def collection_get(self: AbstractExpression,
collection: AbstractExpression,
index: AbstractExpression,
or_null: bool) -> ResolvedExpression:
"""
Get the `index`\\ -th element from `collection`.
Indexes are 0-based. As in Python, `index` can be negative, to retrieve
elements in reverse order. For instance, ``expr.at(-1)`` will return the
last element.
:param or_null: If true, the expression will return null if the index is
not valid for the collection. If False, it will raise an exception.
"""
# index yields a 0-based index and all the Get primitives expect 0-based
# indexes, so there is no need to fiddle indexes here.
index_expr = construct(index, T.Int)
coll_expr = construct(collection)
as_entity = coll_expr.type.is_entity_type
if as_entity:
saved_coll_expr, coll_expr, entity_info = (
coll_expr.destructure_entity()
)
check_source_language(
coll_expr.type.is_collection,
'.at prefix must be a collection: got {} instead'.format(
coll_expr.type.dsl_name
)
)
# We process null list nodes as empty lists, so insert a null check before
# getting the collection item only if asked to raise an exception.
if not or_null:
if coll_expr.type.is_ast_node:
coll_expr = NullCheckExpr(coll_expr)
elif coll_expr.type.is_entity_type:
coll_expr = NullCheckExpr(coll_expr, implicit_deref=True)
coll_expr, element_type = canonicalize_list(coll_expr, to_root_list=True)
or_null_expr = construct(or_null)
result: ResolvedExpression = CallExpr(
'Get_Result', 'Get', element_type,
[coll_expr, index_expr, or_null_expr]
)
if as_entity:
result = SequenceExpr(saved_coll_expr,
make_as_entity(result, entity_info))
result.abstract_expr = self
return result
def parents_access_constructor(
prefix: ResolvedExpression,
node_data: AbstractNodeData,
args: List[Optional[ResolvedExpression]],
abstract_expr: Optional[AbstractExpression] = None
) -> ResolvedExpression:
"""
Return an access to the "fields" parents, whether called on a node or an
entity.
.. todo::
Implement rebindings shedding.
"""
# We expect exactly one argument: with_self. If not provided, use the
# default value.
assert len(args) == 1
with_self: ResolvedExpression = (args[0] or construct(
node_data.natural_arguments[0].abstract_default_value))
cons_args = [with_self]
return build_field_access(
prefix,
'parents',
cons_args,
lambda: CallExpr(
'Node_Parents',
'Parents',
T.root_node.array,
[cast(ResolvedExpression, NullCheckExpr(prefix))] + cons_args,
abstract_expr=abstract_expr,
),
abstract_expr=abstract_expr,
)
def construct_non_null_rebindings(rebindings):
"""
Construct `rebindings` to be an environment rebindings value and wrap it in
a non-null check.
:param AbstractExpression rebindings: Rebindings-returning expression to
process.
:rtype: ResolvedExpression
"""
return NullCheckExpr(construct(rebindings, T.EnvRebindings))
def analysis_unit_root(self, unit):
"""
Return `unit`'s root AST node.
:param ResolvedExpression unit: Expression that yields the analysis
unit for which we want to extract the root AST node.
"""
unit_expr = NullCheckExpr(construct(unit, T.AnalysisUnitType))
return FieldAccessExpr(unit_expr, 'AST_Root', T.root_node,
do_explicit_incref=False, abstract_expr=self)
def collection_get(self, collection, index, or_null):
"""
Get the `index`\ -th element from `collection`.
Indexes are 0-based. As in Python, `index` can be negative, to retrieve
elements in reverse order. For instance, ``expr.at(-1)`` will return the
last element.
:param bool or_null: If true, the expression will return null if the
index is not valid for the collection. If False, it will raise an
exception.
"""
# index yields a 0-based index and all the Get primitives expect 0-based
# indexes, so there is no need to fiddle indexes here.
index_expr = construct(index, T.LongType)
coll_expr = construct(collection)
as_entity = coll_expr.type.is_entity_type
if as_entity:
saved_coll_expr, coll_expr, entity_info = (
coll_expr.destructure_entity())
check_source_language(
coll_expr.type.is_collection,
'.at prefix must be a collection: got {} instead'.format(
coll_expr.type.dsl_name))
if coll_expr.type.is_ast_node:
coll_expr = NullCheckExpr(coll_expr)
elif coll_expr.type.is_entity_type:
coll_expr = NullCheckExpr(coll_expr, implicit_deref=True)
or_null = construct(or_null)
result = CallExpr('Get_Result', 'Get', coll_expr.type.element_type,
[coll_expr, index_expr, or_null])
if as_entity:
result = SequenceExpr(saved_coll_expr,
make_as_entity(result, entity_info))
result.abstract_expr = self
return result
def children(self, node):
"""
Return `node`'s children in the AST.
This works on both bare nodes and entities.
"""
node_expr = construct(node)
check_source_language(
node_expr.type.is_ast_node or node_expr.type.is_entity_type,
'Invalid prefix for "children": got {} but AST node or entity'
' expected'.format(node_expr.type.dsl_name))
return build_field_access(
node_expr,
'children',
[],
lambda: CallExpr('Node_Children',
'Children',
T.root_node.array, [NullCheckExpr(node_expr)],
abstract_expr=self),
abstract_expr=self,
)