Toot-Mastodon-CLI-TUI-clien.../toot/wcstring.py

123 lines
3.2 KiB
Python

"""
Utilities for dealing with string containing wide characters.
"""
import re
from typing import Generator, List
from wcwidth import wcwidth, wcswidth
def _wc_hard_wrap(line: str, length: int) -> Generator[str, None, None]:
"""
Wrap text to length characters, breaking when target length is reached,
taking into account character width.
Used to wrap lines which cannot be wrapped on whitespace.
"""
chars = []
chars_len = 0
for char in line:
char_len = wcwidth(char)
if chars_len + char_len > length:
yield "".join(chars)
chars: List[str] = []
chars_len = 0
chars.append(char)
chars_len += char_len
if chars:
yield "".join(chars)
def wc_wrap(text: str, length: int) -> Generator[str, None, None]:
"""
Wrap text to given length, breaking on whitespace and taking into account
character width.
Meant for use on a single line or paragraph. Will destroy spacing between
words and paragraphs and any indentation.
"""
line_words: List[str] = []
line_len = 0
words = re.split(r"\s+", text.strip())
for word in words:
word_len = wcswidth(word)
if line_words and line_len + word_len > length:
line = " ".join(line_words)
if line_len <= length:
yield line
else:
yield from _wc_hard_wrap(line, length)
line_words = []
line_len = 0
line_words.append(word)
line_len += word_len + 1 # add 1 to account for space between words
if line_words:
line = " ".join(line_words)
if line_len <= length:
yield line
else:
yield from _wc_hard_wrap(line, length)
def trunc(text: str, length: int) -> str:
"""
Truncates text to given length, taking into account wide characters.
If truncated, the last char is replaced by an ellipsis.
"""
if length < 1:
raise ValueError("length should be 1 or larger")
# Remove whitespace first so no unnecessary truncation is done.
text = text.strip()
text_length = wcswidth(text)
if text_length <= length:
return text
# We cannot just remove n characters from the end since we don't know how
# wide these characters are and how it will affect text length.
# Use wcwidth to determine how many characters need to be truncated.
chars_to_truncate = 0
trunc_length = 0
for char in reversed(text):
chars_to_truncate += 1
trunc_length += wcwidth(char)
if text_length - trunc_length <= length:
break
# Additional char to make room for ellipsis
n = chars_to_truncate + 1
return text[:-n].strip() + ''
def pad(text: str, length: int) -> str:
"""Pads text to given length, taking into account wide characters."""
text_length = wcswidth(text)
if text_length < length:
return text + ' ' * (length - text_length)
return text
def fit_text(text: str, length: int) -> str:
"""Makes text fit the given length by padding or truncating it."""
text_length = wcswidth(text)
if text_length > length:
return trunc(text, length)
if text_length < length:
return pad(text, length)
return text