185 lines
6.3 KiB
Python
185 lines
6.3 KiB
Python
# Copyright 2017 Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
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#
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# This file is part of Poezio.
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#
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# Poezio is free software: you can redistribute it and/or modify
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# it under the terms of the zlib license. See the COPYING file.
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'''This is a template module just for instruction. And poopt.'''
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from typing import List, Tuple
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# CFFI codepath.
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from cffi import FFI
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ffi = FFI()
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ffi.cdef("""
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typedef long wchar_t;
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int wcwidth(wchar_t c);
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""")
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libc = ffi.dlopen(None)
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# Cython codepath.
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#cdef extern from "wchar.h":
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# ctypedef Py_UCS4 wchar_t
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# int wcwidth(wchar_t c)
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# Just checking if the return value is -1. In some (all?) implementations,
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# wcwidth("😆") returns -1 while it should return 2. In these cases, we
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# return 1 instead because this is by far the most probable real value.
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# Since the string is received from python, and the unicode character is
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# extracted with mbrtowc(), and supposing these two compononents are not
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# bugged, and since poezio’s code should never pass '\t', '\n' or their
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# friends, a return value of -1 from wcwidth() is considered to be a bug in
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# wcwidth() (until proven otherwise). xwcwidth() is here to work around
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# this bug.
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def xwcwidth(c: str) -> int:
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character = ord(c)
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res = libc.wcwidth(character)
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if res == -1 and c != '\x19':
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return 1
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return res
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# cut_text: takes a string and returns a tuple of int.
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#
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# Each two int tuple is a line, represented by the ending position it
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# (where it should be cut). Not that this position is calculed using the
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# position of the python string characters, not just the individual bytes.
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#
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# For example,
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# poopt_cut_text("vivent les réfrigérateurs", 6);
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# will return [(0, 6), (7, 10), (11, 17), (17, 22), (22, 24)], meaning that
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# the lines are
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# "vivent", "les", "réfrig", "érateu" and "rs"
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def cut_text(string: str, width: int) -> List[Tuple[int, int]]:
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'''cut_text(text, width)
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Return a list of two-tuple, the first int is the starting position of the line and the second is its end.'''
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# The list of tuples that we return
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retlist = []
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# The start position (in the python-string) of the next line
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#: unsigned int
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start_pos = 0
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# The position of the last space seen in the current line. This is used
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# to cut on spaces instead of cutting inside words, if possible (aka if
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# there is a space)
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#: int
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last_space = -1
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# The number of columns taken by chars between start_pos and last_space
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#: size_t
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cols_until_space = 0
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# Number of columns taken to display the current line so far
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#: size_t
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columns = 0
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#: wchar_t
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#wc = 0
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# The position, considering unicode chars (aka, the position in the
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# python string). This is used to determine the position in the python
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# string at which we should cut */
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#: unsigned int
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#spos = -1
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in_special_character = False
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for spos, wc in enumerate(string):
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# Special case to skip poezio special characters that are contained
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# in the python string, but should not be counted as chars because
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# they will not be displayed. Those are the formatting chars (to
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# insert colors or things like that in the string)
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if in_special_character:
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# Skip everything until the end of this format marker, but
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# without increasing the number of columns of the current
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# line. Because these chars are not printed.
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if wc in ('u', 'a', 'i', 'b', 'o', '}'):
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in_special_character = False
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continue
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if wc == '\x19':
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in_special_character = True
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continue
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# This is one condition to end the line: an explicit \n is found
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if wc == '\n':
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spos += 1
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retlist.append((start_pos, spos))
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# And then initiate a new line
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start_pos = spos
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last_space = -1
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columns = 0
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continue
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# Get the number of columns needed to display this character. May be 0, 1 or 2
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cols = xwcwidth(wc)
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# This is the second condition to end the line: we have consumed
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# enough columns to fill a whole line
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if columns + cols > width:
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# If possible, cut on a space
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if last_space != -1:
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retlist.append((start_pos, last_space))
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start_pos = last_space + 1
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last_space = -1
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columns -= (cols_until_space + 1)
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else:
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# Otherwise, cut in the middle of a word
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retlist.append((start_pos, spos))
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start_pos = spos
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columns = 0
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# We save the position of the last space seen in this line, and the
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# number of columns we have until now. This helps us keep track of
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# the columns to count when we will use that space as a cutting
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# point, later
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if wc == ' ':
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last_space = spos
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cols_until_space = columns
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# We advanced from one char, increment spos by one and add the
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# char's columns to the line's columns
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columns += cols
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# We are at the end of the string, append the last line, not finished
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retlist.append((start_pos, spos + 1))
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return retlist
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# wcswidth: An emulation of the POSIX wcswidth(3) function using xwcwidth.
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def wcswidth(string: str) -> int:
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'''wcswidth(s)
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The wcswidth() function returns the number of columns needed to represent the wide-character string pointed to by s. Raise UnicodeError if an invalid unicode value is passed'''
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columns = 0
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for wc in string:
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columns += xwcwidth(wc)
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return columns
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# cut_by_columns: takes a python string and a number of columns, returns a
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# python string truncated to take at most that many columns
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# For example cut_by_columns(n, "エメルカ") will return:
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# - n == 5 -> "エメ" (which takes only 4 columns since we can't cut the
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# next character in half)
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# - n == 2 -> "エ"
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# - n == 1 -> ""
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# - n == 42 -> "エメルカ"
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# - etc
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def cut_by_columns(string: str, limit: int) -> str:
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'''cut_by_columns(string, limit)
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returns a string truncated to take at most limit columns'''
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spos = 0
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columns = 0
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for wc in string:
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if columns == limit:
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break
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cols = xwcwidth(wc)
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if columns + cols > limit:
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break
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spos += 1
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columns += cols
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return string[:spos]
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