def create_present_function() -> UnitPart:
specification = FunctionSpecification(
"Present", "Boolean",
[Parameter(["Ctx"], "Context"),
Parameter(["Fld"], "Field")])
return UnitPart(
[SubprogramDeclaration(specification)],
[
ExpressionFunctionDeclaration(
specification,
AndThen(
Call("Structural_Valid", [
Indexed(Variable("Ctx.Cursors"), Variable("Fld"))
]),
Less(
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")), "First"),
Add(
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")), "Last"),
Number(1),
),
),
),
)
],
)
def create_invalid_function() -> UnitPart:
specification = FunctionSpecification(
"Invalid", "Boolean",
[Parameter(["Ctx"], "Context"),
Parameter(["Fld"], "Field")])
return UnitPart(
[SubprogramDeclaration(specification)],
[
ExpressionFunctionDeclaration(
specification,
Or(
Equal(
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")), "State"),
Variable("S_Invalid"),
),
Equal(
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")), "State"),
Variable("S_Incomplete"),
),
),
)
],
)
def field_value(field: Field, field_type: Type) -> Expr:
if isinstance(field_type, Enumeration):
if public:
return Call(
target_type, [Call("To_Base", [Call(f"Get_{field.name}", [Variable("Ctx")])])],
)
return Call(
target_type,
[
Selected(
Indexed(cursors, Variable(field.affixed_name)), f"Value.{field.name}_Value"
)
],
)
if isinstance(field_type, Scalar):
if public:
return Call(target_type, [Call(f"Get_{field.name}", [Variable("Ctx")])])
return Call(
target_type,
[
Selected(
Indexed(cursors, Variable(field.affixed_name)), f"Value.{field.name}_Value"
)
],
)
if isinstance(field_type, Composite):
return Variable(field.name)
assert False, f'unexpected type "{type(field_type).__name__}"'
return UNDEFINED
def create_composite_accessor_procedures(self, composite_fields: Sequence[Field]) -> UnitPart:
def specification(field: Field) -> ProcedureSpecification:
return ProcedureSpecification(f"Get_{field.name}", [Parameter(["Ctx"], "Context")])
return UnitPart(
[
SubprogramDeclaration(
specification(f),
[
Precondition(
And(
VALID_CONTEXT,
Call("Has_Buffer", [Name("Ctx")]),
Call("Present", [Name("Ctx"), Name(f.affixed_name)]),
)
)
],
[
FormalSubprogramDeclaration(
ProcedureSpecification(
f"Process_{f.name}", [Parameter([f.name], self.types.bytes)]
)
)
],
)
for f in composite_fields
],
[
SubprogramBody(
specification(f),
[
ObjectDeclaration(
["First"],
self.types.index,
Call(
self.types.byte_index,
[Selected(Indexed("Ctx.Cursors", Name(f.affixed_name)), "First")],
),
True,
),
ObjectDeclaration(
["Last"],
self.types.index,
Call(
self.types.byte_index,
[Selected(Indexed("Ctx.Cursors", Name(f.affixed_name)), "Last")],
),
True,
),
],
[
CallStatement(
f"Process_{f.name}",
[Slice("Ctx.Buffer.all", Name("First"), Name("Last"))],
)
],
)
for f in composite_fields
],
)
def invalid_successors_invariant() -> Expr:
return AndThen(
*[
If(
[
(
AndThen(
*[
Call(
"Invalid",
[Indexed(Variable("Cursors"), Variable(p.affixed_name))],
)
for p in message.direct_predecessors(f)
]
),
Call(
"Invalid", [Indexed(Variable("Cursors"), Variable(f.affixed_name))],
),
)
]
)
for f in message.fields
if f not in message.direct_successors(INITIAL)
]
)
def field_length(field: Field) -> Expr:
if public:
return Call("Field_Length", [Variable("Ctx"), Variable(field.affixed_name)])
return Add(
Sub(
Selected(Indexed(cursors, Variable(field.affixed_name)), "Last"),
Selected(Indexed(cursors, Variable(field.affixed_name)), "First"),
),
Number(1),
)
def create_valid_function() -> UnitPart:
specification = FunctionSpecification(
"Valid", "Boolean",
[Parameter(["Ctx"], "Context"),
Parameter(["Fld"], "Field")])
return UnitPart(
[
SubprogramDeclaration(
specification,
[
Postcondition(
If([(
Result("Valid"),
And(
Call(
"Structural_Valid",
[Variable("Ctx"),
Variable("Fld")],
),
Call("Present",
[Variable("Ctx"),
Variable("Fld")]),
),
)])),
],
)
],
[
ExpressionFunctionDeclaration(
specification,
AndThen(
Equal(
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")), "State"),
Variable("S_Valid"),
),
Less(
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")), "First"),
Add(
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")), "Last"),
Number(1),
),
),
),
)
],
)
def result(field: Field, field_type: Type) -> Expr:
value = Selected(
Indexed("Ctx.Cursors", Name(field.affixed_name)), f"Value.{field.name}_Value"
)
if isinstance(field_type, Enumeration):
return Call("Convert", [value])
return value
def create_structural_valid_function() -> UnitPart:
specification = FunctionSpecification(
"Structural_Valid",
"Boolean",
[Parameter(["Ctx"], "Context"),
Parameter(["Fld"], "Field")],
)
return UnitPart(
[SubprogramDeclaration(specification)],
[
ExpressionFunctionDeclaration(
specification,
And(
Or(*[
Equal(
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")), "State"),
Variable(s),
) for s in ("S_Valid", "S_Structural_Valid")
])),
)
],
)
def initialize_field_statements(self, message: Message, field: Field) -> Sequence[Statement]:
return [
CallStatement("Reset_Dependent_Fields", [Name("Ctx"), Name(field.affixed_name)],),
Assignment(
"Ctx",
Aggregate(
Selected("Ctx", "Buffer_First"),
Selected("Ctx", "Buffer_Last"),
Selected("Ctx", "First"),
Name("Last"),
Selected("Ctx", "Buffer"),
Selected("Ctx", "Cursors"),
),
),
# WORKAROUND:
# Limitation of GNAT Community 2019 / SPARK Pro 20.0
# Provability of predicate is increased by adding part of
# predicate as assert
PragmaStatement(
"Assert", [str(self.message_structure_invariant(message, prefix=True))],
),
Assignment(
Indexed(Selected("Ctx", "Cursors"), Name(field.affixed_name)),
NamedAggregate(
("State", Name("S_Structural_Valid")),
("First", Name("First")),
("Last", Name("Last")),
("Value", NamedAggregate(("Fld", Name(field.affixed_name))),),
(
"Predecessor",
Selected(
Indexed(Selected("Ctx", "Cursors"), Name(field.affixed_name),),
"Predecessor",
),
),
),
),
Assignment(
Indexed(
Selected("Ctx", "Cursors"),
Call("Successor", [Name("Ctx"), Name(field.affixed_name)]),
),
NamedAggregate(
("State", Name("S_Invalid")), ("Predecessor", Name(field.affixed_name)),
),
),
]
def valid_predecessors_invariant() -> Expr:
return AndThen(
*[
If(
[
(
Call(
"Structural_Valid",
[Indexed(Variable("Cursors"), Variable(f.affixed_name))],
),
Or(
*[
AndThen(
Call(
"Structural_Valid"
if l.source in composite_fields
else "Valid",
[
Indexed(
Variable("Cursors"),
Variable(l.source.affixed_name),
)
],
),
Equal(
Selected(
Indexed(
Variable("Cursors"), Variable(f.affixed_name),
),
"Predecessor",
),
Variable(l.source.affixed_name),
),
l.condition.substituted(
substitution(message, embedded=True)
),
).simplified()
for l in message.incoming(f)
]
),
)
]
)
for f in message.fields
if f not in message.direct_successors(INITIAL)
]
)
def field_value(field: Field) -> Expr:
if public:
return Call(f"Get_{field.name}", [Variable("Ctx")])
return Selected(
Indexed(
Variable("Ctx.Cursors" if not embedded else "Cursors"),
Variable(field.affixed_name),
),
f"Value.{field.name}_Value",
)
def result(field: Field) -> Expr:
return Call(
"To_Actual",
[
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable(field.affixed_name)),
f"Value.{field.name}_Value",
)
],
)
def create_incomplete_function() -> UnitPart:
specification = FunctionSpecification(
"Incomplete", "Boolean", [Parameter(["Ctx"], "Context"), Parameter(["Fld"], "Field")]
)
return UnitPart(
[SubprogramDeclaration(specification, [Precondition(VALID_CONTEXT)])],
[
ExpressionFunctionDeclaration(
specification,
Equal(
Selected(Indexed("Ctx.Cursors", Name("Fld")), "State"), Name("S_Incomplete")
),
)
],
)
def substitution(self, message: Message, prefix: bool = True) -> Mapping[Name, Expr]:
def prefixed(name: str) -> Expr:
return Selected(Name("Ctx"), name) if prefix else Name(name)
first = prefixed("First")
last = prefixed("Last")
cursors = prefixed("Cursors")
return {
**{First("Message"): first},
**{Last("Message"): last},
**{
First(f.name): Selected(Indexed(cursors, Name(f.affixed_name)), "First")
for f in message.fields
},
**{
Last(f.name): Selected(Indexed(cursors, Name(f.affixed_name)), "Last")
for f in message.fields
},
**{
Length(f.name): Add(
Sub(
Selected(Indexed(cursors, Name(f.affixed_name)), "Last"),
Selected(Indexed(cursors, Name(f.affixed_name)), "First"),
),
Number(1),
)
for f in message.fields
},
**{
Variable(f.name): Call(
self.types.bit_length,
[Selected(Indexed(cursors, Name(f.affixed_name)), f"Value.{f.name}_Value")],
)
for f, t in message.types.items()
if not isinstance(t, Enumeration)
},
**{
Variable(f.name): Call(
self.types.bit_length,
[Selected(Indexed(cursors, Name(f.affixed_name)), f"Value.{f.name}_Value")],
)
for f, t in message.types.items()
if isinstance(t, Enumeration)
},
**{
Variable(l): Call(self.types.bit_length, [Call("Convert", [Name(l)])])
for l in itertools.chain.from_iterable(
t.literals.keys() for t in message.types.values() if isinstance(t, Enumeration)
)
},
}
def create_scalar_setter_procedures(
self, message: Message, scalar_fields: Mapping[Field, Scalar]
) -> UnitPart:
def specification(field: Field, field_type: Type) -> ProcedureSpecification:
type_name = (
field_type.enum_name
if isinstance(field_type, Enumeration) and field_type.always_valid
else field_type.name
)
return ProcedureSpecification(
f"Set_{field.name}",
[
InOutParameter(["Ctx"], "Context"),
Parameter(["Val"], f"{message.package}.{type_name}"),
],
)
return UnitPart(
[
SubprogramDeclaration(
specification(f, t),
[
Precondition(
AndThen(
*self.setter_preconditions(f),
Call(
"Field_Condition",
[
Name("Ctx"),
Aggregate(
Name(f.affixed_name),
Name("Val")
if not isinstance(t, Enumeration)
else Call("Convert", [Name("Val")]),
),
],
),
Call("Valid", [Name("Val")])
if not isinstance(t, Enumeration)
else TRUE,
self.common.sufficient_space_for_field_condition(
Name(f.affixed_name)
),
)
),
Postcondition(
And(
VALID_CONTEXT,
Call("Has_Buffer", [Name("Ctx")]),
Call("Valid", [Name("Ctx"), Name(f.affixed_name)]),
Equal(
Call(f"Get_{f.name}", [Name("Ctx")]),
Aggregate(TRUE, Name("Val"))
if isinstance(t, Enumeration) and t.always_valid
else Name("Val"),
),
*self.setter_postconditions(message, f, t),
*[
Equal(
Call("Cursor", [Name("Ctx"), Name(p.affixed_name)]),
Old(Call("Cursor", [Name("Ctx"), Name(p.affixed_name)])),
)
for p in message.predecessors(f)
],
)
),
],
)
for f, t in scalar_fields.items()
],
[
SubprogramBody(
specification(f, t),
[
ObjectDeclaration(
["Field_Value"],
"Field_Dependent_Value",
Aggregate(
Name(f.affixed_name),
Name("Val")
if not isinstance(t, Enumeration)
else Call("Convert", [Name("Val")]),
),
True,
),
ObjectDeclaration(["First", "Last"], self.types.bit_index),
],
[
CallStatement(
"Reset_Dependent_Fields", [Name("Ctx"), Name(f.affixed_name)],
),
CallStatement(
"Set_Field_Value",
[Name("Ctx"), Name("Field_Value"), Name("First"), Name("Last")],
),
Assignment(
"Ctx",
Aggregate(
Selected("Ctx", "Buffer_First"),
Selected("Ctx", "Buffer_Last"),
Selected("Ctx", "First"),
Name("Last"),
Selected("Ctx", "Buffer"),
Selected("Ctx", "Cursors"),
),
),
Assignment(
Indexed(Selected("Ctx", "Cursors"), Name(f.affixed_name)),
NamedAggregate(
("State", Name("S_Valid")),
("First", Name("First")),
("Last", Name("Last")),
("Value", Name("Field_Value")),
(
"Predecessor",
Selected(
Indexed(Selected("Ctx", "Cursors"), Name(f.affixed_name)),
"Predecessor",
),
),
),
),
Assignment(
Indexed(
Selected("Ctx", "Cursors"),
Call("Successor", [Name("Ctx"), Name(f.affixed_name)]),
),
NamedAggregate(
("State", Name("S_Invalid")), ("Predecessor", Name(f.affixed_name)),
),
),
],
)
for f, t in scalar_fields.items()
],
)
def context_predicate(message: Message, composite_fields: Sequence[Field], prefix: str) -> Expr:
def valid_predecessors_invariant() -> Expr:
return AndThen(
*[
If(
[
(
Call(
"Structural_Valid",
[Indexed(Variable("Cursors"), Variable(f.affixed_name))],
),
Or(
*[
AndThen(
Call(
"Structural_Valid"
if l.source in composite_fields
else "Valid",
[
Indexed(
Variable("Cursors"),
Variable(l.source.affixed_name),
)
],
),
Equal(
Selected(
Indexed(
Variable("Cursors"), Variable(f.affixed_name),
),
"Predecessor",
),
Variable(l.source.affixed_name),
),
l.condition.substituted(
substitution(message, embedded=True)
),
).simplified()
for l in message.incoming(f)
]
),
)
]
)
for f in message.fields
if f not in message.direct_successors(INITIAL)
]
)
def invalid_successors_invariant() -> Expr:
return AndThen(
*[
If(
[
(
AndThen(
*[
Call(
"Invalid",
[Indexed(Variable("Cursors"), Variable(p.affixed_name))],
)
for p in message.direct_predecessors(f)
]
),
Call(
"Invalid", [Indexed(Variable("Cursors"), Variable(f.affixed_name))],
),
)
]
)
for f in message.fields
if f not in message.direct_successors(INITIAL)
]
)
return AndThen(
If(
[
(
NotEqual(Variable("Buffer"), Variable("null")),
And(
Equal(First("Buffer"), Variable("Buffer_First")),
Equal(Last("Buffer"), Variable("Buffer_Last")),
),
)
]
),
public_context_predicate(),
ForAllIn(
"F",
ValueRange(First("Field"), Last("Field")),
If(
[
(
Call("Structural_Valid", [Indexed(Variable("Cursors"), Variable("F"))]),
And(
GreaterEqual(
Selected(Indexed(Variable("Cursors"), Variable("F")), "First"),
Variable("First"),
),
LessEqual(
Selected(Indexed(Variable("Cursors"), Variable("F")), "Last"),
Variable("Last"),
),
LessEqual(
Selected(Indexed(Variable("Cursors"), Variable("F")), "First"),
Add(
Selected(Indexed(Variable("Cursors"), Variable("F")), "Last"),
Number(1),
),
),
Equal(
Selected(
Selected(Indexed(Variable("Cursors"), Variable("F")), "Value"),
"Fld",
),
Variable("F"),
),
),
)
]
),
),
valid_predecessors_invariant(),
invalid_successors_invariant(),
message_structure_invariant(message, prefix, embedded=True),
)
def message_structure_invariant(
message: Message, prefix: str, link: Link = None, embedded: bool = False
) -> Expr:
def prefixed(name: str) -> Expr:
return Selected(Variable("Ctx"), name) if not embedded else Variable(name)
if not link:
return message_structure_invariant(message, prefix, message.outgoing(INITIAL)[0], embedded)
source = link.source
target = link.target
if target is FINAL:
return TRUE
field_type = message.types[target]
condition = link.condition.substituted(substitution(message, embedded)).simplified()
length = (
Size(prefix * full_base_type_name(field_type))
if isinstance(field_type, Scalar)
else link.length.substituted(
substitution(message, embedded, target_type=const.TYPES_BIT_LENGTH)
).simplified()
)
first = (
prefixed("First")
if source == INITIAL
else link.first.substituted(substitution(message, embedded))
.substituted(
mapping={
UNDEFINED: Add(
Selected(Indexed(prefixed("Cursors"), Variable(source.affixed_name)), "Last"),
Number(1),
)
}
)
.simplified()
)
return If(
[
(
AndThen(
Call(
"Structural_Valid",
[Indexed(prefixed("Cursors"), Variable(target.affixed_name))],
),
condition,
),
AndThen(
Equal(
Add(
Sub(
Selected(
Indexed(prefixed("Cursors"), Variable(target.affixed_name)),
"Last",
),
Selected(
Indexed(prefixed("Cursors"), Variable(target.affixed_name)),
"First",
),
),
Number(1),
),
length,
),
Equal(
Selected(
Indexed(prefixed("Cursors"), Variable(target.affixed_name)),
"Predecessor",
),
Variable(source.affixed_name),
),
Equal(
Selected(
Indexed(prefixed("Cursors"), Variable(target.affixed_name)), "First"
),
first,
),
*[
message_structure_invariant(message, prefix, l, embedded)
for l in message.outgoing(target)
],
),
)
]
).simplified()
def create_scalar_setter_procedures(
self, message: Message,
scalar_fields: Mapping[Field, Scalar]) -> UnitPart:
def specification(field: Field,
field_type: Type) -> ProcedureSpecification:
if field_type.package == BUILTINS_PACKAGE:
type_name = ID(field_type.name)
elif isinstance(field_type,
Enumeration) and field_type.always_valid:
type_name = common.prefixed_type_name(
common.full_enum_name(field_type), self.prefix)
else:
type_name = common.prefixed_type_name(field_type.identifier,
self.prefix)
return ProcedureSpecification(
f"Set_{field.name}",
[
InOutParameter(["Ctx"], "Context"),
Parameter(["Val"], type_name)
],
)
return UnitPart(
[
SubprogramDeclaration(
specification(f, t),
[
Precondition(
AndThen(
*self.setter_preconditions(f),
Call(
"Field_Condition",
[
Variable("Ctx"),
Aggregate(
Variable(f.affixed_name),
Call("To_Base", [Variable("Val")]),
),
],
),
Call("Valid",
[Call("To_Base", [Variable("Val")])])
if not isinstance(t, Enumeration) else TRUE,
common.sufficient_space_for_field_condition(
Variable(f.affixed_name)),
)),
Postcondition(
And(
Call("Has_Buffer", [Variable("Ctx")]),
Call("Valid", [
Variable("Ctx"),
Variable(f.affixed_name)
]),
Equal(
Call(f"Get_{f.name}", [Variable("Ctx")]),
Aggregate(TRUE, Variable("Val"))
if isinstance(t, Enumeration)
and t.always_valid else Variable("Val"),
),
*self.setter_postconditions(message, f),
*[
Equal(
Call(
"Context_Cursor",
[
Variable("Ctx"),
Variable(p.affixed_name)
],
),
Old(
Call(
"Context_Cursor",
[
Variable("Ctx"),
Variable(p.affixed_name)
],
)),
) for p in message.predecessors(f)
],
)),
],
) for f, t in scalar_fields.items()
],
[
SubprogramBody(
specification(f, t),
[
ObjectDeclaration(
["Field_Value"],
"Field_Dependent_Value",
Aggregate(
Variable(f.affixed_name),
Call("To_Base", [Variable("Val")]),
),
True,
),
ObjectDeclaration(["First", "Last"],
const.TYPES_BIT_INDEX),
],
[
CallStatement(
"Reset_Dependent_Fields",
[Variable("Ctx"),
Variable(f.affixed_name)],
),
CallStatement(
"Set_Field_Value",
[
Variable("Ctx"),
Variable("Field_Value"),
Variable("First"),
Variable("Last"),
],
),
Assignment(
"Ctx",
Aggregate(
Variable("Ctx.Buffer_First"),
Variable("Ctx.Buffer_Last"),
Variable("Ctx.First"),
Variable("Last"),
Variable("Ctx.Buffer"),
Variable("Ctx.Cursors"),
),
),
Assignment(
Indexed(Variable("Ctx.Cursors"),
Variable(f.affixed_name)),
NamedAggregate(
("State", Variable("S_Valid")),
("First", Variable("First")),
("Last", Variable("Last")),
("Value", Variable("Field_Value")),
(
"Predecessor",
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable(f.affixed_name)),
"Predecessor",
),
),
),
),
Assignment(
Indexed(
Variable("Ctx.Cursors"),
Call("Successor", [
Variable("Ctx"),
Variable(f.affixed_name)
]),
),
NamedAggregate(
("State", Variable("S_Invalid")),
("Predecessor", Variable(f.affixed_name)),
),
),
],
) for f, t in scalar_fields.items()
],
)
def create_composite_setter_empty_procedures(self,
message: Message) -> UnitPart:
def specification(field: Field) -> ProcedureSpecification:
return ProcedureSpecification(f"Set_{field.name}_Empty",
[InOutParameter(["Ctx"], "Context")])
return UnitPart(
[
*[
SubprogramDeclaration(
specification(f),
[
Precondition(
AndThen(
*self.setter_preconditions(f),
*self.
unbounded_composite_setter_preconditions(
message, f),
Equal(
Call(
"Field_Length",
[
Variable("Ctx"),
Variable(f.affixed_name)
],
),
Number(0),
),
)),
Postcondition(
And(*self.composite_setter_postconditions(
message, f))),
],
) for f, t in message.types.items()
if message.is_possibly_empty(f)
],
],
[
SubprogramBody(
specification(f),
[
ObjectDeclaration(
["First"],
const.TYPES_BIT_INDEX,
Call("Field_First",
[Variable("Ctx"),
Variable(f.affixed_name)]),
True,
),
ObjectDeclaration(
["Last"],
const.TYPES_BIT_INDEX,
Call("Field_Last",
[Variable("Ctx"),
Variable(f.affixed_name)]),
True,
),
],
[
CallStatement(
"Reset_Dependent_Fields",
[Variable("Ctx"),
Variable(f.affixed_name)],
),
Assignment(
"Ctx",
Aggregate(
Variable("Ctx.Buffer_First"),
Variable("Ctx.Buffer_Last"),
Variable("Ctx.First"),
Variable("Last"),
Variable("Ctx.Buffer"),
Variable("Ctx.Cursors"),
),
),
Assignment(
Indexed(Variable("Ctx.Cursors"),
Variable(f.affixed_name)),
NamedAggregate(
("State", Variable("S_Valid")),
("First", Variable("First")),
("Last", Variable("Last")),
("Value",
NamedAggregate(
("Fld", Variable(f.affixed_name)))),
(
"Predecessor",
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable(f.affixed_name)),
"Predecessor",
),
),
),
),
Assignment(
Indexed(
Variable("Ctx.Cursors"),
Call("Successor", [
Variable("Ctx"),
Variable(f.affixed_name)
]),
),
NamedAggregate(
("State", Variable("S_Invalid")),
("Predecessor", Variable(f.affixed_name)),
),
),
],
) for f, t in message.types.items()
if message.is_possibly_empty(f)
],
)
def field_last(field: Field) -> Expr:
if public:
return Call("Field_Last", [Variable("Ctx"), Variable(field.affixed_name)])
return Selected(Indexed(cursors, Variable(field.affixed_name)), "Last")
def create_internal_functions(
self, message: Message,
scalar_fields: Mapping[Field, Scalar]) -> UnitPart:
return UnitPart(
[],
[
SubprogramBody(
ProcedureSpecification(
"Set_Field_Value",
[
InOutParameter(["Ctx"], "Context"),
Parameter(["Val"], "Field_Dependent_Value"),
OutParameter(["Fst", "Lst"],
const.TYPES_BIT_INDEX),
],
),
[
*common.field_bit_location_declarations(
Variable("Val.Fld")),
*common.field_byte_location_declarations(),
*unique(
self.insert_function(common.full_base_type_name(t))
for t in message.types.values()
if isinstance(t, Scalar)),
],
[
Assignment("Fst", Variable("First")),
Assignment("Lst", Variable("Last")),
CaseStatement(
Variable("Val.Fld"),
[(
Variable(f.affixed_name),
[
CallStatement(
"Insert",
[
Variable(f"Val.{f.name}_Value"),
Slice(
Variable("Ctx.Buffer.all"),
Variable("Buffer_First"),
Variable("Buffer_Last"),
),
Variable("Offset"),
],
)
if f in scalar_fields else NullStatement()
],
) for f in message.all_fields],
),
],
[
Precondition(
AndThen(
Not(Constrained("Ctx")),
Call("Has_Buffer", [Variable("Ctx")]),
In(Variable("Val.Fld"), Range("Field")),
Call("Valid_Next",
[Variable("Ctx"),
Variable("Val.Fld")]),
common.sufficient_space_for_field_condition(
Variable("Val.Fld")),
ForAllIn(
"F",
Range("Field"),
If([(
Call(
"Structural_Valid",
[
Indexed(
Variable("Ctx.Cursors"),
Variable("F"),
)
],
),
LessEqual(
Selected(
Indexed(
Variable("Ctx.Cursors"),
Variable("F"),
),
"Last",
),
Call(
"Field_Last",
[
Variable("Ctx"),
Variable("Val.Fld")
],
),
),
)]),
),
)),
Postcondition(
And(
Call("Has_Buffer", [Variable("Ctx")]),
Equal(
Variable("Fst"),
Call(
"Field_First",
[Variable("Ctx"),
Variable("Val.Fld")]),
),
Equal(
Variable("Lst"),
Call(
"Field_Last",
[Variable("Ctx"),
Variable("Val.Fld")]),
),
GreaterEqual(Variable("Fst"),
Variable("Ctx.First")),
LessEqual(Variable("Fst"),
Add(Variable("Lst"), Number(1))),
LessEqual(
Call(const.TYPES_BYTE_INDEX,
[Variable("Lst")]),
Variable("Ctx.Buffer_Last"),
),
ForAllIn(
"F",
Range("Field"),
If([(
Call(
"Structural_Valid",
[
Indexed(
Variable("Ctx.Cursors"),
Variable("F"),
)
],
),
LessEqual(
Selected(
Indexed(
Variable("Ctx.Cursors"),
Variable("F"),
),
"Last",
),
Variable("Lst"),
),
)]),
),
*[
Equal(e, Old(e)) for e in [
Variable("Ctx.Buffer_First"),
Variable("Ctx.Buffer_Last"),
Variable("Ctx.First"),
Variable("Ctx.Cursors"),
]
],
)),
],
)
] if scalar_fields else [],
)
def create_verify_procedure(self, message: Message,
context_invariant: Sequence[Expr]) -> UnitPart:
specification = ProcedureSpecification(
"Verify",
[InOutParameter(["Ctx"], "Context"),
Parameter(["Fld"], "Field")])
valid_field_condition = And(
Call(
"Valid_Value",
[Variable("Value")],
),
Call(
"Field_Condition",
[
Variable("Ctx"),
Variable("Value"),
*([
Call(
"Field_Length",
[Variable("Ctx"), Variable("Fld")])
] if common.length_dependent_condition(message) else []),
],
),
)
set_cursors_statements = [
IfStatement(
[(
Call("Composite_Field", [Variable("Fld")]),
[
Assignment(
Indexed(Variable("Ctx.Cursors"), Variable("Fld")),
NamedAggregate(
("State", Variable("S_Structural_Valid")),
(
"First",
Call("Field_First",
[Variable("Ctx"),
Variable("Fld")]),
),
(
"Last",
Call("Field_Last",
[Variable("Ctx"),
Variable("Fld")]),
),
("Value", Variable("Value")),
(
"Predecessor",
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")),
"Predecessor",
),
),
),
)
],
)],
[
Assignment(
Indexed(Variable("Ctx.Cursors"), Variable("Fld")),
NamedAggregate(
("State", Variable("S_Valid")),
("First",
Call("Field_First",
[Variable("Ctx"),
Variable("Fld")])),
("Last",
Call("Field_Last",
[Variable("Ctx"),
Variable("Fld")])),
("Value", Variable("Value")),
(
"Predecessor",
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")), "Predecessor"),
),
),
)
],
),
# WORKAROUND:
# Limitation of GNAT Community 2019 / SPARK Pro 20.0
# Provability of predicate is increased by adding part of
# predicate as assert
PragmaStatement("Assert", [
str(common.message_structure_invariant(message, self.prefix))
]),
# WORKAROUND:
# Limitation of GNAT Community 2019 / SPARK Pro 20.0
# Provability of predicate is increased by splitting
# assignment in multiple statements
IfStatement([(
Equal(Variable("Fld"), Variable(f.affixed_name)),
[
Assignment(
Indexed(
Variable("Ctx.Cursors"),
Call("Successor",
[Variable("Ctx"),
Variable("Fld")]),
),
NamedAggregate(
("State", Variable("S_Invalid")),
("Predecessor", Variable("Fld")),
),
)
],
) for f in message.fields]),
]
return UnitPart(
[
SubprogramDeclaration(
specification,
[
Postcondition(
And(
Equal(
Call("Has_Buffer", [Variable("Ctx")]),
Old(Call("Has_Buffer", [Variable("Ctx")])),
),
*context_invariant,
)),
],
)
],
[
SubprogramBody(
specification,
[ObjectDeclaration(["Value"], "Field_Dependent_Value")],
[
IfStatement([(
AndThen(
Call("Has_Buffer", [Variable("Ctx")]),
Call(
"Invalid",
[
Indexed(Variable("Ctx.Cursors"),
Variable("Fld"))
],
),
Call("Valid_Predecessor",
[Variable("Ctx"),
Variable("Fld")]),
Call("Path_Condition",
[Variable("Ctx"),
Variable("Fld")]),
),
[
IfStatement(
[(
Call(
"Sufficient_Buffer_Length",
[Variable("Ctx"),
Variable("Fld")],
),
[
Assignment(
"Value",
Call(
"Get_Field_Value",
[
Variable("Ctx"),
Variable("Fld")
],
),
),
IfStatement(
[(
valid_field_condition,
set_cursors_statements,
)],
[
Assignment(
Indexed(
Variable(
"Ctx.Cursors"),
Variable("Fld"),
),
NamedAggregate(
(
"State",
Variable(
"S_Invalid"
),
),
(
"Predecessor",
Variable(
FINAL.
affixed_name
),
),
),
)
],
),
],
)],
[
Assignment(
Indexed(Variable("Ctx.Cursors"),
Variable("Fld")),
NamedAggregate(
("State",
Variable("S_Incomplete")),
(
"Predecessor",
Variable(
FINAL.affixed_name),
),
),
)
],
)
],
)], )
],
)
],
)
def context_predicate(self, message: Message, composite_fields: Sequence[Field]) -> Expr:
def valid_predecessors_invariant() -> Expr:
return AndThen(
*[
If(
[
(
Call(
"Structural_Valid", [Indexed("Cursors", Name(f.affixed_name))]
),
Or(
*[
AndThen(
Call(
"Structural_Valid"
if l.source in composite_fields
else "Valid",
[Indexed("Cursors", Name(l.source.affixed_name))],
),
Equal(
Selected(
Indexed("Cursors", Name(f.affixed_name)),
"Predecessor",
),
Name(l.source.affixed_name),
),
l.condition,
).simplified(self.substitution(message, False))
for l in message.incoming(f)
]
),
)
]
)
for f in message.fields
if f not in message.direct_successors(INITIAL)
]
)
def invalid_successors_invariant() -> Expr:
return AndThen(
*[
If(
[
(
AndThen(
*[
Call("Invalid", [Indexed("Cursors", Name(p.affixed_name))])
for p in message.direct_predecessors(f)
]
),
Call("Invalid", [Indexed("Cursors", Name(f.affixed_name))]),
)
]
)
for f in message.fields
if f not in message.direct_successors(INITIAL)
]
)
return AndThen(
If(
[
(
NotEqual(Name(Name("Buffer")), NULL),
And(
Equal(First(Name("Buffer")), Name(Name("Buffer_First"))),
Equal(Last(Name("Buffer")), Name(Name("Buffer_Last"))),
),
)
]
),
GreaterEqual(
Call(self.types.byte_index, [Name(Name("First"))]), Name(Name("Buffer_First"))
),
LessEqual(Call(self.types.byte_index, [Name(Name("Last"))]), Name(Name("Buffer_Last"))),
LessEqual(Name(Name("First")), Name(Name("Last"))),
LessEqual(Name(Name("Last")), Div(Last(self.types.bit_index), Number(2))),
ForAllIn(
"F",
ValueRange(First("Field"), Last("Field")),
If(
[
(
Call("Structural_Valid", [Indexed(Name("Cursors"), Name("F"))]),
And(
GreaterEqual(
Selected(Indexed(Name("Cursors"), Name("F")), "First"),
Name(Name("First")),
),
LessEqual(
Selected(Indexed(Name("Cursors"), Name("F")), "Last"),
Name(Name("Last")),
),
LessEqual(
Selected(Indexed(Name("Cursors"), Name("F")), "First"),
Add(
Selected(Indexed(Name("Cursors"), Name("F")), "Last"),
Number(1),
),
),
Equal(
Selected(
Selected(Indexed(Name("Cursors"), Name("F")), "Value"),
"Fld",
),
Name("F"),
),
),
)
]
),
),
valid_predecessors_invariant(),
invalid_successors_invariant(),
self.message_structure_invariant(message, prefix=False),
)
def message_structure_invariant(
self, message: Message, link: Link = None, prefix: bool = True
) -> Expr:
def prefixed(name: str) -> Expr:
return Selected(Name("Ctx"), name) if prefix else Name(name)
if not link:
return self.message_structure_invariant(message, message.outgoing(INITIAL)[0], prefix)
source = link.source
target = link.target
if target is FINAL:
return TRUE
field_type = message.types[target]
condition = link.condition.simplified(self.substitution(message, prefix))
length = (
Size(base_type_name(field_type))
if isinstance(field_type, Scalar)
else link.length.simplified(self.substitution(message, prefix))
)
first = (
Name(prefixed("First"))
if source == INITIAL
else link.first.simplified(
{
**self.substitution(message, prefix),
**{
UNDEFINED: Add(
Selected(
Indexed(prefixed("Cursors"), Name(source.affixed_name)), "Last"
),
Number(1),
)
},
}
)
)
return If(
[
(
AndThen(
Call(
"Structural_Valid",
[Indexed(prefixed("Cursors"), Name(target.affixed_name))],
),
condition,
),
AndThen(
Equal(
Add(
Sub(
Selected(
Indexed(prefixed("Cursors"), Name(target.affixed_name)),
"Last",
),
Selected(
Indexed(prefixed("Cursors"), Name(target.affixed_name)),
"First",
),
),
Number(1),
),
length,
),
Equal(
Selected(
Indexed(prefixed("Cursors"), Name(target.affixed_name)),
"Predecessor",
),
Name(source.affixed_name),
),
Equal(
Selected(
Indexed(prefixed("Cursors"), Name(target.affixed_name)), "First"
),
first,
),
*[
self.message_structure_invariant(message, l, prefix)
for l in message.outgoing(target)
],
),
)
]
).simplified()
def create_composite_accessor_procedures(
composite_fields: Sequence[Field]) -> UnitPart:
def specification(field: Field) -> ProcedureSpecification:
return ProcedureSpecification(f"Get_{field.name}",
[Parameter(["Ctx"], "Context")])
return UnitPart(
[
SubprogramDeclaration(
specification(f),
[
Precondition(
And(
Call("Has_Buffer", [Variable("Ctx")]),
Call("Present", [
Variable("Ctx"),
Variable(f.affixed_name)
]),
))
],
[
FormalSubprogramDeclaration(
ProcedureSpecification(
f"Process_{f.name}",
[Parameter([f.name], const.TYPES_BYTES)]))
],
) for f in composite_fields
],
[
SubprogramBody(
specification(f),
[
ObjectDeclaration(
["First"],
const.TYPES_INDEX,
Call(
const.TYPES_BYTE_INDEX,
[
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable(f.affixed_name)),
"First",
)
],
),
True,
),
ObjectDeclaration(
["Last"],
const.TYPES_INDEX,
Call(
const.TYPES_BYTE_INDEX,
[
Selected(
Indexed(Variable("Ctx.Cursors"),
Variable(f.affixed_name)),
"Last",
)
],
),
True,
),
],
[
CallStatement(
f"Process_{f.name}",
[
Slice(Variable("Ctx.Buffer.all"),
Variable("First"), Variable("Last"))
],
)
],
) for f in composite_fields
],
)
def func(expression: Expr) -> Expr:
def byte_aggregate(aggregate: Aggregate) -> Aggregate:
return Aggregate(*[Val(const.TYPES_BYTE, e) for e in aggregate.elements])
if isinstance(expression, Name) and expression in facts:
return facts[expression]
if isinstance(expression, (Equal, NotEqual)):
field = None
aggregate = None
if isinstance(expression.left, Variable) and isinstance(expression.right, Aggregate):
field = Field(expression.left.name)
aggregate = byte_aggregate(expression.right)
elif isinstance(expression.left, Aggregate) and isinstance(expression.right, Variable):
field = Field(expression.right.name)
aggregate = byte_aggregate(expression.left)
if field and aggregate:
assert field in message.fields
if embedded:
return Equal(
Indexed(
Variable("Buffer.all"),
ValueRange(
Call(
const.TYPES_BYTE_INDEX,
[
Selected(
Indexed(
Variable("Cursors"), Variable(field.affixed_name),
),
"First",
)
],
),
Call(
const.TYPES_BYTE_INDEX,
[
Selected(
Indexed(
Variable("Cursors"), Variable(field.affixed_name),
),
"Last",
)
],
),
),
),
aggregate,
)
equal_call = Call(
"Equal", [Variable("Ctx"), Variable(field.affixed_name), aggregate]
)
return equal_call if isinstance(expression, Equal) else Not(equal_call)
def field_value(field: Field) -> Expr:
if public:
return Call(f"Get_{field.name}", [Variable("Ctx")])
return Selected(
Indexed(
Variable("Ctx.Cursors" if not embedded else "Cursors"),
Variable(field.affixed_name),
),
f"Value.{field.name}_Value",
)
if isinstance(expression, Relation):
if (
isinstance(expression.left, Variable)
and Field(expression.left.name) in message.fields
and isinstance(expression.right, Number)
):
return expression.__class__(
field_value(Field(expression.left.name)), expression.right
)
if (
isinstance(expression.right, Variable)
and Field(expression.right.name) in message.fields
and isinstance(expression.left, Number)
):
return expression.__class__(
expression.left, field_value(Field(expression.right.name))
)
return expression
def create_internal_functions(
self, message: Message, scalar_fields: Mapping[Field, Scalar]
) -> UnitPart:
return UnitPart(
[],
[
SubprogramBody(
ProcedureSpecification(
"Set_Field_Value",
[
InOutParameter(["Ctx"], "Context"),
Parameter(["Val"], "Field_Dependent_Value"),
OutParameter(["Fst", "Lst"], self.types.bit_index),
],
),
[
*self.common.field_bit_location_declarations(Selected("Val", "Fld")),
*self.common.field_byte_location_declarations(),
],
[
Assignment("Fst", Name("First")),
Assignment("Lst", Name("Last")),
CaseStatement(
Selected("Val", "Fld"),
[
(
Name(f.affixed_name),
[
CallStatement(
"Insert",
[
Selected("Val", f"{f.name}_Value"),
Slice(
Selected(Selected("Ctx", "Buffer"), "all"),
Name("Buffer_First"),
Name("Buffer_Last"),
),
Name("Offset"),
],
)
if f in scalar_fields
else NullStatement()
],
)
for f in message.all_fields
],
),
],
[
Precondition(
AndThen(
Not(Constrained("Ctx")),
Call("Has_Buffer", [Name("Ctx")]),
In(Selected("Val", "Fld"), Range("Field")),
Call("Valid_Next", [Name("Ctx"), Selected("Val", "Fld")]),
self.common.sufficient_space_for_field_condition(
Selected("Val", "Fld")
),
ForAllIn(
"F",
Range("Field"),
If(
[
(
Call(
"Structural_Valid",
[
Indexed(
Selected("Ctx", "Cursors"), Name("F"),
)
],
),
LessEqual(
Selected(
Indexed(
Selected("Ctx", "Cursors"), Name("F"),
),
"Last",
),
Call(
"Field_Last",
[Name("Ctx"), Selected("Val", "Fld")],
),
),
)
]
),
),
)
),
Postcondition(
And(
Call("Has_Buffer", [Name("Ctx")]),
Equal(
Name("Fst"),
Call("Field_First", [Name("Ctx"), Selected("Val", "Fld")]),
),
Equal(
Name("Lst"),
Call("Field_Last", [Name("Ctx"), Selected("Val", "Fld")]),
),
GreaterEqual(Name("Fst"), Selected("Ctx", "First")),
LessEqual(Name("Fst"), Add(Name("Lst"), Number(1))),
LessEqual(
Call(self.types.byte_index, [Name("Lst")]),
Selected("Ctx", "Buffer_Last"),
),
ForAllIn(
"F",
Range("Field"),
If(
[
(
Call(
"Structural_Valid",
[
Indexed(
Selected("Ctx", "Cursors"), Name("F"),
)
],
),
LessEqual(
Selected(
Indexed(
Selected("Ctx", "Cursors"), Name("F"),
),
"Last",
),
Name("Lst"),
),
)
]
),
),
*[
Equal(e, Old(e))
for e in [
Selected("Ctx", "Buffer_First"),
Selected("Ctx", "Buffer_Last"),
Selected("Ctx", "First"),
Selected("Ctx", "Cursors"),
]
],
)
),
],
)
],
)