175 lines
5.0 KiB
Python
175 lines
5.0 KiB
Python
from __future__ import annotations
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from functools import lru_cache
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from typing import Callable
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from ._cell_widths import CELL_WIDTHS
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# Ranges of unicode ordinals that produce a 1-cell wide character
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# This is non-exhaustive, but covers most common Western characters
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_SINGLE_CELL_UNICODE_RANGES: list[tuple[int, int]] = [
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(0x20, 0x7E), # Latin (excluding non-printable)
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(0xA0, 0xAC),
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(0xAE, 0x002FF),
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(0x00370, 0x00482), # Greek / Cyrillic
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(0x02500, 0x025FC), # Box drawing, box elements, geometric shapes
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(0x02800, 0x028FF), # Braille
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]
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# A set of characters that are a single cell wide
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_SINGLE_CELLS = frozenset(
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[
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character
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for _start, _end in _SINGLE_CELL_UNICODE_RANGES
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for character in map(chr, range(_start, _end + 1))
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]
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)
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# When called with a string this will return True if all
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# characters are single-cell, otherwise False
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_is_single_cell_widths: Callable[[str], bool] = _SINGLE_CELLS.issuperset
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@lru_cache(4096)
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def cached_cell_len(text: str) -> int:
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"""Get the number of cells required to display text.
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This method always caches, which may use up a lot of memory. It is recommended to use
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`cell_len` over this method.
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Args:
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text (str): Text to display.
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Returns:
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int: Get the number of cells required to display text.
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"""
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if _is_single_cell_widths(text):
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return len(text)
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return sum(map(get_character_cell_size, text))
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def cell_len(text: str, _cell_len: Callable[[str], int] = cached_cell_len) -> int:
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"""Get the number of cells required to display text.
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Args:
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text (str): Text to display.
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Returns:
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int: Get the number of cells required to display text.
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"""
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if len(text) < 512:
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return _cell_len(text)
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if _is_single_cell_widths(text):
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return len(text)
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return sum(map(get_character_cell_size, text))
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@lru_cache(maxsize=4096)
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def get_character_cell_size(character: str) -> int:
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"""Get the cell size of a character.
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Args:
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character (str): A single character.
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Returns:
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int: Number of cells (0, 1 or 2) occupied by that character.
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"""
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codepoint = ord(character)
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_table = CELL_WIDTHS
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lower_bound = 0
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upper_bound = len(_table) - 1
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index = (lower_bound + upper_bound) // 2
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while True:
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start, end, width = _table[index]
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if codepoint < start:
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upper_bound = index - 1
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elif codepoint > end:
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lower_bound = index + 1
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else:
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return 0 if width == -1 else width
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if upper_bound < lower_bound:
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break
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index = (lower_bound + upper_bound) // 2
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return 1
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def set_cell_size(text: str, total: int) -> str:
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"""Set the length of a string to fit within given number of cells."""
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if _is_single_cell_widths(text):
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size = len(text)
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if size < total:
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return text + " " * (total - size)
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return text[:total]
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if total <= 0:
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return ""
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cell_size = cell_len(text)
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if cell_size == total:
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return text
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if cell_size < total:
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return text + " " * (total - cell_size)
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start = 0
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end = len(text)
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# Binary search until we find the right size
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while True:
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pos = (start + end) // 2
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before = text[: pos + 1]
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before_len = cell_len(before)
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if before_len == total + 1 and cell_len(before[-1]) == 2:
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return before[:-1] + " "
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if before_len == total:
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return before
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if before_len > total:
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end = pos
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else:
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start = pos
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def chop_cells(
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text: str,
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width: int,
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) -> list[str]:
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"""Split text into lines such that each line fits within the available (cell) width.
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Args:
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text: The text to fold such that it fits in the given width.
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width: The width available (number of cells).
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Returns:
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A list of strings such that each string in the list has cell width
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less than or equal to the available width.
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"""
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_get_character_cell_size = get_character_cell_size
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lines: list[list[str]] = [[]]
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append_new_line = lines.append
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append_to_last_line = lines[-1].append
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total_width = 0
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for character in text:
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cell_width = _get_character_cell_size(character)
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char_doesnt_fit = total_width + cell_width > width
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if char_doesnt_fit:
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append_new_line([character])
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append_to_last_line = lines[-1].append
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total_width = cell_width
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else:
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append_to_last_line(character)
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total_width += cell_width
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return ["".join(line) for line in lines]
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if __name__ == "__main__": # pragma: no cover
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print(get_character_cell_size("😽"))
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for line in chop_cells("""这是对亚洲语言支持的测试。面对模棱两可的想法，拒绝猜测的诱惑。""", 8):
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print(line)
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for n in range(80, 1, -1):
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print(set_cell_size("""这是对亚洲语言支持的测试。面对模棱两可的想法，拒绝猜测的诱惑。""", n) + "|")
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print("x" * n)
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