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34d1928766
Completely get rid of StringIO.py and cStringIO.c. I had to fix a few tests and modules beyond what Christian did, and invent a few conventions. E.g. in elementtree, I chose to write/return Unicode strings whe no encoding is given, but bytes when an explicit encoding is given. Also mimetools was made to always assume binary files.
323 lines
11 KiB
Python
323 lines
11 KiB
Python
# Author: Fred L. Drake, Jr.
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# fdrake@acm.org
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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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import sys as _sys
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from io import StringIO as _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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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 = _StringIO()
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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 sepLines:
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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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write(',\n%s%s: ' % (' '*indent, 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 (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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write('[')
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endchar = ']'
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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:
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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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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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write(',\n' + ' '*indent)
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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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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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else:
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closure = "'"
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quotes = {"'": "\\'"}
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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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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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items = object.items()
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try:
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items = sorted(items)
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except TypeError:
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def sortkey(item):
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key, value = item
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return str(type(key)), key, value
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items = sorted(items, key=sortkey)
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for k, v in 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:
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object = [("string", (1, 2), [3, 4], {5: 6, 7: 8})] * 100000
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p = PrettyPrinter()
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t1 = time.time()
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_safe_repr(object, {}, None, 0)
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t2 = time.time()
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p.pformat(object)
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t3 = time.time()
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print("_safe_repr:", t2 - t1)
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print("pformat:", t3 - t2)
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if __name__ == "__main__":
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_perfcheck()
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