"""Object representations for debugging purposes. Unlike the default repr, these expose more information and produce HTML instead of ASCII. Together with the CSS and JavaScript of the debugger this gives a colorful and more compact output. """ import codecs import re import sys import typing as t from collections import deque from html import escape from traceback import format_exception_only missing = object() _paragraph_re = re.compile(r"(?:\r\n|\r|\n){2,}") RegexType = type(_paragraph_re) HELP_HTML = """\

%(title)s

%(text)s
\ """ OBJECT_DUMP_HTML = """\

%(title)s

%(repr)s %(items)s
\ """ def debug_repr(obj: object) -> str: """Creates a debug repr of an object as HTML string.""" return DebugReprGenerator().repr(obj) def dump(obj: object = missing) -> None: """Print the object details to stdout._write (for the interactive console of the web debugger. """ gen = DebugReprGenerator() if obj is missing: rv = gen.dump_locals(sys._getframe(1).f_locals) else: rv = gen.dump_object(obj) sys.stdout._write(rv) # type: ignore class _Helper: """Displays an HTML version of the normal help, for the interactive debugger only because it requires a patched sys.stdout. """ def __repr__(self) -> str: return "Type help(object) for help about object." def __call__(self, topic: t.Optional[t.Any] = None) -> None: if topic is None: sys.stdout._write(f"{self!r}") # type: ignore return import pydoc pydoc.help(topic) rv = sys.stdout.reset() # type: ignore if isinstance(rv, bytes): rv = rv.decode("utf-8", "ignore") paragraphs = _paragraph_re.split(rv) if len(paragraphs) > 1: title = paragraphs[0] text = "\n\n".join(paragraphs[1:]) else: title = "Help" text = paragraphs[0] sys.stdout._write(HELP_HTML % {"title": title, "text": text}) # type: ignore helper = _Helper() def _add_subclass_info( inner: str, obj: object, base: t.Union[t.Type, t.Tuple[t.Type, ...]] ) -> str: if isinstance(base, tuple): for base in base: if type(obj) is base: return inner elif type(obj) is base: return inner module = "" if obj.__class__.__module__ not in ("__builtin__", "exceptions"): module = f'{obj.__class__.__module__}.' return f"{module}{type(obj).__name__}({inner})" def _sequence_repr_maker( left: str, right: str, base: t.Type, limit: int = 8 ) -> t.Callable[["DebugReprGenerator", t.Iterable, bool], str]: def proxy(self: "DebugReprGenerator", obj: t.Iterable, recursive: bool) -> str: if recursive: return _add_subclass_info(f"{left}...{right}", obj, base) buf = [left] have_extended_section = False for idx, item in enumerate(obj): if idx: buf.append(", ") if idx == limit: buf.append('') have_extended_section = True buf.append(self.repr(item)) if have_extended_section: buf.append("") buf.append(right) return _add_subclass_info("".join(buf), obj, base) return proxy class DebugReprGenerator: def __init__(self) -> None: self._stack: t.List[t.Any] = [] list_repr = _sequence_repr_maker("[", "]", list) tuple_repr = _sequence_repr_maker("(", ")", tuple) set_repr = _sequence_repr_maker("set([", "])", set) frozenset_repr = _sequence_repr_maker("frozenset([", "])", frozenset) deque_repr = _sequence_repr_maker( 'collections.deque([', "])", deque ) def regex_repr(self, obj: t.Pattern) -> str: pattern = repr(obj.pattern) pattern = codecs.decode(pattern, "unicode-escape", "ignore") # type: ignore pattern = f"r{pattern}" return f're.compile({pattern})' def string_repr(self, obj: t.Union[str, bytes], limit: int = 70) -> str: buf = [''] r = repr(obj) # shorten the repr when the hidden part would be at least 3 chars if len(r) - limit > 2: buf.extend( ( escape(r[:limit]), '', escape(r[limit:]), "", ) ) else: buf.append(escape(r)) buf.append("") out = "".join(buf) # if the repr looks like a standard string, add subclass info if needed if r[0] in "'\"" or (r[0] == "b" and r[1] in "'\""): return _add_subclass_info(out, obj, (bytes, str)) # otherwise, assume the repr distinguishes the subclass already return out def dict_repr( self, d: t.Union[t.Dict[int, None], t.Dict[str, int], t.Dict[t.Union[str, int], int]], recursive: bool, limit: int = 5, ) -> str: if recursive: return _add_subclass_info("{...}", d, dict) buf = ["{"] have_extended_section = False for idx, (key, value) in enumerate(d.items()): if idx: buf.append(", ") if idx == limit - 1: buf.append('') have_extended_section = True buf.append( f'{self.repr(key)}:' f' {self.repr(value)}' ) if have_extended_section: buf.append("") buf.append("}") return _add_subclass_info("".join(buf), d, dict) def object_repr( self, obj: t.Optional[t.Union[t.Type[dict], t.Callable, t.Type[list]]] ) -> str: r = repr(obj) return f'{escape(r)}' def dispatch_repr(self, obj: t.Any, recursive: bool) -> str: if obj is helper: return f'{helper!r}' if isinstance(obj, (int, float, complex)): return f'{obj!r}' if isinstance(obj, str) or isinstance(obj, bytes): return self.string_repr(obj) if isinstance(obj, RegexType): return self.regex_repr(obj) if isinstance(obj, list): return self.list_repr(obj, recursive) if isinstance(obj, tuple): return self.tuple_repr(obj, recursive) if isinstance(obj, set): return self.set_repr(obj, recursive) if isinstance(obj, frozenset): return self.frozenset_repr(obj, recursive) if isinstance(obj, dict): return self.dict_repr(obj, recursive) if isinstance(obj, deque): return self.deque_repr(obj, recursive) return self.object_repr(obj) def fallback_repr(self) -> str: try: info = "".join(format_exception_only(*sys.exc_info()[:2])) except Exception: info = "?" return ( '' f"<broken repr ({escape(info.strip())})>" ) def repr(self, obj: object) -> str: recursive = False for item in self._stack: if item is obj: recursive = True break self._stack.append(obj) try: try: return self.dispatch_repr(obj, recursive) except Exception: return self.fallback_repr() finally: self._stack.pop() def dump_object(self, obj: object) -> str: repr = None items: t.Optional[t.List[t.Tuple[str, str]]] = None if isinstance(obj, dict): title = "Contents of" items = [] for key, value in obj.items(): if not isinstance(key, str): items = None break items.append((key, self.repr(value))) if items is None: items = [] repr = self.repr(obj) for key in dir(obj): try: items.append((key, self.repr(getattr(obj, key)))) except Exception: pass title = "Details for" title += f" {object.__repr__(obj)[1:-1]}" return self.render_object_dump(items, title, repr) def dump_locals(self, d: t.Dict[str, t.Any]) -> str: items = [(key, self.repr(value)) for key, value in d.items()] return self.render_object_dump(items, "Local variables in frame") def render_object_dump( self, items: t.List[t.Tuple[str, str]], title: str, repr: t.Optional[str] = None ) -> str: html_items = [] for key, value in items: html_items.append(f"{escape(key)}
{value}
") if not html_items: html_items.append("Nothing") return OBJECT_DUMP_HTML % { "title": escape(title), "repr": f"
{repr if repr else ''}
", "items": "\n".join(html_items), }