| 1 | # Author: Fred L. Drake, Jr.
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| 2 | # [email protected]
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| 3 | #
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| 4 | # This is a simple little module I wrote to make life easier. I didn't
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| 5 | # see anything quite like it in the library, though I may have overlooked
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| 6 | # something. I wrote this when I was trying to read some heavily nested
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| 7 | # tuples with fairly non-descriptive content. This is modeled very much
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| 8 | # after Lisp/Scheme - style pretty-printing of lists. If you find it
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| 9 | # useful, thank small children who sleep at night.
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| 10 |
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| 11 | """Support to pretty-print lists, tuples, & dictionaries recursively.
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| 12 |
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| 13 | Very simple, but useful, especially in debugging data structures.
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| 14 |
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| 15 | Classes
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| 16 | -------
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| 17 |
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| 18 | PrettyPrinter()
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| 19 | Handle pretty-printing operations onto a stream using a configured
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| 20 | set of formatting parameters.
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| 21 |
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| 22 | Functions
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| 23 | ---------
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| 24 |
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| 25 | pformat()
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| 26 | Format a Python object into a pretty-printed representation.
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| 27 |
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| 28 | pprint()
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| 29 | Pretty-print a Python object to a stream [default is sys.stdout].
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| 30 |
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| 31 | saferepr()
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| 32 | Generate a 'standard' repr()-like value, but protect against recursive
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| 33 | data structures.
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| 34 |
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| 35 | """
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| 36 |
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| 37 | import sys as _sys
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| 38 |
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| 39 | from cStringIO import StringIO as _StringIO
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| 40 |
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| 41 | __all__ = ["pprint","pformat","isreadable","isrecursive","saferepr",
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| 42 | "PrettyPrinter"]
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| 43 |
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| 44 | # cache these for faster access:
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| 45 | _commajoin = ", ".join
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| 46 | _id = id
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| 47 | _len = len
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| 48 | _type = type
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| 49 |
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| 50 |
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| 51 | def pprint(object, stream=None, indent=1, width=80, depth=None):
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| 52 | """Pretty-print a Python object to a stream [default is sys.stdout]."""
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| 53 | printer = PrettyPrinter(
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| 54 | stream=stream, indent=indent, width=width, depth=depth)
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| 55 | printer.pprint(object)
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| 56 |
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| 57 | def pformat(object, indent=1, width=80, depth=None):
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| 58 | """Format a Python object into a pretty-printed representation."""
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| 59 | return PrettyPrinter(indent=indent, width=width, depth=depth).pformat(object)
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| 60 |
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| 61 | def saferepr(object):
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| 62 | """Version of repr() which can handle recursive data structures."""
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| 63 | return _safe_repr(object, {}, None, 0)[0]
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| 64 |
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| 65 | def isreadable(object):
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| 66 | """Determine if saferepr(object) is readable by eval()."""
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| 67 | return _safe_repr(object, {}, None, 0)[1]
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| 68 |
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| 69 | def isrecursive(object):
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| 70 | """Determine if object requires a recursive representation."""
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| 71 | return _safe_repr(object, {}, None, 0)[2]
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| 72 |
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| 73 | class PrettyPrinter:
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| 74 | def __init__(self, indent=1, width=80, depth=None, stream=None):
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| 75 | """Handle pretty printing operations onto a stream using a set of
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| 76 | configured parameters.
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| 77 |
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| 78 | indent
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| 79 | Number of spaces to indent for each level of nesting.
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| 80 |
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| 81 | width
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| 82 | Attempted maximum number of columns in the output.
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| 83 |
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| 84 | depth
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| 85 | The maximum depth to print out nested structures.
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| 86 |
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| 87 | stream
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| 88 | The desired output stream. If omitted (or false), the standard
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| 89 | output stream available at construction will be used.
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| 90 |
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| 91 | """
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| 92 | indent = int(indent)
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| 93 | width = int(width)
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| 94 | assert indent >= 0, "indent must be >= 0"
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| 95 | assert depth is None or depth > 0, "depth must be > 0"
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| 96 | assert width, "width must be != 0"
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| 97 | self._depth = depth
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| 98 | self._indent_per_level = indent
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| 99 | self._width = width
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| 100 | if stream is not None:
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| 101 | self._stream = stream
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| 102 | else:
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| 103 | self._stream = _sys.stdout
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| 104 |
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| 105 | def pprint(self, object):
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| 106 | self._format(object, self._stream, 0, 0, {}, 0)
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| 107 | self._stream.write("\n")
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| 108 |
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| 109 | def pformat(self, object):
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| 110 | sio = _StringIO()
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| 111 | self._format(object, sio, 0, 0, {}, 0)
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| 112 | return sio.getvalue()
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| 113 |
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| 114 | def isrecursive(self, object):
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| 115 | return self.format(object, {}, 0, 0)[2]
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| 116 |
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| 117 | def isreadable(self, object):
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| 118 | s, readable, recursive = self.format(object, {}, 0, 0)
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| 119 | return readable and not recursive
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| 120 |
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| 121 | def _format(self, object, stream, indent, allowance, context, level):
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| 122 | level = level + 1
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| 123 | objid = _id(object)
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| 124 | if objid in context:
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| 125 | stream.write(_recursion(object))
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| 126 | self._recursive = True
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| 127 | self._readable = False
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| 128 | return
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| 129 | rep = self._repr(object, context, level - 1)
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| 130 | typ = _type(object)
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| 131 | sepLines = _len(rep) > (self._width - 1 - indent - allowance)
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| 132 | write = stream.write
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| 133 |
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| 134 | if sepLines:
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| 135 | r = getattr(typ, "__repr__", None)
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| 136 | if issubclass(typ, dict) and r is dict.__repr__:
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| 137 | write('{')
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| 138 | if self._indent_per_level > 1:
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| 139 | write((self._indent_per_level - 1) * ' ')
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| 140 | length = _len(object)
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| 141 | if length:
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| 142 | context[objid] = 1
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| 143 | indent = indent + self._indent_per_level
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| 144 | items = object.items()
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| 145 | items.sort()
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| 146 | key, ent = items[0]
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| 147 | rep = self._repr(key, context, level)
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| 148 | write(rep)
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| 149 | write(': ')
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| 150 | self._format(ent, stream, indent + _len(rep) + 2,
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| 151 | allowance + 1, context, level)
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| 152 | if length > 1:
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| 153 | for key, ent in items[1:]:
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| 154 | rep = self._repr(key, context, level)
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| 155 | write(',\n%s%s: ' % (' '*indent, rep))
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| 156 | self._format(ent, stream, indent + _len(rep) + 2,
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| 157 | allowance + 1, context, level)
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| 158 | indent = indent - self._indent_per_level
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| 159 | del context[objid]
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| 160 | write('}')
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| 161 | return
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| 162 |
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| 163 | if (issubclass(typ, list) and r is list.__repr__) or \
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| 164 | (issubclass(typ, tuple) and r is tuple.__repr__):
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| 165 | if issubclass(typ, list):
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| 166 | write('[')
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| 167 | endchar = ']'
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| 168 | else:
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| 169 | write('(')
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| 170 | endchar = ')'
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| 171 | if self._indent_per_level > 1:
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| 172 | write((self._indent_per_level - 1) * ' ')
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| 173 | length = _len(object)
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| 174 | if length:
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| 175 | context[objid] = 1
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| 176 | indent = indent + self._indent_per_level
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| 177 | self._format(object[0], stream, indent, allowance + 1,
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| 178 | context, level)
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| 179 | if length > 1:
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| 180 | for ent in object[1:]:
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| 181 | write(',\n' + ' '*indent)
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| 182 | self._format(ent, stream, indent,
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| 183 | allowance + 1, context, level)
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| 184 | indent = indent - self._indent_per_level
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| 185 | del context[objid]
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| 186 | if issubclass(typ, tuple) and length == 1:
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| 187 | write(',')
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| 188 | write(endchar)
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| 189 | return
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| 190 |
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| 191 | write(rep)
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| 192 |
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| 193 | def _repr(self, object, context, level):
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| 194 | repr, readable, recursive = self.format(object, context.copy(),
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| 195 | self._depth, level)
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| 196 | if not readable:
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| 197 | self._readable = False
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| 198 | if recursive:
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| 199 | self._recursive = True
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| 200 | return repr
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| 201 |
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| 202 | def format(self, object, context, maxlevels, level):
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| 203 | """Format object for a specific context, returning a string
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| 204 | and flags indicating whether the representation is 'readable'
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| 205 | and whether the object represents a recursive construct.
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| 206 | """
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| 207 | return _safe_repr(object, context, maxlevels, level)
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| 208 |
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| 209 |
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| 210 | # Return triple (repr_string, isreadable, isrecursive).
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| 211 |
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| 212 | def _safe_repr(object, context, maxlevels, level):
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| 213 | typ = _type(object)
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| 214 | if typ is str:
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| 215 | if 'locale' not in _sys.modules:
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| 216 | return repr(object), True, False
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| 217 | if "'" in object and '"' not in object:
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| 218 | closure = '"'
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| 219 | quotes = {'"': '\\"'}
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| 220 | else:
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| 221 | closure = "'"
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| 222 | quotes = {"'": "\\'"}
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| 223 | qget = quotes.get
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| 224 | sio = _StringIO()
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| 225 | write = sio.write
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| 226 | for char in object:
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| 227 | if char.isalpha():
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| 228 | write(char)
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| 229 | else:
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| 230 | write(qget(char, repr(char)[1:-1]))
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| 231 | return ("%s%s%s" % (closure, sio.getvalue(), closure)), True, False
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| 232 |
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| 233 | r = getattr(typ, "__repr__", None)
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| 234 | if issubclass(typ, dict) and r is dict.__repr__:
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| 235 | if not object:
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| 236 | return "{}", True, False
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| 237 | objid = _id(object)
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| 238 | if maxlevels and level > maxlevels:
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| 239 | return "{...}", False, objid in context
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| 240 | if objid in context:
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| 241 | return _recursion(object), False, True
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| 242 | context[objid] = 1
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| 243 | readable = True
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| 244 | recursive = False
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| 245 | components = []
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| 246 | append = components.append
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| 247 | level += 1
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| 248 | saferepr = _safe_repr
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| 249 | for k, v in sorted(object.items()):
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| 250 | krepr, kreadable, krecur = saferepr(k, context, maxlevels, level)
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| 251 | vrepr, vreadable, vrecur = saferepr(v, context, maxlevels, level)
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| 252 | append("%s: %s" % (krepr, vrepr))
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| 253 | readable = readable and kreadable and vreadable
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| 254 | if krecur or vrecur:
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| 255 | recursive = True
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| 256 | del context[objid]
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| 257 | return "{%s}" % _commajoin(components), readable, recursive
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| 258 |
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| 259 | if (issubclass(typ, list) and r is list.__repr__) or \
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| 260 | (issubclass(typ, tuple) and r is tuple.__repr__):
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| 261 | if issubclass(typ, list):
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| 262 | if not object:
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| 263 | return "[]", True, False
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| 264 | format = "[%s]"
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| 265 | elif _len(object) == 1:
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| 266 | format = "(%s,)"
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| 267 | else:
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| 268 | if not object:
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| 269 | return "()", True, False
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| 270 | format = "(%s)"
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| 271 | objid = _id(object)
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| 272 | if maxlevels and level > maxlevels:
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| 273 | return format % "...", False, objid in context
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| 274 | if objid in context:
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| 275 | return _recursion(object), False, True
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| 276 | context[objid] = 1
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| 277 | readable = True
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| 278 | recursive = False
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| 279 | components = []
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| 280 | append = components.append
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| 281 | level += 1
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| 282 | for o in object:
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| 283 | orepr, oreadable, orecur = _safe_repr(o, context, maxlevels, level)
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| 284 | append(orepr)
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| 285 | if not oreadable:
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| 286 | readable = False
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| 287 | if orecur:
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| 288 | recursive = True
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| 289 | del context[objid]
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| 290 | return format % _commajoin(components), readable, recursive
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| 291 |
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| 292 | rep = repr(object)
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| 293 | return rep, (rep and not rep.startswith('<')), False
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| 294 |
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| 295 |
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| 296 | def _recursion(object):
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| 297 | return ("<Recursion on %s with id=%s>"
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| 298 | % (_type(object).__name__, _id(object)))
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| 299 |
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| 300 |
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| 301 | def _perfcheck(object=None):
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| 302 | import time
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| 303 | if object is None:
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| 304 | object = [("string", (1, 2), [3, 4], {5: 6, 7: 8})] * 100000
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| 305 | p = PrettyPrinter()
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| 306 | t1 = time.time()
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| 307 | _safe_repr(object, {}, None, 0)
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| 308 | t2 = time.time()
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| 309 | p.pformat(object)
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| 310 | t3 = time.time()
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| 311 | print "_safe_repr:", t2 - t1
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| 312 | print "pformat:", t3 - t2
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| 313 |
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| 314 | if __name__ == "__main__":
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| 315 | _perfcheck()
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