From 4fddb32088ebae7cc435c15c73d8d1a71e75db0a Mon Sep 17 00:00:00 2001 From: Sergei Bezymyanniy Date: Sat, 10 Oct 2026 01:07:08 +0300 Subject: [PATCH 1/2] Implement part 3 --- src/part3/crud.py | 187 +++++++++++++++++++---------------------- src/part3/run_admin.py | 137 +++++++++++++----------------- src/part3/storage.py | 33 ++------ src/part3/utils.py | 110 ++++++++---------------- 4 files changed, 182 insertions(+), 285 deletions(-) diff --git a/src/part3/crud.py b/src/part3/crud.py index 68811d7e..9db9745b 100644 --- a/src/part3/crud.py +++ b/src/part3/crud.py @@ -1,87 +1,67 @@ -"""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 check_product(storage: list[Product], product_name: str) -> bool | None: + if not (product_name): + print("product name must not be blank") + return None + + for product in storage: + if product_name == product[NAME_INDEX]: + print(f"product name '{product_name}' is already taken") + return None + return True def generate_product_id(storage: list[Product]) -> int: - """Choose the identifier for the next product added to ``storage``. + if not storage: + return PRODUCT_ID_MIN - Args: - storage: The product store to inspect. + max_id = max(product[PRODUCT_ID_INDEX] for product in storage) - 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 + return max_id + 1 def create_product( - storage: list[Product], fields: tuple[str, Decimal, int] + 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 + product_name, product_price, product_quantity = fields + normalized_name = normalize_product_name(product_name) + if (status := check_product(storage, normalized_name)) is None: + return status -def read_product(storage: list[Product], product_id: int) -> Product | None: - """Return the product stored under ``product_id``. + product_id = generate_product_id(storage) + normalized_price = normalize_price(product_price) + + storage.append( + ( + product_id, + normalized_name, + normalized_price, + product_quantity, + ) + ) - Args: - storage: The product store to search. - product_id: The identifier to look up. + return product_id - 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 +69,48 @@ 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) + product_name, product_price, product_quantity = fields + normalized_name = normalize_product_name(product_name) + + if not normalized_name: + print("product name must not be blank") + return None + + product_index = None + + for index, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + product_index = index + break + + if product_index is None: + print(f"no product with id {product_id}") + return None + + for product in storage: + if ( + product[PRODUCT_ID_INDEX] != product_id + and product[NAME_INDEX] == normalized_name + ): + print(f"product name '{normalized_name}' is already taken") + return None + + new_product: Product = ( + product_id, + normalized_name, + normalize_price(product_price), + product_quantity, + ) + + storage[product_index] = new_product + 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 index, product in enumerate(storage): + if product[PRODUCT_ID_INDEX] == product_id: + storage.pop(index) + return product_id + + print(f"no product with id {product_id}") + return None \ No newline at end of file diff --git a/src/part3/run_admin.py b/src/part3/run_admin.py index c5feeb0b..d9adb38a 100644 --- a/src/part3/run_admin.py +++ b/src/part3/run_admin.py @@ -1,107 +1,84 @@ -"""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 -def show_help() -> None: - """Print the command reference to stdout. +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.""" - 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 +def show_help() -> None: + 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 +def print_result(result: object) -> None: + 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. + parts = line.split() + + match parts: + case ["help"]: + show_help() + + case ["exit"]: + return False + + case ["show"]: + print(get_storage_str_representation(storage)) + + case ["create", *args] if len(args) >= 3: + name = " ".join(args[:-2]) + price = Decimal(args[-2]) + quantity = int(args[-1]) + print_result(create_product(storage, (name, price, quantity))) + + case ["read", product_id]: + print_result(read_product(storage, int(product_id))) + + case ["update", product_id, *args] if len(args) >= 3: + name = " ".join(args[:-2]) + price = Decimal(args[-2]) + quantity = int(args[-1]) + result = update_product( + storage, + int(product_id), + (name, price, quantity), + ) + print_result(result) - 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. + case ["delete", product_id]: + print_result(delete_product(storage, int(product_id))) - 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``. + case _: + print(f"'{line}' is not a command") - 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 + 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 @@ -116,4 +93,4 @@ def main() -> None: if __name__ == "__main__": - main() + main() \ No newline at end of file diff --git a/src/part3/storage.py b/src/part3/storage.py index c5e34be5..8ca9c4e3 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] +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 \ No newline at end of file diff --git a/src/part3/utils.py b/src/part3/utils.py index 318ded0b..73a75c92 100644 --- a/src/part3/utils.py +++ b/src/part3/utils.py @@ -1,95 +1,53 @@ -"""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 -# 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] = 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, str, str, 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: + return " ".join(name.split()).lower() -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: + rows: list[list[str]] = [list(TABLE_HEADERS)] - Args: - name: The raw product name. + for p in storage: + rows.append( + [ + str(p[0]), + str(p[1]), + str(p[2]), + str(p[3]), + ] + ) - 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 "" + col_widths = [max(len(row[i]) for row in rows) for i in range(len(TABLE_HEADERS))] + formatted_rows = [] + for row in rows: + padded_cells = [ + f" {row[i].ljust(col_widths[i])} " for i in range(len(TABLE_HEADERS)) + ] + formatted_rows.append(f"|{'|'.join(padded_cells)}|") -# TODO: при необходимости добавьте свои вспомогательные функции + dash_cells = ["-" * (w + 2) for w in col_widths] + separator_line = f"|{'|'.join(dash_cells)}|" + formatted_rows.insert(1, separator_line) -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 "\n".join(formatted_rows) \ No newline at end of file From 50e0e4598b2c2d4148a5b7daa4c1bbd63dbfd886 Mon Sep 17 00:00:00 2001 From: Sergei Bezymyanniy Date: Sat, 10 Oct 2026 01:12:27 +0300 Subject: [PATCH 2/2] Solve task 3 --- src/part3/crud.py | 2 +- src/part3/run_admin.py | 2 +- src/part3/storage.py | 2 +- src/part3/utils.py | 2 +- 4 files changed, 4 insertions(+), 4 deletions(-) diff --git a/src/part3/crud.py b/src/part3/crud.py index 9db9745b..2774f58c 100644 --- a/src/part3/crud.py +++ b/src/part3/crud.py @@ -113,4 +113,4 @@ def delete_product(storage: list[Product], product_id: int) -> int | None: return product_id print(f"no product with id {product_id}") - return None \ No newline at end of file + return None diff --git a/src/part3/run_admin.py b/src/part3/run_admin.py index d9adb38a..53847ec6 100644 --- a/src/part3/run_admin.py +++ b/src/part3/run_admin.py @@ -93,4 +93,4 @@ def main() -> None: if __name__ == "__main__": - main() \ No newline at end of file + main() diff --git a/src/part3/storage.py b/src/part3/storage.py index 8ca9c4e3..726ab823 100644 --- a/src/part3/storage.py +++ b/src/part3/storage.py @@ -9,4 +9,4 @@ PRICE_INDEX: Final = 2 QUANTITY_INDEX: Final = 3 -PRODUCT_ID_MIN: Final[int] = 1 \ No newline at end of file +PRODUCT_ID_MIN: Final[int] = 1 diff --git a/src/part3/utils.py b/src/part3/utils.py index 73a75c92..f5cc90b5 100644 --- a/src/part3/utils.py +++ b/src/part3/utils.py @@ -50,4 +50,4 @@ def get_storage_str_representation(storage: list[Product]) -> str: formatted_rows.insert(1, separator_line) - return "\n".join(formatted_rows) \ No newline at end of file + return "\n".join(formatted_rows)