diff -r 95eea8624d05 Doc/library/dis.rst --- a/Doc/library/dis.rst Thu Nov 21 11:30:06 2013 -0800 +++ b/Doc/library/dis.rst Thu Nov 21 23:03:44 2013 +0200 @@ -44,7 +44,7 @@ :class:`Bytecode` object that provides easy access to details of the compiled code. -.. class:: Bytecode(x, *, first_line=None) +.. class:: Bytecode(x, *, first_line=None, current_offset=None) Analyse the bytecode corresponding to a function, method, string of source code, or a code object (as returned by :func:`compile`). @@ -59,6 +59,11 @@ Otherwise, the source line information (if any) is taken directly from the disassembled code object. + If *current_offset* is not None, it refers to an instruction offset + in the disassembled code. + It is used by :meth:`Bytecode.from_traceback` to mark the instruction + responsible for the exception. + .. data:: codeobj The compiled code object. @@ -77,6 +82,11 @@ Return a formatted multi-line string with detailed information about the code object, like :func:`code_info`. + .. classmethod:: from_traceback(tb) + + Construct a :class:`Bytecode` from the given traceback. + It will properly set the value of *current_offset* parameter. + Example:: >>> bytecode = dis.Bytecode(myfunc) diff -r 95eea8624d05 Lib/dis.py --- a/Lib/dis.py Thu Nov 21 11:30:06 2013 -0800 +++ b/Lib/dis.py Thu Nov 21 23:03:44 2013 +0200 @@ -406,7 +406,7 @@ Iterating over this yields the bytecode operations as Instruction instances. """ - def __init__(self, x, *, first_line=None): + def __init__(self, x, *, first_line=None, current_offset=None): self.codeobj = co = _get_code_object(x) if first_line is None: self.first_line = co.co_firstlineno @@ -417,6 +417,7 @@ self._cell_names = co.co_cellvars + co.co_freevars self._linestarts = dict(findlinestarts(co)) self._original_object = x + self.current_offset = current_offset def __iter__(self): co = self.codeobj @@ -429,6 +430,13 @@ return "{}({!r})".format(self.__class__.__name__, self._original_object) + @classmethod + def from_traceback(cls, tb): + """ Construct a Bytecode from the given traceback """ + while tb.tb_next: + tb = tb.tb_next + return cls(tb.tb_frame.f_code, current_offset=tb.tb_lasti) + def info(self): """Return formatted information about the code object.""" return _format_code_info(self.codeobj) @@ -436,13 +444,18 @@ def dis(self): """Return a formatted view of the bytecode operations.""" co = self.codeobj - with io.StringIO() as output: + if self.current_offset is not None: + offset = self.current_offset + else: + offset = -1 + with io.StringIO() as output: _disassemble_bytes(co.co_code, varnames=co.co_varnames, names=co.co_names, constants=co.co_consts, cells=self._cell_names, linestarts=self._linestarts, line_offset=self._line_offset, - file=output) + file=output, + lasti=offset) return output.getvalue() diff -r 95eea8624d05 Lib/test/test_dis.py --- a/Lib/test/test_dis.py Thu Nov 21 11:30:06 2013 -0800 +++ b/Lib/test/test_dis.py Thu Nov 21 23:03:44 2013 +0200 @@ -10,6 +10,21 @@ import types import contextlib +def get_tb(): + def _error(): + try: + 1 / 0 + except Exception as e: + tb = e.__traceback__ + return tb + + tb = _error() + while tb.tb_next: + tb = tb.tb_next + return tb + +TRACEBACK_CODE = get_tb().tb_frame.f_code + class _C: def __init__(self, x): self.x = x == 1 @@ -174,6 +189,46 @@ 25 RETURN_VALUE """ +dis_traceback = """\ + %-4d 0 SETUP_EXCEPT 12 (to 15) + + %-4d 3 LOAD_CONST 1 (1) + 6 LOAD_CONST 2 (0) + --> 9 BINARY_TRUE_DIVIDE + 10 POP_TOP + 11 POP_BLOCK + 12 JUMP_FORWARD 46 (to 61) + + %-4d >> 15 DUP_TOP + 16 LOAD_GLOBAL 0 (Exception) + 19 COMPARE_OP 10 (exception match) + 22 POP_JUMP_IF_FALSE 60 + 25 POP_TOP + 26 STORE_FAST 0 (e) + 29 POP_TOP + 30 SETUP_FINALLY 14 (to 47) + + %-4d 33 LOAD_FAST 0 (e) + 36 LOAD_ATTR 1 (__traceback__) + 39 STORE_FAST 1 (tb) + 42 POP_BLOCK + 43 POP_EXCEPT + 44 LOAD_CONST 0 (None) + >> 47 LOAD_CONST 0 (None) + 50 STORE_FAST 0 (e) + 53 DELETE_FAST 0 (e) + 56 END_FINALLY + 57 JUMP_FORWARD 1 (to 61) + >> 60 END_FINALLY + + %-4d >> 61 LOAD_FAST 1 (tb) + 64 RETURN_VALUE +""" % (TRACEBACK_CODE.co_firstlineno + 1, + TRACEBACK_CODE.co_firstlineno + 2, + TRACEBACK_CODE.co_firstlineno + 3, + TRACEBACK_CODE.co_firstlineno + 4, + TRACEBACK_CODE.co_firstlineno + 5) + class DisTests(unittest.TestCase): def get_disassembly(self, func, lasti=-1, wrapper=True): @@ -758,6 +813,17 @@ actual = dis.Bytecode(_f).dis() self.assertEqual(actual, dis_f) + def test_from_traceback(self): + tb = get_tb() + b = dis.Bytecode.from_traceback(tb) + while tb.tb_next: tb = tb.tb_next + + self.assertEqual(b.current_offset, tb.tb_lasti) + + def test_from_traceback_dis(self): + tb = get_tb() + b = dis.Bytecode.from_traceback(tb) + self.assertEqual(b.dis(), dis_traceback) def test_main(): run_unittest(DisTests, DisWithFileTests, CodeInfoTests,