Lib/reprlib.py

   1 """Redo the builtin repr() (representation) but with limits on most sizes."""
   2
   3 __all__ = ["Repr","repr"]
   4
   5 import builtins
   6 from itertools import islice
   7
   8 class Repr:
   9
  10     def __init__(self):
  11         self.maxlevel = 6
  12         self.maxtuple = 6
  13         self.maxlist = 6
  14         self.maxarray = 5
  15         self.maxdict = 4
  16         self.maxset = 6
  17         self.maxfrozenset = 6
  18         self.maxdeque = 6
  19         self.maxstring = 30
  20         self.maxlong = 40
  21         self.maxother = 30
  22
  23     def repr(self, x):
  24         return self.repr1(x, self.maxlevel)
  25
  26     def repr1(self, x, level):
  27         typename = type(x).__name__
  28         if ' ' in typename:
  29             parts = typename.split()
  30             typename = '_'.join(parts)
  31         if hasattr(self, 'repr_' + typename):
  32             return getattr(self, 'repr_' + typename)(x, level)
  33         else:
  34             return self.repr_instance(x, level)
  35
  36     def _repr_iterable(self, x, level, left, right, maxiter, trail=''):
  37         n = len(x)
  38         if level <= 0 and n:
  39             s = '...'
  40         else:
  41             newlevel = level - 1
  42             repr1 = self.repr1
  43             pieces = [repr1(elem, newlevel) for elem in islice(x, maxiter)]
  44             if n > maxiter:  pieces.append('...')
  45             s = ', '.join(pieces)
  46             if n == 1 and trail:  right = trail + right
  47         return '%s%s%s' % (left, s, right)
  48
  49     def repr_tuple(self, x, level):
  50         return self._repr_iterable(x, level, '(', ')', self.maxtuple, ',')
  51
  52     def repr_list(self, x, level):
  53         return self._repr_iterable(x, level, '[', ']', self.maxlist)
  54
  55     def repr_array(self, x, level):
  56         header = "array('%s', [" % x.typecode
  57         return self._repr_iterable(x, level, header, '])', self.maxarray)
  58
  59     def repr_set(self, x, level):
  60         x = _possibly_sorted(x)
  61         return self._repr_iterable(x, level, 'set([', '])', self.maxset)
  62
  63     def repr_frozenset(self, x, level):
  64         x = _possibly_sorted(x)
  65         return self._repr_iterable(x, level, 'frozenset([', '])',
  66                                    self.maxfrozenset)
  67
  68     def repr_deque(self, x, level):
  69         return self._repr_iterable(x, level, 'deque([', '])', self.maxdeque)
  70
  71     def repr_dict(self, x, level):
  72         n = len(x)
  73         if n == 0: return '{}'
  74         if level <= 0: return '{...}'
  75         newlevel = level - 1
  76         repr1 = self.repr1
  77         pieces = []
  78         for key in islice(_possibly_sorted(x), self.maxdict):
  79             keyrepr = repr1(key, newlevel)
  80             valrepr = repr1(x[key], newlevel)
  81             pieces.append('%s: %s' % (keyrepr, valrepr))
  82         if n > self.maxdict: pieces.append('...')
  83         s = ', '.join(pieces)
  84         return '{%s}' % (s,)
  85
  86     def repr_str(self, x, level):
  87         s = builtins.repr(x[:self.maxstring])
  88         if len(s) > self.maxstring:
  89             i = max(0, (self.maxstring-3)//2)
  90             j = max(0, self.maxstring-3-i)
  91             s = builtins.repr(x[:i] + x[len(x)-j:])
  92             s = s[:i] + '...' + s[len(s)-j:]
  93         return s
  94
  95     def repr_int(self, x, level):
  96         s = builtins.repr(x) # XXX Hope this isn't too slow...
  97         if len(s) > self.maxlong:
  98             i = max(0, (self.maxlong-3)//2)
  99             j = max(0, self.maxlong-3-i)
 100             s = s[:i] + '...' + s[len(s)-j:]
 101         return s
 102
 103     def repr_instance(self, x, level):
 104         try:
 105             s = builtins.repr(x)
 106             # Bugs in x.__repr__() can cause arbitrary
 107             # exceptions -- then make up something
 108         except Exception:
 109             return '<%s instance at %x>' % (x.__class__.__name__, id(x))
 110         if len(s) > self.maxother:
 111             i = max(0, (self.maxother-3)//2)
 112             j = max(0, self.maxother-3-i)
 113             s = s[:i] + '...' + s[len(s)-j:]
 114         return s
 115
 116
 117 def _possibly_sorted(x):
 118     # Since not all sequences of items can be sorted and comparison
 119     # functions may raise arbitrary exceptions, return an unsorted
 120     # sequence in that case.
 121     try:
 122         return sorted(x)
 123     except Exception:
 124         return list(x)
 125
 126 aRepr = Repr()
 127 repr = aRepr.repr