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https://github.com/Instagram/LibCST.git
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efc53af608
* Make the nodes fields filtering process - from libcst.tool - public, so that other libraries may provide their own custom representation of LibCST graphs. * Create functions to access & filter CST-node fields (with appropriate docstrings & tests), in libcst.helpers * Add new CST-node fields functions to helpers documentation.
128 lines
4 KiB
Python
128 lines
4 KiB
Python
# Copyright (c) Meta Platforms, Inc. and affiliates.
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#
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# This source code is licensed under the MIT license found in the
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# LICENSE file in the root directory of this source tree.
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from __future__ import annotations
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import dataclasses
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from typing import TYPE_CHECKING
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from libcst import IndentedBlock, Module
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from libcst._nodes.deep_equals import deep_equals
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if TYPE_CHECKING:
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from typing import Sequence
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from libcst import CSTNode
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def get_node_fields(node: CSTNode) -> Sequence[dataclasses.Field[CSTNode]]:
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"""
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Returns the sequence of a given CST-node's fields.
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"""
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return dataclasses.fields(node)
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def is_whitespace_node_field(node: CSTNode, field: dataclasses.Field[CSTNode]) -> bool:
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"""
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Returns True if a given CST-node's field is a whitespace-related field
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(whitespace, indent, header, footer, etc.).
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"""
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if "whitespace" in field.name:
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return True
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if "leading_lines" in field.name:
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return True
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if "lines_after_decorators" in field.name:
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return True
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if isinstance(node, (IndentedBlock, Module)) and field.name in [
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"header",
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"footer",
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]:
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return True
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if isinstance(node, IndentedBlock) and field.name == "indent":
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return True
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return False
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def is_syntax_node_field(node: CSTNode, field: dataclasses.Field[CSTNode]) -> bool:
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"""
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Returns True if a given CST-node's field is a syntax-related field
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(colon, semicolon, dot, encoding, etc.).
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"""
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if isinstance(node, Module) and field.name in [
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"encoding",
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"default_indent",
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"default_newline",
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"has_trailing_newline",
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]:
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return True
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type_str = repr(field.type)
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if (
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"Sentinel" in type_str
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and field.name not in ["star_arg", "star", "posonly_ind"]
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and "whitespace" not in field.name
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):
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# This is a value that can optionally be specified, so its
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# definitely syntax.
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return True
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for name in ["Semicolon", "Colon", "Comma", "Dot", "AssignEqual"]:
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# These are all nodes that exist for separation syntax
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if name in type_str:
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return True
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return False
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def get_field_default_value(field: dataclasses.Field[CSTNode]) -> object:
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"""
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Returns the default value of a CST-node's field.
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"""
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if field.default_factory is not dataclasses.MISSING:
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# pyre-fixme[29]: `Union[dataclasses._MISSING_TYPE,
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# dataclasses._DefaultFactory[object]]` is not a function.
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return field.default_factory()
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return field.default
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def is_default_node_field(node: CSTNode, field: dataclasses.Field[CSTNode]) -> bool:
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"""
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Returns True if a given CST-node's field has its default value.
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"""
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return deep_equals(getattr(node, field.name), get_field_default_value(field))
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def filter_node_fields(
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node: CSTNode,
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*,
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show_defaults: bool,
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show_syntax: bool,
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show_whitespace: bool,
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) -> Sequence[dataclasses.Field[CSTNode]]:
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"""
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Returns a filtered sequence of a CST-node's fields.
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Setting ``show_whitespace`` to ``False`` will filter whitespace fields.
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Setting ``show_defaults`` to ``False`` will filter fields if their value is equal to
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the default value ; while respecting the value of ``show_whitespace``.
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Setting ``show_syntax`` to ``False`` will filter syntax fields ; while respecting
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the value of ``show_whitespace`` & ``show_defaults``.
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"""
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fields: Sequence[dataclasses.Field[CSTNode]] = dataclasses.fields(node)
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# Hide all fields prefixed with "_"
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fields = [f for f in fields if f.name[0] != "_"]
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# Filter whitespace nodes if needed
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if not show_whitespace:
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fields = [f for f in fields if not is_whitespace_node_field(node, f)]
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# Filter values which aren't changed from their defaults
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if not show_defaults:
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fields = [f for f in fields if not is_default_node_field(node, f)]
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# Filter out values which aren't interesting if needed
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if not show_syntax:
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fields = [f for f in fields if not is_syntax_node_field(node, f)]
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return fields
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