nsz Git - libfirm/blob - scripts/jinja2/debug.py

   1 # -*- coding: utf-8 -*-
   2 """
   3     jinja2.debug
   4     ~~~~~~~~~~~~
   5
   6     Implements the debug interface for Jinja.  This module does some pretty
   7     ugly stuff with the Python traceback system in order to achieve tracebacks
   8     with correct line numbers, locals and contents.
   9
  10     :copyright: Copyright 2008 by Armin Ronacher.
  11     :license: BSD.
  12 """
  13 import sys
  14 from jinja2.utils import CodeType
  15
  16
  17 def translate_exception(exc_info):
  18     """If passed an exc_info it will automatically rewrite the exceptions
  19     all the way down to the correct line numbers and frames.
  20     """
  21     result_tb = prev_tb = None
  22     initial_tb = tb = exc_info[2].tb_next
  23
  24     while tb is not None:
  25         template = tb.tb_frame.f_globals.get('__jinja_template__')
  26         if template is not None:
  27             lineno = template.get_corresponding_lineno(tb.tb_lineno)
  28             tb = fake_exc_info(exc_info[:2] + (tb,), template.filename,
  29                                lineno, prev_tb)[2]
  30         if result_tb is None:
  31             result_tb = tb
  32         prev_tb = tb
  33         tb = tb.tb_next
  34
  35     return exc_info[:2] + (result_tb or initial_tb,)
  36
  37
  38 def fake_exc_info(exc_info, filename, lineno, tb_back=None):
  39     """Helper for `translate_exception`."""
  40     exc_type, exc_value, tb = exc_info
  41
  42     # figure the real context out
  43     real_locals = tb.tb_frame.f_locals.copy()
  44     ctx = real_locals.get('context')
  45     if ctx:
  46         locals = ctx.get_all()
  47     else:
  48         locals = {}
  49     for name, value in real_locals.iteritems():
  50         if name.startswith('l_'):
  51             locals[name[2:]] = value
  52
  53     # if there is a local called __jinja_exception__, we get
  54     # rid of it to not break the debug functionality.
  55     locals.pop('__jinja_exception__', None)
  56
  57     # assamble fake globals we need
  58     globals = {
  59         '__name__':             filename,
  60         '__file__':             filename,
  61         '__jinja_exception__':  exc_info[:2]
  62     }
  63
  64     # and fake the exception
  65     code = compile('\n' * (lineno - 1) + 'raise __jinja_exception__[0], ' +
  66                    '__jinja_exception__[1]', filename, 'exec')
  67
  68     # if it's possible, change the name of the code.  This won't work
  69     # on some python environments such as google appengine
  70     try:
  71         function = tb.tb_frame.f_code.co_name
  72         if function == 'root':
  73             location = 'top-level template code'
  74         elif function.startswith('block_'):
  75             location = 'block "%s"' % function[6:]
  76         else:
  77             location = 'template'
  78         code = CodeType(0, code.co_nlocals, code.co_stacksize,
  79                         code.co_flags, code.co_code, code.co_consts,
  80                         code.co_names, code.co_varnames, filename,
  81                         location, code.co_firstlineno,
  82                         code.co_lnotab, (), ())
  83     except:
  84         pass
  85
  86     # execute the code and catch the new traceback
  87     try:
  88         exec code in globals, locals
  89     except:
  90         exc_info = sys.exc_info()
  91         new_tb = exc_info[2].tb_next
  92
  93     # now we can patch the exc info accordingly
  94     if tb_set_next is not None:
  95         if tb_back is not None:
  96             tb_set_next(tb_back, new_tb)
  97         if tb is not None:
  98             tb_set_next(new_tb, tb.tb_next)
  99
 100     # return without this frame
 101     return exc_info[:2] + (new_tb,)
 102
 103
 104 def _init_ugly_crap():
 105     """This function implements a few ugly things so that we can patch the
 106     traceback objects.  The function returned allows resetting `tb_next` on
 107     any python traceback object.
 108     """
 109     import ctypes
 110     from types import TracebackType
 111
 112     # figure out side of _Py_ssize_t
 113     if hasattr(ctypes.pythonapi, 'Py_InitModule4_64'):
 114         _Py_ssize_t = ctypes.c_int64
 115     else:
 116         _Py_ssize_t = ctypes.c_int
 117
 118     # regular python
 119     class _PyObject(ctypes.Structure):
 120         pass
 121     _PyObject._fields_ = [
 122         ('ob_refcnt', _Py_ssize_t),
 123         ('ob_type', ctypes.POINTER(_PyObject))
 124     ]
 125
 126     # python with trace
 127     if object.__basicsize__ != ctypes.sizeof(_PyObject):
 128         class _PyObject(ctypes.Structure):
 129             pass
 130         _PyObject._fields_ = [
 131             ('_ob_next', ctypes.POINTER(_PyObject)),
 132             ('_ob_prev', ctypes.POINTER(_PyObject)),
 133             ('ob_refcnt', _Py_ssize_t),
 134             ('ob_type', ctypes.POINTER(_PyObject))
 135         ]
 136
 137     class _Traceback(_PyObject):
 138         pass
 139     _Traceback._fields_ = [
 140         ('tb_next', ctypes.POINTER(_Traceback)),
 141         ('tb_frame', ctypes.POINTER(_PyObject)),
 142         ('tb_lasti', ctypes.c_int),
 143         ('tb_lineno', ctypes.c_int)
 144     ]
 145
 146     def tb_set_next(tb, next):
 147         """Set the tb_next attribute of a traceback object."""
 148         if not (isinstance(tb, TracebackType) and
 149                 (next is None or isinstance(next, TracebackType))):
 150             raise TypeError('tb_set_next arguments must be traceback objects')
 151         obj = _Traceback.from_address(id(tb))
 152         if tb.tb_next is not None:
 153             old = _Traceback.from_address(id(tb.tb_next))
 154             old.ob_refcnt -= 1
 155         if next is None:
 156             obj.tb_next = ctypes.POINTER(_Traceback)()
 157         else:
 158             next = _Traceback.from_address(id(next))
 159             next.ob_refcnt += 1
 160             obj.tb_next = ctypes.pointer(next)
 161
 162     return tb_set_next
 163
 164
 165 # try to get a tb_set_next implementation
 166 try:
 167     from jinja2._speedups import tb_set_next
 168 except ImportError:
 169     try:
 170         tb_set_next = _init_ugly_crap()
 171     except:
 172         tb_set_next = None
 173 del _init_ugly_crap