The QAPI schema doc comment language provides special syntax for
command and event arguments, struct and union members, alternate
branches, enumeration values, and features: descriptions starting with
"@name:".
By convention, we format them like this:
# @name: Lorem ipsum dolor sit amet, consectetur adipiscing elit,
# sed do eiusmod tempor incididunt ut labore et dolore
# magna aliqua.
Okay for names as short as "name", but we have much longer ones. Their
description gets squeezed against the right margin, like this:
# @dirty-sync-missed-zero-copy: Number of times dirty RAM synchronization could
# not avoid copying dirty pages. This is between
# 0 and @dirty-sync-count * @multifd-channels.
# (since 7.1)
The description text is effectively just 50 characters wide. Easy
enough to read, but can be cumbersome to write.
The awkward squeeze against the right margin makes people go beyond it,
which produces two undesirables: arguments about style, and descriptions
that are unnecessarily hard to read, like this one:
# @postcopy-vcpu-blocktime: list of the postcopy blocktime per vCPU. This is
# only present when the postcopy-blocktime migration capability
# is enabled. (Since 3.0)
We could instead format it like
# @postcopy-vcpu-blocktime:
# list of the postcopy blocktime per vCPU. This is only present
# when the postcopy-blocktime migration capability is
# enabled. (Since 3.0)
or, since the commit before previous, like
# @postcopy-vcpu-blocktime:
# list of the postcopy blocktime per vCPU. This is only present
# when the postcopy-blocktime migration capability is
# enabled. (Since 3.0)
However, I'd rather have
# @postcopy-vcpu-blocktime: list of the postcopy blocktime per vCPU.
# This is only present when the postcopy-blocktime migration
# capability is enabled. (Since 3.0)
because this is how rST field and option lists work.
To get this, we need to let the first non-blank line after the
"@name:" line determine expected indentation.
This fills up the indentation pitfall mentioned in
docs/devel/qapi-code-gen.rst. A related pitfall still exists. Update
the text to show it.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230428105429.1687850-14-armbru@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
[Work around lack of walrus operator in Python 3.7 and older]
To recognize a line starting with a section symbol and or tag, we
first split it at the first space, then examine the part left of the
space. We can just as well examine the unsplit line, so do that.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230428105429.1687850-13-armbru@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
[Work around lack of walrus operator in Python 3.7 and older]
When an argument's description starts on the line after the "#arg: "
line, indentation is stripped only from the description's first line,
as demonstrated by the previous commit. Moreover, subsequent lines
with less indentation are not rejected.
Make the first line's indentation the expected indentation for the
remainder of the description. This fixes indentation stripping, and
also requires at least that much indentation.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230428105429.1687850-12-armbru@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
When the lexer chokes on a stray character, its shows the characters
until the next structural character in the error message. It uses a
regular expression to match a non-empty string of non-structural
characters. Bug: the regular expression treats '"' as structural.
When the lexer chokes on '"', the match fails, and trips
must_match()'s assertion. Fix the regular expression.
Fixes: 14c3279502 (qapi: Improve reporting of lexical errors)
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230428105429.1687850-4-armbru@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
With the two major JSON-ish type hierarchies clarified for distinct
purposes; QAPIExpression for parsed expressions and JSONValue for
introspection data, remove this FIXME as no longer an action item.
A third JSON-y data type, _ExprValue, is not meant to represent JSON in
the abstract but rather only the possible legal return values from a
single function, get_expr(). It isn't appropriate to attempt to merge it
with either of the above two types.
In theory, it may be possible to define a completely agnostic
one-size-fits-all JSON type hierarchy that any other user could borrow -
in practice, it's tough to wrangle the differences between invariant,
covariant and contravariant types: input and output parameters demand
different properties of such a structure.
However, QAPIExpression serves to authoritatively type user input to the
QAPI parser, while JSONValue serves to authoritatively type qapi
generator *output* to be served back to client users at runtime via
QMP. The AST for these two types are different and cannot be wholly
merged into a unified syntax.
They could, in theory, share some JSON primitive definitions. In
practice, this is currently more trouble than it's worth with mypy's
current expressive power. As such, declare this "done enough for now".
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20230215000011.1725012-7-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
This patch creates a new type, QAPIExpression, which represents a parsed
expression complete with QAPIDoc and QAPISourceInfo.
This patch turns parser.exprs into a list of QAPIExpression instead,
and adjusts expr.py to match.
This allows the types we specify in parser.py to be "remembered" all the
way through expr.py and into schema.py. Several assertions around
packing and unpacking this data can be removed as a result.
It also corrects a harmless typing error. Before the patch,
check_exprs() allegedly takes a List[_JSONObject]. It actually takes
a list of dicts of the form
{'expr': E, 'info': I, 'doc': D}
where E is of type _ExprValue, I is of type QAPISourceInfo, and D is
of type QAPIDoc. Key 'doc' is optional. This is not a _JSONObject!
Passes type checking anyway, because _JSONObject is Dict[str, object].
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20230215000011.1725012-5-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message amended to point out the typing fix]
The fix for this comment is forthcoming in a future commit, but this
will keep me honest. The linting configuration in ./python/setup.cfg
prohibits 'FIXME' comments. A goal of this long-running series is to
move ./scripts/qapi to ./python/qemu/qapi so that the QAPI generator is
regularly type-checked by GitLab CI.
This comment is a time-bomb to force me to address this issue prior to
that step.
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210930205716.1148693-11-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Adding static types causes a cycle in the QAPI generator:
[schema -> expr -> parser -> schema]. It exists because the QAPIDoc
class needs the names of types defined by the schema module, but the
schema module needs to import both expr.py/parser.py to do its actual
parsing.
Ultimately, the layering violation is that parser.py should not have any
knowledge of specifics of the Schema. QAPIDoc performs double-duty here
both as a parser *and* as a finalized object that is part of the schema.
In this patch, add the offending type hints alongside the workaround to
avoid the cycle becoming a problem at runtime. See
https://mypy.readthedocs.io/en/latest/runtime_troubles.html#import-cycles
for more information on this workaround technique.
I see three ultimate resolutions here:
(1) Just keep this patch and use the TYPE_CHECKING trick to eliminate
the cycle which is only present during static analysis.
(2) Don't bother to annotate connect_member() et al, give them 'object'
or 'Any'. I don't particularly like this, because it diminishes the
usefulness of type hints for documentation purposes. Still, it's an
extremely quick fix.
(3) Reimplement doc <--> definition correlation directly in schema.py,
integrating doc fields directly into QAPISchemaMember and relieving
the QAPIDoc class of the responsibility. Users of the information
would instead visit the members first and retrieve their
documentation instead of the inverse operation -- visiting the
documentation and retrieving their members.
My preference is (3), but in the short-term (1) is the easiest way to
have my cake (strong type hints) and eat it too (Not have import
cycles). Do (1) for now, but plan for (3).
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210930205716.1148693-9-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Here's the weird bit. QAPIDoc generally expects -- virtually everywhere
-- that it will always have a current section. The sole exception to
this is in the case that end_comment() is called, which leaves us with
*no* section. However, in this case, we also don't expect to actually
ever mutate the comment contents ever again.
NullSection is just a Null-object that allows us to maintain the
invariant that we *always* have a current section, enforced by static
typing -- allowing us to type that field as QAPIDoc.Section instead of
the more ambiguous Optional[QAPIDoc.Section].
end_section is renamed to switch_section and now accepts as an argument
the new section to activate, clarifying that no callers ever just
unilaterally end a section; they only do so when starting a new section.
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210930205716.1148693-8-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
The "if self._section" clause in end_section is mysterious: In which
circumstances might we end a section when we don't have one?
QAPIDoc always expects there to be a "current section", only except
after a call to end_comment(). This actually *shouldn't* ever be 'None',
so let's remove that logic so I don't wonder why it's like this again in
three months.
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210930205716.1148693-7-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
True, we do not check the validity of this symbol -- but we don't check
the validity of definition names during parse, either -- that happens
later, during the expr check. I don't want to introduce a dependency on
expr.py:check_name_str here and introduce a cycle.
Instead, rest assured that a documentation block is required for each
definition. This requirement uses the names of each section to ensure
that we fulfilled this requirement.
e.g., let's say that block-core.json has a comment block for
"Snapshot!Info" by accident. We'll see this error message:
In file included from ../../qapi/block.json:8:
../../qapi/block-core.json: In struct 'SnapshotInfo':
../../qapi/block-core.json:38: documentation comment is for 'Snapshot!Info'
That's a pretty decent error message.
Now, let's say that we actually mangle it twice, identically:
../../qapi/block-core.json: In struct 'Snapshot!Info':
../../qapi/block-core.json:38: struct has an invalid name
That's also pretty decent. If we forget to fix it in both places, we'll
just be back to the first error.
Therefore, let's just drop this FIXME and adjust the error message to
not imply a more thorough check than is actually performed.
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210930205716.1148693-6-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Pylint informs us we're not using these arguments. Oops, it's
right. Correct the error message and remove the remaining unused
parameter.
Fix test output now that the error message is improved.
Fixes: e151941d1b
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210930205716.1148693-4-jsnow@redhat.com>
[Commit message formatting tweaked]
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
TypeGuards wont exist in Python proper until 3.10. Ah well. We can hack
up our own by declaring this function to return the type we claim it
checks for and using this to safely downcast object -> List[str].
In so doing, I bring this function under _pragma so it can use the
'info' object in its closure. Having done this, _pragma also now no
longer needs to take a 'self' parameter, so drop it.
To help with line-length, and with the context evident from its new
scope, rename the function to the shorter check_list_str().
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210519183951.3946870-12-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
When the token can be None (EOF), we can't use 'x in "abc"' style
membership tests to group types of tokens together, because 'None in
"abc"' is a TypeError.
Easy enough to fix. (Use a tuple: It's neither a static typing error nor
a runtime error to check for None in Tuple[str, ...])
Add tests to prevent a regression. (Note: they cannot be added prior to
this fix, as the unhandled stack trace will not match test output in the
CI system.)
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210519183951.3946870-11-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
