Re: [PATCH 12/16] qapi/expr.py: Add docstrings

From: Cleber Rosa <crosa@redhat.com>
To: John Snow <jsnow@redhat.com>
Cc: Michael Roth <mdroth@linux.vnet.ibm.com>,
	Markus Armbruster <armbru@redhat.com>,
	Eduardo Habkost <ehabkost@redhat.com>,
	qemu-devel@nongnu.org
Subject: Re: [PATCH 12/16] qapi/expr.py: Add docstrings
Date: Thu, 24 Sep 2020 20:59:30 -0400	[thread overview]
Message-ID: <20200925005930.GE368253@localhost.localdomain> (raw)
In-Reply-To: <20200922211313.4082880-13-jsnow@redhat.com>

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On Tue, Sep 22, 2020 at 05:13:09PM -0400, John Snow wrote:
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  scripts/qapi/expr.py | 157 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 155 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
> index f244e9648c..4bba09f6e5 100644
> --- a/scripts/qapi/expr.py
> +++ b/scripts/qapi/expr.py
> @@ -1,7 +1,5 @@
>  # -*- coding: utf-8 -*-
>  #
> -# Check (context-free) QAPI schema expression structure
> -#
>  # Copyright IBM, Corp. 2011
>  # Copyright (c) 2013-2019 Red Hat Inc.
>  #
> @@ -14,6 +12,25 @@
>  # This work is licensed under the terms of the GNU GPL, version 2.
>  # See the COPYING file in the top-level directory.
>  
> +"""
> +Normalize and validate (context-free) QAPI schema expression structures.
> +
> +After QAPI expressions are parsed from disk, they are stored in
> +recursively nested Python data structures using Dict, List, str, bool,
> +and int. This module ensures that those nested structures have the
> +correct type(s) and key(s) where appropriate for the QAPI context-free
> +grammar.
> +
> +The QAPI schema expression language also allows for syntactic sugar;
> +this module also handles the normalization process of these nested
> +structures.
> +
> +See `check_exprs` for the main entry point.
> +
> +See `schema.QAPISchema` for processing into native Python data
> +structures and contextual semantic validation.
> +"""
> +
>  import re
>  from typing import (
>      Iterable,
> @@ -46,6 +63,7 @@
>  def check_name_is_str(name: object,
>                        info: QAPISourceInfo,
>                        source: str) -> None:
> +    """Ensures that `name` is a string. [Const]"""
>      if not isinstance(name, str):
>          raise QAPISemError(info, "%s requires a string name" % source)
>  
> @@ -56,6 +74,24 @@ def check_name_str(name: str,
>                     allow_optional: bool = False,
>                     enum_member: bool = False,
>                     permit_upper: bool = False) -> None:
> +    """
> +    Ensures a string is a legal name. [Const]
> +
> +    A name is legal in the default case when:
> +    - It matches ``(__[a-z0-9.-]+_)?[a-z][a-z0-9_-]*``
> +    - It does not start with ``q_`` or ``q-``
> +
> +    :param name:           Name to check.
> +    :param info:           QAPI source file information.
> +    :param source:         Human-readable str describing "what" this name is.
> +    :param allow_optional: Allow the very first character to be ``*``.
> +                           (Cannot be used with `enum_member`)
> +    :param enum_member:    Allow the very first character to be a digit.
> +                           (Cannot be used with `allow_optional`)
> +    :param permit_upper:   Allows upper-case characters wherever
> +                           lower-case characters are allowed.
> +    """
> +    assert not (allow_optional and enum_member)
>      membername = name
>  
>      if allow_optional and name.startswith('*'):
> @@ -76,6 +112,17 @@ def check_name_str(name: str,
>  
>  
>  def check_defn_name_str(name: str, info: QAPISourceInfo, meta: str) -> None:
> +    """
> +    Ensures a name is a legal definition name. [Const]
> +
> +    A legal definition name:
> +     - Adheres to the criteria in `check_name_str`, with uppercase permitted
> +     - Does not end with ``Kind`` or ``List``.
> +
> +    :param name: Name to check.
> +    :param info: QAPI source file information.
> +    :param meta: Type name of the QAPI expression.
> +    """
>      check_name_str(name, info, meta, permit_upper=True)
>      if name.endswith('Kind') or name.endswith('List'):
>          raise QAPISemError(
> @@ -87,6 +134,15 @@ def check_keys(value: _JSObject,
>                 source: str,
>                 required: List[str],
>                 optional: List[str]) -> None:
> +    """
> +    Ensures an object has a specific set of keys. [Const]
> +
> +    :param value:    The object to check.
> +    :param info:     QAPI source file information.
> +    :param source:   Human-readable str describing "what" this object is.
> +    :param required: Keys that *must* be present.
> +    :param optional: Keys that *may* be present.
> +    """
>  
>      def pprint(elems: Iterable[str]) -> str:
>          return ', '.join("'" + e + "'" for e in sorted(elems))
> @@ -109,6 +165,12 @@ def pprint(elems: Iterable[str]) -> str:
>  
>  
>  def check_flags(expr: Expression, info: QAPISourceInfo) -> None:
> +    """
> +    Ensures common fields in an Expression are correct. [Const]
> +
> +    :param expr: Expression to validate.
> +    :param info: QAPI source file information.
> +    """
>      for key in ['gen', 'success-response']:
>          if key in expr and expr[key] is not False:
>              raise QAPISemError(
> @@ -120,6 +182,18 @@ def check_flags(expr: Expression, info: QAPISourceInfo) -> None:
>  
>  
>  def check_if(expr: _JSObject, info: QAPISourceInfo, source: str) -> None:
> +    """
> +    Syntactically validate and normalize the ``if`` field of an object. [RW]
> +
> +    The ``if`` field may be either a `str` or a `List[str]`.
> +    A `str` element will be normalized to `List[str]`.
> +
> +    Sugared: `Union[str, List[str]]`
> +    Ifcond: `List[str]`
> +
> +    :param expr: A `dict`; the ``if`` field, if present, will be validated.
> +    :param info: QAPI source file information.
> +    """
>  
>      def check_if_str(ifcond: object) -> None:
>          if not isinstance(ifcond, str):
> @@ -148,6 +222,16 @@ def check_if_str(ifcond: object) -> None:
>  
>  
>  def normalize_members(members: object) -> None:
> +    """
> +    Normalize a "members" value. [RW]
> +
> +    If `members` is an object, for every value in that object, if that
> +    value is not itself already an object, normalize it to
> +    ``{'type': value}``.
> +
> +    Sugared: `Dict[str, Union[str, TypeRef]]`
> +    Members: `Dict[str, TypeRef]`
> +    """
>      if isinstance(members, dict):
>          for key, arg in members.items():
>              if isinstance(arg, dict):
> @@ -160,6 +244,18 @@ def check_type(value: Optional[object],
>                 source: str,
>                 allow_array: bool = False,
>                 allow_dict: Union[bool, str] = False) -> None:
> +    """
> +    Check the QAPI type of `value`. [RW]
> +
> +    Python types of `str` or `None` are always allowed.
> +
> +    :param value:       The value to check.
> +    :param info:        QAPI Source file information.
> +    :param source:      Human readable string describing "what" the value is.
> +    :param allow_array: Allow a `List[str]` of length 1,
> +                        which indicates an Array<T> type.
> +    :param allow_dict:  Allow a dict, treated as an anonymous type.
> +    """
>      if value is None:
>          return
>  
> @@ -205,6 +301,15 @@ def check_type(value: Optional[object],
>  
>  def check_features(features: Optional[object],
>                     info: QAPISourceInfo) -> None:
> +    """
> +    Syntactically validate and normalize the "features" field. [RW]
> +
> +    `features` may be a List of either `str` or `dict`.
> +    Any `str` element will be normalized to `{'name': element}`.
> +
> +    Sugared: `List[Union[str, Feature]]`
> +    Features: `List[Feature]`
> +    """
>      if features is None:
>          return
>      if not isinstance(features, list):
> @@ -222,6 +327,12 @@ def check_features(features: Optional[object],
>  
>  
>  def check_enum(expr: Expression, info: QAPISourceInfo) -> None:
> +    """
> +    Validate this `Expression` as an ``enum`` expression. [RW]
> +
> +    :param expr: `Expression` to validate.
> +    :param info: QAPI source file information.
> +    """
>      name = expr['enum']
>      members = expr['data']
>      prefix = expr.get('prefix')
> @@ -246,6 +357,12 @@ def check_enum(expr: Expression, info: QAPISourceInfo) -> None:
>  
>  
>  def check_struct(expr: Expression, info: QAPISourceInfo) -> None:
> +    """
> +    Validate this `Expression` as a ``struct`` expression. [RW]
> +
> +    :param expr: `Expression` to validate.
> +    :param info: QAPI source file information.
> +    """
>      name = cast(str, expr['struct'])  # Asserted in check_exprs
>      members = expr['data']
>  
> @@ -254,6 +371,12 @@ def check_struct(expr: Expression, info: QAPISourceInfo) -> None:
>  
>  
>  def check_union(expr: Expression, info: QAPISourceInfo) -> None:
> +    """
> +    Validate this `Expression` as a ``union`` expression. [RW]
> +
> +    :param expr: `Expression` to validate.
> +    :param info: QAPI source file information.
> +    """
>      name = cast(str, expr['union'])  # Asserted in check_exprs
>      base = expr.get('base')
>      discriminator = expr.get('discriminator')
> @@ -280,6 +403,12 @@ def check_union(expr: Expression, info: QAPISourceInfo) -> None:
>  
>  
>  def check_alternate(expr: Expression, info: QAPISourceInfo) -> None:
> +    """
> +    Validate this `Expression` as an ``alternate`` expression. [RW]
> +
> +    :param expr: Expression to validate.
> +    :param info: QAPI source file information.
> +    """
>      members = expr['data']
>  
>      if not members:
> @@ -297,6 +426,12 @@ def check_alternate(expr: Expression, info: QAPISourceInfo) -> None:
>  
>  
>  def check_command(expr: Expression, info: QAPISourceInfo) -> None:
> +    """
> +    Validate this `Expression` as a ``command`` expression. [RW]
> +
> +    :param expr: `Expression` to validate.
> +    :param info: QAPI source file information.
> +    """
>      args = expr.get('data')
>      rets = expr.get('returns')
>      boxed = expr.get('boxed', False)
> @@ -308,6 +443,16 @@ def check_command(expr: Expression, info: QAPISourceInfo) -> None:
>  
>  
>  def check_event(expr: Expression, info: QAPISourceInfo) -> None:
> +    """
> +    Normalize and syntactically validate the ``event`` expression. [RW]
> +
> +    Event:
> +        event:    `str`
> +        data:     `Optional[Dict[str, Member]]`
> +        boxed:    `Optional[bool]`
> +        if:       `Optional[Ifcond]`
> +        features: `Optional[Features]`
> +    """
>      args = expr.get('data')
>      boxed = expr.get('boxed', False)
>  
> @@ -317,6 +462,14 @@ def check_event(expr: Expression, info: QAPISourceInfo) -> None:
>  
>  
>  def check_exprs(exprs: List[_JSObject]) -> List[_JSObject]:
> +    """
> +    Validate and normalize a list of parsed QAPI schema expressions. [RW]
> +
> +    This function accepts a list of expressions + metadta as returned by
> +    the parser. It destructively normalizes the expressions in-place.
> +
> +    :param exprs: The list of expressions to normalize/validate.
> +    """

This is a huge improvement already, but maybe also take the
opportunity to add ":return:" too?  Anyway,

Reviewed-by: Cleber Rosa <crosa@redhat.com>

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