<h2>Editing File: /lib64/python3.8/unittest/util.py</h2><form method='post'><textarea name='content' class='file-edit'>&quot;&quot;&quot;Various utility functions.&quot;&quot;&quot;

from collections import namedtuple, Counter
from os.path import commonprefix

__unittest = True

_MAX_LENGTH = 80
_PLACEHOLDER_LEN = 12
_MIN_BEGIN_LEN = 5
_MIN_END_LEN = 5
_MIN_COMMON_LEN = 5
_MIN_DIFF_LEN = _MAX_LENGTH - \
               (_MIN_BEGIN_LEN + _PLACEHOLDER_LEN + _MIN_COMMON_LEN +
                _PLACEHOLDER_LEN + _MIN_END_LEN)
assert _MIN_DIFF_LEN &gt;= 0

def _shorten(s, prefixlen, suffixlen):
    skip = len(s) - prefixlen - suffixlen
    if skip &gt; _PLACEHOLDER_LEN:
        s = '%s[%d chars]%s' % (s[:prefixlen], skip, s[len(s) - suffixlen:])
    return s

def _common_shorten_repr(*args):
    args = tuple(map(safe_repr, args))
    maxlen = max(map(len, args))
    if maxlen &lt;= _MAX_LENGTH:
        return args

    prefix = commonprefix(args)
    prefixlen = len(prefix)

    common_len = _MAX_LENGTH - \
                 (maxlen - prefixlen + _MIN_BEGIN_LEN + _PLACEHOLDER_LEN)
    if common_len &gt; _MIN_COMMON_LEN:
        assert _MIN_BEGIN_LEN + _PLACEHOLDER_LEN + _MIN_COMMON_LEN + \
               (maxlen - prefixlen) &lt; _MAX_LENGTH
        prefix = _shorten(prefix, _MIN_BEGIN_LEN, common_len)
        return tuple(prefix + s[prefixlen:] for s in args)

    prefix = _shorten(prefix, _MIN_BEGIN_LEN, _MIN_COMMON_LEN)
    return tuple(prefix + _shorten(s[prefixlen:], _MIN_DIFF_LEN, _MIN_END_LEN)
                 for s in args)

def safe_repr(obj, short=False):
    try:
        result = repr(obj)
    except Exception:
        result = object.__repr__(obj)
    if not short or len(result) &lt; _MAX_LENGTH:
        return result
    return result[:_MAX_LENGTH] + ' [truncated]...'

def strclass(cls):
    return &quot;%s.%s&quot; % (cls.__module__, cls.__qualname__)

def sorted_list_difference(expected, actual):
    &quot;&quot;&quot;Finds elements in only one or the other of two, sorted input lists.

    Returns a two-element tuple of lists.    The first list contains those
    elements in the &quot;expected&quot; list but not in the &quot;actual&quot; list, and the
    second contains those elements in the &quot;actual&quot; list but not in the
    &quot;expected&quot; list.    Duplicate elements in either input list are ignored.
    &quot;&quot;&quot;
    i = j = 0
    missing = []
    unexpected = []
    while True:
        try:
            e = expected[i]
            a = actual[j]
            if e &lt; a:
                missing.append(e)
                i += 1
                while expected[i] == e:
                    i += 1
            elif e &gt; a:
                unexpected.append(a)
                j += 1
                while actual[j] == a:
                    j += 1
            else:
                i += 1
                try:
                    while expected[i] == e:
                        i += 1
                finally:
                    j += 1
                    while actual[j] == a:
                        j += 1
        except IndexError:
            missing.extend(expected[i:])
            unexpected.extend(actual[j:])
            break
    return missing, unexpected


def unorderable_list_difference(expected, actual):
    &quot;&quot;&quot;Same behavior as sorted_list_difference but
    for lists of unorderable items (like dicts).

    As it does a linear search per item (remove) it
    has O(n*n) performance.&quot;&quot;&quot;
    missing = []
    while expected:
        item = expected.pop()
        try:
            actual.remove(item)
        except ValueError:
            missing.append(item)

    # anything left in actual is unexpected
    return missing, actual

def three_way_cmp(x, y):
    &quot;&quot;&quot;Return -1 if x &lt; y, 0 if x == y and 1 if x &gt; y&quot;&quot;&quot;
    return (x &gt; y) - (x &lt; y)

_Mismatch = namedtuple('Mismatch', 'actual expected value')

def _count_diff_all_purpose(actual, expected):
    'Returns list of (cnt_act, cnt_exp, elem) triples where the counts differ'
    # elements need not be hashable
    s, t = list(actual), list(expected)
    m, n = len(s), len(t)
    NULL = object()
    result = []
    for i, elem in enumerate(s):
        if elem is NULL:
            continue
        cnt_s = cnt_t = 0
        for j in range(i, m):
            if s[j] == elem:
                cnt_s += 1
                s[j] = NULL
        for j, other_elem in enumerate(t):
            if other_elem == elem:
                cnt_t += 1
                t[j] = NULL
        if cnt_s != cnt_t:
            diff = _Mismatch(cnt_s, cnt_t, elem)
            result.append(diff)

    for i, elem in enumerate(t):
        if elem is NULL:
            continue
        cnt_t = 0
        for j in range(i, n):
            if t[j] == elem:
                cnt_t += 1
                t[j] = NULL
        diff = _Mismatch(0, cnt_t, elem)
        result.append(diff)
    return result

def _count_diff_hashable(actual, expected):
    'Returns list of (cnt_act, cnt_exp, elem) triples where the counts differ'
    # elements must be hashable
    s, t = Counter(actual), Counter(expected)
    result = []
    for elem, cnt_s in s.items():
        cnt_t = t.get(elem, 0)
        if cnt_s != cnt_t:
            diff = _Mismatch(cnt_s, cnt_t, elem)
            result.append(diff)
    for elem, cnt_t in t.items():
        if elem not in s:
            diff = _Mismatch(0, cnt_t, elem)
            result.append(diff)
    return result
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