path: root/src/tblib/__init__.py

import re
import sys
from types import CodeType
from types import FrameType
from types import TracebackType

try:
    from __pypy__ import tproxy
except ImportError:
    tproxy = None
try:
    from .cpython import tb_set_next
except ImportError:
    tb_set_next = None

if not tb_set_next and not tproxy:
    raise ImportError("Cannot use tblib. Runtime not supported.")

__version__ = '1.7.0'
__all__ = 'Traceback', 'TracebackParseError', 'Frame', 'Code'

PY3 = sys.version_info[0] == 3
FRAME_RE = re.compile(r'^\s*File "(?P<co_filename>.+)", line (?P<tb_lineno>\d+)(, in (?P<co_name>.+))?$')


class _AttrDict(dict):
    __slots__ = ()

    def __getattr__(self, name):
        try:
            return self[name]
        except KeyError:
            raise AttributeError(name)


# noinspection PyPep8Naming
class __traceback_maker(Exception):
    pass


class TracebackParseError(Exception):
    pass


class Code(object):
    """
    Class that replicates just enough of the builtin Code object to enable serialization and traceback rendering.
    """
    co_code = None

    def __init__(self, code):
        self.co_filename = code.co_filename
        self.co_name = code.co_name
        self.co_argcount = 0
        self.co_kwonlyargcount = 0
        self.co_varnames = ()
        self.co_nlocals = 0
        self.co_stacksize = 0
        self.co_flags = 64
        self.co_firstlineno = 0

    # noinspection SpellCheckingInspection
    def __tproxy__(self, operation, *args, **kwargs):
        """
        Necessary for PyPy's tproxy.
        """
        if operation in ('__getattribute__', '__getattr__'):
            return getattr(self, args[0])
        else:
            return getattr(self, operation)(*args, **kwargs)


class Frame(object):
    """
    Class that replicates just enough of the builtin Frame object to enable serialization and traceback rendering.
    """
    def __init__(self, frame):
        self.f_locals = {}
        self.f_globals = {
            k: v
            for k, v in frame.f_globals.items()
            if k in ("__file__", "__name__")
        }
        self.f_code = Code(frame.f_code)
        self.f_lineno = frame.f_lineno

    def clear(self):
        """
        For compatibility with PyPy 3.5;
        clear() was added to frame in Python 3.4
        and is called by traceback.clear_frames(), which
        in turn is called by unittest.TestCase.assertRaises
        """

    # noinspection SpellCheckingInspection
    def __tproxy__(self, operation, *args, **kwargs):
        """
        Necessary for PyPy's tproxy.
        """
        if operation in ('__getattribute__', '__getattr__'):
            if args[0] == 'f_code':
                return tproxy(CodeType, self.f_code.__tproxy__)
            else:
                return getattr(self, args[0])
        else:
            return getattr(self, operation)(*args, **kwargs)


class Traceback(object):
    """
    Class that wraps builtin Traceback objects.
    """
    tb_next = None

    def __init__(self, tb):
        self.tb_frame = Frame(tb.tb_frame)
        # noinspection SpellCheckingInspection
        self.tb_lineno = int(tb.tb_lineno)

        # Build in place to avoid exceeding the recursion limit
        tb = tb.tb_next
        prev_traceback = self
        cls = type(self)
        while tb is not None:
            traceback = object.__new__(cls)
            traceback.tb_frame = Frame(tb.tb_frame)
            traceback.tb_lineno = int(tb.tb_lineno)
            prev_traceback.tb_next = traceback
            prev_traceback = traceback
            tb = tb.tb_next

    def as_traceback(self):
        """
        Convert to a builtin Traceback object that is usable for raising or rendering a stacktrace.
        """
        if tproxy:
            return tproxy(TracebackType, self.__tproxy__)
        if not tb_set_next:
            raise RuntimeError("Unsupported Python interpreter!")

        current = self
        top_tb = None
        tb = None
        while current:
            f_code = current.tb_frame.f_code
            code = compile('\n' * (current.tb_lineno - 1) + 'raise __traceback_maker', current.tb_frame.f_code.co_filename, 'exec')
            if hasattr(code, "replace"):
                # Python 3.8 and newer
                code = code.replace(co_argcount=0,
                                    co_filename=f_code.co_filename, co_name=f_code.co_name,
                                    co_freevars=(), co_cellvars=())
            elif PY3:
                code = CodeType(
                    0, code.co_kwonlyargcount,
                    code.co_nlocals, code.co_stacksize, code.co_flags,
                    code.co_code, code.co_consts, code.co_names, code.co_varnames,
                    f_code.co_filename, f_code.co_name,
                    code.co_firstlineno, code.co_lnotab, (), ()
                )
            else:
                code = CodeType(
                    0,
                    code.co_nlocals, code.co_stacksize, code.co_flags,
                    code.co_code, code.co_consts, code.co_names, code.co_varnames,
                    f_code.co_filename.encode(), f_code.co_name.encode(),
                    code.co_firstlineno, code.co_lnotab, (), ()
                )

            # noinspection PyBroadException
            try:
                exec(code, dict(current.tb_frame.f_globals), {})
            except Exception:
                next_tb = sys.exc_info()[2].tb_next
                if top_tb is None:
                    top_tb = next_tb
                if tb is not None:
                    tb_set_next(tb, next_tb)
                tb = next_tb
                del next_tb

            current = current.tb_next
        try:
            return top_tb
        finally:
            del top_tb
            del tb
    to_traceback = as_traceback

    # noinspection SpellCheckingInspection
    def __tproxy__(self, operation, *args, **kwargs):
        """
        Necessary for PyPy's tproxy.
        """
        if operation in ('__getattribute__', '__getattr__'):
            if args[0] == 'tb_next':
                return self.tb_next and self.tb_next.as_traceback()
            elif args[0] == 'tb_frame':
                return tproxy(FrameType, self.tb_frame.__tproxy__)
            else:
                return getattr(self, args[0])
        else:
            return getattr(self, operation)(*args, **kwargs)

    def as_dict(self):
        """
        Converts to a dictionary representation. You can serialize the result to JSON as it only has
        builtin objects like dicts, lists, ints or strings.
        """
        if self.tb_next is None:
            tb_next = None
        else:
            tb_next = self.tb_next.to_dict()

        code = {
            'co_filename': self.tb_frame.f_code.co_filename,
            'co_name': self.tb_frame.f_code.co_name,
        }
        frame = {
            'f_globals': self.tb_frame.f_globals,
            'f_code': code,
            'f_lineno': self.tb_frame.f_lineno,
        }
        return {
            'tb_frame': frame,
            'tb_lineno': self.tb_lineno,
            'tb_next': tb_next,
        }
    to_dict = as_dict

    @classmethod
    def from_dict(cls, dct):
        """
        Creates an instance from a dictionary with the same structure as ``.as_dict()`` returns.
        """
        if dct['tb_next']:
            tb_next = cls.from_dict(dct['tb_next'])
        else:
            tb_next = None

        code = _AttrDict(
            co_filename=dct['tb_frame']['f_code']['co_filename'],
            co_name=dct['tb_frame']['f_code']['co_name'],
        )
        frame = _AttrDict(
            f_globals=dct['tb_frame']['f_globals'],
            f_code=code,
            f_lineno=dct['tb_frame']['f_lineno'],
        )
        tb = _AttrDict(
            tb_frame=frame,
            tb_lineno=dct['tb_lineno'],
            tb_next=tb_next,
        )
        return cls(tb)

    @classmethod
    def from_string(cls, string, strict=True):
        """
        Creates an instance by parsing a stacktrace. Strict means that parsing stops when lines are not indented by at least two spaces
        anymore.
        """
        frames = []
        header = strict

        for line in string.splitlines():
            line = line.rstrip()
            if header:
                if line == 'Traceback (most recent call last):':
                    header = False
                continue
            frame_match = FRAME_RE.match(line)
            if frame_match:
                frames.append(frame_match.groupdict())
            elif line.startswith('  '):
                pass
            elif strict:
                break  # traceback ended

        if frames:
            previous = None
            for frame in reversed(frames):
                previous = _AttrDict(
                    frame,
                    tb_frame=_AttrDict(
                        frame,
                        f_globals=_AttrDict(
                            __file__=frame['co_filename'],
                            __name__='?',
                        ),
                        f_code=_AttrDict(frame),
                        f_lineno=int(frame['tb_lineno']),
                    ),
                    tb_next=previous,
                )
            return cls(previous)
        else:
            raise TracebackParseError("Could not find any frames in %r." % string)