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# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
from __future__ import annotations
import dataclasses
from typing import TYPE_CHECKING
from libcst import IndentedBlock, Module
from libcst._nodes.deep_equals import deep_equals
if TYPE_CHECKING:
from typing import Sequence
from libcst import CSTNode
def get_node_fields(node: CSTNode) -> Sequence[dataclasses.Field[CSTNode]]:
"""
Returns the sequence of a given CST-node's fields.
"""
return dataclasses.fields(node)
def is_whitespace_node_field(node: CSTNode, field: dataclasses.Field[CSTNode]) -> bool:
"""
Returns True if a given CST-node's field is a whitespace-related field
(whitespace, indent, header, footer, etc.).
"""
if "whitespace" in field.name:
return True
if "leading_lines" in field.name:
return True
if "lines_after_decorators" in field.name:
return True
if isinstance(node, (IndentedBlock, Module)) and field.name in [
"header",
"footer",
]:
return True
if isinstance(node, IndentedBlock) and field.name == "indent":
return True
return False
def is_syntax_node_field(node: CSTNode, field: dataclasses.Field[CSTNode]) -> bool:
"""
Returns True if a given CST-node's field is a syntax-related field
(colon, semicolon, dot, encoding, etc.).
"""
if isinstance(node, Module) and field.name in [
"encoding",
"default_indent",
"default_newline",
"has_trailing_newline",
]:
return True
type_str = repr(field.type)
if (
"Sentinel" in type_str
and field.name not in ["star_arg", "star", "posonly_ind"]
and "whitespace" not in field.name
):
# This is a value that can optionally be specified, so its
# definitely syntax.
return True
for name in ["Semicolon", "Colon", "Comma", "Dot", "AssignEqual"]:
# These are all nodes that exist for separation syntax
if name in type_str:
return True
return False
def get_field_default_value(field: dataclasses.Field[CSTNode]) -> object:
"""
Returns the default value of a CST-node's field.
"""
if field.default_factory is not dataclasses.MISSING:
# pyre-fixme[29]: `Union[dataclasses._MISSING_TYPE,
# dataclasses._DefaultFactory[object]]` is not a function.
return field.default_factory()
return field.default
def is_default_node_field(node: CSTNode, field: dataclasses.Field[CSTNode]) -> bool:
"""
Returns True if a given CST-node's field has its default value.
"""
return deep_equals(getattr(node, field.name), get_field_default_value(field))
def filter_node_fields(
node: CSTNode,
*,
show_defaults: bool,
show_syntax: bool,
show_whitespace: bool,
) -> Sequence[dataclasses.Field[CSTNode]]:
"""
Returns a filtered sequence of a CST-node's fields.
Setting ``show_whitespace`` to ``False`` will filter whitespace fields.
Setting ``show_defaults`` to ``False`` will filter fields if their value is equal to
the default value ; while respecting the value of ``show_whitespace``.
Setting ``show_syntax`` to ``False`` will filter syntax fields ; while respecting
the value of ``show_whitespace`` & ``show_defaults``.
"""
fields: Sequence[dataclasses.Field[CSTNode]] = dataclasses.fields(node)
# Hide all fields prefixed with "_"
fields = [f for f in fields if f.name[0] != "_"]
# Filter whitespace nodes if needed
if not show_whitespace:
fields = [f for f in fields if not is_whitespace_node_field(node, f)]
# Filter values which aren't changed from their defaults
if not show_defaults:
fields = [f for f in fields if not is_default_node_field(node, f)]
# Filter out values which aren't interesting if needed
if not show_syntax:
fields = [f for f in fields if not is_syntax_node_field(node, f)]
return fields
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