Beispiel #1
0
DUK_INTERNAL void duk_debug_dump_hobject(duk_hobject *obj) {
	duk_uint_fast32_t i;
	const char *str_empty = "";
	const char *str_excl = "!";

	DUK_UNREF(str_empty);
	DUK_UNREF(str_excl);
	DUK_UNREF(duk__class_names);

	DUK_D(DUK_DPRINT("=== hobject %p ===", (void *) obj));
	if (!obj) {
		return;
	}

	DUK_D(DUK_DPRINT("  %sextensible", (const char *) (DUK_HOBJECT_HAS_EXTENSIBLE(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sconstructable", (const char *) (DUK_HOBJECT_HAS_CONSTRUCTABLE(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sbound", (const char *) (DUK_HOBJECT_HAS_BOUND(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %scompiledfunction", (const char *) (DUK_HOBJECT_HAS_COMPILEDFUNCTION(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %snativefunction", (const char *) (DUK_HOBJECT_HAS_NATIVEFUNCTION(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sthread", (const char *) (DUK_HOBJECT_HAS_THREAD(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sarray_part", (const char *) (DUK_HOBJECT_HAS_ARRAY_PART(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sstrict", (const char *) (DUK_HOBJECT_HAS_STRICT(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %snewenv", (const char *) (DUK_HOBJECT_HAS_NEWENV(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %snamebinding", (const char *) (DUK_HOBJECT_HAS_NAMEBINDING(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %screateargs", (const char *) (DUK_HOBJECT_HAS_CREATEARGS(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %senvrecclosed", (const char *) (DUK_HOBJECT_HAS_ENVRECCLOSED(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sexotic_array", (const char *) (DUK_HOBJECT_HAS_EXOTIC_ARRAY(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sexotic_stringobj", (const char *) (DUK_HOBJECT_HAS_EXOTIC_STRINGOBJ(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sexotic_arguments", (const char *) (DUK_HOBJECT_HAS_EXOTIC_ARGUMENTS(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sexotic_dukfunc", (const char *) (DUK_HOBJECT_HAS_EXOTIC_DUKFUNC(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sexotic_bufferobj", (const char *) (DUK_HOBJECT_HAS_EXOTIC_BUFFEROBJ(obj) ? str_empty : str_excl)));
	DUK_D(DUK_DPRINT("  %sexotic_proxyobj", (const char *) (DUK_HOBJECT_HAS_EXOTIC_PROXYOBJ(obj) ? str_empty : str_excl)));

	DUK_D(DUK_DPRINT("  class: number %ld -> %s",
	                 (long) DUK_HOBJECT_GET_CLASS_NUMBER(obj),
	                 (const char *) (duk__class_names[(DUK_HOBJECT_GET_CLASS_NUMBER(obj)) & ((1 << DUK_HOBJECT_FLAG_CLASS_BITS) - 1)])));

	DUK_D(DUK_DPRINT("  prototype: %p -> %!O",
	                 (void *) obj->prototype,
	                 (duk_heaphdr *) obj->prototype));

	DUK_D(DUK_DPRINT("  props: p=%p, e_size=%ld, e_next=%ld, a_size=%ld, h_size=%ld",
	                 (void *) obj->p,
	                 (long) obj->e_size,
	                 (long) obj->e_next,
	                 (long) obj->a_size,
	                 (long) obj->h_size));

	/*
	 *  Object (struct layout) specific dumping.  Inline code here
	 *  instead of helpers, to ensure debug line prefix is identical.
	 */

	if (DUK_HOBJECT_IS_COMPILEDFUNCTION(obj)) {
		duk_hcompiledfunction *h = (duk_hcompiledfunction *) obj;

		DUK_D(DUK_DPRINT("  hcompiledfunction"));
		DUK_D(DUK_DPRINT("  data: %!O", (duk_heaphdr *) h->data));
		DUK_D(DUK_DPRINT("  nregs: %ld", (long) h->nregs));
		DUK_D(DUK_DPRINT("  nargs: %ld", (long) h->nargs));

		if (h->data && DUK_HBUFFER_HAS_DYNAMIC(h->data) && DUK_HBUFFER_GET_DATA_PTR(h->data)) {
			DUK_D(DUK_DPRINT("  consts: %p (%ld, %ld bytes)",
			                 (void *) DUK_HCOMPILEDFUNCTION_GET_CONSTS_BASE(h),
			                 (long) DUK_HCOMPILEDFUNCTION_GET_CONSTS_COUNT(h),
			                 (long) DUK_HCOMPILEDFUNCTION_GET_CONSTS_SIZE(h)));
			DUK_D(DUK_DPRINT("  funcs: %p (%ld, %ld bytes)",
			                 (void *) DUK_HCOMPILEDFUNCTION_GET_FUNCS_BASE(h),
			                 (long) DUK_HCOMPILEDFUNCTION_GET_FUNCS_COUNT(h),
			                 (long) DUK_HCOMPILEDFUNCTION_GET_FUNCS_SIZE(h)));
			DUK_D(DUK_DPRINT("  bytecode: %p (%ld, %ld bytes)",
			                 (void *) DUK_HCOMPILEDFUNCTION_GET_CODE_BASE(h),
			                 (long) DUK_HCOMPILEDFUNCTION_GET_CODE_COUNT(h),
			                 (long) DUK_HCOMPILEDFUNCTION_GET_CODE_SIZE(h)));
		} else {
			DUK_D(DUK_DPRINT("  consts: ???"));
			DUK_D(DUK_DPRINT("  funcs: ???"));
			DUK_D(DUK_DPRINT("  bytecode: ???"));
		}
	} else if (DUK_HOBJECT_IS_NATIVEFUNCTION(obj)) {
		duk_hnativefunction *h = (duk_hnativefunction *) obj;
		DUK_UNREF(h);

		DUK_D(DUK_DPRINT("  hnativefunction"));
		/* XXX: h->func, cannot print function pointers portably */
		DUK_D(DUK_DPRINT("  nargs: %ld", (long) h->nargs));
	} else if (DUK_HOBJECT_IS_THREAD(obj)) {
		duk_hthread *thr = (duk_hthread *) obj;
		duk_tval *p;

		DUK_D(DUK_DPRINT("  hthread"));
		DUK_D(DUK_DPRINT("  strict: %ld", (long) thr->strict));
		DUK_D(DUK_DPRINT("  state: %ld", (long) thr->state));

		DUK_D(DUK_DPRINT("  valstack_max: %ld, callstack_max: %ld, catchstack_max: %ld",
		                 (long) thr->valstack_max, (long) thr->callstack_max, (long) thr->catchstack_max));

		DUK_D(DUK_DPRINT("  callstack: ptr %p, size %ld, top %ld, preventcount %ld, used size %ld entries (%ld bytes), alloc size %ld entries (%ld bytes)",
		                 (void *) thr->callstack,
		                 (long) thr->callstack_size,
		                 (long) thr->callstack_top,
		                 (long) thr->callstack_preventcount,
		                 (long) thr->callstack_top,
		                 (long) (thr->callstack_top * sizeof(duk_activation)),
		                 (long) thr->callstack_size,
		                 (long) (thr->callstack_size * sizeof(duk_activation))));

		DUK_DEBUG_SUMMARY_INIT();
		DUK_DEBUG_SUMMARY_CHAR('[');
		for (i = 0; i <= (duk_uint_fast32_t) thr->callstack_size; i++) {
			if (i == thr->callstack_top) {
				DUK_DEBUG_SUMMARY_CHAR('|');
			}
			if (!thr->callstack) {
				DUK_DEBUG_SUMMARY_CHAR('@');
			} else if (i < thr->callstack_size) {
				if (i < thr->callstack_top) {
					/* tailcalling is nice to see immediately; other flags (e.g. strict)
					 * not that important.
					 */
					if (thr->callstack[i].flags & DUK_ACT_FLAG_TAILCALLED) {
						DUK_DEBUG_SUMMARY_CHAR('/');
					}
					DUK_DEBUG_SUMMARY_CHAR(duk__get_act_summary_char(thr->callstack + i));
				} else {
					DUK_DEBUG_SUMMARY_CHAR('.');
				}
			}
		}
		DUK_DEBUG_SUMMARY_CHAR(']');
		DUK_DEBUG_SUMMARY_FINISH();

		DUK_D(DUK_DPRINT("  valstack: ptr %p, end %p (%ld), bottom %p (%ld), top %p (%ld), used size %ld entries (%ld bytes), alloc size %ld entries (%ld bytes)",
		                 (void *) thr->valstack,
		                 (void *) thr->valstack_end,
		                 (long) (thr->valstack_end - thr->valstack),
		                 (void *) thr->valstack_bottom,
		                 (long) (thr->valstack_bottom - thr->valstack),
		                 (void *) thr->valstack_top,
		                 (long) (thr->valstack_top - thr->valstack),
		                 (long) (thr->valstack_top - thr->valstack),
		                 (long) (thr->valstack_top - thr->valstack) * sizeof(duk_tval),
		                 (long) (thr->valstack_end - thr->valstack),
		                 (long) (thr->valstack_end - thr->valstack) * sizeof(duk_tval)));

		DUK_DEBUG_SUMMARY_INIT();
		DUK_DEBUG_SUMMARY_CHAR('[');
		p = thr->valstack;
		while (p <= thr->valstack_end) {
			i = (duk_uint_fast32_t) (p - thr->valstack);
			if (thr->callstack &&
			    thr->callstack_top > 0 &&
			    i == (duk_size_t) (thr->callstack + thr->callstack_top - 1)->idx_bottom) {
				DUK_DEBUG_SUMMARY_CHAR('>');
			}
			if (p == thr->valstack_top) {
				DUK_DEBUG_SUMMARY_CHAR('|');
			}
			if (p < thr->valstack_end) {
				if (p < thr->valstack_top) {
					DUK_DEBUG_SUMMARY_CHAR(duk__get_tval_summary_char(p));
				} else {
					/* XXX: safe printer for these?  would be nice, because
					 * we could visualize whether the values are in proper
					 * state.
					 */
					DUK_DEBUG_SUMMARY_CHAR('.');
				}
			}
			p++;
		}
		DUK_DEBUG_SUMMARY_CHAR(']');
		DUK_DEBUG_SUMMARY_FINISH();

		DUK_D(DUK_DPRINT("  catchstack: ptr %p, size %ld, top %ld, used size %ld entries (%ld bytes), alloc size %ld entries (%ld bytes)",
		                 (void *) thr->catchstack,
		                 (long) thr->catchstack_size,
		                 (long) thr->catchstack_top,
		                 (long) thr->catchstack_top,
		                 (long) (thr->catchstack_top * sizeof(duk_catcher)),
		                 (long) thr->catchstack_size,
		                 (long) (thr->catchstack_size * sizeof(duk_catcher))));

		DUK_DEBUG_SUMMARY_INIT();
		DUK_DEBUG_SUMMARY_CHAR('[');
		for (i = 0; i <= (duk_uint_fast32_t) thr->catchstack_size; i++) {
			if (i == thr->catchstack_top) {
				DUK_DEBUG_SUMMARY_CHAR('|');
			}
			if (!thr->catchstack) {
				DUK_DEBUG_SUMMARY_CHAR('@');
			} else if (i < thr->catchstack_size) {
				if (i < thr->catchstack_top) {
					DUK_DEBUG_SUMMARY_CHAR(duk__get_cat_summary_char(thr->catchstack + i));
				} else {
					DUK_DEBUG_SUMMARY_CHAR('.');
				}
			}
		}
		DUK_DEBUG_SUMMARY_CHAR(']');
		DUK_DEBUG_SUMMARY_FINISH();

		DUK_D(DUK_DPRINT("  resumer: ptr %p", (void *) thr->resumer));

#if 0  /* worth dumping? */
		for (i = 0; i < DUK_NUM_BUILTINS; i++) {
			DUK_D(DUK_DPRINT("  builtins[%ld] -> %!@O", (long) i, (duk_heaphdr *) thr->builtins[i]));
		}
#endif
	}

	if (obj->p) {
		DUK_D(DUK_DPRINT("  props alloc size: %ld",
		                 (long) DUK_HOBJECT_P_COMPUTE_SIZE(obj->e_size, obj->a_size, obj->h_size)));
	} else {
		DUK_D(DUK_DPRINT("  props alloc size: n/a"));
	}

	DUK_D(DUK_DPRINT("  prop entries:"));
	for (i = 0; i < (duk_uint_fast32_t) obj->e_size; i++) {
		duk_hstring *k;
		duk_propvalue *v;

		k = DUK_HOBJECT_E_GET_KEY(obj, i);
		v = DUK_HOBJECT_E_GET_VALUE_PTR(obj, i);
		DUK_UNREF(v);

		if (i >= obj->e_next) {
			DUK_D(DUK_DPRINT("    [%ld]: UNUSED", (long) i));
			continue;
		}

		if (!k) {
			DUK_D(DUK_DPRINT("    [%ld]: NULL", (long) i));
			continue;
		}

		if (DUK_HOBJECT_E_SLOT_IS_ACCESSOR(obj, i)) {
			DUK_D(DUK_DPRINT("    [%ld]: [w=%ld e=%ld c=%ld a=%ld] %!O -> get:%p set:%p; get %!O; set %!O",
			                 (long) i,
			                 (long) (DUK_HOBJECT_E_SLOT_IS_WRITABLE(obj, i) ? 1 : 0),
			                 (long) (DUK_HOBJECT_E_SLOT_IS_ENUMERABLE(obj, i) ? 1 : 0),
			                 (long) (DUK_HOBJECT_E_SLOT_IS_CONFIGURABLE(obj, i) ? 1 : 0),
			                 (long) (DUK_HOBJECT_E_SLOT_IS_ACCESSOR(obj, i) ? 1 : 0),
			                 (duk_heaphdr *) k,
			                 (void *) v->a.get,
			                 (void *) v->a.set,
			                 (duk_heaphdr *) v->a.get,
			                 (duk_heaphdr *) v->a.set));
		} else {
			DUK_D(DUK_DPRINT("    [%ld]: [w=%ld e=%ld c=%ld a=%ld] %!O -> %!T",
			                 (long) i,
			                 (long) (DUK_HOBJECT_E_SLOT_IS_WRITABLE(obj, i) ? 1 : 0),
			                 (long) (DUK_HOBJECT_E_SLOT_IS_ENUMERABLE(obj, i) ? 1 : 0),
			                 (long) (DUK_HOBJECT_E_SLOT_IS_CONFIGURABLE(obj, i) ? 1 : 0),
			                 (long) (DUK_HOBJECT_E_SLOT_IS_ACCESSOR(obj, i) ? 1 : 0),
			                 (duk_heaphdr *) k,
			                 (duk_tval *) &v->v));
		}
	}

	DUK_D(DUK_DPRINT("  array entries:"));
	for (i = 0; i < (duk_uint_fast32_t) obj->a_size; i++) {
		DUK_D(DUK_DPRINT("    [%ld]: [w=%ld e=%ld c=%ld a=%ld] %ld -> %!T",
		                 (long) i,
		                 (long) 1,  /* implicit attributes */
		                 (long) 1,
		                 (long) 1,
		                 (long) 0,
		                 (long) i,
		                 (duk_tval *) DUK_HOBJECT_A_GET_VALUE_PTR(obj, i)));
	}

	DUK_D(DUK_DPRINT("  hash entries:"));
	for (i = 0; i < (duk_uint_fast32_t) obj->h_size; i++) {
		duk_uint32_t t = DUK_HOBJECT_H_GET_INDEX(obj, i);
		if (t == DUK_HOBJECT_HASHIDX_UNUSED) {
			DUK_D(DUK_DPRINT("    [%ld]: unused", (long) i));
		} else if (t == DUK_HOBJECT_HASHIDX_DELETED) {
			DUK_D(DUK_DPRINT("    [%ld]: deleted", (long) i));
		} else {
			DUK_D(DUK_DPRINT("    [%ld]: %ld", (long) i, (long) t));
		}
	}
}
DUK_INTERNAL void duk_hthread_create_builtin_objects(duk_hthread *thr) {
	duk_context *ctx = (duk_context *) thr;
	duk_bitdecoder_ctx bd_ctx;
	duk_bitdecoder_ctx *bd = &bd_ctx;  /* convenience */
	duk_hobject *h;
	duk_small_uint_t i, j;

	DUK_D(DUK_DPRINT("INITBUILTINS BEGIN: DUK_NUM_BUILTINS=%d, DUK_NUM_BUILTINS_ALL=%d", (int) DUK_NUM_BUILTINS, (int) DUK_NUM_ALL_BUILTINS));

	DUK_MEMZERO(&bd_ctx, sizeof(bd_ctx));
	bd->data = (const duk_uint8_t *) duk_builtins_data;
	bd->length = (duk_size_t) DUK_BUILTINS_DATA_LENGTH;

	/*
	 *  First create all built-in bare objects on the empty valstack.
	 *
	 *  Built-ins in the index range [0,DUK_NUM_BUILTINS-1] have value
	 *  stack indices matching their eventual thr->builtins[] index.
	 *
	 *  Built-ins in the index range [DUK_NUM_BUILTINS,DUK_NUM_ALL_BUILTINS]
	 *  will exist on the value stack during init but won't be placed
	 *  into thr->builtins[].  These are objects referenced in some way
	 *  from thr->builtins[] roots but which don't need to be indexed by
	 *  Duktape through thr->builtins[] (e.g. user custom objects).
	 */

	duk_require_stack(ctx, DUK_NUM_ALL_BUILTINS);

	DUK_DD(DUK_DDPRINT("create empty built-ins"));
	DUK_ASSERT_TOP(ctx, 0);
	for (i = 0; i < DUK_NUM_ALL_BUILTINS; i++) {
		duk_small_uint_t class_num;
		duk_small_int_t len = -1;  /* must be signed */

		class_num = (duk_small_uint_t) duk_bd_decode(bd, DUK__CLASS_BITS);
		len = (duk_small_int_t) duk_bd_decode_flagged(bd, DUK__LENGTH_PROP_BITS, (duk_int32_t) -1 /*def_value*/);

		if (class_num == DUK_HOBJECT_CLASS_FUNCTION) {
			duk_small_uint_t natidx;
			duk_int_t c_nargs;  /* must hold DUK_VARARGS */
			duk_c_function c_func;
			duk_int16_t magic;

			DUK_DDD(DUK_DDDPRINT("len=%ld", (long) len));
			DUK_ASSERT(len >= 0);

			natidx = (duk_small_uint_t) duk_bd_decode(bd, DUK__NATIDX_BITS);
			c_func = duk_bi_native_functions[natidx];

			c_nargs = (duk_small_uint_t) duk_bd_decode_flagged(bd, DUK__NARGS_BITS, len /*def_value*/);
			if (c_nargs == DUK__NARGS_VARARGS_MARKER) {
				c_nargs = DUK_VARARGS;
			}

			/* XXX: set magic directly here? (it could share the c_nargs arg) */
			duk_push_c_function_noexotic(ctx, c_func, c_nargs);

			h = duk_require_hobject(ctx, -1);
			DUK_ASSERT(h != NULL);

			/* Currently all built-in native functions are strict.
			 * duk_push_c_function() now sets strict flag, so
			 * assert for it.
			 */
			DUK_ASSERT(DUK_HOBJECT_HAS_STRICT(h));

			/* XXX: function properties */

			/* Built-in 'name' is not writable by default.  Function '.name'
			 * is writable to allow user code to set a '.name' on a native
			 * function.
			 */
			duk__push_stridx_or_string(ctx, bd);
			duk_xdef_prop_stridx(ctx,
			                     -2,
			                     DUK_STRIDX_NAME,
			                     (i == DUK_BIDX_FUNCTION_PROTOTYPE) ?
			                         DUK_PROPDESC_FLAGS_W : DUK_PROPDESC_FLAGS_NONE);

			/* Almost all global level Function objects are constructable
			 * but not all: Function.prototype is a non-constructable,
			 * callable Function.
			 */
			if (duk_bd_decode_flag(bd)) {
				DUK_ASSERT(DUK_HOBJECT_HAS_CONSTRUCTABLE(h));
			} else {
				DUK_HOBJECT_CLEAR_CONSTRUCTABLE(h);
			}

			/* Cast converts magic to 16-bit signed value */
			magic = (duk_int16_t) duk_bd_decode_flagged(bd, DUK__MAGIC_BITS, 0 /*def_value*/);
			((duk_hnatfunc *) h)->magic = magic;
		} else if (class_num == DUK_HOBJECT_CLASS_ARRAY) {
			duk_push_array(ctx);
		} else {
			duk_push_object_helper(ctx,
			                       DUK_HOBJECT_FLAG_EXTENSIBLE,
			                       -1);  /* no prototype or class yet */

		}

		h = duk_require_hobject(ctx, -1);
		DUK_ASSERT(h != NULL);
		DUK_HOBJECT_SET_CLASS_NUMBER(h, class_num);

		if (i < DUK_NUM_BUILTINS) {
			thr->builtins[i] = h;
			DUK_HOBJECT_INCREF(thr, &h->hdr);
		}

		if (len >= 0) {
			/*
			 *  For top-level objects, 'length' property has the following
			 *  default attributes: non-writable, non-enumerable, non-configurable
			 *  (E5 Section 15).
			 *
			 *  However, 'length' property for Array.prototype has attributes
			 *  expected of an Array instance which are different: writable,
			 *  non-enumerable, non-configurable (E5 Section 15.4.5.2).
			 *
			 *  Because Array .length is virtual, it's not encoded in the init
			 *  data separately.
			 */

			DUK_ASSERT(class_num != DUK_HOBJECT_CLASS_ARRAY);  /* .length is virtual */
			duk_push_int(ctx, len);
			duk_xdef_prop_stridx(ctx,
			                     -2,
			                     DUK_STRIDX_LENGTH,
			                     DUK_PROPDESC_FLAGS_NONE);
		}

		/* enable exotic behaviors last */

		if (class_num == DUK_HOBJECT_CLASS_ARRAY) {
			DUK_ASSERT(DUK_HOBJECT_HAS_EXOTIC_ARRAY(h));  /* set by duk_push_array() */
		}
		if (class_num == DUK_HOBJECT_CLASS_STRING) {
			DUK_HOBJECT_SET_EXOTIC_STRINGOBJ(h);
		}

		/* some assertions */

		DUK_ASSERT(DUK_HOBJECT_HAS_EXTENSIBLE(h));
		/* DUK_HOBJECT_FLAG_CONSTRUCTABLE varies */
		DUK_ASSERT(!DUK_HOBJECT_HAS_BOUNDFUNC(h));
		DUK_ASSERT(!DUK_HOBJECT_HAS_COMPFUNC(h));
		/* DUK_HOBJECT_FLAG_NATFUNC varies */
		DUK_ASSERT(!DUK_HOBJECT_HAS_THREAD(h));
		DUK_ASSERT(!DUK_HOBJECT_HAS_ARRAY_PART(h) || class_num == DUK_HOBJECT_CLASS_ARRAY);
		/* DUK_HOBJECT_FLAG_STRICT varies */
		DUK_ASSERT(!DUK_HOBJECT_HAS_NATFUNC(h) ||  /* all native functions have NEWENV */
		           DUK_HOBJECT_HAS_NEWENV(h));
		DUK_ASSERT(!DUK_HOBJECT_HAS_NAMEBINDING(h));
		DUK_ASSERT(!DUK_HOBJECT_HAS_CREATEARGS(h));
		DUK_ASSERT(!DUK_HOBJECT_HAS_ENVRECCLOSED(h));
		/* DUK_HOBJECT_FLAG_EXOTIC_ARRAY varies */
		/* DUK_HOBJECT_FLAG_EXOTIC_STRINGOBJ varies */
		DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_ARGUMENTS(h));

		DUK_DDD(DUK_DDDPRINT("created built-in %ld, class=%ld, length=%ld", (long) i, (long) class_num, (long) len));
	}

	/*
	 *  Then decode the builtins init data (see genbuiltins.py) to
	 *  init objects
	 */

	DUK_DD(DUK_DDPRINT("initialize built-in object properties"));
	for (i = 0; i < DUK_NUM_ALL_BUILTINS; i++) {
		duk_small_uint_t t;
		duk_small_uint_t num;

		DUK_DDD(DUK_DDDPRINT("initializing built-in object at index %ld", (long) i));
		h = duk_require_hobject(ctx, i);
		DUK_ASSERT(h != NULL);

		t = (duk_small_uint_t) duk_bd_decode(bd, DUK__BIDX_BITS);
		if (t != DUK__NO_BIDX_MARKER) {
			DUK_DDD(DUK_DDDPRINT("set internal prototype: built-in %ld", (long) t));
			DUK_HOBJECT_SET_PROTOTYPE_UPDREF(thr, h, duk_require_hobject(ctx, t));
		}

		t = (duk_small_uint_t) duk_bd_decode(bd, DUK__BIDX_BITS);
		if (t != DUK__NO_BIDX_MARKER) {
			/* 'prototype' property for all built-in objects (which have it) has attributes:
			 *  [[Writable]] = false,
			 *  [[Enumerable]] = false,
			 *  [[Configurable]] = false
			 */
			DUK_DDD(DUK_DDDPRINT("set external prototype: built-in %ld", (long) t));
			duk_xdef_prop_stridx_builtin(ctx, i, DUK_STRIDX_PROTOTYPE, t, DUK_PROPDESC_FLAGS_NONE);
		}

		t = (duk_small_uint_t) duk_bd_decode(bd, DUK__BIDX_BITS);
		if (t != DUK__NO_BIDX_MARKER) {
			/* 'constructor' property for all built-in objects (which have it) has attributes:
			 *  [[Writable]] = true,
			 *  [[Enumerable]] = false,
			 *  [[Configurable]] = true
			 */
			DUK_DDD(DUK_DDDPRINT("set external constructor: built-in %ld", (long) t));
			duk_xdef_prop_stridx_builtin(ctx, i, DUK_STRIDX_CONSTRUCTOR, t, DUK_PROPDESC_FLAGS_WC);
		}

		/* normal valued properties */
		num = (duk_small_uint_t) duk_bd_decode(bd, DUK__NUM_NORMAL_PROPS_BITS);
		DUK_DDD(DUK_DDDPRINT("built-in object %ld, %ld normal valued properties", (long) i, (long) num));
		for (j = 0; j < num; j++) {
			duk_small_uint_t prop_flags;

			duk__push_stridx_or_string(ctx, bd);

			/*
			 *  Property attribute defaults are defined in E5 Section 15 (first
			 *  few pages); there is a default for all properties and a special
			 *  default for 'length' properties.  Variation from the defaults is
			 *  signaled using a single flag bit in the bitstream.
			 */

			if (duk_bd_decode_flag(bd)) {
				prop_flags = (duk_small_uint_t) duk_bd_decode(bd, DUK__PROP_FLAGS_BITS);
			} else {
				prop_flags = DUK_PROPDESC_FLAGS_WC;
			}

			t = (duk_small_uint_t) duk_bd_decode(bd, DUK__PROP_TYPE_BITS);

			DUK_DDD(DUK_DDDPRINT("built-in %ld, normal-valued property %ld, key %!T, flags 0x%02lx, type %ld",
			                     (long) i, (long) j, duk_get_tval(ctx, -1), (unsigned long) prop_flags, (long) t));

			switch (t) {
			case DUK__PROP_TYPE_DOUBLE: {
				duk__push_double(ctx, bd);
				break;
			}
			case DUK__PROP_TYPE_STRING: {
				duk__push_string(ctx, bd);
				break;
			}
			case DUK__PROP_TYPE_STRIDX: {
				duk__push_stridx(ctx, bd);
				break;
			}
			case DUK__PROP_TYPE_BUILTIN: {
				duk_small_uint_t bidx;

				bidx = (duk_small_uint_t) duk_bd_decode(bd, DUK__BIDX_BITS);
				DUK_ASSERT(bidx != DUK__NO_BIDX_MARKER);
				duk_dup(ctx, (duk_idx_t) bidx);
				break;
			}
			case DUK__PROP_TYPE_UNDEFINED: {
				duk_push_undefined(ctx);
				break;
			}
			case DUK__PROP_TYPE_BOOLEAN_TRUE: {
				duk_push_true(ctx);
				break;
			}
			case DUK__PROP_TYPE_BOOLEAN_FALSE: {
				duk_push_false(ctx);
				break;
			}
			case DUK__PROP_TYPE_ACCESSOR: {
				duk_small_uint_t natidx_getter = (duk_small_uint_t) duk_bd_decode(bd, DUK__NATIDX_BITS);
				duk_small_uint_t natidx_setter = (duk_small_uint_t) duk_bd_decode(bd, DUK__NATIDX_BITS);
				duk_c_function c_func_getter;
				duk_c_function c_func_setter;

				/* XXX: this is a bit awkward because there is no exposed helper
				 * in the API style, only this internal helper.
				 */
				DUK_DDD(DUK_DDDPRINT("built-in accessor property: objidx=%ld, key=%!T, getteridx=%ld, setteridx=%ld, flags=0x%04lx",
				                     (long) i, duk_get_tval(ctx, -1), (long) natidx_getter, (long) natidx_setter, (unsigned long) prop_flags));

				c_func_getter = duk_bi_native_functions[natidx_getter];
				c_func_setter = duk_bi_native_functions[natidx_setter];
				duk_push_c_function_noconstruct_noexotic(ctx, c_func_getter, 0);  /* always 0 args */
				duk_push_c_function_noconstruct_noexotic(ctx, c_func_setter, 1);  /* always 1 arg */

				/* XXX: magic for getter/setter? use duk_def_prop()? */

				DUK_ASSERT((prop_flags & DUK_PROPDESC_FLAG_WRITABLE) == 0);  /* genbuiltins.py ensures */

				prop_flags |= DUK_PROPDESC_FLAG_ACCESSOR;  /* accessor flag not encoded explicitly */
				duk_hobject_define_accessor_internal(thr,
				                                     duk_require_hobject(ctx, i),
				                                     duk_get_hstring(ctx, -3),
				                                     duk_require_hobject(ctx, -2),
				                                     duk_require_hobject(ctx, -1),
				                                     prop_flags);
				duk_pop_3(ctx);  /* key, getter and setter, now reachable through object */
				goto skip_value;
			}
			default: {
				/* exhaustive */
				DUK_UNREACHABLE();
			}
			}

			DUK_ASSERT((prop_flags & DUK_PROPDESC_FLAG_ACCESSOR) == 0);
			duk_xdef_prop(ctx, i, prop_flags);

		 skip_value:
			continue;  /* avoid empty label at the end of a compound statement */
		}

		/* native function properties */
		num = (duk_small_uint_t) duk_bd_decode(bd, DUK__NUM_FUNC_PROPS_BITS);
		DUK_DDD(DUK_DDDPRINT("built-in object %ld, %ld function valued properties", (long) i, (long) num));
		for (j = 0; j < num; j++) {
			duk_hstring *h_key;
			duk_small_uint_t natidx;
			duk_int_t c_nargs;  /* must hold DUK_VARARGS */
			duk_small_uint_t c_length;
			duk_int16_t magic;
			duk_c_function c_func;
			duk_hnatfunc *h_func;
#if defined(DUK_USE_LIGHTFUNC_BUILTINS)
			duk_small_int_t lightfunc_eligible;
#endif

			duk__push_stridx_or_string(ctx, bd);
			h_key = duk_get_hstring(ctx, -1);
			DUK_ASSERT(h_key != NULL);
			DUK_UNREF(h_key);
			natidx = (duk_small_uint_t) duk_bd_decode(bd, DUK__NATIDX_BITS);

			c_length = (duk_small_uint_t) duk_bd_decode(bd, DUK__LENGTH_PROP_BITS);
			c_nargs = (duk_int_t) duk_bd_decode_flagged(bd, DUK__NARGS_BITS, (duk_int32_t) c_length /*def_value*/);
			if (c_nargs == DUK__NARGS_VARARGS_MARKER) {
				c_nargs = DUK_VARARGS;
			}

			c_func = duk_bi_native_functions[natidx];

			DUK_DDD(DUK_DDDPRINT("built-in %ld, function-valued property %ld, key %!O, natidx %ld, length %ld, nargs %ld",
			                     (long) i, (long) j, (duk_heaphdr *) h_key, (long) natidx, (long) c_length,
			                     (c_nargs == DUK_VARARGS ? (long) -1 : (long) c_nargs)));

			/* Cast converts magic to 16-bit signed value */
			magic = (duk_int16_t) duk_bd_decode_flagged(bd, DUK__MAGIC_BITS, 0);

#if defined(DUK_USE_LIGHTFUNC_BUILTINS)
			lightfunc_eligible =
				((c_nargs >= DUK_LFUNC_NARGS_MIN && c_nargs <= DUK_LFUNC_NARGS_MAX) || (c_nargs == DUK_VARARGS)) &&
				(c_length <= DUK_LFUNC_LENGTH_MAX) &&
				(magic >= DUK_LFUNC_MAGIC_MIN && magic <= DUK_LFUNC_MAGIC_MAX);

			if (h_key == DUK_HTHREAD_STRING_EVAL(thr) ||
			    h_key == DUK_HTHREAD_STRING_YIELD(thr) ||
			    h_key == DUK_HTHREAD_STRING_RESUME(thr)) {
				/* These functions have trouble working as lightfuncs.
				 * Some of them have specific asserts and some may have
			         * additional properties (e.g. 'require.id' may be written).
				 */
				DUK_D(DUK_DPRINT("reject as lightfunc: key=%!O, i=%d, j=%d", (duk_heaphdr *) h_key, (int) i, (int) j));
				lightfunc_eligible = 0;
			}

			if (lightfunc_eligible) {
				duk_tval tv_lfunc;
				duk_small_uint_t lf_nargs = (c_nargs == DUK_VARARGS ? DUK_LFUNC_NARGS_VARARGS : c_nargs);
				duk_small_uint_t lf_flags = DUK_LFUNC_FLAGS_PACK(magic, c_length, lf_nargs);
				DUK_TVAL_SET_LIGHTFUNC(&tv_lfunc, c_func, lf_flags);
				duk_push_tval(ctx, &tv_lfunc);
				DUK_D(DUK_DPRINT("built-in function eligible as light function: i=%d, j=%d c_length=%ld, c_nargs=%ld, magic=%ld -> %!iT", (int) i, (int) j, (long) c_length, (long) c_nargs, (long) magic, duk_get_tval(ctx, -1)));
				goto lightfunc_skip;
			}

			DUK_D(DUK_DPRINT("built-in function NOT ELIGIBLE as light function: i=%d, j=%d c_length=%ld, c_nargs=%ld, magic=%ld", (int) i, (int) j, (long) c_length, (long) c_nargs, (long) magic));
#endif  /* DUK_USE_LIGHTFUNC_BUILTINS */

			/* [ (builtin objects) name ] */

			duk_push_c_function_noconstruct_noexotic(ctx, c_func, c_nargs);
			h_func = duk_require_hnatfunc(ctx, -1);
			DUK_UNREF(h_func);

			/* Currently all built-in native functions are strict.
			 * This doesn't matter for many functions, but e.g.
			 * String.prototype.charAt (and other string functions)
			 * rely on being strict so that their 'this' binding is
			 * not automatically coerced.
			 */
			DUK_HOBJECT_SET_STRICT((duk_hobject *) h_func);

			/* No built-in functions are constructable except the top
			 * level ones (Number, etc).
			 */
			DUK_ASSERT(!DUK_HOBJECT_HAS_CONSTRUCTABLE((duk_hobject *) h_func));

			/* XXX: any way to avoid decoding magic bit; there are quite
			 * many function properties and relatively few with magic values.
			 */
			h_func->magic = magic;

			/* [ (builtin objects) name func ] */

			duk_push_int(ctx, c_length);
			duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_LENGTH, DUK_PROPDESC_FLAGS_NONE);

			duk_dup(ctx, -2);
			duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_NAME, DUK_PROPDESC_FLAGS_NONE);

			/* XXX: other properties of function instances; 'arguments', 'caller'. */

			DUK_DD(DUK_DDPRINT("built-in object %ld, function property %ld -> %!T",
			                   (long) i, (long) j, (duk_tval *) duk_get_tval(ctx, -1)));

			/* [ (builtin objects) name func ] */

			/*
			 *  The default property attributes are correct for all
			 *  function valued properties of built-in objects now.
			 */

#if defined(DUK_USE_LIGHTFUNC_BUILTINS)
		 lightfunc_skip:
#endif

			duk_xdef_prop(ctx, i, DUK_PROPDESC_FLAGS_WC);

			/* [ (builtin objects) ] */
		}
	}

	/*
	 *  Special post-tweaks, for cases not covered by the init data format.
	 *
	 *  - Set Date.prototype.toGMTString to Date.prototype.toUTCString.
	 *    toGMTString is required to have the same Function object as
	 *    toUTCString in E5 Section B.2.6.  Note that while Smjs respects
	 *    this, V8 does not (the Function objects are distinct).
	 *
	 *  - Make DoubleError non-extensible.
	 *
	 *  - Add info about most important effective compile options to Duktape.
	 *
	 *  - Possibly remove some properties (values or methods) which are not
	 *    desirable with current feature options but are not currently
	 *    conditional in init data.
	 */

	duk_get_prop_stridx(ctx, DUK_BIDX_DATE_PROTOTYPE, DUK_STRIDX_TO_UTC_STRING);
	duk_xdef_prop_stridx(ctx, DUK_BIDX_DATE_PROTOTYPE, DUK_STRIDX_TO_GMT_STRING, DUK_PROPDESC_FLAGS_WC);

	h = duk_require_hobject(ctx, DUK_BIDX_DOUBLE_ERROR);
	DUK_ASSERT(h != NULL);
	DUK_HOBJECT_CLEAR_EXTENSIBLE(h);

#if !defined(DUK_USE_ES6_OBJECT_PROTO_PROPERTY)
	DUK_DD(DUK_DDPRINT("delete Object.prototype.__proto__ built-in which is not enabled in features"));
	(void) duk_hobject_delprop_raw(thr, thr->builtins[DUK_BIDX_OBJECT_PROTOTYPE], DUK_HTHREAD_STRING___PROTO__(thr), DUK_DELPROP_FLAG_THROW);
#endif

#if !defined(DUK_USE_ES6_OBJECT_SETPROTOTYPEOF)
	DUK_DD(DUK_DDPRINT("delete Object.setPrototypeOf built-in which is not enabled in features"));
	(void) duk_hobject_delprop_raw(thr, thr->builtins[DUK_BIDX_OBJECT_CONSTRUCTOR], DUK_HTHREAD_STRING_SET_PROTOTYPE_OF(thr), DUK_DELPROP_FLAG_THROW);
#endif

	/* XXX: relocate */
	duk_push_string(ctx,
			/* Endianness indicator */
#if defined(DUK_USE_INTEGER_LE)
	                "l"
#elif defined(DUK_USE_INTEGER_BE)
	                "b"
#elif defined(DUK_USE_INTEGER_ME)  /* integer mixed endian not really used now */
	                "m"
#else
	                "?"
#endif
#if defined(DUK_USE_DOUBLE_LE)
	                "l"
#elif defined(DUK_USE_DOUBLE_BE)
	                "b"
#elif defined(DUK_USE_DOUBLE_ME)
	                "m"
#else
	                "?"
#endif
	                " "
			/* Packed or unpacked tval */
#if defined(DUK_USE_PACKED_TVAL)
	                "p"
#else
	                "u"
#endif
#if defined(DUK_USE_FASTINT)
			"f"
#endif
			" "
			/* Low memory options */
#if defined(DUK_USE_STRTAB_CHAIN)
			"c"  /* chain */
#elif defined(DUK_USE_STRTAB_PROBE)
			"p"  /* probe */
#else
			"?"
#endif
#if !defined(DUK_USE_HEAPPTR16) && !defined(DUK_DATAPTR16) && !defined(DUK_FUNCPTR16)
			"n"
#endif
#if defined(DUK_USE_HEAPPTR16)
			"h"
#endif
#if defined(DUK_USE_DATAPTR16)
			"d"
#endif
#if defined(DUK_USE_FUNCPTR16)
			"f"
#endif
#if defined(DUK_USE_REFCOUNT16)
			"R"
#endif
#if defined(DUK_USE_STRHASH16)
			"H"
#endif
#if defined(DUK_USE_STRLEN16)
			"S"
#endif
#if defined(DUK_USE_BUFLEN16)
			"B"
#endif
#if defined(DUK_USE_OBJSIZES16)
			"O"
#endif
#if defined(DUK_USE_LIGHTFUNC_BUILTINS)
			"L"
#endif
#if defined(DUK_USE_ROM_STRINGS) || defined(DUK_USE_ROM_OBJECTS)
			/* XXX: This won't be shown in practice now
			 * because this code is not run when builtins
			 * are in ROM.
			 */
			"Z"
#endif
	                " "
			/* Object property allocation layout */
#if defined(DUK_USE_HOBJECT_LAYOUT_1)
			"p1"
#elif defined(DUK_USE_HOBJECT_LAYOUT_2)
			"p2"
#elif defined(DUK_USE_HOBJECT_LAYOUT_3)
			"p3"
#else
			"p?"
#endif
			" "
			/* Alignment guarantee */
#if (DUK_USE_ALIGN_BY == 4)
			"a4"
#elif (DUK_USE_ALIGN_BY == 8)
			"a8"
#elif (DUK_USE_ALIGN_BY == 1)
			"a1"
#else
#error invalid DUK_USE_ALIGN_BY
#endif
			" "
			/* Architecture, OS, and compiler strings */
	                DUK_USE_ARCH_STRING
			" "
	                DUK_USE_OS_STRING
			" "
	                DUK_USE_COMPILER_STRING);
	duk_xdef_prop_stridx(ctx, DUK_BIDX_DUKTAPE, DUK_STRIDX_ENV, DUK_PROPDESC_FLAGS_WC);

	/*
	 *  InitJS code - Ecmascript code evaluated from a built-in source
	 *  which provides e.g. backward compatibility.  User can also provide
	 *  JS code to be evaluated at startup.
	 */

#ifdef DUK_USE_BUILTIN_INITJS
	/* XXX: compression */
	DUK_DD(DUK_DDPRINT("running built-in initjs"));
	duk_eval_string(ctx, (const char *) duk_initjs_data);  /* initjs data is NUL terminated */
	duk_pop(ctx);
#endif  /* DUK_USE_BUILTIN_INITJS */

#ifdef DUK_USE_USER_INITJS
	/* XXX: compression (as an option) */
	DUK_DD(DUK_DDPRINT("running user initjs"));
	duk_eval_string_noresult(ctx, (const char *) DUK_USE_USER_INITJS);
#endif  /* DUK_USE_USER_INITJS */

	/*
	 *  Since built-ins are not often extended, compact them.
	 */

	DUK_DD(DUK_DDPRINT("compact built-ins"));
	for (i = 0; i < DUK_NUM_ALL_BUILTINS; i++) {
		duk_hobject_compact_props(thr, duk_require_hobject(ctx, i));
	}

	DUK_D(DUK_DPRINT("INITBUILTINS END"));

#if defined(DUK_USE_DEBUG_LEVEL) && (DUK_USE_DEBUG_LEVEL >= 1)
	for (i = 0; i < DUK_NUM_ALL_BUILTINS; i++) {
		DUK_DD(DUK_DDPRINT("built-in object %ld after initialization and compacting: %!@iO",
		                   (long) i, (duk_heaphdr *) duk_require_hobject(ctx, i)));
	}
#endif

	/*
	 *  Pop built-ins from stack: they are now INCREF'd and
	 *  reachable from the builtins[] array or indirectly
	 *  through builtins[].
	 */

	duk_set_top(ctx, 0);
	DUK_ASSERT_TOP(ctx, 0);
}
Beispiel #3
0
DUK_EXTERNAL void duk_new(duk_context *ctx, duk_idx_t nargs) {
	/*
	 *  There are two [[Construct]] operations in the specification:
	 *
	 *    - E5 Section 13.2.2: for Function objects
	 *    - E5 Section 15.3.4.5.2: for "bound" Function objects
	 *
	 *  The chain of bound functions is resolved in Section 15.3.4.5.2,
	 *  with arguments "piling up" until the [[Construct]] internal
	 *  method is called on the final, actual Function object.  Note
	 *  that the "prototype" property is looked up *only* from the
	 *  final object, *before* calling the constructor.
	 *
	 *  Since Duktape 2.2 bound functions are represented with the
	 *  duk_hboundfunc internal type, and bound function chains are
	 *  collapsed when a bound function is created.  As a result, the
	 *  direct target of a duk_hboundfunc is always non-bound and the
	 *  this/argument lists have been resolved.
	 *
	 *  When constructing new Array instances, an unnecessary object is
	 *  created and discarded now: the standard [[Construct]] creates an
	 *  object, and calls the Array constructor.  The Array constructor
	 *  returns an Array instance, which is used as the result value for
	 *  the "new" operation; the object created before the Array constructor
	 *  call is discarded.
	 *
	 *  This would be easy to fix, e.g. by knowing that the Array constructor
	 *  will always create a replacement object and skip creating the fallback
	 *  object in that case.
	 *
	 *  Note: functions called via "new" need to know they are called as a
	 *  constructor.  For instance, built-in constructors behave differently
	 *  depending on how they are called.
	 */

	/* XXX: merge this with duk_js_call.c, as this function implements
	 * core semantics (or perhaps merge the two files altogether).
	 */

	duk_hthread *thr = (duk_hthread *) ctx;
	duk_hobject *proto;
	duk_hobject *cons;
	duk_hobject *fallback;
	duk_idx_t idx_cons;
	duk_small_uint_t call_flags;

	DUK_ASSERT_CTX_VALID(ctx);

	/* [... constructor arg1 ... argN] */

	idx_cons = duk_require_normalize_index(ctx, -nargs - 1);

	DUK_DDD(DUK_DDDPRINT("top=%ld, nargs=%ld, idx_cons=%ld",
	                     (long) duk_get_top(ctx), (long) nargs, (long) idx_cons));

	/* XXX: code duplication */

	/*
	 *  Figure out the final, non-bound constructor, to get "prototype"
	 *  property.
	 */

	duk_dup(ctx, idx_cons);
	duk_resolve_nonbound_function(ctx);
	duk_require_callable(ctx, -1);
	cons = duk_get_hobject(ctx, -1);

	/* Result is a lightfunc or a callable actual function. */
	DUK_ASSERT(cons == NULL || DUK_HOBJECT_IS_CALLABLE(cons));
	if (cons != NULL && !DUK_HOBJECT_HAS_CONSTRUCTABLE(cons)) {
		/* Check constructability from the final, non-bound object.
		 * The constructable flag is 1:1 for the bound function and
		 * its target so this should be sufficient.  Lightfuncs are
		 * always constructable.
		 */
		goto not_constructable;
	}

	DUK_ASSERT(duk_is_callable(ctx, -1));
	DUK_ASSERT(duk_is_lightfunc(ctx, -1) ||
	           (duk_get_hobject(ctx, -1) != NULL && !DUK_HOBJECT_HAS_BOUNDFUNC(duk_get_hobject(ctx, -1))));

	/* [... constructor arg1 ... argN final_cons] */

	/*
	 *  Create "fallback" object to be used as the object instance,
	 *  unless the constructor returns a replacement value.
	 *  Its internal prototype needs to be set based on "prototype"
	 *  property of the constructor.
	 */

	duk_push_object(ctx);  /* class Object, extensible */

	/* [... constructor arg1 ... argN final_cons fallback] */

	duk_get_prop_stridx_short(ctx, -2, DUK_STRIDX_PROTOTYPE);
	proto = duk_get_hobject(ctx, -1);
	if (!proto) {
		DUK_DDD(DUK_DDDPRINT("constructor has no 'prototype' property, or value not an object "
		                     "-> leave standard Object prototype as fallback prototype"));
	} else {
		DUK_DDD(DUK_DDDPRINT("constructor has 'prototype' property with object value "
		                     "-> set fallback prototype to that value: %!iO", (duk_heaphdr *) proto));
		fallback = duk_known_hobject(ctx, -2);
		DUK_ASSERT(fallback != NULL);
		DUK_HOBJECT_SET_PROTOTYPE_UPDREF(thr, fallback, proto);
	}
	duk_pop(ctx);

#if 0  /* XXX: smaller alternative */
	if (duk_is_object(ctx, -1)) {
		DUK_DDD(DUK_DDDPRINT("constructor has 'prototype' property with object value "
		                     "-> set fallback prototype to that value: %!iT", duk_get_tval(ctx, -1)));
		duk_set_prototype(ctx, -2);
	} else {
		DUK_DDD(DUK_DDDPRINT("constructor has no 'prototype' property, or value not an object "
		                     "-> leave standard Object prototype as fallback prototype"));
		duk_pop(ctx);
	}
#endif

	/* [... constructor arg1 ... argN final_cons fallback] */

	/*
	 *  Manipulate value stack for the call.
	 */

	duk_dup_top(ctx);
	duk_insert(ctx, idx_cons + 1);  /* use fallback as 'this' value */
	duk_insert(ctx, idx_cons);      /* also stash it before constructor,
	                                 * in case we need it (as the fallback value)
	                                 */
	duk_pop(ctx);                   /* pop final_cons */


	/* [... fallback constructor fallback(this) arg1 ... argN];
	 * Note: idx_cons points to first 'fallback', not 'constructor'.
	 */

	DUK_DDD(DUK_DDDPRINT("before call, idx_cons+1 (constructor) -> %!T, idx_cons+2 (fallback/this) -> %!T, "
	                     "nargs=%ld, top=%ld",
	                     (duk_tval *) duk_get_tval(ctx, idx_cons + 1),
	                     (duk_tval *) duk_get_tval(ctx, idx_cons + 2),
	                     (long) nargs,
	                     (long) duk_get_top(ctx)));

	/*
	 *  Call the constructor function (called in "constructor mode").
	 */

	call_flags = DUK_CALL_FLAG_CONSTRUCTOR_CALL;  /* not protected, respect reclimit, is a constructor call */

	duk_handle_call_unprotected(thr,           /* thread */
	                            nargs,         /* num_stack_args */
	                            call_flags);   /* call_flags */

	/* [... fallback retval] */

	DUK_DDD(DUK_DDDPRINT("constructor call finished, fallback=%!iT, retval=%!iT",
	                     (duk_tval *) duk_get_tval(ctx, -2),
	                     (duk_tval *) duk_get_tval(ctx, -1)));

	/*
	 *  Determine whether to use the constructor return value as the created
	 *  object instance or not.
	 */

	if (duk_check_type_mask(ctx, -1, DUK_TYPE_MASK_OBJECT |
	                                 DUK_TYPE_MASK_BUFFER |
	                                 DUK_TYPE_MASK_LIGHTFUNC)) {
		duk_remove_m2(ctx);
	} else {
		duk_pop(ctx);
	}

	/*
	 *  Augment created errors upon creation (not when they are thrown or
	 *  rethrown).  __FILE__ and __LINE__ are not desirable here; the call
	 *  stack reflects the caller which is correct.
	 */

#if defined(DUK_USE_AUGMENT_ERROR_CREATE)
	duk_hthread_sync_currpc(thr);
	duk_err_augment_error_create(thr, thr, NULL, 0, 1 /*noblame_fileline*/);
#endif

	/* [... retval] */

	return;

 not_constructable:
#if defined(DUK_USE_VERBOSE_ERRORS)
#if defined(DUK_USE_PARANOID_ERRORS)
	DUK_ERROR_FMT1(thr, DUK_ERR_TYPE_ERROR, "%s not constructable", duk_get_type_name(ctx, -1));
#else
	DUK_ERROR_FMT1(thr, DUK_ERR_TYPE_ERROR, "%s not constructable", duk_push_string_readable(ctx, -1));
#endif
#else
	DUK_ERROR_TYPE(thr, "not constructable");
#endif
}