From ecf93a169c4a3038cc539a2153c808b3d353a26d Mon Sep 17 00:00:00 2001 From: Luminol Date: Sun, 1 Nov 2026 23:53:57 +0300 Subject: [PATCH] Solve task 4 --- src/part4/cart.py | 93 ++++++++------------ src/part4/crud.py | 193 +++++++++++++++-------------------------- src/part4/run_admin.py | 152 ++++++++++++++------------------ src/part4/storage.py | 43 +-------- src/part4/utils.py | 122 ++++++++++---------------- 5 files changed, 225 insertions(+), 378 deletions(-) diff --git a/src/part4/cart.py b/src/part4/cart.py index aed9bb72..bcb88c0d 100644 --- a/src/part4/cart.py +++ b/src/part4/cart.py @@ -9,7 +9,7 @@ an explanatory message to stdout and returns ``None``. """ -from .storage import Product +from .storage import QUANTITY_KEY, Product # TODO: при необходимости добавьте свои вспомогательные функции @@ -22,32 +22,21 @@ def add_to_cart( product_id: str, quantity: int, ) -> int | 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 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. - - 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. - - 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 + if product_id not in storage: + print(f"no product with id {product_id}") + return None + + stock: int = storage[product_id][QUANTITY_KEY] + if stock < quantity: + print( + f"not enough stock for product {product_id}: {stock} available, {quantity} requested" + ) + return None + + storage[product_id][QUANTITY_KEY] -= quantity + cart[product_id] = cart.get(product_id, 0) + quantity + + return cart[product_id] def remove_from_cart( @@ -57,31 +46,25 @@ 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 + + cart_quantity: int = cart[product_id] + if cart_quantity < quantity: + print( + f"cart holds only {cart_quantity} unit(s) of product {product_id}, cannot remove {quantity}" + ) + return None + + if 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 cart.get(product_id, 0) diff --git a/src/part4/crud.py b/src/part4/crud.py index 471eff00..f42613fd 100644 --- a/src/part4/crud.py +++ b/src/part4/crud.py @@ -1,48 +1,21 @@ -"""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 decimal import Decimal 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 +23,39 @@ 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 "" + name: str = fields[NAME_KEY] + price: Decimal = fields[PRICE_KEY] + quantity: int = fields[QUANTITY_KEY] + normalized_name = normalize_product_name(name) -def read_product(storage: dict[str, Product], product_id: str) -> Product | None: - """Return the product stored under ``product_id``. + if not normalized_name: + print("product name must not be blank") + return None + + if normalized_name in product_names: + print(f"product name '{normalized_name}' is already taken") + return None - Args: - storage: The product store to search. - product_id: The identifier to look up. + product_id = generate_product_id() + normalized_price = normalize_price(price) - Returns: - The matching product record, or ``None`` when no product carries - that identifier (a message is printed in that case). - """ - # TODO: реализуйте функцию - return {} + new_product: Product = { + NAME_KEY: normalized_name, + PRICE_KEY: normalized_price, + QUANTITY_KEY: quantity, + } + storage[product_id] = new_product + + return product_id + + +def read_product(storage: dict[str, Product], product_id: str) -> Product | None: + if product_id in storage: + return storage[product_id] + + print(f"no product with id {product_id}") + return None def update_product( @@ -98,39 +64,34 @@ 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_product = storage[product_id] + + if NAME_KEY in fields: + normalized_name = normalize_product_name(fields[NAME_KEY]) + if not normalized_name: + print("product name must not be blank") + return None + if ( + normalized_name != current_product[NAME_KEY] + and normalized_name in product_names + ): + print(f"product name '{normalized_name}' is already taken") + return None + fields[NAME_KEY] = normalized_name + + if PRICE_KEY in fields: + fields[PRICE_KEY] = normalize_price(fields[PRICE_KEY]) + + if NAME_KEY in fields and fields[NAME_KEY] != current_product[NAME_KEY]: + product_names.remove(current_product[NAME_KEY]) + product_names.add(fields[NAME_KEY]) + + current_product.update(fields) + return current_product def delete_product( @@ -138,20 +99,10 @@ 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 "" + if product_id in storage: + product = storage.pop(product_id) + product_names.remove(product[NAME_KEY]) + 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 index 2247b29b..66c41cfc 100644 --- a/src/part4/run_admin.py +++ b/src/part4/run_admin.py @@ -1,110 +1,92 @@ -"""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) + return 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 + input_line = line.strip() + match input_line.split(): + case ["help"]: + show_help() + return True + + case ["exit"]: + return False + + case ["show"]: + print_result(get_storage_str_representation(storage)) + return True + + case ["create", first_name_part, *rest_name, price, quantity]: + name = " ".join([first_name_part] + rest_name) + fields = { + NAME_KEY: name, + PRICE_KEY: Decimal(price), + QUANTITY_KEY: int(quantity), + } + print(create_product(storage, product_names, fields)) + return True + + case ["read", product_id]: + print_result(read_product(storage, product_id)) + + case ["update", product_id, first_name_part, *rest_name, price, quantity]: + name = " ".join([first_name_part] + rest_name) + fields = { + NAME_KEY: name, + PRICE_KEY: Decimal(price), + QUANTITY_KEY: int(quantity), + } + print_result(update_product(storage, product_names, product_id, fields)) + return True + + case ["delete", product_id]: + print_result(delete_product(storage, product_names, product_id)) + return True + + case _: + print(f"'{input_line}' is not a command") + return True return False 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..fe192215 100644 --- a/src/part4/storage.py +++ b/src/part4/storage.py @@ -1,45 +1,8 @@ -"""In-memory product store for the shop CRUD exercise. - -The store is deliberately primitive: a plain dictionary, with no -persistence and no schema enforcement. It maps a product's ``id`` -- a -UUID string assigned by the create operation in :mod:`src.part4.crud` --- to its :data:`Product` record -- a dictionary with the keys ``name``, -``price`` and ``quantity`` -- where: - -* the ``storage`` key itself -- unique string identifier, assigned by the - create operation in :mod:`src.part4.crud`; it is not duplicated - inside the record; -* ``name`` -- human-readable product name, unique across the store, held - in normalised form (see - :func:`src.part4.utils.normalize_product_name`); -* ``price`` -- price of a single unit, held as a :class:`~decimal.Decimal` - amount rounded to a fixed number of decimal places (see - :func:`src.part4.utils.normalize_price`) so that money is never - subject to binary floating-point error; -* ``quantity`` -- number of units currently in stock. - -Field names are exposed as ``*_KEY`` constants so callers never hard-code -the dictionary keys. - -Every caller that mutates the store also threads along a second -structure, a ``set[str]`` of the normalised names currently in use -- -see, for example, the ``product_names`` parameter of -:func:`src.part4.crud.create_product`. Keeping that name index as a -plain set passed next to ``storage``, rather than bundling the two into -an object, lets a name-uniqueness check become an O(1) membership test -against the set instead of a linear scan over ``storage.values()``. The -set must always mirror the normalised names present in ``storage``; the -functions in :mod:`src.part4.crud` keep the two in sync on every -successful create, update and delete. -""" - from typing import Any, Final 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..b91044d7 100644 --- a/src/part4/utils.py +++ b/src/part4/utils.py @@ -1,27 +1,7 @@ -"""Standalone helpers shared by the part4 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 ( # noqa: F401 +from .storage import ( NAME_KEY, PRICE_KEY, QUANTITY_KEY, @@ -29,72 +9,60 @@ ) -# 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") 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 3) - 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 number_length(value: Decimal | float) -> int: + return len(str(value)) - 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 "" +def get_storage_str_representation(storage: dict[str, Product]) -> str: + columns_lengths_sets: list[set[int]] = [set() for _ in range(4)] + for index, header in enumerate(TABLE_HEADERS): + columns_lengths_sets[index].add(len(header)) -# TODO: при необходимости добавьте свои вспомогательные функции + if storage: + for product_id, product in storage.items(): + columns_lengths_sets[0].add(len(product_id)) + columns_lengths_sets[1].add(len(str(product[NAME_KEY]))) + columns_lengths_sets[2].add(number_length(product[PRICE_KEY])) + columns_lengths_sets[3].add(number_length(product[QUANTITY_KEY])) + final_widths: list[int] = [max(length_set) for length_set in columns_lengths_sets] -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 "" + header_parts = [ + TABLE_HEADERS[index].ljust(final_widths[index]) + for index in range(len(TABLE_HEADERS)) + ] + header_line = f"| {' | '.join(header_parts)} |" + + separating_parts = ["-" * (length + 2) for length in final_widths] + separating_line = f"|{'|'.join(separating_parts)}|" + + table = [header_line, separating_line] + + if not storage: + return "\n".join(table) + + for product_id, product in storage.items(): + line = ( + f"| {str(product_id).ljust(final_widths[0])} | " + f"{str(product[NAME_KEY]).ljust(final_widths[1])} | " + f"{str(product[PRICE_KEY]).ljust(final_widths[2])} | " + f"{str(product[QUANTITY_KEY]).ljust(final_widths[3])} |" + ) + table.append(line) + + return "\n".join(table)