This document describes the current stable version of Celery (4.4). For development docs, go here.

Source code for celery.utils.saferepr

# -*- coding: utf-8 -*-
"""Streaming, truncating, non-recursive version of :func:`repr`.

Differences from regular :func:`repr`:

- Sets are represented the Python 3 way: ``{1, 2}`` vs ``set([1, 2])``.
- Unicode strings does not have the ``u'`` prefix, even on Python 2.
- Empty set formatted as ``set()`` (Python 3), not ``set([])`` (Python 2).
- Longs don't have the ``L`` suffix.

Very slow with no limits, super quick with limits.
from __future__ import absolute_import, unicode_literals

import traceback
from collections import deque, namedtuple
from decimal import Decimal
from itertools import chain
from numbers import Number
from pprint import _recursion

from celery.five import PY3, items, range, text_t

from .text import truncate

__all__ = ('saferepr', 'reprstream')

#: Node representing literal text.
#:   - .value: is the literal text value
#:   - .truncate: specifies if this text can be truncated, for things like
#:                LIT_DICT_END this will be False, as we always display
#:                the ending brackets, e.g:  [[[1, 2, 3, ...,], ..., ]]
#:   - .direction: If +1 the current level is increment by one,
#:                 if -1 the current level is decremented by one, and
#:                 if 0 the current level is unchanged.
_literal = namedtuple('_literal', ('value', 'truncate', 'direction'))

#: Node representing a dictionary key.
_key = namedtuple('_key', ('value',))

#: Node representing quoted text, e.g. a string value.
_quoted = namedtuple('_quoted', ('value',))

#: Recursion protection.
_dirty = namedtuple('_dirty', ('objid',))

#: Types that are repsented as chars.
chars_t = (bytes, text_t)

#: Types that are regarded as safe to call repr on.
safe_t = (Number,)

#: Set types.
set_t = (frozenset, set)

LIT_DICT_START = _literal('{', False, +1)
LIT_DICT_KVSEP = _literal(': ', True, 0)
LIT_DICT_END = _literal('}', False, -1)
LIT_LIST_START = _literal('[', False, +1)
LIT_LIST_END = _literal(']', False, -1)
LIT_LIST_SEP = _literal(', ', True, 0)
LIT_SET_START = _literal('{', False, +1)
LIT_SET_END = _literal('}', False, -1)
LIT_TUPLE_START = _literal('(', False, +1)
LIT_TUPLE_END = _literal(')', False, -1)
LIT_TUPLE_END_SV = _literal(',)', False, -1)

[docs]def saferepr(o, maxlen=None, maxlevels=3, seen=None): # type: (Any, int, int, Set) -> str """Safe version of :func:`repr`. Warning: Make sure you set the maxlen argument, or it will be very slow for recursive objects. With the maxlen set, it's often faster than built-in repr. """ return ''.join(_saferepr( o, maxlen=maxlen, maxlevels=maxlevels, seen=seen ))
def _chaindict(mapping, LIT_DICT_KVSEP=LIT_DICT_KVSEP, LIT_LIST_SEP=LIT_LIST_SEP): # type: (Dict, _literal, _literal) -> Iterator[Any] size = len(mapping) for i, (k, v) in enumerate(items(mapping)): yield _key(k) yield LIT_DICT_KVSEP yield v if i < (size - 1): yield LIT_LIST_SEP def _chainlist(it, LIT_LIST_SEP=LIT_LIST_SEP): # type: (List) -> Iterator[Any] size = len(it) for i, v in enumerate(it): yield v if i < (size - 1): yield LIT_LIST_SEP def _repr_empty_set(s): # type: (Set) -> str return '%s()' % (type(s).__name__,) def _safetext(val): # type: (AnyStr) -> str if isinstance(val, bytes): try: val.encode('utf-8') except UnicodeDecodeError: # is bytes with unrepresentable characters, attempt # to convert back to unicode return val.decode('utf-8', errors='backslashreplace') return val def _format_binary_bytes(val, maxlen, ellipsis='...'): # type: (bytes, int, str) -> str if maxlen and len(val) > maxlen: # we don't want to copy all the data, just take what we need. chunk = memoryview(val)[:maxlen].tobytes() return _bytes_prefix("'{0}{1}'".format( _repr_binary_bytes(chunk), ellipsis)) return _bytes_prefix("'{0}'".format(_repr_binary_bytes(val))) def _bytes_prefix(s): return 'b' + s if PY3 else s def _repr_binary_bytes(val): # type: (bytes) -> str try: return val.decode('utf-8') except UnicodeDecodeError: # possibly not unicode, but binary data so format as hex. try: ashex = val.hex except AttributeError: # pragma: no cover # Python 3.4 return val.decode('utf-8', errors='replace') else: # Python 3.5+ return ashex() def _format_chars(val, maxlen): # type: (AnyStr, int) -> str if isinstance(val, bytes): # pragma: no cover return _format_binary_bytes(val, maxlen) else: return "'{0}'".format(truncate(val, maxlen).replace("'", "\\'")) def _repr(obj): # type: (Any) -> str try: return repr(obj) except Exception as exc: return '<Unrepresentable {0!r}{1:#x}: {2!r} {3!r}>'.format( type(obj), id(obj), exc, '\n'.join(traceback.format_stack())) def _saferepr(o, maxlen=None, maxlevels=3, seen=None): # type: (Any, int, int, Set) -> str stack = deque([iter([o])]) for token, it in reprstream(stack, seen=seen, maxlevels=maxlevels): if maxlen is not None and maxlen <= 0: yield ', ...' # move rest back to stack, so that we can include # dangling parens. stack.append(it) break if isinstance(token, _literal): val = token.value elif isinstance(token, _key): val = saferepr(token.value, maxlen, maxlevels) elif isinstance(token, _quoted): val = _format_chars(token.value, maxlen) else: val = _safetext(truncate(token, maxlen)) yield val if maxlen is not None: maxlen -= len(val) for rest1 in stack: # maxlen exceeded, process any dangling parens. for rest2 in rest1: if isinstance(rest2, _literal) and not rest2.truncate: yield rest2.value def _reprseq(val, lit_start, lit_end, builtin_type, chainer): # type: (Sequence, _literal, _literal, Any, Any) -> Tuple[Any, ...] if type(val) is builtin_type: # noqa return lit_start, lit_end, chainer(val) return ( _literal('%s(%s' % (type(val).__name__, lit_start.value), False, +1), _literal('%s)' % (lit_end.value,), False, -1), chainer(val) )
[docs]def reprstream(stack, seen=None, maxlevels=3, level=0, isinstance=isinstance): """Streaming repr, yielding tokens.""" # type: (deque, Set, int, int, Callable) -> Iterator[Any] seen = seen or set() append = stack.append popleft = stack.popleft is_in_seen = seen.__contains__ discard_from_seen = seen.discard add_to_seen = seen.add while stack: lit_start = lit_end = None it = popleft() for val in it: orig = val if isinstance(val, _dirty): discard_from_seen(val.objid) continue elif isinstance(val, _literal): level += val.direction yield val, it elif isinstance(val, _key): yield val, it elif isinstance(val, Decimal): yield _repr(val), it elif isinstance(val, safe_t): yield text_t(val), it elif isinstance(val, chars_t): yield _quoted(val), it elif isinstance(val, range): # pragma: no cover yield _repr(val), it else: if isinstance(val, set_t): if not val: yield _repr_empty_set(val), it continue lit_start, lit_end, val = _reprseq( val, LIT_SET_START, LIT_SET_END, set, _chainlist, ) elif isinstance(val, tuple): lit_start, lit_end, val = ( LIT_TUPLE_START, LIT_TUPLE_END_SV if len(val) == 1 else LIT_TUPLE_END, _chainlist(val)) elif isinstance(val, dict): lit_start, lit_end, val = ( LIT_DICT_START, LIT_DICT_END, _chaindict(val)) elif isinstance(val, list): lit_start, lit_end, val = ( LIT_LIST_START, LIT_LIST_END, _chainlist(val)) else: # other type of object yield _repr(val), it continue if maxlevels and level >= maxlevels: yield '%s...%s' % (lit_start.value, lit_end.value), it continue objid = id(orig) if is_in_seen(objid): yield _recursion(orig), it continue add_to_seen(objid) # Recurse into the new list/tuple/dict/etc by tacking # the rest of our iterable onto the new it: this way # it works similar to a linked list. append(chain([lit_start], val, [_dirty(objid), lit_end], it)) break