error.c

/**
 * See Copyright Notice in picrin.h
 */

#include "picrin.h"
#include "object.h"
#include "state.h"

void
pic_panic(pic_state *pic, const char *msg)
{
  if (pic->panicf) {
    pic->panicf(pic, msg);
  }
#if PIC_USE_LIBC
  abort();
#endif
  PIC_UNREACHABLE();
}

void
pic_warnf(pic_state *pic, const char *fmt, ...)
{
  va_list ap;
  pic_value err;

  va_start(ap, fmt);
  err = pic_vstrf_value(pic, fmt, ap);
  va_end(ap);
  pic_fprintf(pic, pic_stderr(pic), "warn: %s\n", pic_str(pic, err, NULL));
}

#define pic_exc(pic) pic_ref(pic, "current-exception-handlers")

#if PIC_USE_CALLCC

PIC_JMPBUF *
pic_prepare_try(pic_state *pic)
{
  struct context *cxt = pic_malloc(pic, sizeof(struct context));

  cxt->pc = NULL;
  cxt->fp = NULL;
  cxt->sp = NULL;
  cxt->irep = NULL;

  cxt->prev = pic->cxt;
  pic->cxt = cxt;
  return &cxt->jmp;
}

static pic_value
native_exception_handler(pic_state *pic)
{
  pic_value err;

  pic_get_args(pic, "o", &err);

  pic_call(pic, pic_closure_ref(pic, 0), 1, err);
  PIC_UNREACHABLE();
}

void
pic_enter_try(pic_state *pic)
{
  pic_value cont, handler;
  pic_value var, env;

  pic->cxt->ai = pic->ai;

  /* call/cc */
  cont = pic_make_cont(pic, pic_invalid_value(pic));
  handler = pic_lambda(pic, native_exception_handler, 1, cont);
  /* with-exception-handler */
  var = pic_exc(pic);
  env = pic_make_weak(pic);
  pic_weak_set(pic, env, var, pic_cons(pic, handler, pic_call(pic, var, 0)));
  pic->dyn_env = pic_cons(pic, env, pic->dyn_env);

  pic_leave(pic, pic->cxt->ai);
}

void
pic_exit_try(pic_state *pic)
{
  struct context *cxt = pic->cxt;
  pic->dyn_env = pic_cdr(pic, pic->dyn_env);
  pic->cxt = cxt->prev;
  pic_free(pic, cxt);
  /* don't rewind ai here */
}

pic_value
pic_abort_try(pic_state *pic)
{
  struct context *cxt = pic->cxt;
  pic_value err = cxt->sp->regs[1];
  pic->cxt = cxt->prev;
  pic_free(pic, cxt);
  pic_protect(pic, err);
  return err;
}

#else

PIC_JMPBUF *pic_prepare_try(pic_state *PIC_UNUSED(pic)) { return NULL; }
void pic_enter_try(pic_state *PIC_UNUSED(pic)) { }
void pic_exit_try(pic_state *PIC_UNUSED(pic)) { }
pic_value pic_abort_try(pic_state *PIC_UNUSED(pic)) { PIC_UNREACHABLE(); }

#endif

pic_value
pic_make_error(pic_state *pic, const char *type, const char *msg, pic_value irrs)
{
  struct error *e;
  pic_value ty = pic_intern_cstr(pic, type);

  e = (struct error *)pic_obj_alloc(pic, PIC_TYPE_ERROR);
  e->type = sym_ptr(pic, ty);
  e->msg = str_ptr(pic, pic_cstr_value(pic, msg));
  e->irrs = irrs;

  return obj_value(pic, e);
}

static pic_value
with_exception_handlers(pic_state *pic, pic_value handlers, pic_value thunk)
{
  pic_value alist, var = pic_exc(pic);
  alist = pic_list(pic, 1, pic_cons(pic, var, handlers));
  return pic_funcall(pic, "with-dynamic-environment", 2, alist, thunk);
}

static pic_value
on_raise(pic_state *pic)
{
  pic_value handler, err, val;
  bool continuable;

  pic_get_args(pic, "");

  handler = pic_closure_ref(pic, 0);
  err = pic_closure_ref(pic, 1);
  continuable = pic_bool(pic, pic_closure_ref(pic, 2));

  val = pic_call(pic, handler, 1, err);
  if (! continuable) {
    pic_error(pic, "handler returned", 2, handler, err);
  }
  return val;
}

pic_value
pic_raise_continuable(pic_state *pic, pic_value err)
{
  pic_value handlers, var = pic_exc(pic), thunk;

  handlers = pic_call(pic, var, 0);

  if (pic_nil_p(pic, handlers)) {
    pic_panic(pic, "no exception handler");
  }
  thunk = pic_lambda(pic, on_raise, 3, pic_car(pic, handlers), err, pic_true_value(pic));
  return with_exception_handlers(pic, pic_cdr(pic, handlers), thunk);
}

void
pic_raise(pic_state *pic, pic_value err)
{
  pic_value handlers, var = pic_exc(pic), thunk;

  handlers = pic_call(pic, var, 0);

  if (pic_nil_p(pic, handlers)) {
    pic_panic(pic, "no exception handler");
  }
  thunk = pic_lambda(pic, on_raise, 3, pic_car(pic, handlers), err, pic_false_value(pic));
  with_exception_handlers(pic, pic_cdr(pic, handlers), thunk);
  PIC_UNREACHABLE();
}

void
pic_error(pic_state *pic, const char *msg, int n, ...)
{
  va_list ap;
  pic_value irrs;

  va_start(ap, n);
  irrs = pic_vlist(pic, n, ap);
  va_end(ap);
  pic_raise(pic, pic_make_error(pic, "", msg, irrs));
}

static pic_value
pic_error_with_exception_handler(pic_state *pic)
{
  pic_value handler, thunk;
  pic_value handlers, exc = pic_exc(pic);

  pic_get_args(pic, "ll", &handler, &thunk);

  handlers = pic_call(pic, exc, 0);

  return with_exception_handlers(pic, pic_cons(pic, handler, handlers), thunk);
}

static pic_value
pic_error_raise(pic_state *pic)
{
  pic_value v;

  pic_get_args(pic, "o", &v);

  pic_raise(pic, v);
}

static pic_value
pic_error_raise_continuable(pic_state *pic)
{
  pic_value v;

  pic_get_args(pic, "o", &v);

  return pic_raise_continuable(pic, v);
}

static pic_value
pic_error_error(pic_state *pic)
{
  const char *cstr;
  int argc;
  pic_value *argv;

  pic_get_args(pic, "z*", &cstr, &argc, &argv);

  pic_raise(pic, pic_make_error(pic, "", cstr, pic_make_list(pic, argc, argv)));
}

static pic_value
pic_error_error_object_p(pic_state *pic)
{
  pic_value v;

  pic_get_args(pic, "o", &v);

  return pic_bool_value(pic, pic_error_p(pic, v));
}

static pic_value
pic_error_error_object_message(pic_state *pic)
{
  pic_value e;

  pic_get_args(pic, "o", &e);

  TYPE_CHECK(pic, e, error);

  return obj_value(pic, error_ptr(pic, e)->msg);
}

static pic_value
pic_error_error_object_irritants(pic_state *pic)
{
  pic_value e;

  pic_get_args(pic, "o", &e);

  TYPE_CHECK(pic, e, error);

  return error_ptr(pic, e)->irrs;
}

static pic_value
pic_error_error_object_type(pic_state *pic)
{
  pic_value e;

  pic_get_args(pic, "o", &e);

  TYPE_CHECK(pic, e, error);

  return obj_value(pic, error_ptr(pic, e)->type);
}

void
pic_init_error(pic_state *pic)
{
  pic_defvar(pic, "current-exception-handlers", pic_nil_value(pic));
  pic_defun(pic, "with-exception-handler", pic_error_with_exception_handler);
  pic_defun(pic, "raise", pic_error_raise);
  pic_defun(pic, "raise-continuable", pic_error_raise_continuable);
  pic_defun(pic, "error", pic_error_error);
  pic_defun(pic, "error-object?", pic_error_error_object_p);
  pic_defun(pic, "error-object-message", pic_error_error_object_message);
  pic_defun(pic, "error-object-irritants", pic_error_error_object_irritants);
  pic_defun(pic, "error-object-type", pic_error_error_object_type);
}