tools.py

"""Misc. xonsh tools.

The following implementations were forked from the IPython project:

* Copyright (c) 2008-2014, IPython Development Team
* Copyright (C) 2001-2007 Fernando Perez <fperez@colorado.edu>
* Copyright (c) 2001, Janko Hauser <jhauser@zscout.de>
* Copyright (c) 2001, Nathaniel Gray <n8gray@caltech.edu>

Implementations:

* decode()
* encode()
* cast_unicode()
* safe_hasattr()
* indent()

"""
import os
import re
import sys
import builtins
import platform
import traceback
import threading
import subprocess
from itertools import zip_longest
from contextlib import contextmanager
from collections import OrderedDict, Sequence


if sys.version_info[0] >= 3:
    string_types = (str, bytes)
    unicode_type = str
else:
    string_types = (str, unicode)
    unicode_type = unicode

DEFAULT_ENCODING = sys.getdefaultencoding()

ON_WINDOWS = (platform.system() == 'Windows')
ON_MAC = (platform.system() == 'Darwin')
ON_LINUX = (platform.system() == 'Linux')
ON_ARCH = (platform.linux_distribution()[0] == 'arch')
ON_POSIX = (os.name == 'posix')

VER_3_4 = (3, 4)
VER_3_5 = (3, 5)
VER_MAJOR_MINOR = sys.version_info[:2]
V_MAJOR_MINOR = 'v{0}{1}'.format(*sys.version_info[:2])

def docstring_by_version(**kwargs):
    """Sets a docstring by the python version."""
    doc = kwargs.get(V_MAJOR_MINOR, None)
    if V_MAJOR_MINOR is None:
        raise RuntimeError('unrecognized version ' + V_MAJOR_MINOR)
    def dec(f):
        f.__doc__ = doc
        return f
    return dec


class XonshError(Exception):
    pass


def subproc_toks(line, mincol=-1, maxcol=None, lexer=None, returnline=False):
    """Excapsulates tokens in a source code line in a uncaptured
    subprocess $[] starting at a minimum column. If there are no tokens
    (ie in a comment line) this returns None.
    """
    if lexer is None:
        lexer = builtins.__xonsh_execer__.parser.lexer
    if maxcol is None:
        maxcol = len(line) + 1
    lexer.reset()
    lexer.input(line)
    toks = []
    end_offset = 0
    for tok in lexer:
        pos = tok.lexpos
        if tok.type != 'SEMI' and pos >= maxcol:
            break
        if len(toks) == 0 and tok.type in ('WS', 'INDENT'):
            continue  # handle indentation
        elif len(toks) > 0 and toks[-1].type == 'SEMI':
            if pos < maxcol and tok.type not in ('NEWLINE', 'DEDENT', 'WS'):
                toks.clear()
            else:
                break
        if pos < mincol:
            continue
        toks.append(tok)
        if tok.type == 'NEWLINE':
            break
        elif tok.type == 'DEDENT':
            # fake a newline when dedenting without a newline
            tok.type = 'NEWLINE'
            tok.value = '\n'
            tok.lineno -= 1
            tok.lexpos = len(line)
            break
    else:
        if len(toks) == 0:
            return  # handle comment lines
        if toks[-1].type == 'SEMI':
            toks.pop()
        tok = toks[-1]
        pos = tok.lexpos
        if isinstance(tok.value, string_types):
            end_offset = len(tok.value)
        else:
            el = line[pos:].split('#')[0].rstrip()
            end_offset = len(el)
    if len(toks) == 0:
        return  # handle comment lines
    beg, end = toks[0].lexpos, (toks[-1].lexpos + end_offset)
    rtn = '$[' + line[beg:end] + ']'
    if returnline:
        rtn = line[:beg] + rtn + line[end:]
    return rtn


def subexpr_from_unbalanced(expr, ltok, rtok):
    """Attempts to pull out a valid subexpression for unbalanced grouping,
    based on opening tokens, eg. '(', and closing tokens, eg. ')'.  This
    does not do full tokenization, but should be good enough for tab
    completion.
    """
    lcnt = expr.count(ltok)
    if lcnt == 0:
        return expr
    rcnt = expr.count(rtok)
    if lcnt == rcnt:
        return expr
    subexpr = expr.rsplit(ltok, 1)[-1]
    subexpr = subexpr.rsplit(',', 1)[-1]
    subexpr = subexpr.rsplit(':', 1)[-1]
    return subexpr


def decode(s, encoding=None):
    encoding = encoding or DEFAULT_ENCODING
    return s.decode(encoding, "replace")


def encode(u, encoding=None):
    encoding = encoding or DEFAULT_ENCODING
    return u.encode(encoding, "replace")


def cast_unicode(s, encoding=None):
    if isinstance(s, bytes):
        return decode(s, encoding)
    return s


def safe_hasattr(obj, attr):
    """In recent versions of Python, hasattr() only catches AttributeError.
    This catches all errors.
    """
    try:
        getattr(obj, attr)
        return True
    except Exception:  # pylint:disable=bare-except
        return False


def indent(instr, nspaces=4, ntabs=0, flatten=False):
    """Indent a string a given number of spaces or tabstops.

    indent(str,nspaces=4,ntabs=0) -> indent str by ntabs+nspaces.

    Parameters
    ----------
    instr : basestring
        The string to be indented.
    nspaces : int (default: 4)
        The number of spaces to be indented.
    ntabs : int (default: 0)
        The number of tabs to be indented.
    flatten : bool (default: False)
        Whether to scrub existing indentation.  If True, all lines will be
        aligned to the same indentation.  If False, existing indentation will
        be strictly increased.

    Returns
    -------
    outstr : string indented by ntabs and nspaces.

    """
    if instr is None:
        return
    ind = '\t' * ntabs + ' ' * nspaces
    if flatten:
        pat = re.compile(r'^\s*', re.MULTILINE)
    else:
        pat = re.compile(r'^', re.MULTILINE)
    outstr = re.sub(pat, ind, instr)
    if outstr.endswith(os.linesep + ind):
        return outstr[:-len(ind)]
    else:
        return outstr


TERM_COLORS = {
    # Reset
    'NO_COLOR': '\001\033[0m\002',  # Text Reset
    # Regular Colors
    'BLACK': '\001\033[0;30m\002',  # BLACK
    'RED': '\001\033[0;31m\002',  # RED
    'GREEN': '\001\033[0;32m\002',  # GREEN
    'YELLOW': '\001\033[0;33m\002',  # YELLOW
    'BLUE': '\001\033[0;34m\002',  # BLUE
    'PURPLE': '\001\033[0;35m\002',  # PURPLE
    'CYAN': '\001\033[0;36m\002',  # CYAN
    'WHITE': '\001\033[0;37m\002',  # WHITE
    # Bold
    'BOLD_BLACK': '\001\033[1;30m\002',  # BLACK
    'BOLD_RED': '\001\033[1;31m\002',  # RED
    'BOLD_GREEN': '\001\033[1;32m\002',  # GREEN
    'BOLD_YELLOW': '\001\033[1;33m\002',  # YELLOW
    'BOLD_BLUE': '\001\033[1;34m\002',  # BLUE
    'BOLD_PURPLE': '\001\033[1;35m\002',  # PURPLE
    'BOLD_CYAN': '\001\033[1;36m\002',  # CYAN
    'BOLD_WHITE': '\001\033[1;37m\002',  # WHITE
    # Underline
    'UNDERLINE_BLACK': '\001\033[4;30m\002',  # BLACK
    'UNDERLINE_RED': '\001\033[4;31m\002',  # RED
    'UNDERLINE_GREEN': '\001\033[4;32m\002',  # GREEN
    'UNDERLINE_YELLOW': '\001\033[4;33m\002',  # YELLOW
    'UNDERLINE_BLUE': '\001\033[4;34m\002',  # BLUE
    'UNDERLINE_PURPLE': '\001\033[4;35m\002',  # PURPLE
    'UNDERLINE_CYAN': '\001\033[4;36m\002',  # CYAN
    'UNDERLINE_WHITE': '\001\033[4;37m\002',  # WHITE
    # Background
    'BACKGROUND_BLACK': '\001\033[40m\002',  # BLACK
    'BACKGROUND_RED': '\001\033[41m\002',  # RED
    'BACKGROUND_GREEN': '\001\033[42m\002',  # GREEN
    'BACKGROUND_YELLOW': '\001\033[43m\002',  # YELLOW
    'BACKGROUND_BLUE': '\001\033[44m\002',  # BLUE
    'BACKGROUND_PURPLE': '\001\033[45m\002',  # PURPLE
    'BACKGROUND_CYAN': '\001\033[46m\002',  # CYAN
    'BACKGROUND_WHITE': '\001\033[47m\002',  # WHITE
    # High Intensity
    'INTENSE_BLACK': '\001\033[0;90m\002',  # BLACK
    'INTENSE_RED': '\001\033[0;91m\002',  # RED
    'INTENSE_GREEN': '\001\033[0;92m\002',  # GREEN
    'INTENSE_YELLOW': '\001\033[0;93m\002',  # YELLOW
    'INTENSE_BLUE': '\001\033[0;94m\002',  # BLUE
    'INTENSE_PURPLE': '\001\033[0;95m\002',  # PURPLE
    'INTENSE_CYAN': '\001\033[0;96m\002',  # CYAN
    'INTENSE_WHITE': '\001\033[0;97m\002',  # WHITE
    # Bold High Intensity
    'BOLD_INTENSE_BLACK': '\001\033[1;90m\002',  # BLACK
    'BOLD_INTENSE_RED': '\001\033[1;91m\002',  # RED
    'BOLD_INTENSE_GREEN': '\001\033[1;92m\002',  # GREEN
    'BOLD_INTENSE_YELLOW': '\001\033[1;93m\002',  # YELLOW
    'BOLD_INTENSE_BLUE': '\001\033[1;94m\002',  # BLUE
    'BOLD_INTENSE_PURPLE': '\001\033[1;95m\002',  # PURPLE
    'BOLD_INTENSE_CYAN': '\001\033[1;96m\002',  # CYAN
    'BOLD_INTENSE_WHITE': '\001\033[1;97m\002',  # WHITE
    # High Intensity backgrounds
    'BACKGROUND_INTENSE_BLACK': '\001\033[0;100m\002',  # BLACK
    'BACKGROUND_INTENSE_RED': '\001\033[0;101m\002',  # RED
    'BACKGROUND_INTENSE_GREEN': '\001\033[0;102m\002',  # GREEN
    'BACKGROUND_INTENSE_YELLOW': '\001\033[0;103m\002',  # YELLOW
    'BACKGROUND_INTENSE_BLUE': '\001\033[0;104m\002',  # BLUE
    'BACKGROUND_INTENSE_PURPLE': '\001\033[0;105m\002',  # PURPLE
    'BACKGROUND_INTENSE_CYAN': '\001\033[0;106m\002',  # CYAN
    'BACKGROUND_INTENSE_WHITE': '\001\033[0;107m\002',  # WHITE
}


def fallback(cond, backup):
    """Decorator for returning the object if cond is true and a backup if cond is false.
    """
    def dec(obj):
        return obj if cond else backup
    return dec


# The following redirect classes were taken directly from Python 3.5's source
# code (from the contextlib module). This can be removed when 3.5 is released,
# although redirect_stdout exists in 3.4, redirect_stderr does not.
# See the Python software license: https://docs.python.org/3/license.html
# Copyright (c) Python Software Foundation. All rights reserved.
class _RedirectStream:

    _stream = None

    def __init__(self, new_target):
        self._new_target = new_target
        # We use a list of old targets to make this CM re-entrant
        self._old_targets = []

    def __enter__(self):
        self._old_targets.append(getattr(sys, self._stream))
        setattr(sys, self._stream, self._new_target)
        return self._new_target

    def __exit__(self, exctype, excinst, exctb):
        setattr(sys, self._stream, self._old_targets.pop())


class redirect_stdout(_RedirectStream):
    """Context manager for temporarily redirecting stdout to another file::

        # How to send help() to stderr
        with redirect_stdout(sys.stderr):
            help(dir)

        # How to write help() to a file
        with open('help.txt', 'w') as f:
            with redirect_stdout(f):
                help(pow)

    Mostly for backwards compatibility.
    """
    _stream = "stdout"


class redirect_stderr(_RedirectStream):
    """Context manager for temporarily redirecting stderr to another file."""
    _stream = "stderr"


def command_not_found(cmd):
    """Uses the debian/ubuntu command-not-found utility to suggest packages for a
    command that cannot currently be found.
    """
    if not ON_LINUX:
        return ''
    elif not os.path.isfile('/usr/lib/command-not-found'):
        # utility is not on PATH
        return ''
    c = '/usr/lib/command-not-found {0}; exit 0'
    s = subprocess.check_output(c.format(cmd), universal_newlines=True,
                                stderr=subprocess.STDOUT, shell=True)
    s = '\n'.join(s.splitlines()[:-1]).strip()
    return s


def suggest_commands(cmd, env, aliases):
    """Suggests alternative commands given an environment and aliases."""
    suggest_cmds = env.get('SUGGEST_COMMANDS')
    if not suggest_cmds:
        return
    thresh = env.get('SUGGEST_THRESHOLD')
    max_sugg = env.get('SUGGEST_MAX_NUM')
    if max_sugg < 0:
        max_sugg = float('inf')

    cmd = cmd.lower()
    suggested = {}
    for a in builtins.aliases:
        if a not in suggested:
            if levenshtein(a.lower(), cmd, thresh) < thresh:
                suggested[a] = 'Alias'

    for d in filter(os.path.isdir, env.get('PATH')):
        for f in os.listdir(d):
            if f not in suggested:
                if levenshtein(f.lower(), cmd, thresh) < thresh:
                    fname = os.path.join(d, f)
                    suggested[f] = 'Command ({0})'.format(fname)
    suggested = OrderedDict(
        sorted(suggested.items(),
               key=lambda x: suggestion_sort_helper(x[0].lower(), cmd)))
    num = min(len(suggested), max_sugg)

    if num == 0:
        rtn = command_not_found(cmd)
    else:
        oneof = '' if num == 1 else 'one of '
        tips = 'Did you mean {}the following?'.format(oneof)
        items = list(suggested.popitem(False) for _ in range(num))
        length = max(len(key) for key, _ in items) + 2
        alternatives = '\n'.join('    {: <{}} {}'.format(key + ":", length, val)
                                 for key, val in items)
        rtn = '{}\n{}'.format(tips, alternatives)
        c = command_not_found(cmd)
        rtn += ('\n\n' + c) if len(c) > 0 else ''
    return rtn


def print_exception():
    """Print exceptions with/without traceback."""
    if 'XONSH_SHOW_TRACEBACK' not in builtins.__xonsh_env__:
        sys.stderr.write('xonsh: For full traceback set: '
                         '$XONSH_SHOW_TRACEBACK = True\n')
    if builtins.__xonsh_env__.get('XONSH_SHOW_TRACEBACK'):
        traceback.print_exc()
    else:
        exc_type, exc_value, exc_traceback = sys.exc_info()
        exception_only = traceback.format_exception_only(exc_type, exc_value)
        sys.stderr.write(''.join(exception_only))


# Modified from Public Domain code, by Magnus Lie Hetland
# from http://hetland.org/coding/python/levenshtein.py
def levenshtein(a, b, max_dist=float('inf')):
    """Calculates the Levenshtein distance between a and b."""
    n, m = len(a), len(b)
    if abs(n - m) > max_dist:
        return float('inf')
    if n > m:
        # Make sure n <= m, to use O(min(n,m)) space
        a, b = b, a
        n, m = m, n
    current = range(n + 1)
    for i in range(1, m + 1):
        previous, current = current, [i] + [0] * n
        for j in range(1, n + 1):
            add, delete = previous[j] + 1, current[j - 1] + 1
            change = previous[j - 1]
            if a[j - 1] != b[i - 1]:
                change = change + 1
            current[j] = min(add, delete, change)
    return current[n]


def suggestion_sort_helper(x, y):
    """Returns a score (lower is better) for x based on how similar
    it is to y.  Used to rank suggestions."""
    x = x.lower()
    y = y.lower()
    lendiff = len(x) + len(y)
    inx = len([i for i in x if i not in y])
    iny = len([i for i in y if i not in x])
    return lendiff + inx + iny


def escape_windows_title_string(s):
    """Returns a string that is usable by the Windows cmd.exe title
    builtin.  The escaping is based on details here and emperical testing:
    http://www.robvanderwoude.com/escapechars.php
    """
    for c in '^&<>|':
        s = s.replace(c, '^' + c)
    s = s.replace('/?', '/.')
    return s


def on_main_thread():
    """Checks if we are on the main thread or not."""
    return threading.current_thread() is threading.main_thread()


@contextmanager
def swap(namespace, name, value, default=NotImplemented):
    """Swaps a current variable name in a namespace for another value, and then
    replaces it when the context is exited.
    """
    old = getattr(namespace, name, default)
    setattr(namespace, name, value)
    yield value
    if old is default:
        delattr(namespace, name)
    else:
        setattr(namespace, name, old)

#
# Validators and contervers
#


def is_int(x):
    """Tests if something is an integer"""
    return isinstance(x, int)


def is_float(x):
    """Tests if something is a float"""
    return isinstance(x, float)


def is_string(x):
    """Tests if something is a string"""
    return isinstance(x, string_types)


def always_true(x):
    """Returns True"""
    return True


def always_false(x):
    """Returns False"""
    return False


def ensure_string(x):
    """Returns a string if x is not a string, and x if it already is."""
    if isinstance(x, string_types):
        return x
    else:
        return str(x)


def is_env_path(x):
    """This tests if something is an environment path, ie a list of strings."""
    if isinstance(x, string_types):
        return False
    else:
        return (isinstance(x, Sequence) and
                all([isinstance(a, string_types) for a in x]))


def str_to_env_path(x):
    """Converts a string to an environment path, ie a list of strings,
    splitting on the OS separator.
    """
    return x.split(os.pathsep)


def env_path_to_str(x):
    """Converts an environment path to a string by joining on the OS separator."""
    return os.pathsep.join(x)


def is_bool(x):
    """Tests if something is a boolean."""
    return isinstance(x, bool)


_FALSES = frozenset(['', '0', 'n', 'f', 'no', 'none', 'false'])

def to_bool(x):
    """"Converts to a boolean in a semantically meaningful way."""
    if isinstance(x, bool):
        return x
    elif isinstance(x, string_types):
        return False if x.lower() in _FALSES else True
    else:
        return bool(x)


def bool_to_str(x):
    """Converts a bool to an empty string if False and the string '1' if True."""
    return '1' if x else ''


def ensure_int_or_slice(x):
    """Makes sure that x is list-indexable."""
    if x is None:
        return slice(None)
    elif is_int(x):
        return x
    # must have a string from here on
    if ':' in x:
        x = x.strip('[]()')
        return slice(*(int(x) if len(x) > 0 else None for x in x.split(':')))
    else:
        return int(x)


# history validation

_min_to_sec = lambda x: 60.0 * float(x)
_hour_to_sec = lambda x: 60.0 * _min_to_sec(x)
_day_to_sec = lambda x: 24.0 * _hour_to_sec(x)
_month_to_sec = lambda x: 30.4375 * _day_to_sec(x)
_year_to_sec = lambda x: 365.25 * _day_to_sec(x)
_kb_to_b = lambda x: 1024 * int(x)
_mb_to_b = lambda x: 1024 * _kb_to_b(x)
_gb_to_b = lambda x: 1024 * _mb_to_b(x)
_tb_to_b = lambda x: 1024 * _tb_to_b(x)

CANON_HISTORY_UNITS = frozenset(['commands', 'files', 's', 'b'])

HISTORY_UNITS = {
    '': ('commands', int),
    'c': ('commands', int),
    'cmd': ('commands', int),
    'cmds': ('commands', int),
    'command': ('commands', int),
    'commands': ('commands', int),
    'f': ('files', int),
    'files': ('files', int),
    's': ('s', float),
    'sec': ('s', float),
    'second': ('s', float),
    'seconds': ('s', float),
    'm': ('s', _min_to_sec),
    'min': ('s', _min_to_sec),
    'mins': ('s', _min_to_sec),
    'h': ('s', _hour_to_sec),
    'hr': ('s', _hour_to_sec),
    'hour': ('s', _hour_to_sec),
    'hours': ('s', _hour_to_sec),
    'd': ('s', _day_to_sec),
    'day': ('s', _day_to_sec),
    'days': ('s', _day_to_sec),
    'mon': ('s', _month_to_sec),
    'month': ('s', _month_to_sec),
    'months': ('s', _month_to_sec),
    'y': ('s', _year_to_sec),
    'yr': ('s', _year_to_sec),
    'yrs': ('s', _year_to_sec),
    'year': ('s', _year_to_sec),
    'years': ('s', _year_to_sec),
    'b': ('b', int),
    'byte': ('b', int),
    'bytes': ('b', int),
    'kb': ('b', _kb_to_b),
    'kilobyte': ('b', _kb_to_b),
    'kilobytes': ('b', _kb_to_b),
    'mb': ('b', _mb_to_b),
    'meg': ('b', _mb_to_b),
    'megs': ('b', _mb_to_b),
    'megabyte': ('b', _mb_to_b),
    'megabytes': ('b', _mb_to_b),
    'gb': ('b', _gb_to_b),
    'gig': ('b', _gb_to_b),
    'gigs': ('b', _gb_to_b),
    'gigabyte': ('b', _gb_to_b),
    'gigabytes': ('b', _gb_to_b),
    'tb': ('b', _tb_to_b),
    'terabyte': ('b', _tb_to_b),
    'terabytes': ('b', _tb_to_b),
    }
"""Maps lowercase unit names to canonical name and conversion utilities."""

def is_history_tuple(x):
    """Tests if something is a proper history value, units tuple."""
    if isinstance(x, Sequence) and len(x) == 2 and isinstance(x[0], (int, float)) \
                               and x[1].lower() in CANON_HISTORY_UNITS:
         return True
    return False


RE_HISTORY_TUPLE = re.compile('([-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?)\s*([A-Za-z]*)')

def to_history_tuple(x):
    """Converts to a canonincal history tuple."""
    if not isinstance(x, (Sequence, float, int)):
        raise ValueError('history size must be given as a sequence or number')
    if isinstance(x, str):
        m = RE_HISTORY_TUPLE.match(x.strip())
        return to_history_tuple((m.group(1), m.group(3)))
    elif isinstance(x, (float, int)):
        return to_history_tuple((x, 'commands'))
    units, converter = HISTORY_UNITS[x[1]]
    value = converter(x[0])
    return (value, units)


def history_tuple_to_str(x):
    """Converts a valid history tuple to a canonical string."""
    return '{0} {1}'.format(*x)

#
# prompt toolkit tools
#


class FakeChar(str):
    """Class that holds a single char and escape sequences that surround it.

    It is used as a workaround for the fact that prompt_toolkit doesn't display
    colorful prompts correctly.
    It behaves like normal string created with prefix + char + suffix, but has
    two differences:

    * len() always returns 2

    * iterating over instance of this class is the same as iterating over
      the single char - prefix and suffix are ommited.
    """
    def __new__(cls, char, prefix='', suffix=''):
        return str.__new__(cls, prefix + char + suffix)

    def __init__(self, char, prefix='', suffix=''):
        self.char = char
        self.prefix = prefix
        self.suffix = suffix
        self.length = 2
        self.iterated = False

    def __len__(self):
        return self.length

    def __iter__(self):
        return iter(self.char)


RE_HIDDEN_MAX = re.compile('(\001.*?\002)+')


_PT_COLORS = {'BLACK': '#000000',
              'RED': '#FF0000',
              'GREEN': '#008000',
              'YELLOW': '#FFFF00',
              'BLUE': '#0000FF',
              'PURPLE': '#0000FF',
              'CYAN': '#00FFFF',
              'WHITE': '#FFFFFF'}

_PT_STYLE = {'BOLD': 'bold',
             'UNDERLINE': 'underline',
             'INTENSE': 'italic'}


def _make_style(color_name):
    """ Convert color names to pygments styles codes """
    style = []
    for k, v in _PT_STYLE.items():
        if k in color_name:
            style.append(v)
    for k, v in _PT_COLORS.items():
        if k in color_name:
            style.append(v)
    return ' '.join(style)


def get_xonsh_color_names(color_code):
    """ Makes a reverse lookup in TERM_COLORS  """
    try:
        return next(k for k, v in TERM_COLORS.items() if v == color_code)
    except StopIteration:
        return 'NO_COLOR'


def format_prompt_for_prompt_toolkit(prompt):
    """Converts a prompt with color codes to a pygments style and tokens
    """
    parts = RE_HIDDEN_MAX.split(prompt)
    # ensure that parts is [colorcode, string, colorcode, string,...]
    if parts and len(parts[0]) == 0:
        parts = parts[1:]
    else:
        parts.insert(0, '')
    if len(parts) % 2 != 0:
        parts.append()
    strings = parts[1::2]
    token_names = [get_xonsh_color_names(c) for c in parts[::2]]
    cstyles = [_make_style(c) for c in token_names]
    return token_names, cstyles, strings