cpython/Lib/traceback.py at 3.14 · python/cpython · GitHub

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"""Extract, format and print information about Python stack traces."""

import collections.abc

import itertools

import linecache

import sys

import textwrap

import warnings

import codeop

import keyword

import tokenize

import io

import _colorize

from contextlib import suppress

__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

representing the information that is usually printed for a

stack trace. The line attribute is a string with

leading and trailing whitespace stripped; if the source is not

available the corresponding attribute 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 "<implicit>"

_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(file=file)

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:

theme = _colorize.get_theme(force_color=True).traceback

else:

theme = _colorize.get_theme(force_no_color=True).traceback

if value is None or not valuestr:

line = f"{theme.type}{etype}{theme.reset}{end_char}"

else:

line = f"{theme.type}{etype}{theme.reset}: {theme.message}{valuestr}{theme.reset}{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=limit, file=file, chain=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=limit, file=file, chain=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=limit, file=file, chain=chain)

else:

print_exception(sys.last_type, sys.last_value, sys.last_traceback,

limit=limit, file=file, chain=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 FrameSummary object,

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 line

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', '_code')

def __init__(self, filename, lineno, name, *, lookup_line=True,

locals=None, line=None,

end_lineno=None, colno=None, end_colno=None, **kwargs):

"""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._code = kwargs.get("_code")

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 "<FrameSummary file {filename}, line {lineno} in {name}>".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

line = linecache.getline(self.filename, lineno).rstrip()

if not line and self._code is not None and self.filename.startswith("<"):

line = linecache._getline_from_code(self._code, lineno).rstrip()

lines.append(line)

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

def walk_stack_generator(frame):

while frame is not None:

yield frame, frame.f_lineno

frame = frame.f_back

return walk_stack_generator(f)

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,

_code=f.f_code,

)

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("<stdin-") and frame_summary.filename.endswith('>'):

filename = "<stdin>"

if colorize:

theme = _colorize.get_theme(force_color=True).traceback

else:

theme = _colorize.get_theme(force_no_color=True).traceback

row.append(

' File {}"{}"{}, line {}{}{}, in {}{}{}\n'.format(

theme.filename,

filename,

theme.reset,

theme.line_no,

frame_summary.lineno,

theme.reset,

theme.frame,

frame_summary.name,

theme.reset,

)

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(theme.error_highlight + "".join(char for char, _ in caret_group) + theme.reset)

colorized_carets_parts.append(theme.error_highlight + "".join(caret for _, caret in caret_group) + theme.reset)

elif color == "~":

colorized_line_parts.append(theme.error_range + "".join(char for char, _ in caret_group) + theme.reset)

colorized_carets_parts.append(theme.error_range + "".join(caret for _, caret in caret_group) + theme.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 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)

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