nmigen/tracer.py

   1 import sys
   2 from opcode import opname
   3
   4
   5 __all__ = ["NameNotFound", "get_var_name", "get_src_loc"]
   6
   7
   8 class NameNotFound(Exception):
   9     pass
  10
  11
  12 _raise_exception = object()
  13
  14
  15 def get_var_name(depth=2, default=_raise_exception):
  16     frame = sys._getframe(depth)
  17     code = frame.f_code
  18     call_index = frame.f_lasti
  19     while True:
  20         call_opc = opname[code.co_code[call_index]]
  21         if call_opc in ("EXTENDED_ARG",):
  22             call_index += 2
  23         else:
  24             break
  25     if call_opc not in ("CALL_FUNCTION", "CALL_FUNCTION_KW", "CALL_FUNCTION_EX", "CALL_METHOD"):
  26         return None
  27
  28     index = call_index + 2
  29     while True:
  30         opc = opname[code.co_code[index]]
  31         if opc in ("STORE_NAME", "STORE_ATTR"):
  32             name_index = int(code.co_code[index + 1])
  33             return code.co_names[name_index]
  34         elif opc == "STORE_FAST":
  35             name_index = int(code.co_code[index + 1])
  36             return code.co_varnames[name_index]
  37         elif opc == "STORE_DEREF":
  38             name_index = int(code.co_code[index + 1])
  39             return code.co_cellvars[name_index]
  40         elif opc in ("LOAD_GLOBAL", "LOAD_NAME", "LOAD_ATTR", "LOAD_FAST", "LOAD_DEREF",
  41                      "DUP_TOP", "BUILD_LIST"):
  42             index += 2
  43         else:
  44             if default is _raise_exception:
  45                 raise NameNotFound
  46             else:
  47                 return default
  48
  49
  50 def get_src_loc(src_loc_at=0):
  51     # n-th  frame: get_src_loc()
  52     # n-1th frame: caller of get_src_loc() (usually constructor)
  53     # n-2th frame: caller of caller (usually user code)
  54     frame = sys._getframe(2 + src_loc_at)
  55     return (frame.f_code.co_filename, frame.f_lineno)