89 lines
2.6 KiB
Python
89 lines
2.6 KiB
Python
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# SPDX-FileCopyrightText: 2025 Blender Authors
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#
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# SPDX-License-Identifier: GPL-2.0-or-later
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"""
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When writing text checking utilities, it's not always straightforward
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to find line numbers and ranges from an offset within the text.
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This module provides helpers to efficiently do this.
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The main utility is ``finditer_with_line_numbers_and_bounds``,
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an alternative to ``re.finditer`` which yields line numbers and offsets
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for the line bounds - useful for scanning files and reporting errors that include the line contents.
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"""
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__all__ = (
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"finditer_newline_cache_compute",
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"finditer_with_line_numbers_and_bounds",
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"line_to_offset_range",
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)
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from collections.abc import (
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Iterator,
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)
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import re as _re
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def finditer_newline_cache_compute(text: str) -> tuple[dict[int, int], list[int]]:
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"""
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Return a tuple containing:
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Offset to
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"""
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# Offset to line lookup.
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offset_to_line_cache: dict[int, int] = {}
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# Line to offset lookup.
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line_to_offset_cache: list[int] = [0]
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for i, m in enumerate(_re.finditer("\\n", text), 1):
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ofs = m.start()
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offset_to_line_cache[ofs] = i
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line_to_offset_cache.append(ofs)
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return offset_to_line_cache, line_to_offset_cache
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def finditer_with_line_numbers_and_bounds(
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pattern: str,
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text: str,
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*,
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offset_to_line_cache: dict[int, int] | None = None,
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flags: int = 0,
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) -> Iterator[tuple[_re.Match[str], int, tuple[int, int]]]:
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"""
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A version of ``re.finditer`` that returns ``(match, line_number, line_bounds)``.
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Note that ``offset_to_line_cache`` is the first return value from
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``finditer_newline_cache_compute``.
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This should be passed in if the iterator is called multiple times
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on the same buffer, to avoid calculating this every time.
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"""
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if offset_to_line_cache is None:
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offset_to_line_cache, line_to_offset_cache = finditer_newline_cache_compute(text)
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del line_to_offset_cache
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text_len = len(text)
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for m in _re.finditer(pattern, text, flags):
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if (beg := text.rfind("\n", 0, m.start())) == -1:
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beg = 0
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line_number = 0
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else:
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line_number = offset_to_line_cache[beg]
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if (end := text.find("\n", m.end(), text_len)) == -1:
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end = text_len
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yield m, line_number, (beg, end)
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def line_to_offset_range(line: int, offset_limit: int, line_to_offset_cache: list[int]) -> tuple[int, int]:
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"""
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Given an offset, return line bounds.
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"""
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assert line >= 0
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beg = line_to_offset_cache[line]
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end = line_to_offset_cache[line + 1] if (line + 1 < len(line_to_offset_cache)) else offset_limit
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return beg, end
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