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_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 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 extract_function(self, type_name: str) -> Subprogram:
return GenericFunctionInstantiation(
"Extract",
FunctionSpecification(
f"{self.types.types}.Extract",
type_name,
[Parameter(["Buffer"], self.types.bytes), Parameter(["Offset"], self.types.offset)],
),
[self.types.index, self.types.byte, self.types.bytes, self.types.offset, type_name],
)
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 insert_function(self, type_name: ID) -> Subprogram:
return GenericProcedureInstantiation(
"Insert",
ProcedureSpecification(
const.TYPES * "Insert",
[
Parameter(["Val"], type_name),
InOutParameter(["Buffer"], const.TYPES_BYTES),
Parameter(["Offset"], const.TYPES_OFFSET),
],
),
[common.prefixed_type_name(type_name, self.prefix)],
)
def extract_function(self, type_name: ID) -> Subprogram:
return GenericFunctionInstantiation(
"Extract",
FunctionSpecification(
const.TYPES * "Extract",
type_name,
[
Parameter(["Buffer"], const.TYPES_BYTES),
Parameter(["Offset"], const.TYPES_OFFSET),
],
),
[common.prefixed_type_name(type_name, self.prefix)],
)
def insert_function(self, type_name: str) -> Subprogram:
return GenericProcedureInstantiation(
"Insert",
ProcedureSpecification(
f"{self.types.types}.Insert",
[
Parameter(["Val"], type_name),
InOutParameter(["Buffer"], self.types.bytes),
Parameter(["Offset"], self.types.offset),
],
),
[self.types.index, self.types.byte, self.types.bytes, self.types.offset, type_name],
)
def create_valid_message_function(self, message: Message) -> UnitPart:
specification = FunctionSpecification("Valid_Message", "Boolean",
[Parameter(["Ctx"], "Context")])
return UnitPart(
[
SubprogramDeclaration(
specification,
[
Precondition(
Call(
self.prefix * message.identifier *
"Has_Buffer",
[Variable("Ctx")],
))
],
)
],
private=[
ExpressionFunctionDeclaration(
specification,
self.valid_message_condition(message),
)
],
)
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 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 _create_init_proc(self, slots: Sequence[NumberedSlotInfo]) -> UnitPart:
proc = ProcedureSpecification(
"Initialize",
[OutParameter(["S"], "Slots"),
Parameter(["M"], "Memory")])
return UnitPart(
[
SubprogramDeclaration(
proc,
[Postcondition(Call("Initialized", [Variable("S")]))]),
],
[
SubprogramBody(
proc,
declarations=[],
statements=([
Assignment(
"S" * self._slot_name(slot.slot_id),
UnrestrictedAccess(
Variable(ID(f"M.Slot_{slot.slot_id}"))),
) for slot in slots
] if slots else [NullStatement()]),
aspects=[SparkMode(off=True)],
)
],
)
def specification_bounded(field: Field) -> ProcedureSpecification:
return ProcedureSpecification(
f"Initialize_Bounded_{field.name}",
[
InOutParameter(["Ctx"], "Context"),
Parameter(["Length"], const.TYPES_BIT_LENGTH)
],
)
def specification(field: Field) -> ProcedureSpecification:
return ProcedureSpecification(
f"Get_{field.name}",
[
Parameter(["Ctx"], "Context"),
OutParameter(["Data"], const.TYPES_BYTES)
],
)
def specification(field: Field,
field_type: Type) -> FunctionSpecification:
if field_type.package == BUILTINS_PACKAGE:
type_name = ID(field_type.name)
else:
type_name = self.prefix * field_type.identifier
return FunctionSpecification(f"Get_{field.name}", type_name,
[Parameter(["Ctx"], "Context")])
def _create_init_pred(self, slots: Sequence[NumberedSlotInfo]) -> UnitPart:
return UnitPart([
ExpressionFunctionDeclaration(
FunctionSpecification("Initialized", "Boolean",
[Parameter(["S"], "Slots")]),
And(*[
NotEqual(
Variable("S" * self._slot_name(slot.slot_id)),
Variable("null"),
) for slot in slots
]),
)
])
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}"),
],
)
def create_valid_message_function(self, message: Message) -> UnitPart:
specification = FunctionSpecification(
"Valid_Message", "Boolean", [Parameter(["Ctx"], "Context")]
)
return UnitPart(
[SubprogramDeclaration(specification, [Precondition(VALID_CONTEXT)])],
[
ExpressionFunctionDeclaration(
specification,
valid_message_condition(message).simplified(self.common.substitution(message)),
)
],
)
def formal_parameters(
field: Field) -> Sequence[FormalSubprogramDeclaration]:
return [
FormalSubprogramDeclaration(
ProcedureSpecification(
f"Process_{field.name}",
[OutParameter([field.name], const.TYPES_BYTES)],
)),
FormalSubprogramDeclaration(
FunctionSpecification(
"Valid_Length",
"Boolean",
[Parameter(["Length"], const.TYPES_LENGTH)],
)),
]
def create_incomplete_message_function(message: Message) -> UnitPart:
specification = FunctionSpecification("Incomplete_Message", "Boolean",
[Parameter(["Ctx"], "Context")])
return UnitPart(
[SubprogramDeclaration(specification)],
[
ExpressionFunctionDeclaration(
specification,
Or(*[
Call("Incomplete",
[Variable("Ctx"),
Variable(f.affixed_name)])
for f in message.fields
]),
)
],
)
def create_valid_message_function(message: Message) -> UnitPart:
specification = FunctionSpecification("Valid_Message", "Boolean",
[Parameter(["Ctx"], "Context")])
return UnitPart(
[
SubprogramDeclaration(
specification,
[Precondition(Call("Has_Buffer", [Variable("Ctx")]))],
)
],
[
ExpressionFunctionDeclaration(
specification,
valid_message_condition(message).substituted(
common.substitution(message)).simplified(),
)
],
)
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)
],
)
def _create_global_allocated_pred(
self, slots: Sequence[NumberedSlotInfo]) -> UnitPart:
return UnitPart([
ExpressionFunctionDeclaration(
FunctionSpecification("Global_Allocated", "Boolean",
[Parameter(["S"], "Slots")]),
And(
*[
Equal(
Variable("S" * self._slot_name(slot.slot_id)),
Variable("null"),
) for slot in slots if slot.global_
],
*[
NotEqual(
Variable("S" * self._slot_name(slot.slot_id)),
Variable("null"),
) for slot in slots if not slot.global_
],
),
)
])
def create_incomplete_message_function() -> UnitPart:
specification = FunctionSpecification("Incomplete_Message", "Boolean",
[Parameter(["Ctx"], "Context")])
return UnitPart(
[
# https://github.com/Componolit/Workarounds/issues/47
Pragma(
"Warnings",
[
Variable("Off"),
String(
"postcondition does not mention function result")
],
),
SubprogramDeclaration(specification, [Postcondition(TRUE)]),
Pragma(
"Warnings",
[
Variable("On"),
String(
"postcondition does not mention function result")
],
),
],
private=[
ExpressionFunctionDeclaration(
specification,
ForSomeIn(
"F",
Variable("Field"),
Call(
"Incomplete",
[Variable("Ctx"), Variable("F")],
),
),
)
],
)
def create_internal_functions(
self,
message: Message,
scalar_fields: Mapping[Field, Type],
composite_fields: Sequence[Field],
) -> UnitPart:
def result(field: Field, message: Message) -> NamedAggregate:
aggregate: List[Tuple[str, Expr]] = [
("Fld", Variable(field.affixed_name))
]
if field in message.fields and isinstance(message.types[field],
Scalar):
aggregate.append((
f"{field.name}_Value",
Call(
"Extract",
[
Slice(
Variable("Ctx.Buffer.all"),
Variable("Buffer_First"),
Variable("Buffer_Last"),
),
Variable("Offset"),
],
),
))
return NamedAggregate(*aggregate)
return UnitPart(
[],
[
ExpressionFunctionDeclaration(
FunctionSpecification("Composite_Field", "Boolean",
[Parameter(["Fld"], "Field")]),
Case(
Variable("Fld"),
[(Variable(f.affixed_name),
TRUE if f in composite_fields else FALSE)
for f in message.fields],
),
),
SubprogramBody(
FunctionSpecification(
"Get_Field_Value",
"Field_Dependent_Value",
[
Parameter(["Ctx"], "Context"),
Parameter(["Fld"], "Field")
],
),
[
*common.field_bit_location_declarations(
Variable("Fld")),
*common.field_byte_location_declarations(),
*unique(
self.extract_function(common.full_base_type_name(
t)) for t in message.types.values()
if isinstance(t, Scalar)),
] if scalar_fields else [],
[
ReturnStatement(
Case(
Variable("Fld"),
[(Variable(f.affixed_name), result(f, message))
for f in message.fields],
))
],
[
Precondition(
AndThen(
Call("Has_Buffer", [Variable("Ctx")]),
Call("Valid_Next",
[Variable("Ctx"),
Variable("Fld")]),
Call("Sufficient_Buffer_Length",
[Variable("Ctx"),
Variable("Fld")]),
)),
Postcondition(
Equal(
Selected(Result("Get_Field_Value"), "Fld"),
Variable("Fld"),
)),
],
),
],
)
def specification(field: Field) -> ProcedureSpecification:
return ProcedureSpecification(f"Get_{field.name}",
[Parameter(["Ctx"], "Context")])
def specification_bounded(field: Field) -> ProcedureSpecification:
return ProcedureSpecification(
f"Initialize_Bounded_{field.name}",
[InOutParameter(["Ctx"], "Context"), Parameter(["Length"], self.types.bit_length)],
)
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 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"),
]
],
)
),
],
)
],
)
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),
),
),
)
],
)
],
)], )
],
)
],
)