def construct_common(self):
"""
Construct the expressions commonly needed by collection expression
subclasses, and return them as a tuple constituted of:
1. The resolved collection expression.
2. The resolved expression function passed to CollectionExpression's
constructor.
3. The element variable as a resolved expression.
4. The index variable as a resolved expression.
5. The inner scope for the iteration.
:rtype: (ResolvedExpression, ResolvedExpression,
ResolvedExpression, ResolvedExpression,
langkit.expressions.base.LocalVars.Scope)
"""
collection_expr = construct(
self.collection, lambda t: t.is_collection(),
'Map cannot iterate on {expr_type}, which is not a collection'
)
with PropertyDef.get_scope().new_child() as iter_scope:
if self.index_var:
PropertyDef.get_scope().add(self.index_var.local_var)
self.element_var.set_type(collection_expr.type.element_type())
return (collection_expr,
construct(self.expr),
construct(self.element_var),
construct(self.index_var) if self.index_var else None,
iter_scope)
def construct_common(self):
"""
Construct the expressions commonly needed by collection expression
subclasses, and return them as a tuple constituted of:
1. The resolved collection expression.
2. The resolved expression function passed to CollectionExpression's
constructor.
3. If the collection is an AST list, the iteration variable, whose type
is the root grammar type. None otherwise.
4. The element variable as a resolved expression. In the case of an AST
list collection, this is just 3. converted to the specific type.
5. The index variable as a resolved expression.
6. The inner scope for the iteration.
:rtype: (ResolvedExpression,
ResolvedExpression,
ResolvedExpression|None,
ResolvedExpression,
ResolvedExpression,
langkit.expressions.base.LocalVars.Scope)
"""
collection_expr = construct(
self.collection, lambda t: t.is_collection(),
'Map cannot iterate on {expr_type}, which is not a collection')
self.element_var.set_type(collection_expr.type.element_type())
current_scope = PropertyDef.get_scope()
# If we are iterating over an AST list, then we get root grammar typed
# values. We need to convert them to the more specific type to get the
# rest of the expression machinery work. For this, create a new
# variable.
if collection_expr.type.is_list_type:
self.list_element_var = AbstractVariable(
names.Name("List_Item_{}".format(
next(CollectionExpression._counter))),
type=get_context().root_grammar_class)
self.element_var.add_to_scope(current_scope)
with current_scope.new_child() as iter_scope:
if self.index_var:
PropertyDef.get_scope().add(self.index_var.local_var)
return (collection_expr, construct(self.expr), (construct(
self.list_element_var) if self.list_element_var else None),
construct(self.element_var),
construct(self.index_var) if self.index_var else None,
iter_scope)
def construct(self):
# Accept as a prefix:
#
# * any pointer, since it can be checked against "null";
# * any StructType, since structs are nullable;
# * any LexicalEnvType, which has EmptyEnv as a null value.
expr = construct(
self.expr, lambda cls:
(cls.is_ptr or cls.is_struct_type or cls.is_lexical_env_type),
'Invalid prefix type for .then: {expr_type}')
self.var_expr.set_type(expr.type)
# Create a then-expr specific scope to restrict the span of the "then"
# variable in the debugger.
with PropertyDef.get_scope().new_child() as then_scope:
then_scope.add(self.var_expr.local_var)
then_expr = construct(self.then_expr)
var_expr = construct(self.var_expr)
then_expr = BindingScope(then_expr, [var_expr], scope=then_scope)
# Affect default value to the fallback expression
if self.default_val is None:
check_source_language(
then_expr.type.null_allowed or then_expr.type is T.BoolType,
"Then expression should have a default value provided,"
" in cases where the provided function's return type (here"
" {}) does not have a default null value".format(
then_expr.type.dsl_name))
default_expr = construct(No(then_expr.type))
else:
default_expr = construct(self.default_val, then_expr.type)
return Then.Expr(expr, construct(self.var_expr), then_expr,
default_expr, then_scope)
def construct(self):
# Accept as a prefix all types that can have a null value
expr = construct(
self.expr,
lambda cls: cls.null_allowed,
'Invalid prefix type for .then: {expr_type}'
)
self.var_expr.set_type(expr.type)
# Create a then-expr specific scope to restrict the span of the "then"
# variable in the debugger.
with PropertyDef.get_scope().new_child() as then_scope:
then_scope.add(self.var_expr.local_var)
then_expr = construct(self.then_expr)
var_expr = construct(self.var_expr)
then_expr = BindingScope(then_expr, [var_expr], scope=then_scope)
# Affect default value to the fallback expression
then_expr, default_expr = expr_or_null(
then_expr, self.default_val,
'Then expression', "function's return type"
)
return Then.Expr(expr, construct(self.var_expr), then_expr,
default_expr, then_scope)
def construct(self):
# Add var_expr to the scope for this Then expression
PropertyDef.get_scope().add(self.var_expr.local_var)
# Accept as a prefix:
# * any pointer, since it can be checked against "null";
# * any Struct, since its "Is_Null" field can be checked.
expr = construct(self.expr,
lambda cls: cls.is_ptr or issubclass(cls, Struct))
self.var_expr.set_type(expr.type)
then_expr = construct(self.then_expr)
# Affect default value to the fallback expression. For the moment,
# only booleans and structs are handled.
if self.default_val is None:
if then_expr.type.matches(BoolType):
default_expr = construct(False)
elif issubclass(then_expr.type, Struct):
default_expr = construct(
No(
# Because we're doing issubclass instead of isinstance,
# PyCharm do not understand that then_exp.type is a Struct,
# so the following is necessary not to have warnings.
assert_type(then_expr.type, Struct)))
elif then_expr.type.matches(LexicalEnvType):
default_expr = construct(EmptyEnv)
elif then_expr.type.matches(Symbol):
default_expr = LiteralExpr(Symbol.nullexpr(), Symbol)
else:
# The following is not actually used but PyCharm's typer
# requires it.
default_expr = None
check_source_language(
False,
"Then expression should have a default value provided, "
"in cases where the provided function's return type is "
"not Bool, here {}".format(then_expr.type.name().camel))
else:
default_expr = construct(self.default_val, then_expr.type)
return Then.Expr(expr, construct(self.var_expr), then_expr,
default_expr)
def construct(self):
# Add var_expr to the scope for this Then expression
PropertyDef.get_scope().add(self.var_expr.local_var)
# Accept as a prefix:
# * any pointer, since it can be checked against "null";
# * any Struct, since its "Is_Null" field can be checked.
expr = construct(self.expr,
lambda cls: cls.is_ptr or issubclass(cls, Struct))
self.var_expr.set_type(expr.type)
then_expr = construct(self.then_expr)
# Affect default value to the fallback expression. For the moment,
# only booleans and structs are handled.
if self.default_val is None:
if then_expr.type.matches(BoolType):
default_expr = construct(False)
elif issubclass(then_expr.type, Struct):
default_expr = construct(No(
# Because we're doing issubclass instead of isinstance,
# PyCharm do not understand that then_exp.type is a Struct,
# so the following is necessary not to have warnings.
assert_type(then_expr.type, Struct)
))
elif then_expr.type.matches(LexicalEnvType):
default_expr = construct(EmptyEnv)
else:
# The following is not actually used but PyCharm's typer
# requires it.
default_expr = None
check_source_language(
False,
"Then expression should have a default value provided, "
"in cases where the provided function's return type is "
"not Bool, here {}".format(then_expr.type.name().camel)
)
else:
default_expr = construct(self.default_val, then_expr.type)
return Then.Expr(expr, construct(self.var_expr), then_expr,
default_expr)
def construct_common(self):
"""
Construct and return the expressions commonly needed by collection
expression subclasses.
:rtype: CollectionExpression.ConstructCommonResult
"""
current_scope = PropertyDef.get_scope()
# First, build the collection expression. From the result, we can
# deduce the type of the element variable.
collection_expr = construct(self.collection)
with_entities = collection_expr.type.is_entity_type
if with_entities:
saved_entity_coll_expr, collection_expr, entity_info = (
collection_expr.destructure_entity())
collection_expr = SequenceExpr(saved_entity_coll_expr,
collection_expr)
check_source_language(
collection_expr.type.is_collection,
'Cannot iterate on {}, which is not a collection'.format(
collection_expr.type.dsl_name))
elt_type = collection_expr.type.element_type
if with_entities:
elt_type = elt_type.entity
self.element_var.set_type(elt_type)
# List of "element" iteration variables
elt_vars = [construct(self.element_var)]
# List of initializing expressions for them
elt_var_inits = []
if with_entities:
entity_var = elt_vars[-1]
node_var = AbstractVariable(names.Name('Bare') +
self.element_var._name,
type=elt_type.element_type)
elt_var_inits.append(
make_as_entity(construct(node_var), entity_info=entity_info))
elt_vars.append(construct(node_var))
# If we are iterating over an AST list, then we get root grammar typed
# values. We need to convert them to the more specific type to get the
# rest of the expression machinery work.
if collection_expr.type.is_list_type:
typed_elt_var = elt_vars[-1]
untyped_elt_var = AbstractVariable(
names.Name('Untyped') + self.element_var._name,
type=get_context().root_grammar_class)
# Initialize the former last variable with a cast from the new last
# variable and push the new last variable.
elt_var_inits.append(
UncheckedCastExpr(construct(untyped_elt_var),
typed_elt_var.type))
elt_vars.append(construct(untyped_elt_var))
# Only then we can build the inner expression
with current_scope.new_child() as inner_scope:
inner_expr = construct(self.expr)
if with_entities:
entity_var.abstract_var.create_local_variable(inner_scope)
if collection_expr.type.is_list_type:
typed_elt_var.abstract_var.create_local_variable(inner_scope)
if self.index_var:
self.index_var.add_to_scope(inner_scope)
elt_var_inits.append(None)
return self.ConstructCommonResult(
collection_expr, funcy.lzip(elt_vars, elt_var_inits),
construct(self.index_var) if self.index_var else None, inner_expr,
inner_scope)
def construct_common(self) -> CollectionExpression.ConstructCommonResult:
"""
Construct and return the expressions commonly needed by collection
expression subclasses.
"""
assert self.element_var is not None
current_scope = PropertyDef.get_scope()
# Because of the discrepancy between the storage type in list nodes
# (always root nodes) and the element type that user code deals with
# (non-root list elements and/or entities), we may need to introduce
# variables and initializing expressions. This is what the code below
# does.
# First, build the collection expression. From the result, we can
# deduce the type of the user element variable.
collection_expr = construct(self.collection)
# If the collection is actually an entity, unwrap the bare list node
# and save the entity info for later.
with_entities = collection_expr.type.is_entity_type
if with_entities:
saved_entity_coll_expr, collection_expr, entity_info = (
collection_expr.destructure_entity()
)
collection_expr = SequenceExpr(saved_entity_coll_expr,
collection_expr)
check_source_language(
collection_expr.type.is_collection,
'Cannot iterate on {}, which is not a collection'.format(
collection_expr.type.dsl_name
)
)
# Now that potential entity types are unwrapped, we can look for its
# element type.
elt_type = collection_expr.type.element_type
if with_entities:
elt_type = elt_type.entity
self.element_var.set_type(elt_type)
user_element_var = construct(self.element_var)
# List of element variables, and the associated initialization
# expressions (when applicable).
#
# Start with the only element variable that exists at this point: the
# one that the user code for each iteration uses directly. When
# relevant, each step in the code below creates a new variable N and
# initialize variable N-1 from it.
element_vars: List[InitializedVar] = [InitializedVar(user_element_var)]
# Node lists contain bare nodes: if the user code deals with entities,
# create a variable to hold a bare node and initialize the user
# variable using it.
if with_entities:
entity_var = element_vars[-1]
node_var = AbstractVariable(
names.Name('Bare') + self.element_var._name,
type=elt_type.element_type
)
entity_var.init_expr = make_as_entity(
construct(node_var), entity_info=entity_info
)
element_vars.append(InitializedVar(construct(node_var)))
# Node lists contain root nodes: if the user code deals with non-root
# nodes, create a variable to hold the root bare node and initialize
# the non-root node using it.
if (
collection_expr.type.is_list_type
and not collection_expr.type.is_root_node
):
typed_elt_var = element_vars[-1]
untyped_elt_var = AbstractVariable(
names.Name('Untyped') + self.element_var._name,
type=get_context().root_grammar_class
)
typed_elt_var.init_expr = UncheckedCastExpr(
construct(untyped_elt_var), typed_elt_var.var.type
)
element_vars.append(InitializedVar(construct(untyped_elt_var)))
# Keep track of the ultimate "codegen" element variable. Unlike all
# other iteration variable, it is the only one that will be defined by
# the "for" loop in Ada (the other ones must be declared as regular
# local variables).
codegen_element_var = element_vars[-1].var
# Create a scope to contain the code that runs during an iteration and
# lower the iteration expression.
with current_scope.new_child() as inner_scope:
inner_expr = construct(self.expr)
# Build the list of all iteration variables
iter_vars = list(element_vars)
index_var = None
if self.index_var:
index_var = construct(self.index_var)
iter_vars.append(InitializedVar(index_var))
# Create local variables for all iteration variables that need it
for v in iter_vars:
if v.var != codegen_element_var:
v.var.abstract_var.create_local_variable(inner_scope)
return self.ConstructCommonResult(
collection_expr,
codegen_element_var,
user_element_var,
index_var,
iter_vars,
inner_expr,
inner_scope,
)
def construct(self):
"""
Construct a resolved expression for this.
:rtype: ResolvedExpression
"""
# Add the variables created for this expression to the current scope
scope = PropertyDef.get_scope()
for _, var, _ in self.matchers:
scope.add(var.local_var)
matched_expr = construct(self.matched_expr)
check_source_language(issubclass(matched_expr.type, ASTNode)
or matched_expr.type.is_env_element_type,
'Match expressions can only work on AST nodes '
'or env elements')
# Create a local variable so that in the generated code, we don't have
# to re-compute the prefix for each type check.
matched_abstract_var = AbstractVariable(
names.Name('Match_Prefix'),
type=matched_expr.type,
create_local=True
)
PropertyDef.get_scope().add(matched_abstract_var.local_var)
matched_var = construct(matched_abstract_var)
constructed_matchers = []
# Check (i.e. raise an error if no true) the set of matchers is valid:
# * all matchers must target allowed types, i.e. input type subclasses;
for typ, var, expr in self.matchers:
if typ is not None:
check_source_language(
typ.matches(matched_expr.type),
'Cannot match {} (input type is {})'.format(
typ.name().camel,
matched_expr.type.name().camel
)
)
else:
# The default matcher (if any) matches the most general type,
# which is the input type.
var.set_type(matched_expr.type)
constructed_matchers.append((construct(var), construct(expr)))
# * all possible input types must have at least one matcher. Also warn
# if some matchers are unreachable.
self._check_match_coverage(matched_expr.type)
# Compute the return type as the unification of all branches
_, expr = constructed_matchers[-1]
rtype = expr.type
for _, expr in constructed_matchers:
check_source_language(
expr.type.matches(rtype), "Wrong type for match result"
" expression: got {} but expected {} or sub/supertype".format(
expr.type.name().camel, rtype.name().camel
)
)
rtype = expr.type.unify(rtype)
# This is the expression execution will reach if we have a bug in our
# code (i.e. if matchers did not cover all cases).
result = UnreachableExpr(rtype)
# Wrap this "failing" expression with all the cases to match in the
# appropriate order, so that in the end the first matchers are tested
# first.
for match_var, expr in reversed(constructed_matchers):
casted = Cast.Expr(matched_var,
match_var.type,
result_var=match_var)
guard = Not.make_expr(
Eq.make_expr(
casted, LiteralExpr(casted.type.nullexpr(), casted.type)
)
)
if expr.type != rtype:
# We already checked that type matches, so only way this is
# true is if expr.type is an ASTNode type derived from
# rtype. In that case, we need an explicity upcast.
expr = Cast.Expr(expr, rtype)
result = If.Expr(guard, expr, result, rtype)
return Let.Expr(
[matched_var],
[matched_expr],
BindingScope(result,
[construct(var) for _, var, _ in self.matchers])
)
def construct(self):
"""
Construct a resolved expression for this.
:rtype: ResolvedExpression
"""
# Add the variables created for this expression to the current scope
scope = PropertyDef.get_scope()
for _, v, _ in self.matchers:
scope.add(v.local_var)
matched_expr = construct(self.matched_expr)
check_source_language(issubclass(matched_expr.type, ASTNode),
'Match expressions can only work on AST nodes')
# Yes, the assertion below is what we just checked above, but unlike
# check_source_language, assert_type provides type information to
# PyCharm's static analyzer.
matched_type = assert_type(matched_expr.type, ASTNode)
constructed_matchers = []
# Check (i.e. raise an error if no true) the set of matchers is valid:
# * all matchers must target allowed types, i.e. input type subclasses;
for t, v, e in self.matchers:
if t is not None:
check_source_language(
t.matches(matched_expr.type),
'Cannot match {} (input type is {})'.format(
t.name().camel,
matched_expr.type.name().camel
)
)
else:
# The default matcher (if any) matches the most general type,
# which is the input type.
v.set_type(matched_expr.type)
constructed_matchers.append((construct(v), construct(e)))
# * all possible input types must have at least one matcher. Also warn
# if some matchers are unreachable.
self._check_match_coverage(matched_type)
# Compute the return type as the unification of all branches
_, expr = constructed_matchers[-1]
rtype = expr.type
for _, expr in constructed_matchers:
check_source_language(
expr.type.matches(rtype), "Wrong type for match expression : "
"{}, expected {} or sub/supertype".format(
expr.type.name().camel, rtype.name().camel
)
)
rtype = expr.type.unify(rtype)
# This is the expression execution will reach if we have a bug in our
# code (i.e. if matchers did not cover all cases).
result = UnreachableExpr(rtype)
# Wrap this "failing" expression with all the cases to match in the
# appropriate order, so that in the end the first matchers are tested
# first.
for match_var, expr in reversed(constructed_matchers):
casted = Cast.Expr(matched_expr,
match_var.type,
result_var=match_var)
guard = Not.make_expr(
Eq.make_expr(casted, LiteralExpr('null', casted.type))
)
if expr.type != rtype:
# We already checked that type matches, so only way this is
# true is if expr.type is an ASTNode type derived from
# rtype. In that case, we need an explicity upcast.
expr = Cast.Expr(expr, rtype)
result = If.Expr(guard, expr, result, rtype)
return result
