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- # Author: Fred L. Drake, Jr.
- # fdrake@acm.org
- #
- # This is a simple little module I wrote to make life easier. I didn't
- # see anything quite like it in the library, though I may have overlooked
- # something. I wrote this when I was trying to read some heavily nested
- # tuples with fairly non-descriptive content. This is modeled very much
- # after Lisp/Scheme - style pretty-printing of lists. If you find it
- # useful, thank small children who sleep at night.
- """Support to pretty-print lists, tuples, & dictionaries recursively.
- Very simple, but useful, especially in debugging data structures.
- Classes
- -------
- PrettyPrinter()
- Handle pretty-printing operations onto a stream using a configured
- set of formatting parameters.
- Functions
- ---------
- pformat()
- Format a Python object into a pretty-printed representation.
- pprint()
- Pretty-print a Python object to a stream [default is sys.stdout].
- saferepr()
- Generate a 'standard' repr()-like value, but protect against recursive
- data structures.
- """
- import collections as _collections
- import dataclasses as _dataclasses
- import re
- import sys as _sys
- import types as _types
- from io import StringIO as _StringIO
- __all__ = ["pprint","pformat","isreadable","isrecursive","saferepr",
- "PrettyPrinter", "pp"]
- def pprint(object, stream=None, indent=1, width=80, depth=None, *,
- compact=False, sort_dicts=True, underscore_numbers=False):
- """Pretty-print a Python object to a stream [default is sys.stdout]."""
- printer = PrettyPrinter(
- stream=stream, indent=indent, width=width, depth=depth,
- compact=compact, sort_dicts=sort_dicts,
- underscore_numbers=underscore_numbers)
- printer.pprint(object)
- def pformat(object, indent=1, width=80, depth=None, *,
- compact=False, sort_dicts=True, underscore_numbers=False):
- """Format a Python object into a pretty-printed representation."""
- return PrettyPrinter(indent=indent, width=width, depth=depth,
- compact=compact, sort_dicts=sort_dicts,
- underscore_numbers=underscore_numbers).pformat(object)
- def pp(object, *args, sort_dicts=False, **kwargs):
- """Pretty-print a Python object"""
- pprint(object, *args, sort_dicts=sort_dicts, **kwargs)
- def saferepr(object):
- """Version of repr() which can handle recursive data structures."""
- return PrettyPrinter()._safe_repr(object, {}, None, 0)[0]
- def isreadable(object):
- """Determine if saferepr(object) is readable by eval()."""
- return PrettyPrinter()._safe_repr(object, {}, None, 0)[1]
- def isrecursive(object):
- """Determine if object requires a recursive representation."""
- return PrettyPrinter()._safe_repr(object, {}, None, 0)[2]
- class _safe_key:
- """Helper function for key functions when sorting unorderable objects.
- The wrapped-object will fallback to a Py2.x style comparison for
- unorderable types (sorting first comparing the type name and then by
- the obj ids). Does not work recursively, so dict.items() must have
- _safe_key applied to both the key and the value.
- """
- __slots__ = ['obj']
- def __init__(self, obj):
- self.obj = obj
- def __lt__(self, other):
- try:
- return self.obj < other.obj
- except TypeError:
- return ((str(type(self.obj)), id(self.obj)) < \
- (str(type(other.obj)), id(other.obj)))
- def _safe_tuple(t):
- "Helper function for comparing 2-tuples"
- return _safe_key(t[0]), _safe_key(t[1])
- class PrettyPrinter:
- def __init__(self, indent=1, width=80, depth=None, stream=None, *,
- compact=False, sort_dicts=True, underscore_numbers=False):
- """Handle pretty printing operations onto a stream using a set of
- configured parameters.
- indent
- Number of spaces to indent for each level of nesting.
- width
- Attempted maximum number of columns in the output.
- depth
- The maximum depth to print out nested structures.
- stream
- The desired output stream. If omitted (or false), the standard
- output stream available at construction will be used.
- compact
- If true, several items will be combined in one line.
- sort_dicts
- If true, dict keys are sorted.
- """
- indent = int(indent)
- width = int(width)
- if indent < 0:
- raise ValueError('indent must be >= 0')
- if depth is not None and depth <= 0:
- raise ValueError('depth must be > 0')
- if not width:
- raise ValueError('width must be != 0')
- self._depth = depth
- self._indent_per_level = indent
- self._width = width
- if stream is not None:
- self._stream = stream
- else:
- self._stream = _sys.stdout
- self._compact = bool(compact)
- self._sort_dicts = sort_dicts
- self._underscore_numbers = underscore_numbers
- def pprint(self, object):
- if self._stream is not None:
- self._format(object, self._stream, 0, 0, {}, 0)
- self._stream.write("\n")
- def pformat(self, object):
- sio = _StringIO()
- self._format(object, sio, 0, 0, {}, 0)
- return sio.getvalue()
- def isrecursive(self, object):
- return self.format(object, {}, 0, 0)[2]
- def isreadable(self, object):
- s, readable, recursive = self.format(object, {}, 0, 0)
- return readable and not recursive
- def _format(self, object, stream, indent, allowance, context, level):
- objid = id(object)
- if objid in context:
- stream.write(_recursion(object))
- self._recursive = True
- self._readable = False
- return
- rep = self._repr(object, context, level)
- max_width = self._width - indent - allowance
- if len(rep) > max_width:
- p = self._dispatch.get(type(object).__repr__, None)
- if p is not None:
- context[objid] = 1
- p(self, object, stream, indent, allowance, context, level + 1)
- del context[objid]
- return
- elif (_dataclasses.is_dataclass(object) and
- not isinstance(object, type) and
- object.__dataclass_params__.repr and
- # Check dataclass has generated repr method.
- hasattr(object.__repr__, "__wrapped__") and
- "__create_fn__" in object.__repr__.__wrapped__.__qualname__):
- context[objid] = 1
- self._pprint_dataclass(object, stream, indent, allowance, context, level + 1)
- del context[objid]
- return
- stream.write(rep)
- def _pprint_dataclass(self, object, stream, indent, allowance, context, level):
- cls_name = object.__class__.__name__
- indent += len(cls_name) + 1
- items = [(f.name, getattr(object, f.name)) for f in _dataclasses.fields(object) if f.repr]
- stream.write(cls_name + '(')
- self._format_namespace_items(items, stream, indent, allowance, context, level)
- stream.write(')')
- _dispatch = {}
- def _pprint_dict(self, object, stream, indent, allowance, context, level):
- write = stream.write
- write('{')
- if self._indent_per_level > 1:
- write((self._indent_per_level - 1) * ' ')
- length = len(object)
- if length:
- if self._sort_dicts:
- items = sorted(object.items(), key=_safe_tuple)
- else:
- items = object.items()
- self._format_dict_items(items, stream, indent, allowance + 1,
- context, level)
- write('}')
- _dispatch[dict.__repr__] = _pprint_dict
- def _pprint_ordered_dict(self, object, stream, indent, allowance, context, level):
- if not len(object):
- stream.write(repr(object))
- return
- cls = object.__class__
- stream.write(cls.__name__ + '(')
- self._format(list(object.items()), stream,
- indent + len(cls.__name__) + 1, allowance + 1,
- context, level)
- stream.write(')')
- _dispatch[_collections.OrderedDict.__repr__] = _pprint_ordered_dict
- def _pprint_list(self, object, stream, indent, allowance, context, level):
- stream.write('[')
- self._format_items(object, stream, indent, allowance + 1,
- context, level)
- stream.write(']')
- _dispatch[list.__repr__] = _pprint_list
- def _pprint_tuple(self, object, stream, indent, allowance, context, level):
- stream.write('(')
- endchar = ',)' if len(object) == 1 else ')'
- self._format_items(object, stream, indent, allowance + len(endchar),
- context, level)
- stream.write(endchar)
- _dispatch[tuple.__repr__] = _pprint_tuple
- def _pprint_set(self, object, stream, indent, allowance, context, level):
- if not len(object):
- stream.write(repr(object))
- return
- typ = object.__class__
- if typ is set:
- stream.write('{')
- endchar = '}'
- else:
- stream.write(typ.__name__ + '({')
- endchar = '})'
- indent += len(typ.__name__) + 1
- object = sorted(object, key=_safe_key)
- self._format_items(object, stream, indent, allowance + len(endchar),
- context, level)
- stream.write(endchar)
- _dispatch[set.__repr__] = _pprint_set
- _dispatch[frozenset.__repr__] = _pprint_set
- def _pprint_str(self, object, stream, indent, allowance, context, level):
- write = stream.write
- if not len(object):
- write(repr(object))
- return
- chunks = []
- lines = object.splitlines(True)
- if level == 1:
- indent += 1
- allowance += 1
- max_width1 = max_width = self._width - indent
- for i, line in enumerate(lines):
- rep = repr(line)
- if i == len(lines) - 1:
- max_width1 -= allowance
- if len(rep) <= max_width1:
- chunks.append(rep)
- else:
- # A list of alternating (non-space, space) strings
- parts = re.findall(r'\S*\s*', line)
- assert parts
- assert not parts[-1]
- parts.pop() # drop empty last part
- max_width2 = max_width
- current = ''
- for j, part in enumerate(parts):
- candidate = current + part
- if j == len(parts) - 1 and i == len(lines) - 1:
- max_width2 -= allowance
- if len(repr(candidate)) > max_width2:
- if current:
- chunks.append(repr(current))
- current = part
- else:
- current = candidate
- if current:
- chunks.append(repr(current))
- if len(chunks) == 1:
- write(rep)
- return
- if level == 1:
- write('(')
- for i, rep in enumerate(chunks):
- if i > 0:
- write('\n' + ' '*indent)
- write(rep)
- if level == 1:
- write(')')
- _dispatch[str.__repr__] = _pprint_str
- def _pprint_bytes(self, object, stream, indent, allowance, context, level):
- write = stream.write
- if len(object) <= 4:
- write(repr(object))
- return
- parens = level == 1
- if parens:
- indent += 1
- allowance += 1
- write('(')
- delim = ''
- for rep in _wrap_bytes_repr(object, self._width - indent, allowance):
- write(delim)
- write(rep)
- if not delim:
- delim = '\n' + ' '*indent
- if parens:
- write(')')
- _dispatch[bytes.__repr__] = _pprint_bytes
- def _pprint_bytearray(self, object, stream, indent, allowance, context, level):
- write = stream.write
- write('bytearray(')
- self._pprint_bytes(bytes(object), stream, indent + 10,
- allowance + 1, context, level + 1)
- write(')')
- _dispatch[bytearray.__repr__] = _pprint_bytearray
- def _pprint_mappingproxy(self, object, stream, indent, allowance, context, level):
- stream.write('mappingproxy(')
- self._format(object.copy(), stream, indent + 13, allowance + 1,
- context, level)
- stream.write(')')
- _dispatch[_types.MappingProxyType.__repr__] = _pprint_mappingproxy
- def _pprint_simplenamespace(self, object, stream, indent, allowance, context, level):
- if type(object) is _types.SimpleNamespace:
- # The SimpleNamespace repr is "namespace" instead of the class
- # name, so we do the same here. For subclasses; use the class name.
- cls_name = 'namespace'
- else:
- cls_name = object.__class__.__name__
- indent += len(cls_name) + 1
- items = object.__dict__.items()
- stream.write(cls_name + '(')
- self._format_namespace_items(items, stream, indent, allowance, context, level)
- stream.write(')')
- _dispatch[_types.SimpleNamespace.__repr__] = _pprint_simplenamespace
- def _format_dict_items(self, items, stream, indent, allowance, context,
- level):
- write = stream.write
- indent += self._indent_per_level
- delimnl = ',\n' + ' ' * indent
- last_index = len(items) - 1
- for i, (key, ent) in enumerate(items):
- last = i == last_index
- rep = self._repr(key, context, level)
- write(rep)
- write(': ')
- self._format(ent, stream, indent + len(rep) + 2,
- allowance if last else 1,
- context, level)
- if not last:
- write(delimnl)
- def _format_namespace_items(self, items, stream, indent, allowance, context, level):
- write = stream.write
- delimnl = ',\n' + ' ' * indent
- last_index = len(items) - 1
- for i, (key, ent) in enumerate(items):
- last = i == last_index
- write(key)
- write('=')
- if id(ent) in context:
- # Special-case representation of recursion to match standard
- # recursive dataclass repr.
- write("...")
- else:
- self._format(ent, stream, indent + len(key) + 1,
- allowance if last else 1,
- context, level)
- if not last:
- write(delimnl)
- def _format_items(self, items, stream, indent, allowance, context, level):
- write = stream.write
- indent += self._indent_per_level
- if self._indent_per_level > 1:
- write((self._indent_per_level - 1) * ' ')
- delimnl = ',\n' + ' ' * indent
- delim = ''
- width = max_width = self._width - indent + 1
- it = iter(items)
- try:
- next_ent = next(it)
- except StopIteration:
- return
- last = False
- while not last:
- ent = next_ent
- try:
- next_ent = next(it)
- except StopIteration:
- last = True
- max_width -= allowance
- width -= allowance
- if self._compact:
- rep = self._repr(ent, context, level)
- w = len(rep) + 2
- if width < w:
- width = max_width
- if delim:
- delim = delimnl
- if width >= w:
- width -= w
- write(delim)
- delim = ', '
- write(rep)
- continue
- write(delim)
- delim = delimnl
- self._format(ent, stream, indent,
- allowance if last else 1,
- context, level)
- def _repr(self, object, context, level):
- repr, readable, recursive = self.format(object, context.copy(),
- self._depth, level)
- if not readable:
- self._readable = False
- if recursive:
- self._recursive = True
- return repr
- def format(self, object, context, maxlevels, level):
- """Format object for a specific context, returning a string
- and flags indicating whether the representation is 'readable'
- and whether the object represents a recursive construct.
- """
- return self._safe_repr(object, context, maxlevels, level)
- def _pprint_default_dict(self, object, stream, indent, allowance, context, level):
- if not len(object):
- stream.write(repr(object))
- return
- rdf = self._repr(object.default_factory, context, level)
- cls = object.__class__
- indent += len(cls.__name__) + 1
- stream.write('%s(%s,\n%s' % (cls.__name__, rdf, ' ' * indent))
- self._pprint_dict(object, stream, indent, allowance + 1, context, level)
- stream.write(')')
- _dispatch[_collections.defaultdict.__repr__] = _pprint_default_dict
- def _pprint_counter(self, object, stream, indent, allowance, context, level):
- if not len(object):
- stream.write(repr(object))
- return
- cls = object.__class__
- stream.write(cls.__name__ + '({')
- if self._indent_per_level > 1:
- stream.write((self._indent_per_level - 1) * ' ')
- items = object.most_common()
- self._format_dict_items(items, stream,
- indent + len(cls.__name__) + 1, allowance + 2,
- context, level)
- stream.write('})')
- _dispatch[_collections.Counter.__repr__] = _pprint_counter
- def _pprint_chain_map(self, object, stream, indent, allowance, context, level):
- if not len(object.maps):
- stream.write(repr(object))
- return
- cls = object.__class__
- stream.write(cls.__name__ + '(')
- indent += len(cls.__name__) + 1
- for i, m in enumerate(object.maps):
- if i == len(object.maps) - 1:
- self._format(m, stream, indent, allowance + 1, context, level)
- stream.write(')')
- else:
- self._format(m, stream, indent, 1, context, level)
- stream.write(',\n' + ' ' * indent)
- _dispatch[_collections.ChainMap.__repr__] = _pprint_chain_map
- def _pprint_deque(self, object, stream, indent, allowance, context, level):
- if not len(object):
- stream.write(repr(object))
- return
- cls = object.__class__
- stream.write(cls.__name__ + '(')
- indent += len(cls.__name__) + 1
- stream.write('[')
- if object.maxlen is None:
- self._format_items(object, stream, indent, allowance + 2,
- context, level)
- stream.write('])')
- else:
- self._format_items(object, stream, indent, 2,
- context, level)
- rml = self._repr(object.maxlen, context, level)
- stream.write('],\n%smaxlen=%s)' % (' ' * indent, rml))
- _dispatch[_collections.deque.__repr__] = _pprint_deque
- def _pprint_user_dict(self, object, stream, indent, allowance, context, level):
- self._format(object.data, stream, indent, allowance, context, level - 1)
- _dispatch[_collections.UserDict.__repr__] = _pprint_user_dict
- def _pprint_user_list(self, object, stream, indent, allowance, context, level):
- self._format(object.data, stream, indent, allowance, context, level - 1)
- _dispatch[_collections.UserList.__repr__] = _pprint_user_list
- def _pprint_user_string(self, object, stream, indent, allowance, context, level):
- self._format(object.data, stream, indent, allowance, context, level - 1)
- _dispatch[_collections.UserString.__repr__] = _pprint_user_string
- def _safe_repr(self, object, context, maxlevels, level):
- # Return triple (repr_string, isreadable, isrecursive).
- typ = type(object)
- if typ in _builtin_scalars:
- return repr(object), True, False
- r = getattr(typ, "__repr__", None)
- if issubclass(typ, int) and r is int.__repr__:
- if self._underscore_numbers:
- return f"{object:_d}", True, False
- else:
- return repr(object), True, False
- if issubclass(typ, dict) and r is dict.__repr__:
- if not object:
- return "{}", True, False
- objid = id(object)
- if maxlevels and level >= maxlevels:
- return "{...}", False, objid in context
- if objid in context:
- return _recursion(object), False, True
- context[objid] = 1
- readable = True
- recursive = False
- components = []
- append = components.append
- level += 1
- if self._sort_dicts:
- items = sorted(object.items(), key=_safe_tuple)
- else:
- items = object.items()
- for k, v in items:
- krepr, kreadable, krecur = self.format(
- k, context, maxlevels, level)
- vrepr, vreadable, vrecur = self.format(
- v, context, maxlevels, level)
- append("%s: %s" % (krepr, vrepr))
- readable = readable and kreadable and vreadable
- if krecur or vrecur:
- recursive = True
- del context[objid]
- return "{%s}" % ", ".join(components), readable, recursive
- if (issubclass(typ, list) and r is list.__repr__) or \
- (issubclass(typ, tuple) and r is tuple.__repr__):
- if issubclass(typ, list):
- if not object:
- return "[]", True, False
- format = "[%s]"
- elif len(object) == 1:
- format = "(%s,)"
- else:
- if not object:
- return "()", True, False
- format = "(%s)"
- objid = id(object)
- if maxlevels and level >= maxlevels:
- return format % "...", False, objid in context
- if objid in context:
- return _recursion(object), False, True
- context[objid] = 1
- readable = True
- recursive = False
- components = []
- append = components.append
- level += 1
- for o in object:
- orepr, oreadable, orecur = self.format(
- o, context, maxlevels, level)
- append(orepr)
- if not oreadable:
- readable = False
- if orecur:
- recursive = True
- del context[objid]
- return format % ", ".join(components), readable, recursive
- rep = repr(object)
- return rep, (rep and not rep.startswith('<')), False
- _builtin_scalars = frozenset({str, bytes, bytearray, float, complex,
- bool, type(None)})
- def _recursion(object):
- return ("<Recursion on %s with id=%s>"
- % (type(object).__name__, id(object)))
- def _wrap_bytes_repr(object, width, allowance):
- current = b''
- last = len(object) // 4 * 4
- for i in range(0, len(object), 4):
- part = object[i: i+4]
- candidate = current + part
- if i == last:
- width -= allowance
- if len(repr(candidate)) > width:
- if current:
- yield repr(current)
- current = part
- else:
- current = candidate
- if current:
- yield repr(current)
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