Edit: wcwidth.py
""" This is a python implementation of wcwidth() and wcswidth(). https://github.com/jquast/wcwidth from Markus Kuhn's C code, retrieved from: 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/ Latest version: http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c """ from __future__ import division # std imports import os import sys import warnings # local from .table_wide import WIDE_EASTASIAN from .table_zero import ZERO_WIDTH from .unicode_versions import list_versions try: # std imports from functools import lru_cache except ImportError: # lru_cache was added in Python 3.2 # 3rd party from backports.functools_lru_cache import lru_cache # global cache _UNICODE_CMPTABLE = None _PY3 = (sys.version_info[0] >= 3) # 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. # Also includes some Cc, Mn, Zl, and Zp characters ZERO_WIDTH_CF = set([ 0, # Null (Cc) 0x034F, # Combining grapheme joiner (Mn) 0x200B, # Zero width space 0x200C, # Zero width non-joiner 0x200D, # Zero width joiner 0x200E, # Left-to-right mark 0x200F, # Right-to-left mark 0x2028, # Line separator (Zl) 0x2029, # Paragraph separator (Zp) 0x202A, # Left-to-right embedding 0x202B, # Right-to-left embedding 0x202C, # Pop directional formatting 0x202D, # Left-to-right override 0x202E, # Right-to-left override 0x2060, # Word joiner 0x2061, # Function application 0x2062, # Invisible times 0x2063, # Invisible separator ]) def _bisearch(ucs, table): """ Auxiliary function for binary search in interval table. :arg int ucs: Ordinal value of unicode character. :arg list table: List of starting and ending ranges of ordinal values, in form of ``[(start, end), ...]``. :rtype: int :returns: 1 if ordinal value ucs is found within lookup table, else 0. """ 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 @lru_cache(maxsize=1000) def wcwidth(wc, unicode_version='auto'): r""" Given one Unicode character, return its printable length on a terminal. :param str wc: A single Unicode character. :param str unicode_version: A Unicode version number, such as ``'6.0.0'``, the list of available version levels may be listed by pairing function :func:`list_versions`. Any version string may be specified without error -- the nearest matching version is selected. When ``latest`` (default), the highest Unicode version level is used. :return: The width, in cells, necessary to display the character of Unicode string character, ``wc``. 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, such as a control character. Otherwise, the number of column positions the character occupies on a graphic terminal (1 or 2) is returned. :rtype: int The following have a column width of -1: - 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: - Non-spacing and enclosing combining characters (general category code Mn or Me in the Unicode database). - NULL (``U+0000``). - COMBINING GRAPHEME JOINER (``U+034F``). - ZERO WIDTH SPACE (``U+200B``) *through* RIGHT-TO-LEFT MARK (``U+200F``). - LINE SEPARATOR (``U+2028``) *and* PARAGRAPH SEPARATOR (``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``). - All remaining characters, including all printable ISO 8859-1 and WGL4 characters, Unicode control characters, etc. 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. - Some kinds of Emoji or symbols. """ # 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. ucs = ord(wc) if ucs in ZERO_WIDTH_CF: return 0 # C0/C1 control characters if ucs < 32 or 0x07F <= ucs < 0x0A0: return -1 _unicode_version = _wcmatch_version(unicode_version) # combining characters with zero width if _bisearch(ucs, ZERO_WIDTH[_unicode_version]): return 0 # "Wide AastAsian" (and emojis) return 1 + _bisearch(ucs, WIDE_EASTASIAN[_unicode_version]) def wcswidth(pwcs, n=None, unicode_version='auto'): """ Given a unicode string, return its printable length on a terminal. :param str pwcs: Measure width of given unicode string. :param int n: When ``n`` is None (default), return the length of the entire string, otherwise width the first ``n`` characters specified. :param str unicode_version: An explicit definition of the unicode version level to use for determination, may be ``auto`` (default), which uses the Environment Variable, ``UNICODE_VERSION`` if defined, or the latest available unicode version, otherwise. :rtype: int :returns: The width, in cells, necessary to display the first ``n`` characters of the unicode string ``pwcs``. Returns ``-1`` if a non-printable character is encountered. """ # pylint: disable=C0103 # Invalid argument name "n" end = len(pwcs) if n is None else n idx = slice(0, end) width = 0 for char in pwcs[idx]: wcw = wcwidth(char, unicode_version) if wcw < 0: return -1 width += wcw return width @lru_cache(maxsize=128) def _wcversion_value(ver_string): """ Integer-mapped value of given dotted version string. :param str ver_string: Unicode version string, of form ``n.n.n``. :rtype: tuple(int) :returns: tuple of digit tuples, ``tuple(int, [...])``. """ retval = tuple(map(int, (ver_string.split('.')))) return retval @lru_cache(maxsize=8) def _wcmatch_version(given_version): """ Return nearest matching supported Unicode version level. If an exact match is not determined, the nearest lowest version level is returned after a warning is emitted. For example, given supported levels ``4.1.0`` and ``5.0.0``, and a version string of ``4.9.9``, then ``4.1.0`` is selected and returned: >>> _wcmatch_version('4.9.9') '4.1.0' >>> _wcmatch_version('8.0') '8.0.0' >>> _wcmatch_version('1') '4.1.0' :param str given_version: given version for compare, may be ``auto`` (default), to select Unicode Version from Environment Variable, ``UNICODE_VERSION``. If the environment variable is not set, then the latest is used. :rtype: str :returns: unicode string, or non-unicode ``str`` type for python 2 when given ``version`` is also type ``str``. """ # Design note: the choice to return the same type that is given certainly # complicates it for python 2 str-type, but allows us to define an api that # to use 'string-type', for unicode version level definitions, so all of our # example code works with all versions of python. That, along with the # string-to-numeric and comparisons of earliest, latest, matching, or # nearest, greatly complicates this function. _return_str = not _PY3 and isinstance(given_version, str) if _return_str: unicode_versions = [ucs.encode() for ucs in list_versions()] else: unicode_versions = list_versions() latest_version = unicode_versions[-1] if given_version in (u'auto', 'auto'): given_version = os.environ.get( 'UNICODE_VERSION', 'latest' if not _return_str else latest_version.encode()) if given_version in (u'latest', 'latest'): # default match, when given as 'latest', use the most latest unicode # version specification level supported. return latest_version if not _return_str else latest_version.encode() if given_version in unicode_versions: # exact match, downstream has specified an explicit matching version # matching any value of list_versions(). return given_version if not _return_str else given_version.encode() # The user's version is not supported by ours. We return the newest unicode # version level that we support below their given value. try: cmp_given = _wcversion_value(given_version) except ValueError: # submitted value raises ValueError in int(), warn and use latest. warnings.warn("UNICODE_VERSION value, {given_version!r}, is invalid. " "Value should be in form of `integer[.]+', the latest " "supported unicode version {latest_version!r} has been " "inferred.".format(given_version=given_version, latest_version=latest_version)) return latest_version if not _return_str else latest_version.encode() # given version is less than any available version, return earliest # version. earliest_version = unicode_versions[0] cmp_earliest_version = _wcversion_value(earliest_version) if cmp_given <= cmp_earliest_version: # this probably isn't what you wanted, the oldest wcwidth.c you will # find in the wild is likely version 5 or 6, which we both support, # but it's better than not saying anything at all. warnings.warn("UNICODE_VERSION value, {given_version!r}, is lower " "than any available unicode version. Returning lowest " "version level, {earliest_version!r}".format( given_version=given_version, earliest_version=earliest_version)) return earliest_version if not _return_str else earliest_version.encode() # create list of versions which are less than our equal to given version, # and return the tail value, which is the highest level we may support, # or the latest value we support, when completely unmatched or higher # than any supported version. # # function will never complete, always returns. for idx, unicode_version in enumerate(unicode_versions): # look ahead to next value try: cmp_next_version = _wcversion_value(unicode_versions[idx + 1]) except IndexError: # at end of list, return latest version return latest_version if not _return_str else latest_version.encode() # Maybe our given version has less parts, as in tuple(8, 0), than the # next compare version tuple(8, 0, 0). Test for an exact match by # comparison of only the leading dotted piece(s): (8, 0) == (8, 0). if cmp_given == cmp_next_version[:len(cmp_given)]: return unicode_versions[idx + 1] # Or, if any next value is greater than our given support level # version, return the current value in index. Even though it must # be less than the given value, its our closest possible match. That # is, 4.1 is returned for given 4.9.9, where 4.1 and 5.0 are available. if cmp_next_version > cmp_given: return unicode_version assert False, ("Code path unreachable", given_version, unicode_versions)
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