3. Васильев Егор Евгеньевич. 613

src/part3/crud.py

@@ -1,131 +1,85 @@
-"""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 len(storage) == 0:
+        return PRODUCT_ID_MIN
+    return max(p[PRODUCT_ID_INDEX] for p in storage) + 1
 
 
 def create_product(
     storage: list[Product], fields: tuple[str, Decimal, int]
 ) -> int | None:
-    """Append a new product to ``storage`` and return its new identifier.
-
-    Args:
-        storage: The product store to append to; modified in place on
-            success.
-        fields: A ``(name, price, quantity)`` tuple describing the product.
-            ``name`` is normalised (surrounding whitespace stripped,
-            lower-cased) before it is stored or compared. ``price`` is a
-            :class:`~decimal.Decimal` amount and is rounded to the stored
-            money precision before it is saved.
-
-    Returns:
-        The identifier generated for the new product, or ``None`` when
-        ``name`` is blank once normalised or a product with the same
-        normalised name already exists. In the ``None`` case ``storage``
-        is left unchanged and an explanatory message is printed.
-    """
-    # TODO: реализуйте функцию
-    return 0
+    name = normalize_product_name(fields[0])
+    price = normalize_price(fields[1])
+    quantity = fields[2]
+    if not name:
+        print("product name must not be blank")
+        return None
+    for cor in storage:
+        if cor[NAME_INDEX] == name:
+            print(f"product name '{name}' is already taken")
+            return None
+    new_id = generate_product_id(storage)
+    storage.append((new_id, name, price, quantity))
+    return new_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 (используйте своё решение части 2)
-    return (0, "", Decimal(0), 0)
+    for cor in storage:
+        if cor[PRODUCT_ID_INDEX] == product_id:
+            return cor
+    print(f"no product with id {product_id}")
+    return None
 
 
 def update_product(
     storage: list[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)
+    name = normalize_product_name(fields[0])
+    price = normalize_price(fields[1])
+    quantity = fields[2]
+    if not name:
+        print("product name must not be blank")
+        return None
+    index_id = next(
+        (i for i, p in enumerate(storage) if p[PRODUCT_ID_INDEX] == product_id), None
+    )
+    if index_id is None:
+        print(f"no product with id {product_id}")
+        return None
+    index_name = next(
+        (
+            i
+            for i, p in enumerate(storage)
+            if (p[NAME_INDEX] == name) and (p[PRODUCT_ID_INDEX] != product_id)
+        ),
+        None,
+    )
+    if index_name is not None:
+        print(f"product name '{name}' is already taken")
+        return None
+    fields_new = (product_id, name, price, quantity)
+    storage[index_id] = fields_new
+    return fields_new
 
 
 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
+    index = next(
+        (i for i, p in enumerate(storage) if p[PRODUCT_ID_INDEX] == product_id), None
+    )
+    if index is None:
+        print(f"no product with id {product_id}")
+        return None
+    storage.pop(index)
+    return product_id

src/part3/run_admin.py

@@ -1,107 +1,88 @@
-"""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 <name...> <price> <quantity>`` -- add a product;
-* ``read <id>`` -- print one product;
-* ``update <id> <name...> <price> <quantity>`` -- overwrite a product;
-* ``delete <id>`` -- 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 <name...> <price> <quantity>        add a product, print its new id
+  read <id>                                  print the product with that id
+  update <id> <name...> <price> <quantity>   overwrite that product's fields
+  delete <id>                                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
+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
+    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
+    parts = line.split()
+
+    match parts:
+        case ["exit"]:
+            return False
+
+        case ["help"]:
+            show_help()
+            return True
+
+        case ["show"]:
+            print(get_storage_str_representation(storage))
+            return True
+
+        case ["create", *name_parts, price_str, quantity_str] if name_parts:
+            name = " ".join(name_parts)
+            price = Decimal(price_str)
+            quantity = int(quantity_str)
+            print_result(create_product(storage, (name, price, quantity)))
+            return True
+
+        case ["read", product_id_str]:
+            product_id = int(product_id_str)
+            print_result(read_product(storage, product_id))
+            return True
+
+        case ["update", product_id_str, *name_parts, price_str, quantity_str] if (
+            name_parts
+        ):
+            product_id = int(product_id_str)
+            name = " ".join(name_parts)
+            price = Decimal(price_str)
+            quantity = int(quantity_str)
+            print_result(update_product(storage, product_id, (name, price, quantity)))
+            return True
+
+        case ["delete", product_id_str]:
+            product_id = int(product_id_str)
+            print_result(delete_product(storage, product_id))
+            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
 

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