"""Extract, format and print information about Python stack traces.""" import collections.abc import itertools import linecache import sys import textwrap import warnings from contextlib import suppress import _colorize from _colorize import ANSIColors __all__ = ['extract_stack', 'extract_tb', 'format_exception', 'format_exception_only', 'format_list', 'format_stack', 'format_tb', 'print_exc', 'format_exc', 'print_exception', 'print_last', 'print_stack', 'print_tb', 'clear_frames', 'FrameSummary', 'StackSummary', 'TracebackException', 'walk_stack', 'walk_tb', 'print_list'] # # Formatting and printing lists of traceback lines. # def print_list(extracted_list, file=None): """Print the list of tuples as returned by extract_tb() or extract_stack() as a formatted stack trace to the given file.""" if file is None: file = sys.stderr for item in StackSummary.from_list(extracted_list).format(): print(item, file=file, end="") def format_list(extracted_list): """Format a list of tuples or FrameSummary objects for printing. Given a list of tuples or FrameSummary objects as returned by extract_tb() or extract_stack(), return a list of strings ready for printing. Each string in the resulting list corresponds to the item with the same index in the argument list. Each string ends in a newline; the strings may contain internal newlines as well, for those items whose source text line is not None. """ return StackSummary.from_list(extracted_list).format() # # Printing and Extracting Tracebacks. # def print_tb(tb, limit=None, file=None): """Print up to 'limit' stack trace entries from the traceback 'tb'. If 'limit' is omitted or None, all entries are printed. If 'file' is omitted or None, the output goes to sys.stderr; otherwise 'file' should be an open file or file-like object with a write() method. """ print_list(extract_tb(tb, limit=limit), file=file) def format_tb(tb, limit=None): """A shorthand for 'format_list(extract_tb(tb, limit))'.""" return extract_tb(tb, limit=limit).format() def extract_tb(tb, limit=None): """ Return a StackSummary object representing a list of pre-processed entries from traceback. This is useful for alternate formatting of stack traces. If 'limit' is omitted or None, all entries are extracted. A pre-processed stack trace entry is a FrameSummary object containing attributes filename, lineno, name, and line representing the information that is usually printed for a stack trace. The line is a string with leading and trailing whitespace stripped; if the source is not available it is None. """ return StackSummary._extract_from_extended_frame_gen( _walk_tb_with_full_positions(tb), limit=limit) # # Exception formatting and output. # _cause_message = ( "\nThe above exception was the direct cause " "of the following exception:\n\n") _context_message = ( "\nDuring handling of the above exception, " "another exception occurred:\n\n") class _Sentinel: def __repr__(self): return "" _sentinel = _Sentinel() def _parse_value_tb(exc, value, tb): if (value is _sentinel) != (tb is _sentinel): raise ValueError("Both or neither of value and tb must be given") if value is tb is _sentinel: if exc is not None: if isinstance(exc, BaseException): return exc, exc.__traceback__ raise TypeError(f'Exception expected for value, ' f'{type(exc).__name__} found') else: return None, None return value, tb def print_exception(exc, /, value=_sentinel, tb=_sentinel, limit=None, \ file=None, chain=True, **kwargs): """Print exception up to 'limit' stack trace entries from 'tb' to 'file'. This differs from print_tb() in the following ways: (1) if traceback is not None, it prints a header "Traceback (most recent call last):"; (2) it prints the exception type and value after the stack trace; (3) if type is SyntaxError and value has the appropriate format, it prints the line where the syntax error occurred with a caret on the next line indicating the approximate position of the error. """ colorize = kwargs.get("colorize", False) value, tb = _parse_value_tb(exc, value, tb) te = TracebackException(type(value), value, tb, limit=limit, compact=True) te.print(file=file, chain=chain, colorize=colorize) BUILTIN_EXCEPTION_LIMIT = object() def _print_exception_bltin(exc, /): file = sys.stderr if sys.stderr is not None else sys.__stderr__ colorize = _colorize.can_colorize() return print_exception(exc, limit=BUILTIN_EXCEPTION_LIMIT, file=file, colorize=colorize) def format_exception(exc, /, value=_sentinel, tb=_sentinel, limit=None, \ chain=True, **kwargs): """Format a stack trace and the exception information. The arguments have the same meaning as the corresponding arguments to print_exception(). The return value is a list of strings, each ending in a newline and some containing internal newlines. When these lines are concatenated and printed, exactly the same text is printed as does print_exception(). """ colorize = kwargs.get("colorize", False) value, tb = _parse_value_tb(exc, value, tb) te = TracebackException(type(value), value, tb, limit=limit, compact=True) return list(te.format(chain=chain, colorize=colorize)) def format_exception_only(exc, /, value=_sentinel, *, show_group=False, **kwargs): """Format the exception part of a traceback. The return value is a list of strings, each ending in a newline. The list contains the exception's message, which is normally a single string; however, for :exc:`SyntaxError` exceptions, it contains several lines that (when printed) display detailed information about where the syntax error occurred. Following the message, the list contains the exception's ``__notes__``. When *show_group* is ``True``, and the exception is an instance of :exc:`BaseExceptionGroup`, the nested exceptions are included as well, recursively, with indentation relative to their nesting depth. """ colorize = kwargs.get("colorize", False) if value is _sentinel: value = exc te = TracebackException(type(value), value, None, compact=True) return list(te.format_exception_only(show_group=show_group, colorize=colorize)) # -- not official API but folk probably use these two functions. def _format_final_exc_line(etype, value, *, insert_final_newline=True, colorize=False): valuestr = _safe_string(value, 'exception') end_char = "\n" if insert_final_newline else "" if colorize: if value is None or not valuestr: line = f"{ANSIColors.BOLD_MAGENTA}{etype}{ANSIColors.RESET}{end_char}" else: line = f"{ANSIColors.BOLD_MAGENTA}{etype}{ANSIColors.RESET}: {ANSIColors.MAGENTA}{valuestr}{ANSIColors.RESET}{end_char}" else: if value is None or not valuestr: line = f"{etype}{end_char}" else: line = f"{etype}: {valuestr}{end_char}" return line def _safe_string(value, what, func=str): try: return func(value) except: return f'<{what} {func.__name__}() failed>' # -- def print_exc(limit=None, file=None, chain=True): """Shorthand for 'print_exception(sys.exception(), limit, file, chain)'.""" print_exception(sys.exception(), limit=limit, file=file, chain=chain) def format_exc(limit=None, chain=True): """Like print_exc() but return a string.""" return "".join(format_exception(sys.exception(), limit=limit, chain=chain)) def print_last(limit=None, file=None, chain=True): """This is a shorthand for 'print_exception(sys.last_exc, limit, file, chain)'.""" if not hasattr(sys, "last_exc") and not hasattr(sys, "last_type"): raise ValueError("no last exception") if hasattr(sys, "last_exc"): print_exception(sys.last_exc, limit, file, chain) else: print_exception(sys.last_type, sys.last_value, sys.last_traceback, limit, file, chain) # # Printing and Extracting Stacks. # def print_stack(f=None, limit=None, file=None): """Print a stack trace from its invocation point. The optional 'f' argument can be used to specify an alternate stack frame at which to start. The optional 'limit' and 'file' arguments have the same meaning as for print_exception(). """ if f is None: f = sys._getframe().f_back print_list(extract_stack(f, limit=limit), file=file) def format_stack(f=None, limit=None): """Shorthand for 'format_list(extract_stack(f, limit))'.""" if f is None: f = sys._getframe().f_back return format_list(extract_stack(f, limit=limit)) def extract_stack(f=None, limit=None): """Extract the raw traceback from the current stack frame. The return value has the same format as for extract_tb(). The optional 'f' and 'limit' arguments have the same meaning as for print_stack(). Each item in the list is a quadruple (filename, line number, function name, text), and the entries are in order from oldest to newest stack frame. """ if f is None: f = sys._getframe().f_back stack = StackSummary.extract(walk_stack(f), limit=limit) stack.reverse() return stack def clear_frames(tb): "Clear all references to local variables in the frames of a traceback." while tb is not None: try: tb.tb_frame.clear() except RuntimeError: # Ignore the exception raised if the frame is still executing. pass tb = tb.tb_next class FrameSummary: """Information about a single frame from a traceback. - :attr:`filename` The filename for the frame. - :attr:`lineno` The line within filename for the frame that was active when the frame was captured. - :attr:`name` The name of the function or method that was executing when the frame was captured. - :attr:`line` The text from the linecache module for the of code that was running when the frame was captured. - :attr:`locals` Either None if locals were not supplied, or a dict mapping the name to the repr() of the variable. """ __slots__ = ('filename', 'lineno', 'end_lineno', 'colno', 'end_colno', 'name', '_lines', '_lines_dedented', 'locals') def __init__(self, filename, lineno, name, *, lookup_line=True, locals=None, line=None, end_lineno=None, colno=None, end_colno=None): """Construct a FrameSummary. :param lookup_line: If True, `linecache` is consulted for the source code line. Otherwise, the line will be looked up when first needed. :param locals: If supplied the frame locals, which will be captured as object representations. :param line: If provided, use this instead of looking up the line in the linecache. """ self.filename = filename self.lineno = lineno self.end_lineno = lineno if end_lineno is None else end_lineno self.colno = colno self.end_colno = end_colno self.name = name self._lines = line self._lines_dedented = None if lookup_line: self.line self.locals = {k: _safe_string(v, 'local', func=repr) for k, v in locals.items()} if locals else None def __eq__(self, other): if isinstance(other, FrameSummary): return (self.filename == other.filename and self.lineno == other.lineno and self.name == other.name and self.locals == other.locals) if isinstance(other, tuple): return (self.filename, self.lineno, self.name, self.line) == other return NotImplemented def __getitem__(self, pos): return (self.filename, self.lineno, self.name, self.line)[pos] def __iter__(self): return iter([self.filename, self.lineno, self.name, self.line]) def __repr__(self): return "".format( filename=self.filename, lineno=self.lineno, name=self.name) def __len__(self): return 4 def _set_lines(self): if ( self._lines is None and self.lineno is not None and self.end_lineno is not None ): lines = [] for lineno in range(self.lineno, self.end_lineno + 1): # treat errors (empty string) and empty lines (newline) as the same lines.append(linecache.getline(self.filename, lineno).rstrip()) self._lines = "\n".join(lines) + "\n" @property def _original_lines(self): # Returns the line as-is from the source, without modifying whitespace. self._set_lines() return self._lines @property def _dedented_lines(self): # Returns _original_lines, but dedented self._set_lines() if self._lines_dedented is None and self._lines is not None: self._lines_dedented = textwrap.dedent(self._lines) return self._lines_dedented @property def line(self): self._set_lines() if self._lines is None: return None # return only the first line, stripped return self._lines.partition("\n")[0].strip() def walk_stack(f): """Walk a stack yielding the frame and line number for each frame. This will follow f.f_back from the given frame. If no frame is given, the current stack is used. Usually used with StackSummary.extract. """ if f is None: f = sys._getframe().f_back.f_back.f_back.f_back while f is not None: yield f, f.f_lineno f = f.f_back def walk_tb(tb): """Walk a traceback yielding the frame and line number for each frame. This will follow tb.tb_next (and thus is in the opposite order to walk_stack). Usually used with StackSummary.extract. """ while tb is not None: yield tb.tb_frame, tb.tb_lineno tb = tb.tb_next def _walk_tb_with_full_positions(tb): # Internal version of walk_tb that yields full code positions including # end line and column information. while tb is not None: positions = _get_code_position(tb.tb_frame.f_code, tb.tb_lasti) # Yield tb_lineno when co_positions does not have a line number to # maintain behavior with walk_tb. if positions[0] is None: yield tb.tb_frame, (tb.tb_lineno, ) + positions[1:] else: yield tb.tb_frame, positions tb = tb.tb_next def _get_code_position(code, instruction_index): if instruction_index < 0: return (None, None, None, None) positions_gen = code.co_positions() return next(itertools.islice(positions_gen, instruction_index // 2, None)) _RECURSIVE_CUTOFF = 3 # Also hardcoded in traceback.c. class StackSummary(list): """A list of FrameSummary objects, representing a stack of frames.""" @classmethod def extract(klass, frame_gen, *, limit=None, lookup_lines=True, capture_locals=False): """Create a StackSummary from a traceback or stack object. :param frame_gen: A generator that yields (frame, lineno) tuples whose summaries are to be included in the stack. :param limit: None to include all frames or the number of frames to include. :param lookup_lines: If True, lookup lines for each frame immediately, otherwise lookup is deferred until the frame is rendered. :param capture_locals: If True, the local variables from each frame will be captured as object representations into the FrameSummary. """ def extended_frame_gen(): for f, lineno in frame_gen: yield f, (lineno, None, None, None) return klass._extract_from_extended_frame_gen( extended_frame_gen(), limit=limit, lookup_lines=lookup_lines, capture_locals=capture_locals) @classmethod def _extract_from_extended_frame_gen(klass, frame_gen, *, limit=None, lookup_lines=True, capture_locals=False): # Same as extract but operates on a frame generator that yields # (frame, (lineno, end_lineno, colno, end_colno)) in the stack. # Only lineno is required, the remaining fields can be None if the # information is not available. builtin_limit = limit is BUILTIN_EXCEPTION_LIMIT if limit is None or builtin_limit: limit = getattr(sys, 'tracebacklimit', None) if limit is not None and limit < 0: limit = 0 if limit is not None: if builtin_limit: frame_gen = tuple(frame_gen) frame_gen = frame_gen[len(frame_gen) - limit:] elif limit >= 0: frame_gen = itertools.islice(frame_gen, limit) else: frame_gen = collections.deque(frame_gen, maxlen=-limit) result = klass() fnames = set() for f, (lineno, end_lineno, colno, end_colno) in frame_gen: co = f.f_code filename = co.co_filename name = co.co_name fnames.add(filename) linecache.lazycache(filename, f.f_globals) # Must defer line lookups until we have called checkcache. if capture_locals: f_locals = f.f_locals else: f_locals = None result.append(FrameSummary( filename, lineno, name, lookup_line=False, locals=f_locals, end_lineno=end_lineno, colno=colno, end_colno=end_colno)) for filename in fnames: linecache.checkcache(filename) # If immediate lookup was desired, trigger lookups now. if lookup_lines: for f in result: f.line return result @classmethod def from_list(klass, a_list): """ Create a StackSummary object from a supplied list of FrameSummary objects or old-style list of tuples. """ # While doing a fast-path check for isinstance(a_list, StackSummary) is # appealing, idlelib.run.cleanup_traceback and other similar code may # break this by making arbitrary frames plain tuples, so we need to # check on a frame by frame basis. result = StackSummary() for frame in a_list: if isinstance(frame, FrameSummary): result.append(frame) else: filename, lineno, name, line = frame result.append(FrameSummary(filename, lineno, name, line=line)) return result def format_frame_summary(self, frame_summary, **kwargs): """Format the lines for a single FrameSummary. Returns a string representing one frame involved in the stack. This gets called for every frame to be printed in the stack summary. """ colorize = kwargs.get("colorize", False) row = [] filename = frame_summary.filename if frame_summary.filename.startswith("-"): filename = "" if colorize: row.append(' File {}"{}"{}, line {}{}{}, in {}{}{}\n'.format( ANSIColors.MAGENTA, filename, ANSIColors.RESET, ANSIColors.MAGENTA, frame_summary.lineno, ANSIColors.RESET, ANSIColors.MAGENTA, frame_summary.name, ANSIColors.RESET, ) ) else: row.append(' File "{}", line {}, in {}\n'.format( filename, frame_summary.lineno, frame_summary.name)) if frame_summary._dedented_lines and frame_summary._dedented_lines.strip(): if ( frame_summary.colno is None or frame_summary.end_colno is None ): # only output first line if column information is missing row.append(textwrap.indent(frame_summary.line, ' ') + "\n") else: # get first and last line all_lines_original = frame_summary._original_lines.splitlines() first_line = all_lines_original[0] # assume all_lines_original has enough lines (since we constructed it) last_line = all_lines_original[frame_summary.end_lineno - frame_summary.lineno] # character index of the start/end of the instruction start_offset = _byte_offset_to_character_offset(first_line, frame_summary.colno) end_offset = _byte_offset_to_character_offset(last_line, frame_summary.end_colno) all_lines = frame_summary._dedented_lines.splitlines()[ :frame_summary.end_lineno - frame_summary.lineno + 1 ] # adjust start/end offset based on dedent dedent_characters = len(first_line) - len(all_lines[0]) start_offset = max(0, start_offset - dedent_characters) end_offset = max(0, end_offset - dedent_characters) # When showing this on a terminal, some of the non-ASCII characters # might be rendered as double-width characters, so we need to take # that into account when calculating the length of the line. dp_start_offset = _display_width(all_lines[0], offset=start_offset) dp_end_offset = _display_width(all_lines[-1], offset=end_offset) # get exact code segment corresponding to the instruction segment = "\n".join(all_lines) segment = segment[start_offset:len(segment) - (len(all_lines[-1]) - end_offset)] # attempt to parse for anchors anchors = None show_carets = False with suppress(Exception): anchors = _extract_caret_anchors_from_line_segment(segment) show_carets = self._should_show_carets(start_offset, end_offset, all_lines, anchors) result = [] # only display first line, last line, and lines around anchor start/end significant_lines = {0, len(all_lines) - 1} anchors_left_end_offset = 0 anchors_right_start_offset = 0 primary_char = "^" secondary_char = "^" if anchors: anchors_left_end_offset = anchors.left_end_offset anchors_right_start_offset = anchors.right_start_offset # computed anchor positions do not take start_offset into account, # so account for it here if anchors.left_end_lineno == 0: anchors_left_end_offset += start_offset if anchors.right_start_lineno == 0: anchors_right_start_offset += start_offset # account for display width anchors_left_end_offset = _display_width( all_lines[anchors.left_end_lineno], offset=anchors_left_end_offset ) anchors_right_start_offset = _display_width( all_lines[anchors.right_start_lineno], offset=anchors_right_start_offset ) primary_char = anchors.primary_char secondary_char = anchors.secondary_char significant_lines.update( range(anchors.left_end_lineno - 1, anchors.left_end_lineno + 2) ) significant_lines.update( range(anchors.right_start_lineno - 1, anchors.right_start_lineno + 2) ) # remove bad line numbers significant_lines.discard(-1) significant_lines.discard(len(all_lines)) def output_line(lineno): """output all_lines[lineno] along with carets""" result.append(all_lines[lineno] + "\n") if not show_carets: return num_spaces = len(all_lines[lineno]) - len(all_lines[lineno].lstrip()) carets = [] num_carets = dp_end_offset if lineno == len(all_lines) - 1 else _display_width(all_lines[lineno]) # compute caret character for each position for col in range(num_carets): if col < num_spaces or (lineno == 0 and col < dp_start_offset): # before first non-ws char of the line, or before start of instruction carets.append(' ') elif anchors and ( lineno > anchors.left_end_lineno or (lineno == anchors.left_end_lineno and col >= anchors_left_end_offset) ) and ( lineno < anchors.right_start_lineno or (lineno == anchors.right_start_lineno and col < anchors_right_start_offset) ): # within anchors carets.append(secondary_char) else: carets.append(primary_char) if colorize: # Replace the previous line with a red version of it only in the parts covered # by the carets. line = result[-1] colorized_line_parts = [] colorized_carets_parts = [] for color, group in itertools.groupby(itertools.zip_longest(line, carets, fillvalue=""), key=lambda x: x[1]): caret_group = list(group) if color == "^": colorized_line_parts.append(ANSIColors.BOLD_RED + "".join(char for char, _ in caret_group) + ANSIColors.RESET) colorized_carets_parts.append(ANSIColors.BOLD_RED + "".join(caret for _, caret in caret_group) + ANSIColors.RESET) elif color == "~": colorized_line_parts.append(ANSIColors.RED + "".join(char for char, _ in caret_group) + ANSIColors.RESET) colorized_carets_parts.append(ANSIColors.RED + "".join(caret for _, caret in caret_group) + ANSIColors.RESET) else: colorized_line_parts.append("".join(char for char, _ in caret_group)) colorized_carets_parts.append("".join(caret for _, caret in caret_group)) colorized_line = "".join(colorized_line_parts) colorized_carets = "".join(colorized_carets_parts) result[-1] = colorized_line result.append(colorized_carets + "\n") else: result.append("".join(carets) + "\n") # display significant lines sig_lines_list = sorted(significant_lines) for i, lineno in enumerate(sig_lines_list): if i: linediff = lineno - sig_lines_list[i - 1] if linediff == 2: # 1 line in between - just output it output_line(lineno - 1) elif linediff > 2: # > 1 line in between - abbreviate result.append(f"...<{linediff - 1} lines>...\n") output_line(lineno) row.append( textwrap.indent(textwrap.dedent("".join(result)), ' ', lambda line: True) ) if frame_summary.locals: for name, value in sorted(frame_summary.locals.items()): row.append(' {name} = {value}\n'.format(name=name, value=value)) return ''.join(row) def _should_show_carets(self, start_offset, end_offset, all_lines, anchors): with suppress(SyntaxError, ImportError): import ast tree = ast.parse('\n'.join(all_lines)) if not tree.body: return False statement = tree.body[0] value = None def _spawns_full_line(value): return ( value.lineno == 1 and value.end_lineno == len(all_lines) and value.col_offset == start_offset and value.end_col_offset == end_offset ) match statement: case ast.Return(value=ast.Call()): if isinstance(statement.value.func, ast.Name): value = statement.value case ast.Assign(value=ast.Call()): if ( len(statement.targets) == 1 and isinstance(statement.targets[0], ast.Name) ): value = statement.value if value is not None and _spawns_full_line(value): return False if anchors: return True if all_lines[0][:start_offset].lstrip() or all_lines[-1][end_offset:].rstrip(): return True return False def format(self, **kwargs): """Format the stack ready for printing. Returns a list of strings ready for printing. Each string in the resulting list corresponds to a single frame from the stack. Each string ends in a newline; the strings may contain internal newlines as well, for those items with source text lines. For long sequences of the same frame and line, the first few repetitions are shown, followed by a summary line stating the exact number of further repetitions. """ colorize = kwargs.get("colorize", False) result = [] last_file = None last_line = None last_name = None count = 0 for frame_summary in self: formatted_frame = self.format_frame_summary(frame_summary, colorize=colorize) if formatted_frame is None: continue if (last_file is None or last_file != frame_summary.filename or last_line is None or last_line != frame_summary.lineno or last_name is None or last_name != frame_summary.name): if count > _RECURSIVE_CUTOFF: count -= _RECURSIVE_CUTOFF result.append( f' [Previous line repeated {count} more ' f'time{"s" if count > 1 else ""}]\n' ) last_file = frame_summary.filename last_line = frame_summary.lineno last_name = frame_summary.name count = 0 count += 1 if count > _RECURSIVE_CUTOFF: continue result.append(formatted_frame) if count > _RECURSIVE_CUTOFF: count -= _RECURSIVE_CUTOFF result.append( f' [Previous line repeated {count} more ' f'time{"s" if count > 1 else ""}]\n' ) return result def _byte_offset_to_character_offset(str, offset): as_utf8 = str.encode('utf-8') return len(as_utf8[:offset].decode("utf-8", errors="replace")) _Anchors = collections.namedtuple( "_Anchors", [ "left_end_lineno", "left_end_offset", "right_start_lineno", "right_start_offset", "primary_char", "secondary_char", ], defaults=["~", "^"] ) def _extract_caret_anchors_from_line_segment(segment): """ Given source code `segment` corresponding to a FrameSummary, determine: - for binary ops, the location of the binary op - for indexing and function calls, the location of the brackets. `segment` is expected to be a valid Python expression. """ import ast try: # Without parentheses, `segment` is parsed as a statement. # Binary ops, subscripts, and calls are expressions, so # we can wrap them with parentheses to parse them as # (possibly multi-line) expressions. # e.g. if we try to highlight the addition in # x = ( # a + # b # ) # then we would ast.parse # a + # b # which is not a valid statement because of the newline. # Adding brackets makes it a valid expression. # ( # a + # b # ) # Line locations will be different than the original, # which is taken into account later on. tree = ast.parse(f"(\n{segment}\n)") except SyntaxError: return None if len(tree.body) != 1: return None lines = segment.splitlines() def normalize(lineno, offset): """Get character index given byte offset""" return _byte_offset_to_character_offset(lines[lineno], offset) def next_valid_char(lineno, col): """Gets the next valid character index in `lines`, if the current location is not valid. Handles empty lines. """ while lineno < len(lines) and col >= len(lines[lineno]): col = 0 lineno += 1 assert lineno < len(lines) and col < len(lines[lineno]) return lineno, col def increment(lineno, col): """Get the next valid character index in `lines`.""" col += 1 lineno, col = next_valid_char(lineno, col) return lineno, col def nextline(lineno, col): """Get the next valid character at least on the next line""" col = 0 lineno += 1 lineno, col = next_valid_char(lineno, col) return lineno, col def increment_until(lineno, col, stop): """Get the next valid non-"\\#" character that satisfies the `stop` predicate""" while True: ch = lines[lineno][col] if ch in "\\#": lineno, col = nextline(lineno, col) elif not stop(ch): lineno, col = increment(lineno, col) else: break return lineno, col def setup_positions(expr, force_valid=True): """Get the lineno/col position of the end of `expr`. If `force_valid` is True, forces the position to be a valid character (e.g. if the position is beyond the end of the line, move to the next line) """ # -2 since end_lineno is 1-indexed and because we added an extra # bracket + newline to `segment` when calling ast.parse lineno = expr.end_lineno - 2 col = normalize(lineno, expr.end_col_offset) return next_valid_char(lineno, col) if force_valid else (lineno, col) statement = tree.body[0] match statement: case ast.Expr(expr): match expr: case ast.BinOp(): # ast gives these locations for BinOp subexpressions # ( left_expr ) + ( right_expr ) # left^^^^^ right^^^^^ lineno, col = setup_positions(expr.left) # First operator character is the first non-space/')' character lineno, col = increment_until(lineno, col, lambda x: not x.isspace() and x != ')') # binary op is 1 or 2 characters long, on the same line, # before the right subexpression right_col = col + 1 if ( right_col < len(lines[lineno]) and ( # operator char should not be in the right subexpression expr.right.lineno - 2 > lineno or right_col < normalize(expr.right.lineno - 2, expr.right.col_offset) ) and not (ch := lines[lineno][right_col]).isspace() and ch not in "\\#" ): right_col += 1 # right_col can be invalid since it is exclusive return _Anchors(lineno, col, lineno, right_col) case ast.Subscript(): # ast gives these locations for value and slice subexpressions # ( value_expr ) [ slice_expr ] # value^^^^^ slice^^^^^ # subscript^^^^^^^^^^^^^^^^^^^^ # find left bracket left_lineno, left_col = setup_positions(expr.value) left_lineno, left_col = increment_until(left_lineno, left_col, lambda x: x == '[') # find right bracket (final character of expression) right_lineno, right_col = setup_positions(expr, force_valid=False) return _Anchors(left_lineno, left_col, right_lineno, right_col) case ast.Call(): # ast gives these locations for function call expressions # ( func_expr ) (args, kwargs) # func^^^^^ # call^^^^^^^^^^^^^^^^^^^^^^^^ # find left bracket left_lineno, left_col = setup_positions(expr.func) left_lineno, left_col = increment_until(left_lineno, left_col, lambda x: x == '(') # find right bracket (final character of expression) right_lineno, right_col = setup_positions(expr, force_valid=False) return _Anchors(left_lineno, left_col, right_lineno, right_col) return None _WIDE_CHAR_SPECIFIERS = "WF" def _display_width(line, offset=None): """Calculate the extra amount of width space the given source code segment might take if it were to be displayed on a fixed width output device. Supports wide unicode characters and emojis.""" if offset is None: offset = len(line) # Fast track for ASCII-only strings if line.isascii(): return offset import unicodedata return sum( 2 if unicodedata.east_asian_width(char) in _WIDE_CHAR_SPECIFIERS else 1 for char in line[:offset] ) class _ExceptionPrintContext: def __init__(self): self.seen = set() self.exception_group_depth = 0 self.need_close = False def indent(self): return ' ' * (2 * self.exception_group_depth) def emit(self, text_gen, margin_char=None): if margin_char is None: margin_char = '|' indent_str = self.indent() if self.exception_group_depth: indent_str += margin_char + ' ' if isinstance(text_gen, str): yield textwrap.indent(text_gen, indent_str, lambda line: True) else: for text in text_gen: yield textwrap.indent(text, indent_str, lambda line: True) class TracebackException: """An exception ready for rendering. The traceback module captures enough attributes from the original exception to this intermediary form to ensure that no references are held, while still being able to fully print or format it. max_group_width and max_group_depth control the formatting of exception groups. The depth refers to the nesting level of the group, and the width refers to the size of a single exception group's exceptions array. The formatted output is truncated when either limit is exceeded. Use `from_exception` to create TracebackException instances from exception objects, or the constructor to create TracebackException instances from individual components. - :attr:`__cause__` A TracebackException of the original *__cause__*. - :attr:`__context__` A TracebackException of the original *__context__*. - :attr:`exceptions` For exception groups - a list of TracebackException instances for the nested *exceptions*. ``None`` for other exceptions. - :attr:`__suppress_context__` The *__suppress_context__* value from the original exception. - :attr:`stack` A `StackSummary` representing the traceback. - :attr:`exc_type` (deprecated) The class of the original traceback. - :attr:`exc_type_str` String display of exc_type - :attr:`filename` For syntax errors - the filename where the error occurred. - :attr:`lineno` For syntax errors - the linenumber where the error occurred. - :attr:`end_lineno` For syntax errors - the end linenumber where the error occurred. Can be `None` if not present. - :attr:`text` For syntax errors - the text where the error occurred. - :attr:`offset` For syntax errors - the offset into the text where the error occurred. - :attr:`end_offset` For syntax errors - the end offset into the text where the error occurred. Can be `None` if not present. - :attr:`msg` For syntax errors - the compiler error message. """ def __init__(self, exc_type, exc_value, exc_traceback, *, limit=None, lookup_lines=True, capture_locals=False, compact=False, max_group_width=15, max_group_depth=10, save_exc_type=True, _seen=None): # NB: we need to accept exc_traceback, exc_value, exc_traceback to # permit backwards compat with the existing API, otherwise we # need stub thunk objects just to glue it together. # Handle loops in __cause__ or __context__. is_recursive_call = _seen is not None if _seen is None: _seen = set() _seen.add(id(exc_value)) self.max_group_width = max_group_width self.max_group_depth = max_group_depth self.stack = StackSummary._extract_from_extended_frame_gen( _walk_tb_with_full_positions(exc_traceback), limit=limit, lookup_lines=lookup_lines, capture_locals=capture_locals) self._exc_type = exc_type if save_exc_type else None # Capture now to permit freeing resources: only complication is in the # unofficial API _format_final_exc_line self._str = _safe_string(exc_value, 'exception') try: self.__notes__ = getattr(exc_value, '__notes__', None) except Exception as e: self.__notes__ = [ f'Ignored error getting __notes__: {_safe_string(e, '__notes__', repr)}'] self._is_syntax_error = False self._have_exc_type = exc_type is not None if exc_type is not None: self.exc_type_qualname = exc_type.__qualname__ self.exc_type_module = exc_type.__module__ else: self.exc_type_qualname = None self.exc_type_module = None if exc_type and issubclass(exc_type, SyntaxError): # Handle SyntaxError's specially self.filename = exc_value.filename lno = exc_value.lineno self.lineno = str(lno) if lno is not None else None end_lno = exc_value.end_lineno self.end_lineno = str(end_lno) if end_lno is not None else None self.text = exc_value.text self.offset = exc_value.offset self.end_offset = exc_value.end_offset self.msg = exc_value.msg self._is_syntax_error = True elif exc_type and issubclass(exc_type, ImportError) and \ getattr(exc_value, "name_from", None) is not None: wrong_name = getattr(exc_value, "name_from", None) suggestion = _compute_suggestion_error(exc_value, exc_traceback, wrong_name) if suggestion: self._str += f". Did you mean: '{suggestion}'?" elif exc_type and issubclass(exc_type, (NameError, AttributeError)) and \ getattr(exc_value, "name", None) is not None: wrong_name = getattr(exc_value, "name", None) suggestion = _compute_suggestion_error(exc_value, exc_traceback, wrong_name) if suggestion: self._str += f". Did you mean: '{suggestion}'?" if issubclass(exc_type, NameError): wrong_name = getattr(exc_value, "name", None) if wrong_name is not None and wrong_name in sys.stdlib_module_names: if suggestion: self._str += f" Or did you forget to import '{wrong_name}'?" else: self._str += f". Did you forget to import '{wrong_name}'?" if lookup_lines: self._load_lines() self.__suppress_context__ = \ exc_value.__suppress_context__ if exc_value is not None else False # Convert __cause__ and __context__ to `TracebackExceptions`s, use a # queue to avoid recursion (only the top-level call gets _seen == None) if not is_recursive_call: queue = [(self, exc_value)] while queue: te, e = queue.pop() if (e and e.__cause__ is not None and id(e.__cause__) not in _seen): cause = TracebackException( type(e.__cause__), e.__cause__, e.__cause__.__traceback__, limit=limit, lookup_lines=lookup_lines, capture_locals=capture_locals, max_group_width=max_group_width, max_group_depth=max_group_depth, _seen=_seen) else: cause = None if compact: need_context = (cause is None and e is not None and not e.__suppress_context__) else: need_context = True if (e and e.__context__ is not None and need_context and id(e.__context__) not in _seen): context = TracebackException( type(e.__context__), e.__context__, e.__context__.__traceback__, limit=limit, lookup_lines=lookup_lines, capture_locals=capture_locals, max_group_width=max_group_width, max_group_depth=max_group_depth, _seen=_seen) else: context = None if e and isinstance(e, BaseExceptionGroup): exceptions = [] for exc in e.exceptions: texc = TracebackException( type(exc), exc, exc.__traceback__, limit=limit, lookup_lines=lookup_lines, capture_locals=capture_locals, max_group_width=max_group_width, max_group_depth=max_group_depth, _seen=_seen) exceptions.append(texc) else: exceptions = None te.__cause__ = cause te.__context__ = context te.exceptions = exceptions if cause: queue.append((te.__cause__, e.__cause__)) if context: queue.append((te.__context__, e.__context__)) if exceptions: queue.extend(zip(te.exceptions, e.exceptions)) @classmethod def from_exception(cls, exc, *args, **kwargs): """Create a TracebackException from an exception.""" return cls(type(exc), exc, exc.__traceback__, *args, **kwargs) @property def exc_type(self): warnings.warn('Deprecated in 3.13. Use exc_type_str instead.', DeprecationWarning, stacklevel=2) return self._exc_type @property def exc_type_str(self): if not self._have_exc_type: return None stype = self.exc_type_qualname smod = self.exc_type_module if smod not in ("__main__", "builtins"): if not isinstance(smod, str): smod = "" stype = smod + '.' + stype return stype def _load_lines(self): """Private API. force all lines in the stack to be loaded.""" for frame in self.stack: frame.line def __eq__(self, other): if isinstance(other, TracebackException): return self.__dict__ == other.__dict__ return NotImplemented def __str__(self): return self._str def format_exception_only(self, *, show_group=False, _depth=0, **kwargs): """Format the exception part of the traceback. The return value is a generator of strings, each ending in a newline. Generator yields the exception message. For :exc:`SyntaxError` exceptions, it also yields (before the exception message) several lines that (when printed) display detailed information about where the syntax error occurred. Following the message, generator also yields all the exception's ``__notes__``. When *show_group* is ``True``, and the exception is an instance of :exc:`BaseExceptionGroup`, the nested exceptions are included as well, recursively, with indentation relative to their nesting depth. """ colorize = kwargs.get("colorize", False) indent = 3 * _depth * ' ' if not self._have_exc_type: yield indent + _format_final_exc_line(None, self._str, colorize=colorize) return stype = self.exc_type_str if not self._is_syntax_error: if _depth > 0: # Nested exceptions needs correct handling of multiline messages. formatted = _format_final_exc_line( stype, self._str, insert_final_newline=False, colorize=colorize ).split('\n') yield from [ indent + l + '\n' for l in formatted ] else: yield _format_final_exc_line(stype, self._str, colorize=colorize) else: yield from [indent + l for l in self._format_syntax_error(stype, colorize=colorize)] if ( isinstance(self.__notes__, collections.abc.Sequence) and not isinstance(self.__notes__, (str, bytes)) ): for note in self.__notes__: note = _safe_string(note, 'note') yield from [indent + l + '\n' for l in note.split('\n')] elif self.__notes__ is not None: yield indent + "{}\n".format(_safe_string(self.__notes__, '__notes__', func=repr)) if self.exceptions and show_group: for ex in self.exceptions: yield from ex.format_exception_only(show_group=show_group, _depth=_depth+1, colorize=colorize) def _format_syntax_error(self, stype, **kwargs): """Format SyntaxError exceptions (internal helper).""" # Show exactly where the problem was found. colorize = kwargs.get("colorize", False) filename_suffix = '' if self.lineno is not None: if colorize: yield ' File {}"{}"{}, line {}{}{}\n'.format( ANSIColors.MAGENTA, self.filename or "", ANSIColors.RESET, ANSIColors.MAGENTA, self.lineno, ANSIColors.RESET, ) else: yield ' File "{}", line {}\n'.format( self.filename or "", self.lineno) elif self.filename is not None: filename_suffix = ' ({})'.format(self.filename) text = self.text if text is not None: # text = " foo\n" # rtext = " foo" # ltext = "foo" rtext = text.rstrip('\n') ltext = rtext.lstrip(' \n\f') spaces = len(rtext) - len(ltext) if self.offset is None: yield ' {}\n'.format(ltext) else: offset = self.offset if self.lineno == self.end_lineno: end_offset = self.end_offset if self.end_offset not in {None, 0} else offset else: end_offset = len(rtext) + 1 if self.text and offset > len(self.text): offset = len(rtext) + 1 if self.text and end_offset > len(self.text): end_offset = len(rtext) + 1 if offset >= end_offset or end_offset < 0: end_offset = offset + 1 # Convert 1-based column offset to 0-based index into stripped text colno = offset - 1 - spaces end_colno = end_offset - 1 - spaces caretspace = ' ' if colno >= 0: # non-space whitespace (likes tabs) must be kept for alignment caretspace = ((c if c.isspace() else ' ') for c in ltext[:colno]) start_color = end_color = "" if colorize: # colorize from colno to end_colno ltext = ( ltext[:colno] + ANSIColors.BOLD_RED + ltext[colno:end_colno] + ANSIColors.RESET + ltext[end_colno:] ) start_color = ANSIColors.BOLD_RED end_color = ANSIColors.RESET yield ' {}\n'.format(ltext) yield ' {}{}{}{}\n'.format( "".join(caretspace), start_color, ('^' * (end_colno - colno)), end_color, ) else: yield ' {}\n'.format(ltext) msg = self.msg or "" if colorize: yield "{}{}{}: {}{}{}{}\n".format( ANSIColors.BOLD_MAGENTA, stype, ANSIColors.RESET, ANSIColors.MAGENTA, msg, ANSIColors.RESET, filename_suffix) else: yield "{}: {}{}\n".format(stype, msg, filename_suffix) def format(self, *, chain=True, _ctx=None, **kwargs): """Format the exception. If chain is not *True*, *__cause__* and *__context__* will not be formatted. The return value is a generator of strings, each ending in a newline and some containing internal newlines. `print_exception` is a wrapper around this method which just prints the lines to a file. The message indicating which exception occurred is always the last string in the output. """ colorize = kwargs.get("colorize", False) if _ctx is None: _ctx = _ExceptionPrintContext() output = [] exc = self if chain: while exc: if exc.__cause__ is not None: chained_msg = _cause_message chained_exc = exc.__cause__ elif (exc.__context__ is not None and not exc.__suppress_context__): chained_msg = _context_message chained_exc = exc.__context__ else: chained_msg = None chained_exc = None output.append((chained_msg, exc)) exc = chained_exc else: output.append((None, exc)) for msg, exc in reversed(output): if msg is not None: yield from _ctx.emit(msg) if exc.exceptions is None: if exc.stack: yield from _ctx.emit('Traceback (most recent call last):\n') yield from _ctx.emit(exc.stack.format(colorize=colorize)) yield from _ctx.emit(exc.format_exception_only(colorize=colorize)) elif _ctx.exception_group_depth > self.max_group_depth: # exception group, but depth exceeds limit yield from _ctx.emit( f"... (max_group_depth is {self.max_group_depth})\n") else: # format exception group is_toplevel = (_ctx.exception_group_depth == 0) if is_toplevel: _ctx.exception_group_depth += 1 if exc.stack: yield from _ctx.emit( 'Exception Group Traceback (most recent call last):\n', margin_char = '+' if is_toplevel else None) yield from _ctx.emit(exc.stack.format(colorize=colorize)) yield from _ctx.emit(exc.format_exception_only(colorize=colorize)) num_excs = len(exc.exceptions) if num_excs <= self.max_group_width: n = num_excs else: n = self.max_group_width + 1 _ctx.need_close = False for i in range(n): last_exc = (i == n-1) if last_exc: # The closing frame may be added by a recursive call _ctx.need_close = True if self.max_group_width is not None: truncated = (i >= self.max_group_width) else: truncated = False title = f'{i+1}' if not truncated else '...' yield (_ctx.indent() + ('+-' if i==0 else ' ') + f'+---------------- {title} ----------------\n') _ctx.exception_group_depth += 1 if not truncated: yield from exc.exceptions[i].format(chain=chain, _ctx=_ctx, colorize=colorize) else: remaining = num_excs - self.max_group_width plural = 's' if remaining > 1 else '' yield from _ctx.emit( f"and {remaining} more exception{plural}\n") if last_exc and _ctx.need_close: yield (_ctx.indent() + "+------------------------------------\n") _ctx.need_close = False _ctx.exception_group_depth -= 1 if is_toplevel: assert _ctx.exception_group_depth == 1 _ctx.exception_group_depth = 0 def print(self, *, file=None, chain=True, **kwargs): """Print the result of self.format(chain=chain) to 'file'.""" colorize = kwargs.get("colorize", False) if file is None: file = sys.stderr for line in self.format(chain=chain, colorize=colorize): print(line, file=file, end="") _MAX_CANDIDATE_ITEMS = 750 _MAX_STRING_SIZE = 40 _MOVE_COST = 2 _CASE_COST = 1 def _substitution_cost(ch_a, ch_b): if ch_a == ch_b: return 0 if ch_a.lower() == ch_b.lower(): return _CASE_COST return _MOVE_COST def _compute_suggestion_error(exc_value, tb, wrong_name): if wrong_name is None or not isinstance(wrong_name, str): return None if isinstance(exc_value, AttributeError): obj = exc_value.obj try: d = dir(obj) hide_underscored = (wrong_name[:1] != '_') if hide_underscored and tb is not None: while tb.tb_next is not None: tb = tb.tb_next frame = tb.tb_frame if 'self' in frame.f_locals and frame.f_locals['self'] is obj: hide_underscored = False if hide_underscored: d = [x for x in d if x[:1] != '_'] except Exception: return None elif isinstance(exc_value, ImportError): try: mod = __import__(exc_value.name) d = dir(mod) if wrong_name[:1] != '_': d = [x for x in d if x[:1] != '_'] except Exception: return None else: assert isinstance(exc_value, NameError) # find most recent frame if tb is None: return None while tb.tb_next is not None: tb = tb.tb_next frame = tb.tb_frame d = ( list(frame.f_locals) + list(frame.f_globals) + list(frame.f_builtins) ) # Check first if we are in a method and the instance # has the wrong name as attribute if 'self' in frame.f_locals: self = frame.f_locals['self'] if hasattr(self, wrong_name): return f"self.{wrong_name}" try: import _suggestions except ImportError: pass else: return _suggestions._generate_suggestions(d, wrong_name) # Compute closest match if len(d) > _MAX_CANDIDATE_ITEMS: return None wrong_name_len = len(wrong_name) if wrong_name_len > _MAX_STRING_SIZE: return None best_distance = wrong_name_len suggestion = None for possible_name in d: if possible_name == wrong_name: # A missing attribute is "found". Don't suggest it (see GH-88821). continue # No more than 1/3 of the involved characters should need changed. max_distance = (len(possible_name) + wrong_name_len + 3) * _MOVE_COST // 6 # Don't take matches we've already beaten. max_distance = min(max_distance, best_distance - 1) current_distance = _levenshtein_distance(wrong_name, possible_name, max_distance) if current_distance > max_distance: continue if not suggestion or current_distance < best_distance: suggestion = possible_name best_distance = current_distance return suggestion def _levenshtein_distance(a, b, max_cost): # A Python implementation of Python/suggestions.c:levenshtein_distance. # Both strings are the same if a == b: return 0 # Trim away common affixes pre = 0 while a[pre:] and b[pre:] and a[pre] == b[pre]: pre += 1 a = a[pre:] b = b[pre:] post = 0 while a[:post or None] and b[:post or None] and a[post-1] == b[post-1]: post -= 1 a = a[:post or None] b = b[:post or None] if not a or not b: return _MOVE_COST * (len(a) + len(b)) if len(a) > _MAX_STRING_SIZE or len(b) > _MAX_STRING_SIZE: return max_cost + 1 # Prefer shorter buffer if len(b) < len(a): a, b = b, a # Quick fail when a match is impossible if (len(b) - len(a)) * _MOVE_COST > max_cost: return max_cost + 1 # Instead of producing the whole traditional len(a)-by-len(b) # matrix, we can update just one row in place. # Initialize the buffer row row = list(range(_MOVE_COST, _MOVE_COST * (len(a) + 1), _MOVE_COST)) result = 0 for bindex in range(len(b)): bchar = b[bindex] distance = result = bindex * _MOVE_COST minimum = sys.maxsize for index in range(len(a)): # 1) Previous distance in this row is cost(b[:b_index], a[:index]) substitute = distance + _substitution_cost(bchar, a[index]) # 2) cost(b[:b_index], a[:index+1]) from previous row distance = row[index] # 3) existing result is cost(b[:b_index+1], a[index]) insert_delete = min(result, distance) + _MOVE_COST result = min(insert_delete, substitute) # cost(b[:b_index+1], a[:index+1]) row[index] = result if result < minimum: minimum = result if minimum > max_cost: # Everything in this row is too big, so bail early. return max_cost + 1 return result