# This file is part of Hypothesis, which may be found at # https://github.com/HypothesisWorks/hypothesis/ # # Copyright the Hypothesis Authors. # Individual contributors are listed in AUTHORS.rst and the git log. # # This Source Code Form is subject to the terms of the Mozilla Public License, # v. 2.0. If a copy of the MPL was not distributed with this file, You can # obtain one at https://mozilla.org/MPL/2.0/. """ Python advanced pretty printer. This pretty printer is intended to replace the old `pprint` python module which does not allow developers to provide their own pretty print callbacks. This module is based on ruby's `prettyprint.rb` library by `Tanaka Akira`. Example Usage ------------- To get a string of the output use `pretty`:: from pretty import pretty string = pretty(complex_object) Extending --------- The pretty library allows developers to add pretty printing rules for their own objects. This process is straightforward. All you have to do is to add a `_repr_pretty_` method to your object and call the methods on the pretty printer passed:: class MyObject(object): def _repr_pretty_(self, p, cycle): ... Here is an example implementation of a `_repr_pretty_` method for a list subclass:: class MyList(list): def _repr_pretty_(self, p, cycle): if cycle: p.text('MyList(...)') else: with p.group(8, 'MyList([', '])'): for idx, item in enumerate(self): if idx: p.text(',') p.breakable() p.pretty(item) The `cycle` parameter is `True` if pretty detected a cycle. You *have* to react to that or the result is an infinite loop. `p.text()` just adds non breaking text to the output, `p.breakable()` either adds a whitespace or breaks here. If you pass it an argument it's used instead of the default space. `p.pretty` prettyprints another object using the pretty print method. The first parameter to the `group` function specifies the extra indentation of the next line. In this example the next item will either be on the same line (if the items are short enough) or aligned with the right edge of the opening bracket of `MyList`. If you just want to indent something you can use the group function without open / close parameters. You can also use this code:: with p.indent(2): ... Inheritance diagram: .. inheritance-diagram:: IPython.lib.pretty :parts: 3 :copyright: 2007 by Armin Ronacher. Portions (c) 2009 by Robert Kern. :license: BSD License. """ import datetime import re import struct import sys import types import warnings from collections import defaultdict, deque from contextlib import contextmanager from enum import Flag from io import StringIO from math import copysign, isnan __all__ = [ "pretty", "IDKey", "RepresentationPrinter", ] def _safe_getattr(obj, attr, default=None): """Safe version of getattr. Same as getattr, but will return ``default`` on any Exception, rather than raising. """ try: return getattr(obj, attr, default) except Exception: return default def pretty(obj): """Pretty print the object's representation.""" printer = RepresentationPrinter() printer.pretty(obj) return printer.getvalue() class IDKey: def __init__(self, value): self.value = value def __hash__(self) -> int: return hash((type(self), id(self.value))) def __eq__(self, __o: object) -> bool: return isinstance(__o, type(self)) and id(self.value) == id(__o.value) class RepresentationPrinter: """Special pretty printer that has a `pretty` method that calls the pretty printer for a python object. This class stores processing data on `self` so you must *never* use this class in a threaded environment. Always lock it or reinstantiate it. """ def __init__(self, output=None, *, context=None): """Pass the output stream, and optionally the current build context. We use the context to represent objects constructed by strategies by showing *how* they were constructed, and add annotations showing which parts of the minimal failing example can vary without changing the test result. """ self.broken = False self.output = StringIO() if output is None else output self.max_width = 79 self.max_seq_length = 1000 self.output_width = 0 self.buffer_width = 0 self.buffer = deque() root_group = Group(0) self.group_stack = [root_group] self.group_queue = GroupQueue(root_group) self.indentation = 0 self.snans = 0 self.stack = [] self.singleton_pprinters = {} self.type_pprinters = {} self.deferred_pprinters = {} # If IPython has been imported, load up their pretty-printer registry if "IPython.lib.pretty" in sys.modules: ipp = sys.modules["IPython.lib.pretty"] self.singleton_pprinters.update(ipp._singleton_pprinters) self.type_pprinters.update(ipp._type_pprinters) self.deferred_pprinters.update(ipp._deferred_type_pprinters) # If there's overlap between our pprinters and IPython's, we'll use ours. self.singleton_pprinters.update(_singleton_pprinters) self.type_pprinters.update(_type_pprinters) self.deferred_pprinters.update(_deferred_type_pprinters) # for which-parts-matter, we track a mapping from the (start_idx, end_idx) # of slices into the minimal failing example; this is per-interesting_origin # but we report each separately so that's someone else's problem here. # Invocations of self.repr_call() can report the slice for each argument, # which will then be used to look up the relevant comment if any. if context is None: self.known_object_printers = defaultdict(list) self.slice_comments = {} else: self.known_object_printers = context.known_object_printers self.slice_comments = context.data.slice_comments assert all(isinstance(k, IDKey) for k in self.known_object_printers) def pretty(self, obj): """Pretty print the given object.""" obj_id = id(obj) cycle = obj_id in self.stack self.stack.append(obj_id) try: with self.group(): obj_class = _safe_getattr(obj, "__class__", None) or type(obj) # First try to find registered singleton printers for the type. try: printer = self.singleton_pprinters[obj_id] except (TypeError, KeyError): pass else: return printer(obj, self, cycle) # Next walk the mro and check for either: # 1) a registered printer # 2) a _repr_pretty_ method for cls in obj_class.__mro__: if cls in self.type_pprinters: # printer registered in self.type_pprinters return self.type_pprinters[cls](obj, self, cycle) else: # Check if the given class is specified in the deferred type # registry; move it to the regular type registry if so. key = ( _safe_getattr(cls, "__module__", None), _safe_getattr(cls, "__name__", None), ) if key in self.deferred_pprinters: # Move the printer over to the regular registry. printer = self.deferred_pprinters.pop(key) self.type_pprinters[cls] = printer return printer(obj, self, cycle) else: # Finally look for special method names. # Some objects automatically create any requested # attribute. Try to ignore most of them by checking for # callability. if "_repr_pretty_" in cls.__dict__: meth = cls._repr_pretty_ if callable(meth): return meth(obj, self, cycle) # Now check for object-specific printers which show how this # object was constructed (a Hypothesis special feature). printers = self.known_object_printers[IDKey(obj)] if len(printers) == 1: return printers[0](obj, self, cycle) elif printers: # We've ended up with multiple registered functions for the same # object, which must have been returned from multiple calls due to # e.g. memoization. If they all return the same string, we'll use # the first; otherwise we'll pretend that *none* were registered. # # It's annoying, but still seems to be the best option for which- # parts-matter too, as unreportable results aren't very useful. strs = set() for f in printers: p = RepresentationPrinter() f(obj, p, cycle) strs.add(p.getvalue()) if len(strs) == 1: return printers[0](obj, self, cycle) # A user-provided repr. Find newlines and replace them with p.break_() return _repr_pprint(obj, self, cycle) finally: self.stack.pop() def _break_outer_groups(self): while self.max_width < self.output_width + self.buffer_width: group = self.group_queue.deq() if not group: return while group.breakables: x = self.buffer.popleft() self.output_width = x.output(self.output, self.output_width) self.buffer_width -= x.width while self.buffer and isinstance(self.buffer[0], Text): x = self.buffer.popleft() self.output_width = x.output(self.output, self.output_width) self.buffer_width -= x.width def text(self, obj): """Add literal text to the output.""" width = len(obj) if self.buffer: text = self.buffer[-1] if not isinstance(text, Text): text = Text() self.buffer.append(text) text.add(obj, width) self.buffer_width += width self._break_outer_groups() else: self.output.write(obj) self.output_width += width def breakable(self, sep=" "): """Add a breakable separator to the output. This does not mean that it will automatically break here. If no breaking on this position takes place the `sep` is inserted which default to one space. """ width = len(sep) group = self.group_stack[-1] if group.want_break: self.flush() self.output.write("\n" + " " * self.indentation) self.output_width = self.indentation self.buffer_width = 0 else: self.buffer.append(Breakable(sep, width, self)) self.buffer_width += width self._break_outer_groups() def break_(self): """Explicitly insert a newline into the output, maintaining correct indentation.""" self.flush() self.output.write("\n" + " " * self.indentation) self.output_width = self.indentation self.buffer_width = 0 @contextmanager def indent(self, indent): """`with`-statement support for indenting/dedenting.""" self.indentation += indent try: yield finally: self.indentation -= indent @contextmanager def group(self, indent=0, open="", close=""): """Context manager for an indented group. with p.group(1, '{', '}'): The first parameter specifies the indentation for the next line (usually the width of the opening text), the second and third the opening and closing delimiters. """ self.begin_group(indent=indent, open=open) try: yield finally: self.end_group(dedent=indent, close=close) def begin_group(self, indent=0, open=""): """Use the `with group(...) context manager instead. The begin_group() and end_group() methods are for IPython compatibility only; see https://github.com/HypothesisWorks/hypothesis/issues/3721 for details. """ if open: self.text(open) group = Group(self.group_stack[-1].depth + 1) self.group_stack.append(group) self.group_queue.enq(group) self.indentation += indent def end_group(self, dedent=0, close=""): """See begin_group().""" self.indentation -= dedent group = self.group_stack.pop() if not group.breakables: self.group_queue.remove(group) if close: self.text(close) def _enumerate(self, seq): """Like enumerate, but with an upper limit on the number of items.""" for idx, x in enumerate(seq): if self.max_seq_length and idx >= self.max_seq_length: self.text(",") self.breakable() self.text("...") return yield idx, x def flush(self): """Flush data that is left in the buffer.""" if self.snans: # Reset self.snans *before* calling breakable(), which might flush() snans = self.snans self.snans = 0 self.breakable(" ") self.text(f"# Saw {snans} signaling NaN" + "s" * (snans > 1)) for data in self.buffer: self.output_width += data.output(self.output, self.output_width) self.buffer.clear() self.buffer_width = 0 def getvalue(self): assert isinstance(self.output, StringIO) self.flush() return self.output.getvalue() def repr_call( self, func_name, args, kwargs, *, force_split=None, arg_slices=None, leading_comment=None, ): """Helper function to represent a function call. - func_name, args, and kwargs should all be pretty obvious. - If split_lines, we'll force one-argument-per-line; otherwise we'll place calls that fit on a single line (and split otherwise). - arg_slices is a mapping from pos-idx or keyword to (start_idx, end_idx) of the Conjecture buffer, by which we can look up comments to add. """ assert isinstance(func_name, str) if func_name.startswith(("lambda:", "lambda ")): func_name = f"({func_name})" self.text(func_name) all_args = [(None, v) for v in args] + list(kwargs.items()) comments = { k: self.slice_comments[v] for k, v in (arg_slices or {}).items() if v in self.slice_comments } if leading_comment or any(k in comments for k, _ in all_args): # We have to split one arg per line in order to leave comments on them. force_split = True if force_split is None: # We're OK with printing this call on a single line, but will it fit? # If not, we'd rather fall back to one-argument-per-line instead. p = RepresentationPrinter() p.stack = self.stack.copy() p.known_object_printers = self.known_object_printers p.repr_call("_" * self.output_width, args, kwargs, force_split=False) s = p.getvalue() force_split = "\n" in s with self.group(indent=4, open="(", close=""): for i, (k, v) in enumerate(all_args): if force_split: if i == 0 and leading_comment: self.break_() self.text(leading_comment) self.break_() else: self.breakable(" " if i else "") if k: self.text(f"{k}=") self.pretty(v) if force_split or i + 1 < len(all_args): self.text(",") # Optional comments are used to annotate which-parts-matter comment = comments.get(i) or comments.get(k) if comment: self.text(f" # {comment}") if all_args and force_split: self.break_() self.text(")") # after dedent class Printable: def output(self, stream, output_width): # pragma: no cover raise NotImplementedError class Text(Printable): def __init__(self): self.objs = [] self.width = 0 def output(self, stream, output_width): for obj in self.objs: stream.write(obj) return output_width + self.width def add(self, obj, width): self.objs.append(obj) self.width += width class Breakable(Printable): def __init__(self, seq, width, pretty): self.obj = seq self.width = width self.pretty = pretty self.indentation = pretty.indentation self.group = pretty.group_stack[-1] self.group.breakables.append(self) def output(self, stream, output_width): self.group.breakables.popleft() if self.group.want_break: stream.write("\n" + " " * self.indentation) return self.indentation if not self.group.breakables: self.pretty.group_queue.remove(self.group) stream.write(self.obj) return output_width + self.width class Group(Printable): def __init__(self, depth): self.depth = depth self.breakables = deque() self.want_break = False class GroupQueue: def __init__(self, *groups): self.queue = [] for group in groups: self.enq(group) def enq(self, group): depth = group.depth while depth > len(self.queue) - 1: self.queue.append([]) self.queue[depth].append(group) def deq(self): for stack in self.queue: for idx, group in enumerate(reversed(stack)): if group.breakables: del stack[idx] group.want_break = True return group for group in stack: group.want_break = True del stack[:] def remove(self, group): try: self.queue[group.depth].remove(group) except ValueError: pass def _seq_pprinter_factory(start, end, basetype): """Factory that returns a pprint function useful for sequences. Used by the default pprint for tuples, dicts, and lists. """ def inner(obj, p, cycle): typ = type(obj) if ( basetype is not None and typ is not basetype and typ.__repr__ != basetype.__repr__ ): # If the subclass provides its own repr, use it instead. return p.text(typ.__repr__(obj)) if cycle: return p.text(start + "..." + end) step = len(start) with p.group(step, start, end): for idx, x in p._enumerate(obj): if idx: p.text(",") p.breakable() p.pretty(x) if len(obj) == 1 and type(obj) is tuple: # Special case for 1-item tuples. p.text(",") return inner def _set_pprinter_factory(start, end, basetype): """Factory that returns a pprint function useful for sets and frozensets.""" def inner(obj, p, cycle): typ = type(obj) if ( basetype is not None and typ is not basetype and typ.__repr__ != basetype.__repr__ ): # If the subclass provides its own repr, use it instead. return p.text(typ.__repr__(obj)) if cycle: return p.text(start + "..." + end) if not obj: # Special case. p.text(basetype.__name__ + "()") else: step = len(start) with p.group(step, start, end): # Like dictionary keys, try to sort the items if there aren't too many items = obj if not (p.max_seq_length and len(obj) >= p.max_seq_length): try: items = sorted(obj) except Exception: # Sometimes the items don't sort. pass for idx, x in p._enumerate(items): if idx: p.text(",") p.breakable() p.pretty(x) return inner def _dict_pprinter_factory(start, end, basetype=None): """Factory that returns a pprint function used by the default pprint of dicts and dict proxies.""" def inner(obj, p, cycle): typ = type(obj) if ( basetype is not None and typ is not basetype and typ.__repr__ != basetype.__repr__ ): # If the subclass provides its own repr, use it instead. return p.text(typ.__repr__(obj)) if cycle: return p.text("{...}") with p.group(1, start, end): # If the dict contains both "" and b"" (empty string and empty bytes), we # ignore the BytesWarning raised by `python -bb` mode. We can't use # `.items()` because it might be a non-`dict` type of mapping. with warnings.catch_warnings(): warnings.simplefilter("ignore", BytesWarning) for idx, key in p._enumerate(obj): if idx: p.text(",") p.breakable() p.pretty(key) p.text(": ") p.pretty(obj[key]) inner.__name__ = f"_dict_pprinter_factory({start!r}, {end!r}, {basetype!r})" return inner def _super_pprint(obj, p, cycle): """The pprint for the super type.""" with p.group(8, ""): p.pretty(obj.__thisclass__) p.text(",") p.breakable() p.pretty(obj.__self__) def _re_pattern_pprint(obj, p, cycle): """The pprint function for regular expression patterns.""" p.text("re.compile(") pattern = repr(obj.pattern) if pattern[:1] in "uU": # pragma: no cover pattern = pattern[1:] prefix = "ur" else: prefix = "r" pattern = prefix + pattern.replace("\\\\", "\\") p.text(pattern) if obj.flags: p.text(",") p.breakable() done_one = False for flag in ( "TEMPLATE", "IGNORECASE", "LOCALE", "MULTILINE", "DOTALL", "UNICODE", "VERBOSE", "DEBUG", ): if obj.flags & getattr(re, flag, 0): if done_one: p.text("|") p.text("re." + flag) done_one = True p.text(")") def _type_pprint(obj, p, cycle): """The pprint for classes and types.""" # Heap allocated types might not have the module attribute, # and others may set it to None. # Checks for a __repr__ override in the metaclass # != rather than is not because pypy compatibility if type(obj).__repr__ != type.__repr__: _repr_pprint(obj, p, cycle) return mod = _safe_getattr(obj, "__module__", None) try: name = obj.__qualname__ if not isinstance(name, str): # pragma: no cover # This can happen if the type implements __qualname__ as a property # or other descriptor in Python 2. raise Exception("Try __name__") except Exception: # pragma: no cover name = obj.__name__ if not isinstance(name, str): name = "" if mod in (None, "__builtin__", "builtins", "exceptions"): p.text(name) else: p.text(mod + "." + name) def _repr_pprint(obj, p, cycle): """A pprint that just redirects to the normal repr function.""" # Find newlines and replace them with p.break_() output = repr(obj) for idx, output_line in enumerate(output.splitlines()): if idx: p.break_() p.text(output_line) def _function_pprint(obj, p, cycle): """Base pprint for all functions and builtin functions.""" from hypothesis.internal.reflection import get_pretty_function_description p.text(get_pretty_function_description(obj)) def _exception_pprint(obj, p, cycle): """Base pprint for all exceptions.""" name = getattr(obj.__class__, "__qualname__", obj.__class__.__name__) if obj.__class__.__module__ not in ("exceptions", "builtins"): name = f"{obj.__class__.__module__}.{name}" step = len(name) + 1 with p.group(step, name + "(", ")"): for idx, arg in enumerate(getattr(obj, "args", ())): if idx: p.text(",") p.breakable() p.pretty(arg) def _repr_float_counting_nans(obj, p, cycle): if isnan(obj) and hasattr(p, "snans"): if struct.pack("!d", abs(obj)) != struct.pack("!d", float("nan")): p.snans += 1 if copysign(1.0, obj) == -1.0: p.text("-nan") return p.text(repr(obj)) #: printers for builtin types _type_pprinters = { int: _repr_pprint, float: _repr_float_counting_nans, str: _repr_pprint, tuple: _seq_pprinter_factory("(", ")", tuple), list: _seq_pprinter_factory("[", "]", list), dict: _dict_pprinter_factory("{", "}", dict), set: _set_pprinter_factory("{", "}", set), frozenset: _set_pprinter_factory("frozenset({", "})", frozenset), super: _super_pprint, re.Pattern: _re_pattern_pprint, type: _type_pprint, types.FunctionType: _function_pprint, types.BuiltinFunctionType: _function_pprint, types.MethodType: _repr_pprint, datetime.datetime: _repr_pprint, datetime.timedelta: _repr_pprint, BaseException: _exception_pprint, slice: _repr_pprint, range: _repr_pprint, bytes: _repr_pprint, } #: printers for types specified by name _deferred_type_pprinters = {} # type: ignore def for_type_by_name(type_module, type_name, func): """Add a pretty printer for a type specified by the module and name of a type rather than the type object itself.""" key = (type_module, type_name) oldfunc = _deferred_type_pprinters.get(key, None) _deferred_type_pprinters[key] = func return oldfunc #: printers for the default singletons _singleton_pprinters = dict.fromkeys( map(id, [None, True, False, Ellipsis, NotImplemented]), _repr_pprint ) def _defaultdict_pprint(obj, p, cycle): name = obj.__class__.__name__ with p.group(len(name) + 1, name + "(", ")"): if cycle: p.text("...") else: p.pretty(obj.default_factory) p.text(",") p.breakable() p.pretty(dict(obj)) def _ordereddict_pprint(obj, p, cycle): name = obj.__class__.__name__ with p.group(len(name) + 1, name + "(", ")"): if cycle: p.text("...") elif obj: p.pretty(list(obj.items())) def _deque_pprint(obj, p, cycle): name = obj.__class__.__name__ with p.group(len(name) + 1, name + "(", ")"): if cycle: p.text("...") else: p.pretty(list(obj)) def _counter_pprint(obj, p, cycle): name = obj.__class__.__name__ with p.group(len(name) + 1, name + "(", ")"): if cycle: p.text("...") elif obj: p.pretty(dict(obj)) def _repr_dataframe(obj, p, cycle): # pragma: no cover with p.indent(4): p.break_() _repr_pprint(obj, p, cycle) p.break_() def _repr_enum(obj, p, cycle): tname = type(obj).__name__ if isinstance(obj, Flag): p.text( " | ".join(f"{tname}.{x.name}" for x in type(obj) if x & obj == x) or f"{tname}({obj.value!r})" # if no matching members ) else: p.text(f"{tname}.{obj.name}") class _ReprDots: def __repr__(self) -> str: return "..." def _repr_partial(obj, p, cycle): args, kw = obj.args, obj.keywords if cycle: args, kw = (_ReprDots(),), {} p.repr_call(pretty(type(obj)), (obj.func, *args), kw) for_type_by_name("collections", "defaultdict", _defaultdict_pprint) for_type_by_name("collections", "OrderedDict", _ordereddict_pprint) for_type_by_name("ordereddict", "OrderedDict", _ordereddict_pprint) for_type_by_name("collections", "deque", _deque_pprint) for_type_by_name("collections", "Counter", _counter_pprint) for_type_by_name("pandas.core.frame", "DataFrame", _repr_dataframe) for_type_by_name("enum", "Enum", _repr_enum) for_type_by_name("functools", "partial", _repr_partial)