mirror of
https://github.com/Instagram/LibCST.git
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70 lines
2.3 KiB
Python
70 lines
2.3 KiB
Python
# Copyright (c) Facebook, Inc. and its 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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# pyre-strict
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from dataclasses import dataclass
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from typing import Iterable, Optional, Sequence, Tuple
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from libcst._tabs import expand_tabs
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_EOF_STR: str = "end of file (EOF)"
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_NEWLINE_CHARS: str = "\r\n"
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@dataclass(frozen=True, eq=False)
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class ParserSyntaxError(Exception):
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"""
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Contains error information about the parser tree.
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"""
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message: str
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encountered: Optional[str] # None means EOF
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expected: Optional[Iterable[str]] # None means EOF
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pos: Tuple[int, int] # (one-indexed line, zero-indexed column)
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lines: Sequence[str] # source code, used to generate a human-readable output
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def __str__(self) -> str:
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"""
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A human-readable error message of where the syntax error is in their code.
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"""
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if self.encountered is not None:
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encountered_str = repr(self.encountered)
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else:
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encountered_str = _EOF_STR
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if self.expected is not None:
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expected_str = f"one of {repr(list(self.expected))}"
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else:
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expected_str = _EOF_STR
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pos_line, pos_column = self.pos
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editor_line = self.editor_line
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editor_column = self.editor_column
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return (
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f"Syntax Error: {self.message} @ {editor_line}:{editor_column}.\n"
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+ f"Encountered {encountered_str}, but expected {expected_str}.\n\n"
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+ f"{expand_tabs(self.lines[pos_line - 1]).rstrip(_NEWLINE_CHARS)}\n"
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+ f"{' ' * (editor_column - 1)}^"
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)
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@property
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def editor_line(self) -> int:
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"""
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The one-indexed line in the user's editor.
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"""
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return self.pos[0] # the line in pos is already one-indexed.
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@property
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def editor_column(self) -> int:
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"""
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The one-indexed column in the user's editor, assuming tabs expand to 1-8 spaces.
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"""
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pos_line, pos_column = self.pos
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tab_adjusted_column = len(expand_tabs(self.lines[pos_line - 1][:pos_column]))
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# Text editors use a one-indexed column, so we need to add one to our
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# zero-indexed column to get a human-readable result.
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return tab_adjusted_column + 1
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