| Message ID | 20210422030720.3685766-7-jsnow@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | qapi: static typing conversion, pt5a | expand |
John Snow <jsnow@redhat.com> writes: > get_expr can return many things, depending on where it is used. In the > outer parsing loop, we expect and require it to return a dict. > > (It's (maybe) a bit involved to teach mypy that when nested is False, > this is already always True. I'll look into it later, maybe.) > > Signed-off-by: John Snow <jsnow@redhat.com> > --- > scripts/qapi/parser.py | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py > index c75434e75a5..6b443b1247e 100644 > --- a/scripts/qapi/parser.py > +++ b/scripts/qapi/parser.py > @@ -78,6 +78,8 @@ def _parse(self): > continue > > expr = self.get_expr(False) > + assert isinstance(expr, dict) # Guaranteed when nested=False > + > if 'include' in expr: > self.reject_expr_doc(cur_doc) > if len(expr) != 1: > @@ -278,6 +280,7 @@ def get_values(self): > self.accept() > > def get_expr(self, nested): > + # TODO: Teach mypy that nested=False means the retval is a Dict. > if self.tok != '{' and not nested: > raise QAPIParseError(self, "expected '{'") > if self.tok == '{': The better place to assert a post condition would be ... self.accept() expr = self.get_members() elif self.tok == '[': self.accept() expr = self.get_values() elif self.tok in "'tf": expr = self.val self.accept() else: raise QAPIParseError( self, "expected '{', '[', string, or boolean") ... here. return expr But then it may not help mypy over the hump, which is the whole point of the patch. Alternative ways to skin this cat: * Split get_object() off get_expr(). diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py index ca5e8e18e0..c79b3c7d08 100644 --- a/scripts/qapi/parser.py +++ b/scripts/qapi/parser.py @@ -262,9 +262,12 @@ def get_values(self): raise QAPIParseError(self, "expected ',' or ']'") self.accept() - def get_expr(self, nested): - if self.tok != '{' and not nested: + def get_object(self): + if self.tok != '{': raise QAPIParseError(self, "expected '{'") + return self.get_expr() + + def get_expr(self): if self.tok == '{': self.accept() expr = self.get_members() * Shift "top-level expression must be dict" up: diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py index ca5e8e18e0..ee8cbf3531 100644 --- a/scripts/qapi/parser.py +++ b/scripts/qapi/parser.py @@ -68,7 +68,10 @@ def __init__(self, fname, previously_included=None, incl_info=None): self.docs.append(cur_doc) continue - expr = self.get_expr(False) + expr = self.get_expr() + if not isinstance(expr, OrderedDict): + raise QAPISemError( + info, "top-level expression must be an object") if 'include' in expr: self.reject_expr_doc(cur_doc) if len(expr) != 1: @@ -262,9 +265,7 @@ def get_values(self): raise QAPIParseError(self, "expected ',' or ']'") self.accept() - def get_expr(self, nested): - if self.tok != '{' and not nested: - raise QAPIParseError(self, "expected '{'") + def get_expr(self): if self.tok == '{': self.accept() expr = self.get_members() * Shift it further, into expr.py: diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py index 496f7e0333..0a83c493a0 100644 --- a/scripts/qapi/expr.py +++ b/scripts/qapi/expr.py @@ -600,7 +600,10 @@ def check_exprs(exprs: List[_JSONObject]) -> List[_JSONObject]: """ for expr_elem in exprs: # Expression - assert isinstance(expr_elem['expr'], dict) + if not isinstance(expr_elem['expr'], dict): + raise QAPISemError( + info, "top-level expression must be an object") + for key in expr_elem['expr'].keys(): assert isinstance(key, str) expr: _JSONObject = expr_elem['expr'] Shifting it up would be closer to qapi-code-gen.txt than what we have now. All observations, no demands.
On 4/25/21 3:23 AM, Markus Armbruster wrote: > John Snow <jsnow@redhat.com> writes: > >> get_expr can return many things, depending on where it is used. In the >> outer parsing loop, we expect and require it to return a dict. >> >> (It's (maybe) a bit involved to teach mypy that when nested is False, >> this is already always True. I'll look into it later, maybe.) >> >> Signed-off-by: John Snow <jsnow@redhat.com> >> --- >> scripts/qapi/parser.py | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py >> index c75434e75a5..6b443b1247e 100644 >> --- a/scripts/qapi/parser.py >> +++ b/scripts/qapi/parser.py >> @@ -78,6 +78,8 @@ def _parse(self): >> continue >> >> expr = self.get_expr(False) >> + assert isinstance(expr, dict) # Guaranteed when nested=False >> + >> if 'include' in expr: >> self.reject_expr_doc(cur_doc) >> if len(expr) != 1: >> @@ -278,6 +280,7 @@ def get_values(self): >> self.accept() >> >> def get_expr(self, nested): >> + # TODO: Teach mypy that nested=False means the retval is a Dict. >> if self.tok != '{' and not nested: >> raise QAPIParseError(self, "expected '{'") >> if self.tok == '{': > > The better place to assert a post condition would be ... > > self.accept() > expr = self.get_members() > elif self.tok == '[': > self.accept() > expr = self.get_values() > elif self.tok in "'tf": > expr = self.val > self.accept() > else: > raise QAPIParseError( > self, "expected '{', '[', string, or boolean") > > ... here. > > return expr > > But then it may not help mypy over the hump, which is the whole point of > the patch. > Right, the problem is that 'expr' here actually doesn't have to be a Dict. It can be a List, str, or bool too. The type narrowing occurs only when you pass nested=False. > Alternative ways to skin this cat: > > * Split get_object() off get_expr(). > > diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py > index ca5e8e18e0..c79b3c7d08 100644 > --- a/scripts/qapi/parser.py > +++ b/scripts/qapi/parser.py > @@ -262,9 +262,12 @@ def get_values(self): > raise QAPIParseError(self, "expected ',' or ']'") > self.accept() > > - def get_expr(self, nested): > - if self.tok != '{' and not nested: > + def get_object(self): > + if self.tok != '{': > raise QAPIParseError(self, "expected '{'") > + return self.get_expr() > + > + def get_expr(self): > if self.tok == '{': > self.accept() > expr = self.get_members() > That'd work well. no @overload. > * Shift "top-level expression must be dict" up: > > diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py > index ca5e8e18e0..ee8cbf3531 100644 > --- a/scripts/qapi/parser.py > +++ b/scripts/qapi/parser.py > @@ -68,7 +68,10 @@ def __init__(self, fname, previously_included=None, incl_info=None): > self.docs.append(cur_doc) > continue > > - expr = self.get_expr(False) > + expr = self.get_expr() > + if not isinstance(expr, OrderedDict): > + raise QAPISemError( > + info, "top-level expression must be an object") Also works. As a benefit (to both previous suggestions), it leaves get_expr completely generic and expresses the grammatical constraint up here in the parseloop. It leaves the JSON parsing more generic and further consolidates QAPI Schema specific stuff to this region. > if 'include' in expr: > self.reject_expr_doc(cur_doc) > if len(expr) != 1: > @@ -262,9 +265,7 @@ def get_values(self): > raise QAPIParseError(self, "expected ',' or ']'") > self.accept() > > - def get_expr(self, nested): > - if self.tok != '{' and not nested: > - raise QAPIParseError(self, "expected '{'") > + def get_expr(self): > if self.tok == '{': > self.accept() > expr = self.get_members() > > * Shift it further, into expr.py: > > diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py > index 496f7e0333..0a83c493a0 100644 > --- a/scripts/qapi/expr.py > +++ b/scripts/qapi/expr.py > @@ -600,7 +600,10 @@ def check_exprs(exprs: List[_JSONObject]) -> List[_JSONObject]: > """ > for expr_elem in exprs: > # Expression > - assert isinstance(expr_elem['expr'], dict) > + if not isinstance(expr_elem['expr'], dict): > + raise QAPISemError( > + info, "top-level expression must be an object") > + > for key in expr_elem['expr'].keys(): > assert isinstance(key, str) > expr: _JSONObject = expr_elem['expr'] > > Shifting it up would be closer to qapi-code-gen.txt than what we have > now. > This is also pretty nice, as it furthers the splitting of the JSON syntax from the abstract QAPI syntax, which is a distinct end-goal I have. A slight downside is that the type of a value now needs to follow outside of parser.py, which will warrant a type name. > All observations, no demands. >
diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py index c75434e75a5..6b443b1247e 100644 --- a/scripts/qapi/parser.py +++ b/scripts/qapi/parser.py @@ -78,6 +78,8 @@ def _parse(self): continue expr = self.get_expr(False) + assert isinstance(expr, dict) # Guaranteed when nested=False + if 'include' in expr: self.reject_expr_doc(cur_doc) if len(expr) != 1: @@ -278,6 +280,7 @@ def get_values(self): self.accept() def get_expr(self, nested): + # TODO: Teach mypy that nested=False means the retval is a Dict. if self.tok != '{' and not nested: raise QAPIParseError(self, "expected '{'") if self.tok == '{':
get_expr can return many things, depending on where it is used. In the outer parsing loop, we expect and require it to return a dict. (It's (maybe) a bit involved to teach mypy that when nested is False, this is already always True. I'll look into it later, maybe.) Signed-off-by: John Snow <jsnow@redhat.com> --- scripts/qapi/parser.py | 3 +++ 1 file changed, 3 insertions(+)