text: #include <string.h>
  #include <stdarg.h>
  #include <assert.h>
  
  #include "nlr.h"
  #include "misc.h"
  #include "mpconfig.h"
  #include "qstr.h"
  #include "obj.h"
  #include "objtuple.h"
  #include "runtime.h"
  #include "runtime0.h"
  
  typedef struct _mp_obj_exception_t {
      mp_obj_base_t base;
      mp_obj_t traceback; // a list object, holding (file,line,block) as numbers (not Python objects); a hack for now
      mp_obj_tuple_t args;
  } mp_obj_exception_t;
  
  // Instance of MemoryError exception - needed by mp_malloc_fail
  const mp_obj_exception_t mp_const_MemoryError_obj = {{&mp_type_MemoryError}, MP_OBJ_NULL, {{&mp_type_tuple}, 0}};
  
  // Local non-heap memory for allocating an exception when we run out of RAM
  STATIC mp_obj_exception_t mp_emergency_exception_obj;
  
  // Instance of GeneratorExit exception - needed by generator.close()
  // This would belong to objgenerator.c, but to keep mp_obj_exception_t
  // definition module-private so far, have it here.
  const mp_obj_exception_t mp_const_GeneratorExit_obj = {{&mp_type_GeneratorExit}, MP_OBJ_NULL, {{&mp_type_tuple}, 0}};
  
  STATIC void mp_obj_exception_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t o_in, mp_print_kind_t kind) {
      mp_obj_exception_t *o = o_in;
      if (kind == PRINT_REPR) {
          print(env, "%s", qstr_str(o->base.type->name));
      } else if (kind == PRINT_EXC) {
          print(env, "%s: ", qstr_str(o->base.type->name));
      }
      if (kind == PRINT_STR || kind == PRINT_EXC) {
          if (o->args.len == 0) {
              print(env, "");
              return;
          } else if (o->args.len == 1) {
              mp_obj_print_helper(print, env, o->args.items[0], PRINT_STR);
              return;
          }
      }
      tuple_print(print, env, &o->args, kind);
  }
  
  STATIC mp_obj_t mp_obj_exception_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_obj_t *args) {
      mp_obj_type_t *type = type_in;
  
      if (n_kw != 0) {
          nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "%s does not take keyword arguments", mp_obj_get_type_str(type_in)));
      }
  
      mp_obj_exception_t *o = m_new_obj_var_maybe(mp_obj_exception_t, mp_obj_t, n_args);
      if (o == NULL) {
          // Couldn't allocate heap memory; use local data instead.
          o = &mp_emergency_exception_obj;
          // We can't store any args.
          n_args = 0;
      }
      o->base.type = type;
      o->traceback = MP_OBJ_NULL;
      o->args.base.type = &mp_type_tuple;
      o->args.len = n_args;
      memcpy(o->args.items, args, n_args * sizeof(mp_obj_t));
      return o;
  }
  
  // Get exception "value" - that is, first argument, or None
  mp_obj_t mp_obj_exception_get_value(mp_obj_t self_in) {
      mp_obj_exception_t *self = self_in;
      if (self->args.len == 0) {
          return mp_const_none;
      } else {
          return self->args.items[0];
      }
  }
  
  STATIC void exception_load_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
      mp_obj_exception_t *self = self_in;
      if (attr == MP_QSTR_args) {
          dest[0] = &self->args;
      } else if (self->base.type == &mp_type_StopIteration && attr == MP_QSTR_value) {
          dest[0] = mp_obj_exception_get_value(self);
      }
  }
  
  const mp_obj_type_t mp_type_BaseException = {
      { &mp_type_type },
      .name = MP_QSTR_BaseException,
      .print = mp_obj_exception_print,
      .make_new = mp_obj_exception_make_new,
      .load_attr = exception_load_attr,
  };
  
  #define MP_DEFINE_EXCEPTION_BASE(base_name) \
  STATIC const mp_obj_tuple_t mp_type_ ## base_name ## _base_tuple = {{&mp_type_tuple}, 1, {(mp_obj_t)&mp_type_ ## base_name}};\
  
  #define MP_DEFINE_EXCEPTION(exc_name, base_name) \
  const mp_obj_type_t mp_type_ ## exc_name = { \
      { &mp_type_type }, \
      .name = MP_QSTR_ ## exc_name, \
      .print = mp_obj_exception_print, \
      .make_new = mp_obj_exception_make_new, \
      .load_attr = exception_load_attr, \
      .bases_tuple = (mp_obj_t)&mp_type_ ## base_name ## _base_tuple, \
  };
  
  // List of all exceptions, arranged as in the table at:
  // http://docs.python.org/3.3/library/exceptions.html
  MP_DEFINE_EXCEPTION_BASE(BaseException)
  //MP_DEFINE_EXCEPTION(SystemExit, BaseException)
  //MP_DEFINE_EXCEPTION(KeyboardInterrupt, BaseException)
  MP_DEFINE_EXCEPTION(GeneratorExit, BaseException)
  MP_DEFINE_EXCEPTION(Exception, BaseException)
    MP_DEFINE_EXCEPTION_BASE(Exception)
    MP_DEFINE_EXCEPTION(StopIteration, Exception)
    MP_DEFINE_EXCEPTION(ArithmeticError, Exception)
      MP_DEFINE_EXCEPTION_BASE(ArithmeticError)
      //MP_DEFINE_EXCEPTION(FloatingPointError, ArithmeticError)
      MP_DEFINE_EXCEPTION(OverflowError, ArithmeticError)
      MP_DEFINE_EXCEPTION(ZeroDivisionError, ArithmeticError)
    MP_DEFINE_EXCEPTION(AssertionError, Exception)
    MP_DEFINE_EXCEPTION(AttributeError, Exception)
    //MP_DEFINE_EXCEPTION(BufferError, Exception)
    //MP_DEFINE_EXCEPTION(EnvironmentError, Exception)
    MP_DEFINE_EXCEPTION(EOFError, Exception)
    MP_DEFINE_EXCEPTION(ImportError, Exception)
    MP_DEFINE_EXCEPTION(IOError, Exception)
    MP_DEFINE_EXCEPTION(LookupError, Exception)
      MP_DEFINE_EXCEPTION_BASE(LookupError)
      MP_DEFINE_EXCEPTION(IndexError, LookupError)
      MP_DEFINE_EXCEPTION(KeyError, LookupError)
    MP_DEFINE_EXCEPTION(MemoryError, Exception)
    MP_DEFINE_EXCEPTION(NameError, Exception)
      MP_DEFINE_EXCEPTION_BASE(NameError)
      //MP_DEFINE_EXCEPTION(UnboundLocalError, NameError)
    MP_DEFINE_EXCEPTION(OSError, Exception)
      MP_DEFINE_EXCEPTION_BASE(OSError)
      /*
      MP_DEFINE_EXCEPTION(BlockingIOError, OSError)
      MP_DEFINE_EXCEPTION(ChildProcessError, OSError)
      MP_DEFINE_EXCEPTION(ConnectionError, OSError)
        MP_DEFINE_EXCEPTION(BrokenPipeError, ConnectionError)
        MP_DEFINE_EXCEPTION(ConnectionAbortedError, ConnectionError)
        MP_DEFINE_EXCEPTION(ConnectionRefusedError, ConnectionError)
        MP_DEFINE_EXCEPTION(ConnectionResetError, ConnectionError)
      MP_DEFINE_EXCEPTION(InterruptedError, OSError)
      MP_DEFINE_EXCEPTION(IsADirectoryError, OSError)
      MP_DEFINE_EXCEPTION(NotADirectoryError, OSError)
      MP_DEFINE_EXCEPTION(PermissionError, OSError)
      MP_DEFINE_EXCEPTION(ProcessLookupError, OSError)
      MP_DEFINE_EXCEPTION(TimeoutError, OSError)
      MP_DEFINE_EXCEPTION(FileExistsError, OSError)
      MP_DEFINE_EXCEPTION(FileNotFoundError, OSError)
      MP_DEFINE_EXCEPTION(ReferenceError, Exception)
      */
    MP_DEFINE_EXCEPTION(RuntimeError, Exception)
      MP_DEFINE_EXCEPTION_BASE(RuntimeError)
      MP_DEFINE_EXCEPTION(NotImplementedError, RuntimeError)
    MP_DEFINE_EXCEPTION(SyntaxError, Exception)
      MP_DEFINE_EXCEPTION_BASE(SyntaxError)
      MP_DEFINE_EXCEPTION(IndentationError, SyntaxError)
      /*
        MP_DEFINE_EXCEPTION_BASE(IndentationError)
        MP_DEFINE_EXCEPTION(TabError, IndentationError)
        */
    MP_DEFINE_EXCEPTION(SystemError, Exception)
    MP_DEFINE_EXCEPTION(TypeError, Exception)
    MP_DEFINE_EXCEPTION(ValueError, Exception)
      //TODO: Implement UnicodeErrors which take arguments
    /*
    MP_DEFINE_EXCEPTION(Warning, Exception)
      MP_DEFINE_EXCEPTION_BASE(Warning)
      MP_DEFINE_EXCEPTION(DeprecationWarning, Warning)
      MP_DEFINE_EXCEPTION(PendingDeprecationWarning, Warning)
      MP_DEFINE_EXCEPTION(RuntimeWarning, Warning)
      MP_DEFINE_EXCEPTION(SyntaxWarning, Warning)
      MP_DEFINE_EXCEPTION(UserWarning, Warning)
      MP_DEFINE_EXCEPTION(FutureWarning, Warning)
      MP_DEFINE_EXCEPTION(ImportWarning, Warning)
      MP_DEFINE_EXCEPTION(UnicodeWarning, Warning)
      MP_DEFINE_EXCEPTION(BytesWarning, Warning)
      MP_DEFINE_EXCEPTION(ResourceWarning, Warning)
      */
  
  mp_obj_t mp_obj_new_exception(const mp_obj_type_t *exc_type) {
      return mp_obj_new_exception_args(exc_type, 0, NULL);
  }
  
  mp_obj_t mp_obj_new_exception_args(const mp_obj_type_t *exc_type, uint n_args, const mp_obj_t *args) {
      assert(exc_type->make_new == mp_obj_exception_make_new);
      return exc_type->make_new((mp_obj_t)exc_type, n_args, 0, args);
  }
  
  mp_obj_t mp_obj_new_exception_msg(const mp_obj_type_t *exc_type, const char *msg) {
      return mp_obj_new_exception_msg_varg(exc_type, msg);
  }
  
  mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const char *fmt, ...) {
      // check that the given type is an exception type
      assert(exc_type->make_new == mp_obj_exception_make_new);
  
      // make exception object
      mp_obj_exception_t *o = m_new_obj_var_maybe(mp_obj_exception_t, mp_obj_t, 1);
      if (o == NULL) {
          // Couldn't allocate heap memory; use local data instead.
          // Unfortunately, we won't be able to format the string...
          o = &mp_emergency_exception_obj;
          o->base.type = exc_type;
          o->traceback = MP_OBJ_NULL;
          o->args.base.type = &mp_type_tuple;
          o->args.len = 0;
      } else {
          o->base.type = exc_type;
          o->traceback = MP_OBJ_NULL;
          o->args.base.type = &mp_type_tuple;
          o->args.len = 1;
  
          if (fmt == NULL) {
              // no message
              assert(0);
          } else {
              // render exception message and store as .args[0]
              // TODO: optimize bufferbloat
              vstr_t *vstr = vstr_new();
              va_list ap;
              va_start(ap, fmt);
              vstr_vprintf(vstr, fmt, ap);
              va_end(ap);
              o->args.items[0] = mp_obj_new_str((byte*)vstr->buf, vstr->len, false);
              vstr_free(vstr);
          }
      }
  
      return o;
  }
  
  // return true if the given object is an exception type
  bool mp_obj_is_exception_type(mp_obj_t self_in) {
      if (MP_OBJ_IS_TYPE(self_in, &mp_type_type)) {
          // optimisation when self_in is a builtin exception
          mp_obj_type_t *self = self_in;
          if (self->make_new == mp_obj_exception_make_new) {
              return true;
          }
      }
      return mp_obj_is_subclass_fast(self_in, &mp_type_BaseException);
  }
  
  // return true if the given object is an instance of an exception type
  bool mp_obj_is_exception_instance(mp_obj_t self_in) {
      return mp_obj_is_exception_type(mp_obj_get_type(self_in));
  }
  
  // return true if exception (type or instance) is a subclass of given
  // exception type.
  bool mp_obj_exception_match(mp_obj_t exc, const mp_obj_type_t *exc_type) {
      // TODO: move implementation from RT_BINARY_OP_EXCEPTION_MATCH here.
      return mp_binary_op(MP_BINARY_OP_EXCEPTION_MATCH, exc, (mp_obj_t)exc_type) == mp_const_true;
  }
  
  void mp_obj_exception_clear_traceback(mp_obj_t self_in) {
      // make sure self_in is an exception instance
      // TODO add traceback information to user-defined exceptions (need proper builtin subclassing for that)
      if (mp_obj_get_type(self_in)->make_new == mp_obj_exception_make_new) {
          mp_obj_exception_t *self = self_in;
  
          // just set the traceback to the null object
          // we don't want to call any memory management functions here
          self->traceback = MP_OBJ_NULL;
      }
  }
  
  void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, machine_uint_t line, qstr block) {
      // make sure self_in is an exception instance
      // TODO add traceback information to user-defined exceptions (need proper builtin subclassing for that)
      if (mp_obj_get_type(self_in)->make_new == mp_obj_exception_make_new && self_in != &mp_emergency_exception_obj) {
          mp_obj_exception_t *self = self_in;
  
          // for traceback, we are just using the list object for convenience, it's not really a list of Python objects
          if (self->traceback == MP_OBJ_NULL) {
              self->traceback = mp_obj_new_list(0, NULL);
          }
          mp_obj_list_append(self->traceback, (mp_obj_t)(machine_uint_t)file);
          mp_obj_list_append(self->traceback, (mp_obj_t)(machine_uint_t)line);
          mp_obj_list_append(self->traceback, (mp_obj_t)(machine_uint_t)block);
      }
  }
  
  void mp_obj_exception_get_traceback(mp_obj_t self_in, machine_uint_t *n, machine_uint_t **values) {
      // make sure self_in is an exception instance
      assert(mp_obj_get_type(self_in)->make_new == mp_obj_exception_make_new);
      mp_obj_exception_t *self = self_in;
  
      if (self->traceback == MP_OBJ_NULL) {
          *n = 0;
          *values = NULL;
      } else {
          uint n2;
          mp_obj_list_get(self->traceback, &n2, (mp_obj_t**)values);
          *n = n2;
      }
  }
  