358 lines
11 KiB
Python
358 lines
11 KiB
Python
# Urwid unicode character processing tables
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# Copyright (C) 2004-2011 Ian Ward
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#
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# Urwid web site: https://urwid.org/
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from __future__ import annotations
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import re
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import typing
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import warnings
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import wcwidth
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if typing.TYPE_CHECKING:
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from typing_extensions import Literal
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SAFE_ASCII_RE = re.compile("^[ -~]*$")
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SAFE_ASCII_BYTES_RE = re.compile(b"^[ -~]*$")
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_byte_encoding: Literal["utf8", "narrow", "wide"] = "narrow"
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def get_char_width(char: str) -> Literal[0, 1, 2]:
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width = wcwidth.wcwidth(char)
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if width < 0:
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return 0
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return width
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def get_width(o: int) -> Literal[0, 1, 2]:
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"""Return the screen column width for unicode ordinal o."""
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return get_char_width(chr(o))
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def decode_one(text: bytes | str, pos: int) -> tuple[int, int]:
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"""
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Return (ordinal at pos, next position) for UTF-8 encoded text.
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"""
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lt = len(text) - pos
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b2 = 0 # Fallback, not changing anything
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b3 = 0 # Fallback, not changing anything
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b4 = 0 # Fallback, not changing anything
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try:
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if isinstance(text, str):
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b1 = ord(text[pos])
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if lt > 1:
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b2 = ord(text[pos + 1])
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if lt > 2:
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b3 = ord(text[pos + 2])
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if lt > 3:
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b4 = ord(text[pos + 3])
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else:
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b1 = text[pos]
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if lt > 1:
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b2 = text[pos + 1]
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if lt > 2:
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b3 = text[pos + 2]
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if lt > 3:
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b4 = text[pos + 3]
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except Exception as e:
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raise ValueError(f"{e}: text={text!r}, pos={pos!r}, lt={lt!r}").with_traceback(e.__traceback__) from e
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if not b1 & 0x80:
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return b1, pos + 1
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error = ord("?"), pos + 1
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if lt < 2:
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return error
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if b1 & 0xE0 == 0xC0:
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if b2 & 0xC0 != 0x80:
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return error
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o = ((b1 & 0x1F) << 6) | (b2 & 0x3F)
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if o < 0x80:
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return error
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return o, pos + 2
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if lt < 3:
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return error
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if b1 & 0xF0 == 0xE0:
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if b2 & 0xC0 != 0x80:
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return error
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if b3 & 0xC0 != 0x80:
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return error
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o = ((b1 & 0x0F) << 12) | ((b2 & 0x3F) << 6) | (b3 & 0x3F)
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if o < 0x800:
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return error
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return o, pos + 3
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if lt < 4:
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return error
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if b1 & 0xF8 == 0xF0:
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if b2 & 0xC0 != 0x80:
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return error
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if b3 & 0xC0 != 0x80:
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return error
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if b4 & 0xC0 != 0x80:
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return error
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o = ((b1 & 0x07) << 18) | ((b2 & 0x3F) << 12) | ((b3 & 0x3F) << 6) | (b4 & 0x3F)
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if o < 0x10000:
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return error
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return o, pos + 4
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return error
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def decode_one_uni(text: str, i: int) -> tuple[int, int]:
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"""
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decode_one implementation for unicode strings
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"""
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return ord(text[i]), i + 1
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def decode_one_right(text: bytes, pos: int) -> tuple[int, int] | None:
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"""
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Return (ordinal at pos, next position) for UTF-8 encoded text.
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pos is assumed to be on the trailing byte of a utf-8 sequence.
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"""
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if not isinstance(text, bytes):
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raise TypeError(text)
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error = ord("?"), pos - 1
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p = pos
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while p >= 0:
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if text[p] & 0xC0 != 0x80:
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o, _next_pos = decode_one(text, p)
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return o, p - 1
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p -= 1
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if p == p - 4:
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return error
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return None
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def set_byte_encoding(enc: Literal["utf8", "narrow", "wide"]) -> None:
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if enc not in {"utf8", "narrow", "wide"}:
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raise ValueError(enc)
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global _byte_encoding # noqa: PLW0603 # pylint: disable=global-statement
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_byte_encoding = enc
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def get_byte_encoding() -> Literal["utf8", "narrow", "wide"]:
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return _byte_encoding
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def calc_string_text_pos(text: str, start_offs: int, end_offs: int, pref_col: int) -> tuple[int, int]:
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"""
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Calculate the closest position to the screen column pref_col in text
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where start_offs is the offset into text assumed to be screen column 0
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and end_offs is the end of the range to search.
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:param text: string
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:param start_offs: starting text position
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:param end_offs: ending text position
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:param pref_col: target column
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:returns: (position, actual_col)
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..note:: this method is a simplified version of `wcwidth.wcswidth` and ideally should be in wcwidth package.
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"""
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if start_offs > end_offs:
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raise ValueError((start_offs, end_offs))
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cols = 0
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for idx in range(start_offs, end_offs):
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width = get_char_width(text[idx])
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if width + cols > pref_col:
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return idx, cols
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cols += width
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return end_offs, cols
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def calc_text_pos(text: str | bytes, start_offs: int, end_offs: int, pref_col: int) -> tuple[int, int]:
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"""
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Calculate the closest position to the screen column pref_col in text
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where start_offs is the offset into text assumed to be screen column 0
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and end_offs is the end of the range to search.
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text may be unicode or a byte string in the target _byte_encoding
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Returns (position, actual_col).
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"""
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if start_offs > end_offs:
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raise ValueError((start_offs, end_offs))
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if isinstance(text, str):
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return calc_string_text_pos(text, start_offs, end_offs, pref_col)
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if not isinstance(text, bytes):
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raise TypeError(text)
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if _byte_encoding == "utf8":
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i = start_offs
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sc = 0
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while i < end_offs:
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o, n = decode_one(text, i)
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w = get_width(o)
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if w + sc > pref_col:
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return i, sc
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i = n
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sc += w
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return i, sc
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# "wide" and "narrow"
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i = start_offs + pref_col
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if i >= end_offs:
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return end_offs, end_offs - start_offs
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if _byte_encoding == "wide" and within_double_byte(text, start_offs, i) == 2:
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i -= 1
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return i, i - start_offs
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def calc_width(text: str | bytes, start_offs: int, end_offs: int) -> int:
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"""
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Return the screen column width of text between start_offs and end_offs.
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text may be unicode or a byte string in the target _byte_encoding
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Some characters are wide (take two columns) and others affect the
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previous character (take zero columns). Use the widths table above
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to calculate the screen column width of text[start_offs:end_offs]
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"""
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if start_offs > end_offs:
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raise ValueError((start_offs, end_offs))
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if isinstance(text, str):
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return sum(get_char_width(char) for char in text[start_offs:end_offs])
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if _byte_encoding == "utf8":
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try:
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return sum(get_char_width(char) for char in text[start_offs:end_offs].decode("utf-8"))
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except UnicodeDecodeError as exc:
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warnings.warn(
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"`calc_width` with text encoded to bytes can produce incorrect results"
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f"due to possible offset in the middle of character: {exc}",
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UnicodeWarning,
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stacklevel=2,
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)
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i = start_offs
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sc = 0
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while i < end_offs:
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o, i = decode_one(text, i)
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w = get_width(o)
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sc += w
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return sc
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# "wide", "narrow" or all printable ASCII, just return the character count
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return end_offs - start_offs
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def is_wide_char(text: str | bytes, offs: int) -> bool:
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"""
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Test if the character at offs within text is wide.
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text may be unicode or a byte string in the target _byte_encoding
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"""
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if isinstance(text, str):
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return get_char_width(text[offs]) == 2
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if not isinstance(text, bytes):
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raise TypeError(text)
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if _byte_encoding == "utf8":
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o, _n = decode_one(text, offs)
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return get_width(o) == 2
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if _byte_encoding == "wide":
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return within_double_byte(text, offs, offs) == 1
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return False
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def move_prev_char(text: str | bytes, start_offs: int, end_offs: int) -> int:
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"""
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Return the position of the character before end_offs.
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"""
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if start_offs >= end_offs:
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raise ValueError((start_offs, end_offs))
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if isinstance(text, str):
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return end_offs - 1
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if not isinstance(text, bytes):
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raise TypeError(text)
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if _byte_encoding == "utf8":
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o = end_offs - 1
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while text[o] & 0xC0 == 0x80:
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o -= 1
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return o
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if _byte_encoding == "wide" and within_double_byte(text, start_offs, end_offs - 1) == 2:
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return end_offs - 2
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return end_offs - 1
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def move_next_char(text: str | bytes, start_offs: int, end_offs: int) -> int:
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"""
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Return the position of the character after start_offs.
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"""
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if start_offs >= end_offs:
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raise ValueError((start_offs, end_offs))
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if isinstance(text, str):
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return start_offs + 1
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if not isinstance(text, bytes):
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raise TypeError(text)
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if _byte_encoding == "utf8":
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o = start_offs + 1
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while o < end_offs and text[o] & 0xC0 == 0x80:
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o += 1
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return o
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if _byte_encoding == "wide" and within_double_byte(text, start_offs, start_offs) == 1:
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return start_offs + 2
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return start_offs + 1
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def within_double_byte(text: bytes, line_start: int, pos: int) -> Literal[0, 1, 2]:
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"""Return whether pos is within a double-byte encoded character.
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text -- byte string in question
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line_start -- offset of beginning of line (< pos)
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pos -- offset in question
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Return values:
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0 -- not within dbe char, or double_byte_encoding == False
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1 -- pos is on the 1st half of a dbe char
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2 -- pos is on the 2nd half of a dbe char
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"""
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if not isinstance(text, bytes):
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raise TypeError(text)
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v = text[pos]
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if 0x40 <= v < 0x7F:
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# might be second half of big5, uhc or gbk encoding
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if pos == line_start:
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return 0
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if text[pos - 1] >= 0x81 and within_double_byte(text, line_start, pos - 1) == 1:
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return 2
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return 0
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if v < 0x80:
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return 0
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i = pos - 1
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while i >= line_start:
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if text[i] < 0x80:
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break
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i -= 1
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if (pos - i) & 1:
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return 1
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return 2
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