ZerethShell — File Manager

cells.py

from __future__ import annotations

from functools import lru_cache
from typing import Callable

from ._cell_widths import CELL_WIDTHS

# Ranges of unicode ordinals that produce a 1-cell wide character
# This is non-exhaustive, but covers most common Western characters
_SINGLE_CELL_UNICODE_RANGES: list[tuple[int, int]] = [
    (0x20, 0x7E),  # Latin (excluding non-printable)
    (0xA0, 0xAC),
    (0xAE, 0x002FF),
    (0x00370, 0x00482),  # Greek / Cyrillic
    (0x02500, 0x025FC),  # Box drawing, box elements, geometric shapes
    (0x02800, 0x028FF),  # Braille
]

# A set of characters that are a single cell wide
_SINGLE_CELLS = frozenset(
    [
        character
        for _start, _end in _SINGLE_CELL_UNICODE_RANGES
        for character in map(chr, range(_start, _end + 1))
    ]
)

# When called with a string this will return True if all
# characters are single-cell, otherwise False
_is_single_cell_widths: Callable[[str], bool] = _SINGLE_CELLS.issuperset

@lru_cache(4096)
def cached_cell_len(text: str) -> int:
    """Get the number of cells required to display text.

This method always caches, which may use up a lot of memory. It is recommended to use
    `cell_len` over this method.

Args:
        text (str): Text to display.

Returns:
        int: Get the number of cells required to display text.
    """
    if _is_single_cell_widths(text):
        return len(text)
    return sum(map(get_character_cell_size, text))

def cell_len(text: str, _cell_len: Callable[[str], int] = cached_cell_len) -> int:
    """Get the number of cells required to display text.

Args:
        text (str): Text to display.

Returns:
        int: Get the number of cells required to display text.
    """
    if len(text) < 512:
        return _cell_len(text)
    if _is_single_cell_widths(text):
        return len(text)
    return sum(map(get_character_cell_size, text))

@lru_cache(maxsize=4096)
def get_character_cell_size(character: str) -> int:
    """Get the cell size of a character.

Args:
        character (str): A single character.

Returns:
        int: Number of cells (0, 1 or 2) occupied by that character.
    """
    codepoint = ord(character)
    _table = CELL_WIDTHS
    lower_bound = 0
    upper_bound = len(_table) - 1
    index = (lower_bound + upper_bound) // 2
    while True:
        start, end, width = _table[index]
        if codepoint < start:
            upper_bound = index - 1
        elif codepoint > end:
            lower_bound = index + 1
        else:
            return 0 if width == -1 else width
        if upper_bound < lower_bound:
            break
        index = (lower_bound + upper_bound) // 2
    return 1

def set_cell_size(text: str, total: int) -> str:
    """Set the length of a string to fit within given number of cells."""

if _is_single_cell_widths(text):
        size = len(text)
        if size < total:
            return text + " " * (total - size)
        return text[:total]

if total <= 0:
        return ""
    cell_size = cell_len(text)
    if cell_size == total:
        return text
    if cell_size < total:
        return text + " " * (total - cell_size)

start = 0
    end = len(text)

# Binary search until we find the right size
    while True:
        pos = (start + end) // 2
        before = text[: pos + 1]
        before_len = cell_len(before)
        if before_len == total + 1 and cell_len(before[-1]) == 2:
            return before[:-1] + " "
        if before_len == total:
            return before
        if before_len > total:
            end = pos
        else:
            start = pos

def chop_cells(
    text: str,
    width: int,
) -> list[str]:
    """Split text into lines such that each line fits within the available (cell) width.

Args:
        text: The text to fold such that it fits in the given width.
        width: The width available (number of cells).

Returns:
        A list of strings such that each string in the list has cell width
        less than or equal to the available width.
    """
    _get_character_cell_size = get_character_cell_size
    lines: list[list[str]] = [[]]

append_new_line = lines.append
    append_to_last_line = lines[-1].append

total_width = 0

for character in text:
        cell_width = _get_character_cell_size(character)
        char_doesnt_fit = total_width + cell_width > width

if char_doesnt_fit:
            append_new_line([character])
            append_to_last_line = lines[-1].append
            total_width = cell_width
        else:
            append_to_last_line(character)
            total_width += cell_width

return ["".join(line) for line in lines]

if __name__ == "__main__":  # pragma: no cover
    print(get_character_cell_size("😽"))
    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):
        print(line)
    for n in range(80, 1, -1):
        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) + "|")
        print("x" * n)

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