/*

 * Copyright (c) 2016-2025  Moddable Tech, Inc.

 *

 *   This file is part of the Moddable SDK Runtime.

 * 

 *   The Moddable SDK Runtime is free software: you can redistribute it and/or modify

 *   it under the terms of the GNU Lesser General Public License as published by

 *   the Free Software Foundation, either version 3 of the License, or

 *   (at your option) any later version.

 * 

 *   The Moddable SDK Runtime is distributed in the hope that it will be useful,

 *   but WITHOUT ANY WARRANTY; without even the implied warranty of

 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *   GNU Lesser General Public License for more details.

 * 

 *   You should have received a copy of the GNU Lesser General Public License

 *   along with the Moddable SDK Runtime.  If not, see <http://www.gnu.org/licenses/>.

 *

 * This file incorporates work covered by the following copyright and  

 * permission notice:  

 *

 *       Copyright (C) 2010-2016 Marvell International Ltd.

 *       Copyright (C) 2002-2010 Kinoma, Inc.

 *

 *       Licensed under the Apache License, Version 2.0 (the "License");

 *       you may not use this file except in compliance with the License.

 *       You may obtain a copy of the License at

 *

 *        http://www.apache.org/licenses/LICENSE-2.0

 *

 *       Unless required by applicable law or agreed to in writing, software

 *       distributed under the License is distributed on an "AS IS" BASIS,

 *       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 *       See the License for the specific language governing permissions and

 *       limitations under the License.

 */

#include "xsAll.h"

static txSlot* fxCheckFunctionInstance(txMachine* the, txSlot* slot);

static void fxStepAsync(txMachine* the, txSlot* instance, txFlag status);

static const txByte gxTailCode[1] = { XS_CODE_RUN_TAIL };

void fxBuildFunction(txMachine* the)

{

  txSlot* slot;

  txSlot* function;

  txSlot* constructor;

  mxPush(mxFunctionPrototype);

  slot = fxLastProperty(the, the->stack->value.reference);

  slot = fxNextHostFunctionProperty(the, slot, mxCallback(fx_Function_prototype_apply), 2, mxID(_apply), XS_DONT_ENUM_FLAG);

  slot = fxNextHostFunctionProperty(the, slot, mxCallback(fx_Function_prototype_bind), 1, mxID(_bind), XS_DONT_ENUM_FLAG);

  slot = fxNextHostFunctionProperty(the, slot, mxCallback(fx_Function_prototype_call), 1, mxID(_call), XS_DONT_ENUM_FLAG);

  slot = fxNextHostFunctionProperty(the, slot, mxCallback(fx_Function_prototype_toString), 0, mxID(_toString), XS_DONT_ENUM_FLAG);

    slot = fxNextHostFunctionProperty(the, slot, mxCallback(fx_Function_prototype_hasInstance), 1, mxID(_Symbol_hasInstance), XS_GET_ONLY);

  function = mxThrowTypeErrorFunction.value.reference;

  slot = slot->next = fxNewSlot(the);

  slot->flag = XS_DONT_ENUM_FLAG;

  slot->ID = mxID(_arguments);

  slot->kind = XS_ACCESSOR_KIND;

  slot->value.accessor.getter = function;

  slot->value.accessor.setter = function;

  slot = slot->next = fxNewSlot(the);

  slot->flag = XS_DONT_ENUM_FLAG;

  slot->ID = mxID(_caller);

  slot->kind = XS_ACCESSOR_KIND;

  slot->value.accessor.getter = function;

  slot->value.accessor.setter = function;

  constructor = fxBuildHostConstructor(the, mxCallback(fx_Function), 1, mxID(_Function));

  mxFunctionConstructor = *the->stack;

  mxPop();

  mxPush(mxFunctionPrototype);

  slot = fxLastProperty(the, fxNewObjectInstance(the));

  slot = fxNextStringXProperty(the, slot, "AsyncFunction", mxID(_Symbol_toStringTag), XS_DONT_ENUM_FLAG | XS_DONT_SET_FLAG);

  mxAsyncFunctionPrototype = *the->stack;

  slot = fxBuildHostConstructor(the, mxCallback(fx_AsyncFunction), 1, mxID(_AsyncFunction));

  slot->value.instance.prototype = constructor;

  mxPop();

  slot = mxBehaviorGetProperty(the, mxAsyncFunctionPrototype.value.reference, mxID(_constructor), 0, XS_OWN);

  slot->flag |= XS_DONT_SET_FLAG;

}

void fxCheckCallable(txMachine* the, txSlot* slot)

{

  if (fxIsCallable(the, slot))

    return;

  mxTypeError("this: not a Function instance");

}

txSlot* fxCheckFunctionInstance(txMachine* the, txSlot* slot)

{

  if (slot->kind == XS_REFERENCE_KIND) {

    slot = slot->value.reference;

    if (fxIsFunction(the, slot))

      return slot;

  }

  mxTypeError("this: not a Function instance");

  return C_NULL;

}

txBoolean fxIsCallable(txMachine* the, txSlot* slot) 

{

  if (slot->kind == XS_REFERENCE_KIND)

    return fxIsFunction(the, slot->value.reference);

#if mxHostFunctionPrimitive

  if (slot->kind == XS_HOST_FUNCTION_KIND)

    return 1;

#endif

  return 0;

}

txBoolean fxIsFunction(txMachine* the, txSlot* instance)

{

  if (instance) {

    txSlot* exotic = instance->next;

    if (exotic && (exotic->flag & XS_INTERNAL_FLAG)) {

      if (((exotic->kind == XS_CALLBACK_KIND) || (exotic->kind == XS_CALLBACK_X_KIND) || (exotic->kind == XS_CODE_KIND) || (exotic->kind == XS_CODE_X_KIND)))

        return 1;

      if ((exotic->kind == XS_PROXY_KIND) && (instance->flag & XS_CAN_CALL_FLAG))

        return 1;

    }

  }

  return 0;

}

txSlot* fxNewFunctionInstance(txMachine* the, txID name)

{

  txSlot* instance;

  txSlot* property;

  instance = fxNewObjectInstance(the);

  instance->flag |= XS_CAN_CALL_FLAG;

  /* CODE */

  property = instance->next = fxNewSlot(the);

  property->flag = XS_INTERNAL_FLAG;

  property->kind = mxEmptyCode.kind;

  property->value.code.address = mxEmptyCode.value.code.address;

  property->value.code.closures = C_NULL;

  /* HOME */

  property = property->next = fxNewSlot(the);

  property->flag = XS_INTERNAL_FLAG;

  property->kind = XS_HOME_KIND;

  property->value.home.object = C_NULL;

  if (the->frame && (mxFunction->kind == XS_REFERENCE_KIND) && (mxIsFunction(mxFunction->value.reference))) {

    txSlot* slot = mxFunctionInstanceHome(mxFunction->value.reference);

    property->value.home.module = slot->value.home.module;

  }

  else

    property->value.home.module = C_NULL;

  /* LENGTH */

  if (gxDefaults.newFunctionLength)

    gxDefaults.newFunctionLength(the, instance, 0);

  /* NAME */

  fxRenameFunction(the, instance, name, 0, XS_NO_ID, C_NULL);

  return instance;

}

void fxDefaultFunctionPrototype(txMachine* the)

{

  txSlot* instance;

  txSlot* property;

  instance = the->stack->value.reference;

  instance->flag |= XS_CAN_CONSTRUCT_FLAG;

  property = fxLastProperty(the, instance);

  mxPush(mxObjectPrototype);

  instance = fxNewObjectInstance(the);

  fxNextSlotProperty(the, property, the->stack, mxID(_prototype), XS_DONT_DELETE_FLAG | XS_DONT_ENUM_FLAG);

  mxPop();

  fxNextSlotProperty(the, instance, the->stack, mxID(_constructor), XS_DONT_ENUM_FLAG);

}

txSlot* fxGetPrototypeFromConstructor(txMachine* the, txSlot* defaultPrototype)

{

  txSlot* result = the->stack;

  fxCheckCallable(the, result);

  mxDub();

  mxGetID(mxID(_prototype));

  if (!mxIsReference(the->stack)) {

    txSlot* instance = result->value.reference;

    txSlot* proxy = instance->next;

    if (proxy->kind == XS_PROXY_KIND) {

      if (!proxy->value.proxy.handler)

        mxTypeError("(proxy).%s: no handler", fxName(the, mxID(_prototype)));

      if (!proxy->value.proxy.target)

        mxTypeError("(proxy).%s: no target", fxName(the, mxID(_prototype)));

    }

    the->stack->kind = defaultPrototype->kind;

    the->stack->value = defaultPrototype->value;

  }

  mxPullSlot(result);

  return result->value.reference;

}

#ifndef mxLink

txSlot* fxNewFunctionLength(txMachine* the, txSlot* instance, txNumber length)

{

  txSlot* property = mxBehaviorGetProperty(the, instance, mxID(_length), 0, XS_OWN);

  if (!property)

    property = fxNextIntegerProperty(the, fxLastProperty(the, instance), 0, mxID(_length), XS_DONT_ENUM_FLAG | XS_DONT_SET_FLAG);

  if (length <= 0x7FFFFFFF) {

    property->kind = XS_INTEGER_KIND;

    property->value.integer = (txInteger)length;

  }

  else {

    property->kind = XS_NUMBER_KIND;

    property->value.number = length;

  }

  return property;

}

txSlot* fxNewFunctionName(txMachine* the, txSlot* instance, txID id, txIndex index, txID former, txString prefix)

{

  txSlot* property;

  property = mxBehaviorGetProperty(the, instance, mxID(_name), 0, XS_OWN);

  if (property) {

    if ((property->kind != mxEmptyString.kind) || (property->value.string != mxEmptyString.value.string))

      return property;

  }

  else

    property = fxNextSlotProperty(the, fxLastProperty(the, instance), &mxEmptyString, mxID(_name), XS_DONT_ENUM_FLAG | XS_DONT_SET_FLAG);

  if (id != XS_NO_ID) {

    txBoolean adorn;

    fxPushKeyString(the, id, &adorn);

    mxPullSlot(property);

    if (adorn)

      fxAdornStringC(the, "[", property, "]");

  }

  else if (former) {

    char buffer[16];

    fxCopyStringC(the, property, fxNumberToString(the, index, buffer, sizeof(buffer), 0, 0)); 

  }

  if (prefix) 

    fxAdornStringC(the, prefix, property, C_NULL);

  return property;

}

#endif

void fxRenameFunction(txMachine* the, txSlot* instance, txID id, txIndex index, txID former, txString prefix)

{

  txSlot* property;

  if (instance->flag & XS_MARK_FLAG)

    return;

  property = mxFunctionInstanceCode(instance);

  if ((property->ID == XS_NO_ID) || (property->ID == former)) {

    if (id != XS_NO_ID)

      property->ID = (txID)id;

  }

  if (gxDefaults.newFunctionName)

    property = gxDefaults.newFunctionName(the, instance, id, index, former, prefix);

}

void fx_Function(txMachine* the)

{ 

  txInteger c, i;

  txStringStream stream;

  txSlot* module = mxFunctionInstanceHome(mxFunction->value.reference)->value.home.module;

  if (!module) module = mxProgram.value.reference;

  c = mxArgc;

  i = 0;

  mxPushStringX("(function anonymous(");

  while (c > 1) {

    fxToString(the, mxArgv(i));

    fxConcatString(the, the->stack, mxArgv(i));

    if (c > 2)

      fxConcatStringC(the, the->stack, ", ");

    c--;

    i++;

  }

  fxConcatStringC(the, the->stack, "\n){");

  if (c > 0) {

    fxToString(the, mxArgv(i));

    fxConcatString(the, the->stack, mxArgv(i));

  }

  fxConcatStringC(the, the->stack, "\n})");

  stream.slot = the->stack;

  stream.offset = 0;

  stream.size = mxStringLength(the->stack->value.string);

  fxRunScript(the, fxParseScript(the, &stream, fxStringGetter, mxProgramFlag | mxFunctionFlag), C_NULL, C_NULL, C_NULL, C_NULL, module);

  mxPullSlot(mxResult);

  if (mxHasTarget && !fxIsSameSlot(the, mxTarget, mxFunction)) {

    mxPushSlot(mxTarget);

    fxGetPrototypeFromConstructor(the, &mxFunctionPrototype);

    mxResult->value.reference->value.instance.prototype = the->stack->value.reference;

    mxPop();

  }

}

void fx_Function_prototype_apply(txMachine* the)

{

  txIndex c, i;

  fxCheckCallable(the, mxThis);

  /* THIS */

  if (mxArgc < 1)

    mxPushUndefined();

  else

    mxPushSlot(mxArgv(0));

  /* FUNCTION */

  mxPushSlot(mxThis);

  mxCall();

  /* ARGUMENTS */

  if ((mxArgc < 2) || (mxArgv(1)->kind == XS_UNDEFINED_KIND) || (mxArgv(1)->kind == XS_NULL_KIND))

    c = 0;

  else {

    if (mxArgv(1)->kind != XS_REFERENCE_KIND)

      mxTypeError("argArray: not an object");

    fxToInstance(the, mxArgv(1));

    mxPushSlot(mxArgv(1));

    mxGetID(mxID(_length));

    c = (txIndex)fxToLength(the, the->stack);

    mxPop();

    for (i = 0; i < c; i++) {

      mxPushSlot(mxArgv(1));

      mxGetIndex(i);

    }

  }

  mxPushInteger(c);

  the->code = (txByte *)gxTailCode;

}

void fx_Function_prototype_bind(txMachine* the)

{

  txSlot* function = fxToInstance(the, mxThis);

  txSlot* instance;

  txSlot* property;

  txSlot* arguments;

  txSlot* argument;

  txSize c = mxArgc, i;

  fxCheckCallable(the, mxThis);

  mxPushNull();

  if (mxBehaviorGetPrototype(the, function, the->stack))

    instance = fxNewObjectInstance(the);

  else {

    mxPop();

    instance = fxNewInstance(the);

  }

  instance->flag |= function->flag & (XS_CAN_CALL_FLAG | XS_CAN_CONSTRUCT_FLAG);

    mxPullSlot(mxResult);

  /* CODE */

  property = instance->next = fxNewSlot(the);

  property->flag = XS_INTERNAL_FLAG;

  property->kind = XS_CALLBACK_KIND;

  property->value.callback.address = fx_Function_prototype_bound;

  property->value.callback.closures = C_NULL;

  /* HOME */

  property = property->next = fxNewSlot(the);

  property->flag = XS_INTERNAL_FLAG;

  property->kind = XS_HOME_KIND;

  property->value.home.object = C_NULL;

  property->value.home.module = C_NULL;

  property = fxNextSlotProperty(the, property, mxThis, mxID(_boundFunction), XS_INTERNAL_FLAG);

  if (c > 0)

    property = fxNextSlotProperty(the, property, mxArgv(0), mxID(_boundThis), XS_INTERNAL_FLAG);

  else

    property = fxNextUndefinedProperty(the, property, mxID(_boundThis), XS_INTERNAL_FLAG);

  if (c > 1) {

    mxPush(mxArrayPrototype);

    arguments = fxNewArrayInstance(the);

    argument = fxLastProperty(the, arguments);

    for (i = 1; i < c; i++) {

      argument->next = fxNewSlot(the);

      argument = argument->next;

      argument->kind = mxArgv(i)->kind;

      argument->value = mxArgv(i)->value;

    }

    arguments->next->value.array.length = c - 1;

    fxCacheArray(the, arguments);

    property = fxNextSlotProperty(the, property, the->stack, mxID(_boundArguments), XS_INTERNAL_FLAG);

    mxPop();

  }

  else {

    property = fxNextNullProperty(the, property, mxID(_boundArguments), XS_INTERNAL_FLAG);

  }

  if (gxDefaults.newFunctionLength) {

    txNumber length = 0;

    mxPushUndefined();

    if (mxBehaviorGetOwnProperty(the, mxThis->value.reference, mxID(_length), 0, the->stack)) {

      mxPushSlot(mxThis);

      mxGetID(mxID(_length));

      property = the->stack;

      if (property->kind == XS_INTEGER_KIND) {

        length = property->value.integer;

      }

      else if (property->kind == XS_NUMBER_KIND) {

        length = property->value.number;

        if (c_isnan(length))

          length = 0;

        else

          length = c_trunc(length);

      }

      if (c > 1)

        length -= c - 1;

      if (length < 0)

        length = 0;

      mxPop();

    }

    mxPop();

    gxDefaults.newFunctionLength(the, instance, length);

  }

  if (gxDefaults.newFunctionName) {

    txSize length = 0;

    txString name;

    mxPushSlot(mxThis);

    mxGetID(mxID(_name));

    if ((the->stack->kind == XS_STRING_KIND) || (the->stack->kind == XS_STRING_X_KIND))

      length = mxStringLength(the->stack->value.string);

    property = fxNextSlotProperty(the, fxLastProperty(the, instance), &mxEmptyString, mxID(_name), XS_DONT_ENUM_FLAG | XS_DONT_SET_FLAG);

    name = (txString)fxNewChunk(the, fxAddChunkSizes(the, length, 6 + 1));

    c_memcpy(name, "bound ", 6);

    if (length)

      c_memcpy(name + 6, the->stack->value.string, length);

    name[6 + length] = 0;

    property->value.string = name;

    property->kind = XS_STRING_KIND;

    mxPop();

  }

}

void fx_Function_prototype_bound(txMachine* the)

{

  txSlot* function = fxToInstance(the, mxFunction);

  txSlot* boundArguments;

  txInteger c, i;

  txSlot* argument;

  /* TARGET */

  if (mxHasTarget) {

    if (fxIsSameSlot(the, mxFunction, mxTarget)) {

      mxPushSlot(mxFunctionInstanceHome(function)->next);

    }

    else

      mxPushSlot(mxTarget);

  }

  /* THIS */

  if (!mxHasTarget) {

    mxPushSlot(mxFunctionInstanceHome(function)->next->next);

  }

  else

    mxPushUninitialized();

  /* FUNCTION */

  mxPushSlot(mxFunctionInstanceHome(function)->next);

  /* RESULT */

  mxPushUndefined();

  mxPushUninitialized();

  /* ARGUMENTS */

  mxPushSlot(mxFunctionInstanceHome(function)->next->next->next);

  if (the->stack->kind == XS_REFERENCE_KIND) {

    boundArguments = fxGetInstance(the, the->stack);

    mxPop();

    c = boundArguments->next->value.array.length;

    argument = boundArguments->next->value.array.address;

    for (i = 0; i < c; i++) {

      mxPushSlot(argument);

      argument++;

    }

  }

  else {

    mxPop();

    c = 0;

  }

  for (i = 0; i < mxArgc; i++)

    mxPushSlot(mxArgv(i));

  if (mxHasTarget) {

    mxRunCount(c + i);

    mxPullSlot(mxResult);

  }

  else {

    mxPushInteger(c + i);

    the->code = (txByte *)gxTailCode;

  }

}

void fx_Function_prototype_call(txMachine* the)

{ 

  txInteger c, i;

  fxCheckCallable(the, mxThis);

  /* THIS */

  if (mxArgc < 1)

    mxPushUndefined();

  else

    mxPushSlot(mxArgv(0));

  /* FUNCTION */

  mxPushSlot(mxThis);

  mxCall();

  /* ARGUMENTS */

  c = mxArgc;

  i = 1;

  while (i < c) {

    mxPushSlot(mxArgv(i));

    i++;

  }

  mxPushInteger(i - 1);

  the->code = (txByte *)gxTailCode;

}

void fx_Function_prototype_hasInstance(txMachine* the)

{ 

  txSlot* function;

  txSlot* slot;

  txSlot* instance;

  txSlot* prototype;

  mxResult->kind = XS_BOOLEAN_KIND;

  mxResult->value.boolean = 0;

  if (!fxIsCallable(the, mxThis))

    return;

  function = fxToInstance(the, mxThis);

  if (!function)

    return;

  if (mxArgc == 0)

    return;

  if (mxIsFunction(function)) {

    slot = mxFunctionInstanceHome(function)->next;

    if (slot && (slot->flag & XS_INTERNAL_FLAG) && (slot->ID == mxID(_boundFunction))) {

      mxPushSlot(slot);

      mxDub();

      mxGetID(mxID(_Symbol_hasInstance));

      mxCall();

      mxPushSlot(mxArgv(0));

      mxRunCount(1);

      fxToBoolean(the, the->stack);

      mxPullSlot(mxResult);

      return;

    }

  }

  instance = fxGetInstance(the, mxArgv(0));

  if (!instance)

    return;

  mxPushReference(function);

  mxGetID(mxID(_prototype));

  prototype = fxGetInstance(the, the->stack);

  mxPop();

  if (!prototype)

    mxTypeError("this.prototype: not an object");

#if mxAliasInstance

  if (prototype->ID) {

    txSlot* alias = the->aliasArray[prototype->ID];

    if (alias)

      prototype = alias;

  }

#endif

  mxPushNull();

  while (mxBehaviorGetPrototype(the, instance, the->stack)) {

    instance = the->stack->value.reference;

    if (instance == prototype) {

      mxResult->value.boolean = 1;

      break;

    }

  }

  mxPop();

}

void fx_Function_prototype_toString(txMachine* the)

{ 

  fxCheckFunctionInstance(the, mxThis);

  mxPushStringX("function [\"");

  mxPushSlot(mxThis);

  mxGetID(mxID(_name));

  if ((the->stack->kind == XS_STRING_KIND) || (the->stack->kind == XS_STRING_X_KIND))

    fxConcatString(the, the->stack + 1, the->stack);

  mxPop();

  mxPushStringX("\"] (){[native code]}");

  fxConcatString(the, the->stack + 1, the->stack);

  mxPop();

  mxPullSlot(mxResult);

}

txSlot* fxNewAsyncInstance(txMachine* the)

{

  txSlot* instance;

  txSlot* property;

  txSlot* promise;

  txSlot* status;

  txSlot* function;

  txSlot* home;

  mxPushUndefined();

  instance = fxNewSlot(the);

  instance->kind = XS_INSTANCE_KIND;

  instance->value.instance.garbage = C_NULL;

  instance->value.instance.prototype = C_NULL;

  the->stack->value.reference = instance;

  the->stack->kind = XS_REFERENCE_KIND;

  property = instance->next = fxNewSlot(the);

  property->flag = XS_INTERNAL_FLAG;

  property->kind = XS_STACK_KIND;

  property->ID = XS_NO_ID;

  property->value.stack.length = 0;

  property->value.stack.address = C_NULL;

    property = fxNextIntegerProperty(the, property, XS_CODE_START_ASYNC, XS_NO_ID, XS_INTERNAL_FLAG);

  mxPush(mxPromisePrototype);

  promise = fxNewPromiseInstance(the);

  status = mxPromiseStatus(promise);

  status->value.integer = mxPendingStatus;

    property = fxNextSlotProperty(the, property, the->stack, XS_NO_ID, XS_INTERNAL_FLAG);

  mxPop();

  fxPushPromiseFunctions(the, promise);

    property = fxNextSlotProperty(the, property, the->stack + 1, XS_NO_ID, XS_INTERNAL_FLAG);

    property = fxNextSlotProperty(the, property, the->stack, XS_NO_ID, XS_INTERNAL_FLAG);

  mxPop();

  mxPop();

  function = fxNewHostFunction(the, fxResolveAwait, 1, XS_NO_ID, mxResolveAwaitProfileID);

  home = mxFunctionInstanceHome(function);

  home->value.home.object = instance;

    property = fxNextSlotProperty(the, property, the->stack, XS_NO_ID, XS_INTERNAL_FLAG);

  mxPop();

  function = fxNewHostFunction(the, fxRejectAwait, 1, XS_NO_ID, mxRejectAwaitProfileID);

  home = mxFunctionInstanceHome(function);

  home->value.home.object = instance;

    property = fxNextSlotProperty(the, property, the->stack, XS_NO_ID, XS_INTERNAL_FLAG);

  mxPop();

  return instance;

}

void fxResolveAwait(txMachine* the)

{

  txSlot* slot = mxFunctionInstanceHome(mxFunction->value.reference);

  txSlot* instance = slot->value.home.object;

  the->scratch.kind = mxArgv(0)->kind;

  the->scratch.value = mxArgv(0)->value;

  fxStepAsync(the, instance, XS_NO_STATUS);

}

void fxRejectAwait(txMachine* the)

{

  txSlot* slot = mxFunctionInstanceHome(mxFunction->value.reference);

  txSlot* instance = slot->value.home.object;

  the->scratch.kind = mxArgv(0)->kind;

  the->scratch.value = mxArgv(0)->value;

  fxStepAsync(the, instance, XS_THROW_STATUS);

}

void fxRunAsync(txMachine* the, txSlot* instance)

{

  txSlot* promise = instance->next->next->next;

  fxBeginHost(the);

  the->scratch.kind = XS_UNDEFINED_KIND;

  fxStepAsync(the, instance, XS_NO_STATUS);

  fxEndHost(the);

  mxResult->kind = promise->kind;

  mxResult->value = promise->value;

}

void fxStepAsync(txMachine* the, txSlot* instance, txFlag status)

{

  txSlot* state = instance->next->next;

  txSlot* promise = state->next;

  txSlot* resolveFunction = promise->next;

  txSlot* rejectFunction = resolveFunction->next;

  txSlot* resolveAwaitFunction = rejectFunction->next;

  txSlot* rejectAwaitFunction = resolveAwaitFunction->next;

  txSlot* value;

  mxTry(the) {

    the->status = status;

    state->value.integer = XS_NO_CODE;

    fxRunID(the, instance, XS_NO_ID);

    value = the->stack;

    if (state->value.integer == XS_NO_CODE) {

      /* THIS */

      mxPushUndefined();

      /* FUNCTION */

      mxPushSlot(resolveFunction);

      mxCall();

      /* ARGUMENTS */

      mxPushSlot(value);

      mxRunCount(1);

      mxPop();

    }

    else {

      if (mxIsReference(value) && mxIsPromise(value->value.reference)) {

        mxDub();

        mxGetID(mxID(_constructor));

        if (fxIsSameValue(the, &mxPromiseConstructor, the->stack, 0)) {

          mxPop();

          fxPromiseThen(the, value->value.reference, resolveAwaitFunction, rejectAwaitFunction, C_NULL, C_NULL);

          goto exit;

        }

        mxPop();

      }

      mxTemporary(resolveFunction);

      mxTemporary(rejectFunction);

      mxPush(mxPromiseConstructor);

      fxNewPromiseCapability(the, resolveFunction, rejectFunction);

#ifdef mxPromisePrint

      fprintf(stderr, "fxStepAsync %d\n", the->stack->value.reference->next->ID);

#endif

      fxPromiseThen(the, the->stack->value.reference, resolveAwaitFunction, rejectAwaitFunction, C_NULL, C_NULL);

      /* THIS */

      mxPushUndefined();

      /* FUNCTION */

      mxPushSlot(resolveFunction);

      mxCall();

      /* ARGUMENTS */

      mxPushSlot(value);

      /* COUNT */

      mxRunCount(1);

      mxPop();

    }

exit:     

    mxPop();

  }

  mxCatch(the) {

    fxRejectException(the, rejectFunction);

  }

}

void fx_AsyncFunction(txMachine* the)

{ 

  txInteger c, i;

  txStringStream stream;

  txSlot* module = mxFunctionInstanceHome(mxFunction->value.reference)->value.home.module;

  if (!module) module = mxProgram.value.reference;

  c = mxArgc;

  i = 0;

  mxPushStringX("(async function anonymous(");

  while (c > 1) {

    fxToString(the, mxArgv(i));

    fxConcatString(the, the->stack, mxArgv(i));

    if (c > 2)

      fxConcatStringC(the, the->stack, ", ");

    c--;

    i++;

  }

  fxConcatStringC(the, the->stack, "\n){");

  if (c > 0) {

    fxToString(the, mxArgv(i));

    fxConcatString(the, the->stack, mxArgv(i));

  }

  fxConcatStringC(the, the->stack, "\n})");

  stream.slot = the->stack;

  stream.offset = 0;

  stream.size = mxStringLength(the->stack->value.string);

  fxRunScript(the, fxParseScript(the, &stream, fxStringGetter, mxProgramFlag | mxFunctionFlag), C_NULL, C_NULL, C_NULL, C_NULL, module);

  mxPullSlot(mxResult);

  if (mxHasTarget && !fxIsSameSlot(the, mxTarget, mxFunction)) {

    mxPushSlot(mxTarget);

    fxGetPrototypeFromConstructor(the, &mxAsyncFunctionPrototype);

    mxResult->value.reference->value.instance.prototype = the->stack->value.reference;

    mxPop();

  }

}