чтобы mypy не ругался + return None + + if updated_cartline[LINE_QUANTITY_INDEX] == 0: + cart.remove(updated_cartline) + return (product_id, 0) + + return updated_cartline diff --git a/src/part2/crud.py b/src/part2/crud.py index d026cbcb..a0cffd84 100644 --- a/src/part2/crud.py +++ b/src/part2/crud.py @@ -14,66 +14,39 @@ 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: - """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. - """ - # TODO: реализуйте функцию - return 0 + if not storage: + return PRODUCT_ID_MIN + return max(product[PRODUCT_ID_INDEX] for product 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. + if fields[0] in (product[NAME_INDEX] for product in storage): + print(f'The name "{fields[0]}" is already used') + return None - 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. - """ - # TODO: реализуйте функцию - return 0 + product_id = generate_product_id(storage) + storage.append((product_id, fields[0], normalize_price(fields[1]), fields[2])) + 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. - 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( @@ -81,40 +54,26 @@ 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. + id_list = [product[PRODUCT_ID_INDEX] for product in storage] - 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. + if product_id not in id_list: + print(f"no product with id {product_id}") + return None - 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). - """ - # TODO: реализуйте функцию - return (0, "", Decimal(0), 0) + for old_product in storage: + if product_id == old_product[PRODUCT_ID_INDEX]: + new_product = (product_id, fields[0], normalize_price(fields[1]), fields[2]) + storage.append(new_product) + storage.remove(old_product) + break + return new_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). - """ - # TODO: реализуйте функцию - return 0 + for product in storage: + if product[PRODUCT_ID_INDEX] == product_id: + storage.remove(product) + return product[PRODUCT_ID_INDEX] + + print(f"no product with id {product_id}") + return None diff --git a/src/part2/storage.py b/src/part2/storage.py index b63d5fc7..e4bceff1 100644 --- a/src/part2/storage.py +++ b/src/part2/storage.py @@ -24,11 +24,9 @@ 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 +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..955a239f 100644 --- a/src/part2/utils.py +++ b/src/part2/utils.py @@ -6,24 +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: - """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 Decimal(0) + return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP) From dbff7be45532c5efb76b9bdb7bd219c4a4c6d02f Mon Sep 17 00:00:00 2001 From: SpiridonovOleg Date: Mon, 12 Oct 2026 20:54:36 +0300 Subject: [PATCH 13/14] Solve task 3 --- src/part2/crud.py | 2 +- src/part3/crud.py | 168 ++++++++++++++++------------------------- src/part3/run_admin.py | 150 +++++++++++++++++------------------- src/part3/storage.py | 31 +------- src/part3/utils.py | 105 +++++++------------------- 5 files changed, 168 insertions(+), 288 deletions(-) diff --git a/src/part2/crud.py b/src/part2/crud.py index a0cffd84..0288e7d0 100644 --- a/src/part2/crud.py +++ b/src/part2/crud.py @@ -33,7 +33,7 @@ def create_product( storage: list[Product], fields: tuple[str, Decimal, int] ) -> int | None: if fields[0] in (product[NAME_INDEX] for product in storage): - print(f'The name "{fields[0]}" is already used') + print(f'product name "{fields[0]}" is already used') return None product_id = generate_product_id(storage) diff --git a/src/part3/crud.py b/src/part3/crud.py index 68811d7e..ca51cd19 100644 --- a/src/part3/crud.py +++ b/src/part3/crud.py @@ -1,87 +1,43 @@ -"""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 ( # 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: - """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.part3.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 + return max(product[PRODUCT_ID_INDEX] for product 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. - """ - # TODO: реализуйте функцию - return 0 + normalized_name = normalize_product_name(fields[0]) + if not normalized_name: + print("product name must not be blank") + return None + elif normalized_name in (product[NAME_INDEX] for product in storage): + print(f"product name '{normalized_name}' is already taken") + return None -def read_product(storage: list[Product], product_id: int) -> Product | None: - """Return the product stored under ``product_id``. + product_id = generate_product_id(storage) + storage.append((product_id, normalized_name, normalize_price(fields[1]), fields[2])) + return product_id - 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) +def read_product(storage: list[Product], product_id: int) -> Product | None: + 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( @@ -89,43 +45,51 @@ 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. - """ - # TODO: реализуйте функцию - return (0, "", Decimal(0), 0) + normalized_name = normalize_product_name(fields[0]) + + if not normalized_name: + print("product name must not be blank") + return None + + id_existance = False + name_already_taken = False + + for product in storage: + if product[PRODUCT_ID_INDEX] == product_id: + id_existance = True + if ( + product[NAME_INDEX] == normalized_name + and product[PRODUCT_ID_INDEX] != product_id + ): + name_already_taken = True + + if not id_existance: + print(f"no product with id {product_id}") + return None + + if name_already_taken: + print(f"product name '{normalized_name}' is already taken") + return None + + for old_product in storage: + if product_id == old_product[PRODUCT_ID_INDEX]: + new_product = ( + product_id, + normalized_name, + normalize_price(fields[1]), + fields[2], + ) + storage.append(new_product) + storage.remove(old_product) + break + return new_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). - """ - # TODO: реализуйте функцию (используйте своё решение части 2) - return 0 + for product in storage: + if product[PRODUCT_ID_INDEX] == product_id: + storage.remove(product) + return product[PRODUCT_ID_INDEX] + + 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..bfb3c371 100644 --- a/src/part3/run_admin.py +++ b/src/part3/run_admin.py @@ -1,107 +1,95 @@ -"""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 # 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: - """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. - """ - # TODO: реализуйте функцию + 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. - """ - # TODO: реализуйте функцию + 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. - """ - # TODO: реализуйте функцию - return False + splitted_line = line.split() + + if not splitted_line: + print(f"'{line}' is not a command") + return True + + match splitted_line.pop(0): + case "help" if not splitted_line: + show_help() + return True + case "exit" if not splitted_line: + return False + case "show" if not splitted_line: + print(get_storage_str_representation(storage)) + return True + case "create" if len(splitted_line) >= 3: + print_result( + create_product( + storage, + ( + " ".join(splitted_line[:-2]), + Decimal(splitted_line[-2]), + int(splitted_line[-1]), + ), + ) + ) + return True + case "update" if len(splitted_line) >= 4: + print_result( + update_product( + storage, + int(splitted_line[0]), + ( + " ".join(splitted_line[1:-2]), + Decimal(splitted_line[-2]), + int(splitted_line[-1]), + ), + ) + ) + return True + case "read" if len(splitted_line) == 1: + print_result(read_product(storage, int(splitted_line[0]))) + return True + case "delete" if len(splitted_line) == 1: + print_result(delete_product(storage, int(splitted_line[0]))) + return True + case _: + print(f"'{line}' 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 c5e34be5..81651a75 100644 --- a/src/part3/storage.py +++ b/src/part3/storage.py @@ -1,35 +1,12 @@ -"""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 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..56a8b6e3 100644 --- a/src/part3/utils.py +++ b/src/part3/utils.py @@ -1,95 +1,46 @@ -"""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 # noqa: F401 +from decimal import ROUND_HALF_UP, Decimal from typing import Final -from .storage import Product +from .storage import NAME_INDEX, PRICE_INDEX, PRODUCT_ID_INDEX, QUANTITY_INDEX, 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] = 0 -PRICE_STEP: Final = Decimal(0) +PRICE_PRECISION: Final[int] = 2 +PRICE_STEP: Final = 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: - """Round a price to the precision every stored record uses. + return price.quantize(PRICE_STEP, rounding=ROUND_HALF_UP) - Args: - price: The raw price amount. - Returns: - ``price`` quantised to :data:`PRICE_PRECISION` fractional digits, - with halves rounded up. - """ - # TODO: реализуйте функцию (используйте своё решение части 2) - return Decimal(0) +def normalize_product_name(name: str) -> str: + normalized_name = " ".join(name.split()).lower() + return normalized_name -def normalize_product_name(name: str) -> str: - """Reduce a product name to the canonical form the store keeps. +def get_storage_str_representation(storage: list[Product]) -> str: + lens = [[len(h)] for h in TABLE_HEADERS] - Args: - name: The raw product name. + for product in storage: + for elem, pointer in zip( + product, [PRODUCT_ID_INDEX, NAME_INDEX, PRICE_INDEX, QUANTITY_INDEX] + ): + lens[pointer].append(len(str(elem))) - 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. - """ - # TODO: реализуйте функцию - return "" + maxlens = list(map(max, lens)) + header_str = "|" + separating_str = "|" + for header, length in zip(TABLE_HEADERS, maxlens): + header_str += f" {header.ljust(length)} |" + separating_str += "-" + "-" * length + "-|" -# TODO: при необходимости добавьте свои вспомогательные функции + table = header_str + "\n" + separating_str + for product in storage: + table += "\n|" + for elem, length in zip(product, maxlens): + table += f" {str(elem).ljust(length)} |" -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. - """ - # TODO: реализуйте функцию - return "" + return table From 0ae937306fefac242e5d48d15947585cf7c4b360 Mon Sep 17 00:00:00 2001 From: SpiridonovOleg Date: Sun, 1 Nov 2026 12:21:00 +0300 Subject: [PATCH 14/14] Solve task 4 --- src/part4/cart.py | 102 ++++++++--------------- src/part4/crud.py | 183 ++++++++++++++--------------------------- src/part4/run_admin.py | 160 +++++++++++++++++------------------ src/part4/storage.py | 8 +- src/part4/utils.py | 99 +++++++++------------- 5 files changed, 216 insertions(+), 336 deletions(-) diff --git a/src/part4/cart.py b/src/part4/cart.py index aed9bb72..47f0b9d6 100644 --- a/src/part4/cart.py +++ b/src/part4/cart.py @@ -1,18 +1,4 @@ -"""Shopping-cart operations layered on top of the product store. - -The cart is a plain dictionary mapping each product identifier to the -number of units of that product in the cart. Moving units between the -store and the cart keeps the two sides in balance: :func:`add_to_cart` takes -units out of stock, :func:`remove_from_cart` puts them back. - -Like the CRUD layer, the failure path never raises -- the operation prints -an explanatory message to stdout and returns ``None``. -""" - -from .storage import Product - - -# TODO: при необходимости добавьте свои вспомогательные функции +from .storage import QUANTITY_KEY, Product def add_to_cart( @@ -22,32 +8,22 @@ def add_to_cart( product_id: str, quantity: int, ) -> int | None: - """Move ``quantity`` units of ``product_id`` from the store into ``cart``. + if product_id not in storage: + print(f"no product with id {product_id}") + return None + elif (storage_quantity := storage[product_id][QUANTITY_KEY]) < quantity: + print( + f"not enough stock for product {product_id}:" + f" {storage_quantity} available," + f" {quantity} requested" + ) + return None - The product is looked up in ``storage``. If it is missing, a message is - printed 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 - gains ``quantity`` units of ``product_id`` -- the product is added when - the cart had none of it. + storage[product_id][QUANTITY_KEY] -= quantity - Args: - storage: The product store to draw stock from; modified in place on - success. - product_names: The normalised names in ``storage``; a - quantity-only change never renames a product, so it is left - unchanged here. - 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. + cart[product_id] = cart.get(product_id, 0) + quantity - Returns: - The quantity of ``product_id`` in the cart after the addition, or - ``None`` when the product is unknown or the store cannot cover the - request. - """ - # TODO: реализуйте функцию - return 0 + return cart[product_id] def remove_from_cart( @@ -57,31 +33,25 @@ def remove_from_cart( product_id: str, quantity: int, ) -> int | None: - """Move ``quantity`` units of ``product_id`` from ``cart`` back to the store. - - If the cart holds no units of ``product_id``, a message is printed and - nothing changes. If it holds fewer units than requested, an explanatory - message is printed and nothing changes. If the product is missing from - ``storage``, a message is printed and nothing changes. Otherwise the cart loses - ``quantity`` units of the product -- the product is dropped from the - cart when its quantity reaches zero -- and the store record gains - ``quantity`` units back. - - Args: - storage: The product store to return stock to; modified in place on - success. - product_names: The normalised names in ``storage``; a - quantity-only change never renames a product, so it is left - unchanged here. - 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 quantity of ``product_id`` left in the cart after the removal - (zero means the product was dropped from the cart), or ``None`` when - the cart does not hold the product or holds too few units. - """ - # TODO: реализуйте функцию - return 0 + if product_id not in cart: + print(f"product {product_id} is not in the cart") + return None + elif (cart_quantity := cart[product_id]) < quantity: + print( + f"cart holds only {cart_quantity}" + f" unit(s) of product {product_id}," + f" cannot remove {quantity}" + ) + return None + elif product_id not in storage: + print(f"no product with id {product_id}") + return None + + storage[product_id][QUANTITY_KEY] += quantity + cart[product_id] -= quantity + + if cart[product_id] == 0: + del cart[product_id] + return 0 + else: + return cart[product_id] diff --git a/src/part4/crud.py b/src/part4/crud.py index 471eff00..638f5738 100644 --- a/src/part4/crud.py +++ b/src/part4/crud.py @@ -1,48 +1,17 @@ -"""Create/read/update/delete operations over the in-memory product store. - -Every operation takes the store -- a dictionary mapping product id to its -:data:`~src.part4.storage.Product` record -- as its first argument and -works on it in place. ``create_product``, ``update_product`` and -``delete_product`` additionally take ``product_names``, the ``set[str]`` -of normalised names currently in ``storage`` (see -:mod:`src.part4.storage`), and keep it in sync with ``storage`` on -every successful call. The failure path never raises: the operation -prints an explanatory message to stdout and returns ``None``. - -The identifier of a new product is a freshly generated UUID string -(:func:`generate_product_id`), independent of insertion order or of any -identifier already in ``storage``. - -Every product name that reaches the store is passed through -:func:`~src.part4.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 -- via an O(1) membership test against ``product_names`` rather -than a scan over ``storage.values()``. -""" - -import uuid # noqa: F401 +import uuid from typing import Any -from .storage import ( # noqa: F401 +from .storage import ( NAME_KEY, PRICE_KEY, QUANTITY_KEY, Product, ) -from .utils import normalize_price, normalize_product_name # noqa: F401 +from .utils import normalize_price, normalize_product_name def generate_product_id() -> str: - """Generate an identifier for a new product. - - Returns: - A freshly generated UUID, stringified. - """ - # TODO: реализуйте функцию - return "" + return str(uuid.uuid4()) def create_product( @@ -50,46 +19,32 @@ def create_product( product_names: set[str], fields: dict[str, Any], ) -> str | None: - """Add a new product to ``storage`` and return its new identifier. - - Args: - storage: The product store to add to; modified in place on - success. - product_names: The normalised names already in ``storage``; the - new name is added to it in place on success. - fields: A dictionary with the ``name``, ``price`` and ``quantity`` - keys (see :data:`~src.part4.storage.NAME_KEY`, - :data:`~src.part4.storage.PRICE_KEY` and - :data:`~src.part4.storage.QUANTITY_KEY`) 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`` - and ``product_names`` are left unchanged and an explanatory - message is printed. - """ - # TODO: реализуйте функцию - return "" + normalized_name = normalize_product_name(fields[NAME_KEY]) + normalized_price = normalize_price(fields[PRICE_KEY]) + if not normalized_name: + print("product name must not be blank") + return None + elif normalized_name in product_names: + print(f"product name '{normalized_name}' is already taken") + return None -def read_product(storage: dict[str, Product], product_id: str) -> Product | None: - """Return the product stored under ``product_id``. + product_id = generate_product_id() + storage[product_id] = { + NAME_KEY: normalized_name, + PRICE_KEY: normalized_price, + QUANTITY_KEY: fields[QUANTITY_KEY], + } + product_names.add(normalized_name) - Args: - storage: The product store to search. - product_id: The identifier to look up. + return product_id - Returns: - The matching product record, or ``None`` when no product carries - that identifier (a message is printed in that case). - """ - # TODO: реализуйте функцию - return {} + +def read_product(storage: dict[str, Product], product_id: str) -> Product | None: + if product_id not in storage: + print(f"no product with id {product_id}") + return None + return storage[product_id] def update_product( @@ -98,39 +53,34 @@ def update_product( product_id: str, fields: dict[str, Any], ) -> Product | None: - """Overwrite the fields of the product stored under ``product_id``. - - The identifier itself is preserved. ``fields`` may carry any subset of - ``name``, ``price`` and ``quantity``; a key that is missing keeps the - value the product already has, so a caller can update a single field - without repeating the other two. - - Args: - storage: The product store to modify; the matching record is - updated in place on success. - product_names: The normalised names already in ``storage``; on a - successful rename the old name is removed from it and the new - one added. - product_id: The identifier of the product to change. - fields: A dictionary with any of the ``name``, ``price`` and - ``quantity`` keys (see :data:`~src.part4.storage.NAME_KEY`, - :data:`~src.part4.storage.PRICE_KEY` and - :data:`~src.part4.storage.QUANTITY_KEY`) holding the new - values. ``price`` is a :class:`~decimal.Decimal` amount and is - rounded to the stored money precision before it is saved. - Mutated in place: a ``name`` or ``price`` value present in - ``fields`` is overwritten with its normalised form. - - Returns: - The updated product record, or ``None`` when ``name`` is present - and blank once normalised, no product carries that identifier, or - the normalised name is already taken by another product. In every - ``None`` case ``storage`` and ``product_names`` are left unchanged - and an explanatory message is printed. Renaming a product to its - own current name is allowed. - """ - # TODO: реализуйте функцию - return {} + + if product_id not in storage: + print(f"no product with id {product_id}") + return None + + current_name = storage[product_id][NAME_KEY] + + if NAME_KEY in fields: + normalized_name = normalize_product_name(fields[NAME_KEY]) + fields[NAME_KEY] = normalized_name + if not normalized_name: + print("product name must not be blank") + return None + elif (normalized_name != current_name) and (normalized_name in product_names): + print(f"product name '{normalized_name}' is already taken") + return None + + if normalized_name != current_name: + product_names.discard(current_name) + product_names.add(normalized_name) + + if PRICE_KEY in fields: + normalized_price = normalize_price(fields[PRICE_KEY]) + fields[PRICE_KEY] = normalized_price + + storage[product_id].update(fields) + + return storage[product_id] def delete_product( @@ -138,20 +88,11 @@ def delete_product( product_names: set[str], product_id: str, ) -> str | None: - """Remove the product stored under ``product_id`` from ``storage``. - - Args: - storage: The product store to remove from; modified in place on - success. - product_names: The normalised names already in ``storage``; the - departing product's name is removed from it 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`` and ``product_names`` - are left unchanged and a message is printed). - """ - # TODO: реализуйте функцию - return "" + deleted = storage.pop(product_id, None) + + if deleted is None: + print(f"no product with id {product_id}") + return None + + product_names.remove(deleted[NAME_KEY]) + return product_id diff --git a/src/part4/run_admin.py b/src/part4/run_admin.py index 2247b29b..48c9cd2b 100644 --- a/src/part4/run_admin.py +++ b/src/part4/run_admin.py @@ -1,110 +1,98 @@ -"""Interactive admin console for the part4 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, -with a ``match`` statement, 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.part4.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 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 # 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 NAME_KEY, PRICE_KEY, QUANTITY_KEY, Product # noqa: F401 -from .utils import get_storage_str_representation # noqa: F401 - - -# TODO: задайте приглашение и текст справки (используйте своё решение части 3) -PROMPT: Final[str] = "" -HELP_TEXT: Final[str] = "" +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 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. - """ - # TODO: реализуйте функцию (используйте своё решение части 3) + 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. - """ - # TODO: реализуйте функцию (используйте своё решение части 3) + if result is not None: + print(result) def run_command( storage: dict[str, Product], product_names: set[str], 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. - product_names: The normalised names already in ``storage``; kept - in sync 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 the 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. - """ - # TODO: реализуйте функцию - return False + splitted_line = line.split() + + if not splitted_line: + print(f"'{line}' is not a command") + return True + + match splitted_line.pop(0): + case "help" if not splitted_line: + show_help() + return True + case "exit" if not splitted_line: + return False + case "show" if not splitted_line: + print(get_storage_str_representation(storage)) + return True + case "create" if len(splitted_line) >= 3: + print_result( + create_product( + storage, + product_names, + { + NAME_KEY: " ".join(splitted_line[:-2]), + PRICE_KEY: Decimal(splitted_line[-2]), + QUANTITY_KEY: int(splitted_line[-1]), + }, + ) + ) + return True + case "update" if len(splitted_line) >= 4: + print_result( + update_product( + storage, + product_names, + splitted_line[0], + { + NAME_KEY: " ".join(splitted_line[1:-2]), + PRICE_KEY: Decimal(splitted_line[-2]), + QUANTITY_KEY: int(splitted_line[-1]), + }, + ) + ) + return True + case "read" if len(splitted_line) == 1: + print_result(read_product(storage, splitted_line[0])) + return True + case "delete" if len(splitted_line) == 1: + print_result(delete_product(storage, product_names, splitted_line[0])) + return True + case _: + print(f"'{line}' is not a command") + return True def main() -> None: - """Run the admin console until the ``exit`` command is entered. - - A single product store, and the set of normalised names it holds, are - 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 price - or quantity argument does not parse is caught here and reported - without stopping the loop; only ``exit`` ends it. - """ storage: dict[str, Product] = {} product_names: set[str] = set() running = True diff --git a/src/part4/storage.py b/src/part4/storage.py index 9acedf07..01afb14f 100644 --- a/src/part4/storage.py +++ b/src/part4/storage.py @@ -38,8 +38,6 @@ type Product = dict[str, Any] -# Name of each field inside a Product record. -# TODO: задайте имена полей записи -NAME_KEY: Final = "" -PRICE_KEY: Final = "" -QUANTITY_KEY: Final = "" +NAME_KEY: Final = "name" +PRICE_KEY: Final = "price" +QUANTITY_KEY: Final = "quantity" diff --git a/src/part4/utils.py b/src/part4/utils.py index d2a940ea..7e637505 100644 --- a/src/part4/utils.py +++ b/src/part4/utils.py @@ -18,10 +18,10 @@ 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 ( # noqa: F401 +from .storage import ( NAME_KEY, PRICE_KEY, QUANTITY_KEY, @@ -29,72 +29,55 @@ ) -# 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 3) -PRICE_PRECISION: Final[int] = 0 -PRICE_STEP: Final = Decimal(0) +PRICE_PRECISION: Final[int] = 2 +PRICE_STEP: Final = 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 (используйте своё решение части 3) -TABLE_HEADERS: Final[tuple[str, ...]] = () +TABLE_HEADERS: Final[tuple[str, ...]] = ("ID", "name", "price", "quantity") +ID_KEY: Final[str] = TABLE_HEADERS[0] 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 (используйте своё решение части 3) - return Decimal(0) + 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. - """ - # TODO: реализуйте функцию (используйте своё решение части 3) - return "" + normalized_name = " ".join(name.split()).lower() + return normalized_name # TODO: при необходимости добавьте свои вспомогательные функции def get_storage_str_representation(storage: dict[str, 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 insertion order. When - ``storage`` is empty only the header and separator rows are - returned, sized to the header labels. - """ - # TODO: реализуйте функцию (используйте своё решение части 3) - return "" + lens = { + key: [len(h)] + for key, h in zip((ID_KEY, NAME_KEY, PRICE_KEY, QUANTITY_KEY), TABLE_HEADERS) + } + + for product_id, product in storage.items(): + lens[ID_KEY].append(len(product_id)) + for key in (NAME_KEY, PRICE_KEY, QUANTITY_KEY): + lens[key].append(len(str(product[key]))) + + maxlens = list(map(max, lens.values())) + + header_str = "|" + separating_str = "|" + for header, length in zip(TABLE_HEADERS, maxlens): + header_str += f" {header.ljust(length)} |" + separating_str += "-" + "-" * length + "-|" + + table = header_str + "\n" + separating_str + + for product_id, product in storage.items(): + table += "\n|" + elems = ( + product_id, + product[NAME_KEY], + product[PRICE_KEY], + product[QUANTITY_KEY], + ) + for elem, length in zip(elems, maxlens): + table += f" {str(elem).ljust(length)} |" + + return table