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364 lines
13 KiB
364 lines
13 KiB
# Copyright 2016 Grist Labs, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import ast
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import collections
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import sys
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import token
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import tokenize
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from abc import ABCMeta
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from ast import Module, expr, AST
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from typing import Callable, Dict, Iterator, List, Optional, Tuple, Union, cast, Any, TYPE_CHECKING
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from six import iteritems
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if TYPE_CHECKING:
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from astroid.node_classes import NodeNG
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# Type class used to expand out the definition of AST to include fields added by this library
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# It's not actually used for anything other than type checking though!
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class EnhancedAST(AST):
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# Additional attributes set by mark_tokens
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first_token = None # type: Token
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last_token = None # type: Token
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lineno = 0 # type: int
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AstNode = Union[EnhancedAST, NodeNG]
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def token_repr(tok_type, string):
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# type: (int, Optional[str]) -> str
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"""Returns a human-friendly representation of a token with the given type and string."""
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# repr() prefixes unicode with 'u' on Python2 but not Python3; strip it out for consistency.
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return '%s:%s' % (token.tok_name[tok_type], repr(string).lstrip('u'))
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class Token(collections.namedtuple('Token', 'type string start end line index startpos endpos')):
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"""
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TokenInfo is an 8-tuple containing the same 5 fields as the tokens produced by the tokenize
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module, and 3 additional ones useful for this module:
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- [0] .type Token type (see token.py)
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- [1] .string Token (a string)
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- [2] .start Starting (row, column) indices of the token (a 2-tuple of ints)
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- [3] .end Ending (row, column) indices of the token (a 2-tuple of ints)
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- [4] .line Original line (string)
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- [5] .index Index of the token in the list of tokens that it belongs to.
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- [6] .startpos Starting character offset into the input text.
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- [7] .endpos Ending character offset into the input text.
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"""
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def __str__(self):
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# type: () -> str
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return token_repr(self.type, self.string)
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if sys.version_info >= (3, 6):
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AstConstant = ast.Constant
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else:
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class AstConstant:
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value = object()
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def match_token(token, tok_type, tok_str=None):
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# type: (Token, int, Optional[str]) -> bool
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"""Returns true if token is of the given type and, if a string is given, has that string."""
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return token.type == tok_type and (tok_str is None or token.string == tok_str)
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def expect_token(token, tok_type, tok_str=None):
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# type: (Token, int, Optional[str]) -> None
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"""
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Verifies that the given token is of the expected type. If tok_str is given, the token string
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is verified too. If the token doesn't match, raises an informative ValueError.
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"""
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if not match_token(token, tok_type, tok_str):
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raise ValueError("Expected token %s, got %s on line %s col %s" % (
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token_repr(tok_type, tok_str), str(token),
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token.start[0], token.start[1] + 1))
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# These were previously defined in tokenize.py and distinguishable by being greater than
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# token.N_TOKEN. As of python3.7, they are in token.py, and we check for them explicitly.
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if sys.version_info >= (3, 7):
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def is_non_coding_token(token_type):
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# type: (int) -> bool
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"""
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These are considered non-coding tokens, as they don't affect the syntax tree.
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"""
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return token_type in (token.NL, token.COMMENT, token.ENCODING)
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else:
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def is_non_coding_token(token_type):
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# type: (int) -> bool
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"""
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These are considered non-coding tokens, as they don't affect the syntax tree.
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"""
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return token_type >= token.N_TOKENS
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def iter_children_func(node):
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# type: (Module) -> Callable
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"""
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Returns a function which yields all direct children of a AST node,
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skipping children that are singleton nodes.
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The function depends on whether ``node`` is from ``ast`` or from the ``astroid`` module.
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"""
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return iter_children_astroid if hasattr(node, 'get_children') else iter_children_ast
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def iter_children_astroid(node):
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# type: (NodeNG) -> Union[Iterator, List]
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# Don't attempt to process children of JoinedStr nodes, which we can't fully handle yet.
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if is_joined_str(node):
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return []
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return node.get_children()
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SINGLETONS = {c for n, c in iteritems(ast.__dict__) if isinstance(c, type) and
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issubclass(c, (ast.expr_context, ast.boolop, ast.operator, ast.unaryop, ast.cmpop))}
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def iter_children_ast(node):
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# type: (AST) -> Iterator[Union[AST, expr]]
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# Don't attempt to process children of JoinedStr nodes, which we can't fully handle yet.
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if is_joined_str(node):
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return
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if isinstance(node, ast.Dict):
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# override the iteration order: instead of <all keys>, <all values>,
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# yield keys and values in source order (key1, value1, key2, value2, ...)
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for (key, value) in zip(node.keys, node.values):
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if key is not None:
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yield key
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yield value
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return
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for child in ast.iter_child_nodes(node):
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# Skip singleton children; they don't reflect particular positions in the code and break the
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# assumptions about the tree consisting of distinct nodes. Note that collecting classes
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# beforehand and checking them in a set is faster than using isinstance each time.
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if child.__class__ not in SINGLETONS:
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yield child
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stmt_class_names = {n for n, c in iteritems(ast.__dict__)
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if isinstance(c, type) and issubclass(c, ast.stmt)}
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expr_class_names = ({n for n, c in iteritems(ast.__dict__)
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if isinstance(c, type) and issubclass(c, ast.expr)} |
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{'AssignName', 'DelName', 'Const', 'AssignAttr', 'DelAttr'})
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# These feel hacky compared to isinstance() but allow us to work with both ast and astroid nodes
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# in the same way, and without even importing astroid.
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def is_expr(node):
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# type: (AstNode) -> bool
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"""Returns whether node is an expression node."""
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return node.__class__.__name__ in expr_class_names
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def is_stmt(node):
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# type: (AstNode) -> bool
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"""Returns whether node is a statement node."""
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return node.__class__.__name__ in stmt_class_names
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def is_module(node):
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# type: (AstNode) -> bool
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"""Returns whether node is a module node."""
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return node.__class__.__name__ == 'Module'
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def is_joined_str(node):
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# type: (AstNode) -> bool
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"""Returns whether node is a JoinedStr node, used to represent f-strings."""
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# At the moment, nodes below JoinedStr have wrong line/col info, and trying to process them only
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# leads to errors.
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return node.__class__.__name__ == 'JoinedStr'
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def is_starred(node):
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# type: (AstNode) -> bool
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"""Returns whether node is a starred expression node."""
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return node.__class__.__name__ == 'Starred'
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def is_slice(node):
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# type: (AstNode) -> bool
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"""Returns whether node represents a slice, e.g. `1:2` in `x[1:2]`"""
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# Before 3.9, a tuple containing a slice is an ExtSlice,
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# but this was removed in https://bugs.python.org/issue34822
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return (
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node.__class__.__name__ in ('Slice', 'ExtSlice')
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or (
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node.__class__.__name__ == 'Tuple'
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and any(map(is_slice, cast(ast.Tuple, node).elts))
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)
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)
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# Sentinel value used by visit_tree().
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_PREVISIT = object()
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def visit_tree(node, previsit, postvisit):
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# type: (Module, Callable[[AstNode, Optional[Token]], Tuple[Optional[Token], Optional[Token]]], Optional[Callable[[AstNode, Optional[Token], Optional[Token]], None]]) -> None
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"""
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Scans the tree under the node depth-first using an explicit stack. It avoids implicit recursion
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via the function call stack to avoid hitting 'maximum recursion depth exceeded' error.
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It calls ``previsit()`` and ``postvisit()`` as follows:
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* ``previsit(node, par_value)`` - should return ``(par_value, value)``
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``par_value`` is as returned from ``previsit()`` of the parent.
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* ``postvisit(node, par_value, value)`` - should return ``value``
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``par_value`` is as returned from ``previsit()`` of the parent, and ``value`` is as
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returned from ``previsit()`` of this node itself. The return ``value`` is ignored except
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the one for the root node, which is returned from the overall ``visit_tree()`` call.
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For the initial node, ``par_value`` is None. ``postvisit`` may be None.
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"""
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if not postvisit:
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postvisit = lambda node, pvalue, value: None
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iter_children = iter_children_func(node)
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done = set()
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ret = None
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stack = [(node, None, _PREVISIT)] # type: List[Tuple[AstNode, Optional[Token], Union[Optional[Token], object]]]
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while stack:
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current, par_value, value = stack.pop()
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if value is _PREVISIT:
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assert current not in done # protect againt infinite loop in case of a bad tree.
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done.add(current)
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pvalue, post_value = previsit(current, par_value)
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stack.append((current, par_value, post_value))
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# Insert all children in reverse order (so that first child ends up on top of the stack).
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ins = len(stack)
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for n in iter_children(current):
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stack.insert(ins, (n, pvalue, _PREVISIT))
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else:
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ret = postvisit(current, par_value, cast(Optional[Token], value))
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return ret
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def walk(node):
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# type: (Module) -> Iterator[Union[Module, AstNode]]
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"""
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Recursively yield all descendant nodes in the tree starting at ``node`` (including ``node``
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itself), using depth-first pre-order traversal (yieling parents before their children).
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This is similar to ``ast.walk()``, but with a different order, and it works for both ``ast`` and
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``astroid`` trees. Also, as ``iter_children()``, it skips singleton nodes generated by ``ast``.
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"""
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iter_children = iter_children_func(node)
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done = set()
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stack = [node]
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while stack:
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current = stack.pop()
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assert current not in done # protect againt infinite loop in case of a bad tree.
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done.add(current)
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yield current
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# Insert all children in reverse order (so that first child ends up on top of the stack).
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# This is faster than building a list and reversing it.
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ins = len(stack)
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for c in iter_children(current):
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stack.insert(ins, c)
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def replace(text, replacements):
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# type: (str, List[Tuple[int, int, str]]) -> str
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"""
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Replaces multiple slices of text with new values. This is a convenience method for making code
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modifications of ranges e.g. as identified by ``ASTTokens.get_text_range(node)``. Replacements is
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an iterable of ``(start, end, new_text)`` tuples.
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For example, ``replace("this is a test", [(0, 4, "X"), (8, 9, "THE")])`` produces
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``"X is THE test"``.
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"""
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p = 0
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parts = []
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for (start, end, new_text) in sorted(replacements):
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parts.append(text[p:start])
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parts.append(new_text)
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p = end
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parts.append(text[p:])
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return ''.join(parts)
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class NodeMethods(object):
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"""
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Helper to get `visit_{node_type}` methods given a node's class and cache the results.
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"""
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def __init__(self):
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# type: () -> None
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self._cache = {} # type: Dict[Union[ABCMeta, type], Callable[[AstNode, Token, Token], Tuple[Token, Token]]]
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def get(self, obj, cls):
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# type: (Any, Union[ABCMeta, type]) -> Callable
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"""
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Using the lowercase name of the class as node_type, returns `obj.visit_{node_type}`,
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or `obj.visit_default` if the type-specific method is not found.
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"""
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method = self._cache.get(cls)
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if not method:
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name = "visit_" + cls.__name__.lower()
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method = getattr(obj, name, obj.visit_default)
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self._cache[cls] = method
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return method
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if sys.version_info[0] == 2:
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# Python 2 doesn't support non-ASCII identifiers, and making the real patched_generate_tokens support Python 2
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# means working with raw tuples instead of tokenize.TokenInfo namedtuples.
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def patched_generate_tokens(original_tokens):
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# type: (Any) -> Any
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return original_tokens
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else:
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def patched_generate_tokens(original_tokens):
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# type: (Iterator[tokenize.TokenInfo]) -> Iterator[tokenize.TokenInfo]
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"""
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Fixes tokens yielded by `tokenize.generate_tokens` to handle more non-ASCII characters in identifiers.
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Workaround for https://github.com/python/cpython/issues/68382.
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Should only be used when tokenizing a string that is known to be valid syntax,
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because it assumes that error tokens are not actually errors.
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Combines groups of consecutive NAME, NUMBER, and/or ERRORTOKEN tokens into a single NAME token.
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"""
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group = [] # type: List[tokenize.TokenInfo]
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for tok in original_tokens:
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if (
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tok.type in (tokenize.NAME, tokenize.ERRORTOKEN, tokenize.NUMBER)
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# Only combine tokens if they have no whitespace in between
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and (not group or group[-1].end == tok.start)
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):
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group.append(tok)
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else:
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for combined_token in combine_tokens(group):
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yield combined_token
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group = []
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yield tok
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for combined_token in combine_tokens(group):
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yield combined_token
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def combine_tokens(group):
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# type: (List[tokenize.TokenInfo]) -> List[tokenize.TokenInfo]
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if not any(tok.type == tokenize.ERRORTOKEN for tok in group) or len({tok.line for tok in group}) != 1:
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return group
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return [
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tokenize.TokenInfo(
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type=tokenize.NAME,
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string="".join(t.string for t in group),
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start=group[0].start,
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end=group[-1].end,
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line=group[0].line,
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)
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]
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