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# Author: Fred L. Drake, Jr. |
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# fdrake@... |
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# |
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# This is a simple little module I wrote to make life easier. I didn't |
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# see anything quite like it in the library, though I may have overlooked |
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# something. I wrote this when I was trying to read some heavily nested |
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# tuples with fairly non-descriptive content. This is modeled very much |
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# after Lisp/Scheme - style pretty-printing of lists. If you find it |
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# useful, thank small children who sleep at night. |
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"""Support to pretty-print lists, tuples, & dictionaries recursively. |
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Very simple, but useful, especially in debugging data structures. |
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Classes |
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------- |
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PrettyPrinter() |
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Handle pretty-printing operations onto a stream using a configured |
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set of formatting parameters. |
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Functions |
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--------- |
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pformat() |
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Format a Python object into a pretty-printed representation. |
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pprint() |
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Pretty-print a Python object to a stream [default is sys.stdout]. |
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saferepr() |
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Generate a 'standard' repr()-like value, but protect against recursive |
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data structures. |
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""" |
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from __future__ import print_function |
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import six |
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import sys as _sys |
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from io import BytesIO, StringIO |
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__all__ = ["pprint", "pformat", "isreadable", "isrecursive", "saferepr", |
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"PrettyPrinter"] |
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# cache these for faster access: |
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_commajoin = ", ".join |
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_id = id |
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_len = len |
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_type = type |
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def pprint(object, stream=None, indent=1, width=80, depth=None): |
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"""Pretty-print a Python object to a stream [default is sys.stdout].""" |
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printer = PrettyPrinter( |
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stream=stream, indent=indent, width=width, depth=depth) |
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printer.pprint(object) |
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def pformat(object, indent=1, width=80, depth=None): |
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"""Format a Python object into a pretty-printed representation.""" |
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return PrettyPrinter(indent=indent, width=width, depth=depth).pformat(object) |
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def saferepr(object): |
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"""Version of repr() which can handle recursive data structures.""" |
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return _safe_repr(object, {}, None, 0)[0] |
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def isreadable(object): |
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"""Determine if saferepr(object) is readable by eval().""" |
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return _safe_repr(object, {}, None, 0)[1] |
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def isrecursive(object): |
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"""Determine if object requires a recursive representation.""" |
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return _safe_repr(object, {}, None, 0)[2] |
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def _sorted(iterable): |
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return sorted(iterable) |
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class PrettyPrinter: |
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def __init__(self, indent=1, width=80, depth=None, stream=None): |
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"""Handle pretty printing operations onto a stream using a set of |
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configured parameters. |
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indent |
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Number of spaces to indent for each level of nesting. |
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width |
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Attempted maximum number of columns in the output. |
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depth |
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The maximum depth to print out nested structures. |
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stream |
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The desired output stream. If omitted (or false), the standard |
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output stream available at construction will be used. |
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""" |
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indent = int(indent) |
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width = int(width) |
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assert indent >= 0, "indent must be >= 0" |
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assert depth is None or depth > 0, "depth must be > 0" |
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assert width, "width must be != 0" |
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self._depth = depth |
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self._indent_per_level = indent |
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self._width = width |
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if stream is not None: |
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self._stream = stream |
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else: |
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self._stream = _sys.stdout |
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def pprint(self, object): |
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self._format(object, self._stream, 0, 0, {}, 0) |
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self._stream.write("\n") |
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def pformat(self, object): |
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sio = BytesIO() |
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self._format(object, sio, 0, 0, {}, 0) |
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return sio.getvalue() |
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def isrecursive(self, object): |
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return self.format(object, {}, 0, 0)[2] |
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def isreadable(self, object): |
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s, readable, recursive = self.format(object, {}, 0, 0) |
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return readable and not recursive |
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def _format(self, object, stream, indent, allowance, context, level): |
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level = level + 1 |
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objid = _id(object) |
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if objid in context: |
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stream.write(_recursion(object)) |
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self._recursive = True |
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self._readable = False |
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return |
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rep = self._repr(object, context, level - 1) |
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typ = _type(object) |
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sepLines = _len(rep) > (self._width - 1 - indent - allowance) |
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write = stream.write |
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if self._depth and level > self._depth: |
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write(rep) |
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return |
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r = getattr(typ, "__repr__", None) |
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if issubclass(typ, dict) and r is dict.__repr__: |
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write('{') |
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if self._indent_per_level > 1: |
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write((self._indent_per_level - 1) * ' ') |
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length = _len(object) |
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if length: |
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context[objid] = 1 |
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indent = indent + self._indent_per_level |
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items = _sorted(object.items()) |
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key, ent = items[0] |
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rep = self._repr(key, context, level) |
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write(rep) |
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write(': ') |
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self._format(ent, stream, indent + _len(rep) + 2, |
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allowance + 1, context, level) |
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if length > 1: |
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for key, ent in items[1:]: |
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rep = self._repr(key, context, level) |
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if sepLines: |
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write(',\n%s%s: ' % (' ' * indent, rep)) |
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else: |
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write(', %s: ' % rep) |
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self._format(ent, stream, indent + _len(rep) + 2, |
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allowance + 1, context, level) |
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indent = indent - self._indent_per_level |
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del context[objid] |
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write('}') |
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return |
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if ( |
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(issubclass(typ, list) and r is list.__repr__) or |
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(issubclass(typ, tuple) and r is tuple.__repr__) or |
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(issubclass(typ, set) and r is set.__repr__) or |
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(issubclass(typ, frozenset) and r is frozenset.__repr__) |
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): |
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length = _len(object) |
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if issubclass(typ, list): |
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write('[') |
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endchar = ']' |
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elif issubclass(typ, set): |
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if not length: |
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write('set()') |
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return |
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write('set([') |
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endchar = '])' |
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object = _sorted(object) |
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indent += 4 |
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elif issubclass(typ, frozenset): |
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if not length: |
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write('frozenset()') |
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return |
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write('frozenset([') |
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endchar = '])' |
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object = _sorted(object) |
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indent += 10 |
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else: |
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write('(') |
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endchar = ')' |
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if self._indent_per_level > 1 and sepLines: |
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write((self._indent_per_level - 1) * ' ') |
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if length: |
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context[objid] = 1 |
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indent = indent + self._indent_per_level |
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self._format(object[0], stream, indent, allowance + 1, |
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context, level) |
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if length > 1: |
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for ent in object[1:]: |
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if sepLines: |
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write(',\n' + ' ' * indent) |
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else: |
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write(', ') |
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self._format(ent, stream, indent, |
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allowance + 1, context, level) |
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indent = indent - self._indent_per_level |
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del context[objid] |
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if issubclass(typ, tuple) and length == 1: |
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write(',') |
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write(endchar) |
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return |
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write(rep) |
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def _repr(self, object, context, level): |
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repr, readable, recursive = self.format(object, context.copy(), |
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self._depth, level) |
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if not readable: |
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self._readable = False |
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if recursive: |
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self._recursive = True |
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return repr |
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def format(self, object, context, maxlevels, level): |
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"""Format object for a specific context, returning a string |
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and flags indicating whether the representation is 'readable' |
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and whether the object represents a recursive construct. |
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""" |
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return _safe_repr(object, context, maxlevels, level) |
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# Return triple (repr_string, isreadable, isrecursive). |
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def _safe_repr(object, context, maxlevels, level): |
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typ = _type(object) |
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if typ is str: |
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string = object |
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string = string.replace('\n', '\\n').replace('\r', '\\r').replace('\t', '\\t') |
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if 'locale' not in _sys.modules: |
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return repr(object), True, False |
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if "'" in object and '"' not in object: |
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closure = '"' |
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quotes = {'"': '\\"'} |
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string = string.replace('"', '\\"') |
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else: |
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closure = "'" |
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quotes = {"'": "\\'"} |
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string = string.replace("'", "\\'") |
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try: |
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string.decode('utf8').encode('gbk', 'replace') |
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return ("%s%s%s" % (closure, string, closure)), True, False |
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except: |
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pass |
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qget = quotes.get |
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sio = StringIO() |
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write = sio.write |
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for char in object: |
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if char.isalpha(): |
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write(char) |
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else: |
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write(qget(char, repr(char)[1:-1])) |
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return ("%s%s%s" % (closure, sio.getvalue(), closure)), True, False |
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if typ is six.text_type: |
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string = object.encode("utf8", 'replace') |
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string = string.replace('\n', '\\n').replace('\r', '\\r').replace('\t', '\\t') |
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if "'" in object and '"' not in object: |
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closure = '"' |
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quotes = {'"': '\\"'} |
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string = string.replace('"', '\\"') |
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else: |
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closure = "'" |
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quotes = {"'": "\\'"} |
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string = string.replace("'", "\\'") |
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return ("u%s%s%s" % (closure, string, closure)), True, False |
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r = getattr(typ, "__repr__", None) |
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if issubclass(typ, dict) and r is dict.__repr__: |
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if not object: |
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return "{}", True, False |
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objid = _id(object) |
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if maxlevels and level >= maxlevels: |
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return "{...}", False, objid in context |
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if objid in context: |
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return _recursion(object), False, True |
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context[objid] = 1 |
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readable = True |
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recursive = False |
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components = [] |
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append = components.append |
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level += 1 |
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saferepr = _safe_repr |
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for k, v in _sorted(object.items()): |
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krepr, kreadable, krecur = saferepr(k, context, maxlevels, level) |
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vrepr, vreadable, vrecur = saferepr(v, context, maxlevels, level) |
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append("%s: %s" % (krepr, vrepr)) |
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readable = readable and kreadable and vreadable |
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if krecur or vrecur: |
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recursive = True |
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del context[objid] |
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return "{%s}" % _commajoin(components), readable, recursive |
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if (issubclass(typ, list) and r is list.__repr__) or \ |
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(issubclass(typ, tuple) and r is tuple.__repr__): |
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if issubclass(typ, list): |
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if not object: |
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return "[]", True, False |
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format = "[%s]" |
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elif _len(object) == 1: |
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format = "(%s,)" |
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else: |
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if not object: |
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return "()", True, False |
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format = "(%s)" |
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objid = _id(object) |
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if maxlevels and level >= maxlevels: |
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return format % "...", False, objid in context |
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if objid in context: |
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return _recursion(object), False, True |
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context[objid] = 1 |
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readable = True |
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recursive = False |
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components = [] |
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append = components.append |
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level += 1 |
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for o in object: |
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orepr, oreadable, orecur = _safe_repr(o, context, maxlevels, level) |
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append(orepr) |
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if not oreadable: |
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readable = False |
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if orecur: |
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recursive = True |
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del context[objid] |
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return format % _commajoin(components), readable, recursive |
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rep = repr(object) |
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return rep, (rep and not rep.startswith('<')), False |
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def _recursion(object): |
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return ("<Recursion on %s with id=%s>" |
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% (_type(object).__name__, _id(object))) |
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def _perfcheck(object=None): |
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import time |
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|
|
if object is None: |
367
|
|
|
object = [("string", (1, 2), [3, 4], {5: 6, 7: 8})] * 100000 |
368
|
|
|
p = PrettyPrinter() |
369
|
|
|
t1 = time.time() |
370
|
|
|
_safe_repr(object, {}, None, 0) |
371
|
|
|
t2 = time.time() |
372
|
|
|
p.pformat(object) |
373
|
|
|
t3 = time.time() |
374
|
|
|
print("_safe_repr:", t2 - t1) |
375
|
|
|
print("pformat:", t3 - t2) |
376
|
|
|
|
377
|
|
|
if __name__ == "__main__": |
378
|
|
|
_perfcheck() |
379
|
|
|
|