""" This is an implementation of wcwidth() and wcswidth() (defined in IEEE Std 1002.1-2001) for Unicode. https://github.com/jquast/wcwidth """ # from Markus Kuhn's C code at: # # http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c # # This is an implementation of wcwidth() and wcswidth() (defined in # IEEE Std 1002.1-2001) for Unicode. # # http://www.opengroup.org/onlinepubs/007904975/functions/wcwidth.html # http://www.opengroup.org/onlinepubs/007904975/functions/wcswidth.html # # In fixed-width output devices, Latin characters all occupy a single # "cell" position of equal width, whereas ideographic CJK characters # occupy two such cells. Interoperability between terminal-line # applications and (teletype-style) character terminals using the # UTF-8 encoding requires agreement on which character should advance # the cursor by how many cell positions. No established formal # standards exist at present on which Unicode character shall occupy # how many cell positions on character terminals. These routines are # a first attempt of defining such behavior based on simple rules # applied to data provided by the Unicode Consortium. # # For some graphical characters, the Unicode standard explicitly # defines a character-cell width via the definition of the East Asian # FullWidth (F), Wide (W), Half-width (H), and Narrow (Na) classes. # In all these cases, there is no ambiguity about which width a # terminal shall use. For characters in the East Asian Ambiguous (A) # class, the width choice depends purely on a preference of backward # compatibility with either historic CJK or Western practice. # Choosing single-width for these characters is easy to justify as # the appropriate long-term solution, as the CJK practice of # displaying these characters as double-width comes from historic # implementation simplicity (8-bit encoded characters were displayed # single-width and 16-bit ones double-width, even for Greek, # Cyrillic, etc.) and not any typographic considerations. # # Much less clear is the choice of width for the Not East Asian # (Neutral) class. Existing practice does not dictate a width for any # of these characters. It would nevertheless make sense # typographically to allocate two character cells to characters such # as for instance EM SPACE or VOLUME INTEGRAL, which cannot be # represented adequately with a single-width glyph. The following # routines at present merely assign a single-cell width to all # neutral characters, in the interest of simplicity. This is not # entirely satisfactory and should be reconsidered before # establishing a formal standard in this area. At the moment, the # decision which Not East Asian (Neutral) characters should be # represented by double-width glyphs cannot yet be answered by # applying a simple rule from the Unicode database content. Setting # up a proper standard for the behavior of UTF-8 character terminals # will require a careful analysis not only of each Unicode character, # but also of each presentation form, something the author of these # routines has avoided to do so far. # # http://www.unicode.org/unicode/reports/tr11/ # # Markus Kuhn -- 2007-05-26 (Unicode 5.0) # # Permission to use, copy, modify, and distribute this software # for any purpose and without fee is hereby granted. The author # disclaims all warranties with regard to this software. # # Latest version: http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c from __future__ import division from .table_wide import WIDE_EASTASIAN from .table_comb import NONZERO_COMBINING def _bisearch(ucs, table): " auxiliary function for binary search in interval table " lbound = 0 ubound = len(table) - 1 if ucs < table[0][0] or ucs > table[ubound][1]: return 0 while ubound >= lbound: mid = (lbound + ubound) // 2 if ucs > table[mid][1]: lbound = mid + 1 elif ucs < table[mid][0]: ubound = mid - 1 else: return 1 return 0 def wcwidth(wc): """wcwidth(wc) -> int The wcwidth() function returns 0 if the wc argument has no printable effect on a terminal (such as NUL '\0'), -1 if wc is not printable, or has an indeterminate effect on the terminal (control or combining). Otherwise, the number of column positions the character occupies on a graphic terminal (1 or 2). The following have a column width of -1: - Non-spacing and enclosing combining characters (general category code Mn or Me in the Unicode database). Generally, having a non-zero value returned by ``unicodedata.combining()``. - C0 control characters (U+001 through U+01F). - C1 control characters and DEL (U+07F through U+0A0). The following have a column width of 0: - NULL (U+0000, 0). - COMBINING GRAPHEME JOINER (U+034F). - ZERO WIDTH SPACE (U+200B) through RIGHT-TO-LEFT MARK (U+200F). - LINE SEPERATOR (U+2028) and PARAGRAPH SEPERATOR (U+2029). - LEFT-TO-RIGHT EMBEDDING (U+202A) through RIGHT-TO-LEFT OVERRIDE (U+202E). - WORD JOINER (U+2060) through INVISIBLE SEPARATOR (U+2063). The following have a column width of 1: - SOFT HYPHEN (U+00AD) has a column width of 1. - All remaining characters (including all printable ISO 8859-1 and WGL4 characters, Unicode control characters, etc.) have a column width of 1. The following have a column width of 2: - Spacing characters in the East Asian Wide (W) or East Asian Full-width (F) category as defined in Unicode Technical Report #11 have a column width of 2. """ ucs = ord(wc) # NOTE: created by hand, there isn't anything identifiable other than # general Cf category code to identify these, and some characters in Cf # category code are of non-zero width. if (0 == ucs or 0x034F == ucs or 0x200B <= ucs <= 0x200F or 0x2028 == ucs or 0x2029 == ucs or 0x202A <= ucs <= 0x202E or 0x2060 <= ucs <= 0x2063): return 0 # C0/C1 control characters if ucs < 32 or 0x07F <= ucs < 0x0A0: return -1 # combining characters have indeterminate effects unless # combined with additional characters. if _bisearch(ucs, NONZERO_COMBINING): return -1 return 1 + _bisearch(ucs, WIDE_EASTASIAN) def wcswidth(pwcs, n=None): """ Return the width in character cells of the first ``n`` unicode string pwcs, or -1 if a non-printable character is encountered. When ``n`` is None (default), return the length of the entire string. """ end = len(pwcs) if n is not None else n idx = slice(0, end) width = 0 for char in pwcs[idx]: wcw = wcwidth(char) if wcw < 0: return -1 else: width += wcw return width