/*

 * 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 void fx_trace_aux(txMachine* the, txInteger flags);

static const char ICACHE_RODATA_ATTR gxURIEmptySet[128] = {

  /* 0 1 2 3 4 5 6 7 8 9 A B C D E F */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 0x                    */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 1x                    */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 2x   !"#$%&'()*+,-./  */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 3x  0123456789:;<=>?  */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 4x  @ABCDEFGHIJKLMNO  */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 5X  PQRSTUVWXYZ[\]^_  */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 6x  `abcdefghijklmno  */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0  /* 7X  pqrstuvwxyz{|}~   */

};

static const char ICACHE_RODATA_ATTR gxURIReservedSet[128] = {

  /* 0 1 2 3 4 5 6 7 8 9 A B C D E F */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 0x                    */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 1x                    */

   0,0,0,1,1,0,1,0,0,0,0,1,1,0,0,1, /* 2x   !"#$%&'()*+,-./  */

   0,0,0,0,0,0,0,0,0,0,1,1,0,1,0,1, /* 3x  0123456789:;<=>?  */

   1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 4x  @ABCDEFGHIJKLMNO  */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 5X  PQRSTUVWXYZ[\]^_  */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 6x  `abcdefghijklmno  */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0  /* 7X  pqrstuvwxyz{|}~   */

};

static const char ICACHE_RODATA_ATTR gxURIUnescapedSet[128] = {

  /* 0 1 2 3 4 5 6 7 8 9 A B C D E F */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 0x                    */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 1x                    */

   0,1,0,0,0,0,0,1,1,1,1,0,0,1,1,0, /* 2x   !"#$%&'()*+,-./  */

   1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0, /* 3x  0123456789:;<=>?  */

   0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, /* 4x  @ABCDEFGHIJKLMNO  */

   1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,1, /* 5X  PQRSTUVWXYZ[\]^_  */

   0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, /* 6x  `abcdefghijklmno  */

   1,1,1,1,1,1,1,1,1,1,1,0,0,0,1,0  /* 7X  pqrstuvwxyz{|}~   */

};

static const char ICACHE_RODATA_ATTR gxURIReservedAndUnescapedSet[128] = {

  /* 0 1 2 3 4 5 6 7 8 9 A B C D E F */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 0x                    */

   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 1x                    */

   0,1,0,1,1,0,1,1,1,1,1,1,1,1,1,1, /* 2x   !"#$%&'()*+,-./  */

   1,1,1,1,1,1,1,1,1,1,1,1,0,1,0,1, /* 3x  0123456789:;<=>?  */

   1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, /* 4x  @ABCDEFGHIJKLMNO  */

   1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,1, /* 5X  PQRSTUVWXYZ[\]^_  */

   0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, /* 6x  `abcdefghijklmno  */

   1,1,1,1,1,1,1,1,1,1,1,0,0,0,1,0  /* 7X  pqrstuvwxyz{|}~   */

};

const txBehavior ICACHE_FLASH_ATTR gxGlobalBehavior = {

  fxGlobalGetProperty,

  fxGlobalSetProperty,

  fxOrdinaryCall,

  fxOrdinaryConstruct,

  fxOrdinaryDefineOwnProperty,

  fxGlobalDeleteProperty,

  fxOrdinaryGetOwnProperty,

  fxOrdinaryGetPropertyValue,

  fxOrdinaryGetPrototype,

  fxOrdinaryHasProperty,

  fxOrdinaryIsExtensible,

  fxOrdinaryOwnKeys,

  fxOrdinaryPreventExtensions,

  fxOrdinarySetPropertyValue,

  fxOrdinarySetPrototype,

};

void fxBuildGlobal(txMachine* the)

{

  txSlot* slot;

  fxNewInstance(the);

  mxPull(mxObjectPrototype);

  mxPush(mxObjectPrototype);

  fxNewFunctionInstance(the, XS_NO_ID);

  mxPull(mxFunctionPrototype);

  mxPush(mxObjectPrototype);

  slot = fxNewObjectInstance(the);

  mxPull(mxIteratorPrototype);

  fxBuildHostFunction(the, mxCallback(fx_isFinite), 1, mxID(_isFinite));

  mxPull(mxIsFiniteFunction);

  fxBuildHostFunction(the, mxCallback(fx_isNaN), 1, mxID(_isNaN));

  mxPull(mxIsNaNFunction);

  fxBuildHostFunction(the, mxCallback(fx_parseFloat), 1, mxID(_parseFloat));

  mxPull(mxParseFloatFunction);

  fxBuildHostFunction(the, mxCallback(fx_parseInt), 2, mxID(_parseInt));

  mxPull(mxParseIntFunction);

  fxBuildHostFunction(the, mxCallback(fx_decodeURI), 1, mxID(_decodeURI));

  mxPull(mxDecodeURIFunction);

  fxBuildHostFunction(the, mxCallback(fx_decodeURIComponent), 1, mxID(_decodeURIComponent));

  mxPull(mxDecodeURIComponentFunction);

  fxBuildHostFunction(the, mxCallback(fx_encodeURI), 1, mxID(_encodeURI));

  mxPull(mxEncodeURIFunction);

  fxBuildHostFunction(the, mxCallback(fx_encodeURIComponent), 1, mxID(_encodeURIComponent));

  mxPull(mxEncodeURIComponentFunction);

  fxBuildHostFunction(the, mxCallback(fx_escape), 1, mxID(_escape));

  mxPull(mxEscapeFunction);

  fxBuildHostFunction(the, mxCallback(fx_eval), 1, mxID(_eval));

  mxPull(mxEvalFunction);

  fxBuildHostFunction(the, mxCallback(fx_unescape), 1, mxID(_unescape));

  mxPull(mxUnescapeFunction);

  slot = fxBuildHostFunction(the, mxCallback(fx_trace), 1, mxID(_trace));

  slot = fxLastProperty(the, slot);

  slot = fxNextHostFunctionProperty(the, slot, mxCallback(fx_trace_center), 1, mxID(_center), XS_DONT_ENUM_FLAG);

  slot = fxNextHostFunctionProperty(the, slot, mxCallback(fx_trace_left), 1, mxID(_left), XS_DONT_ENUM_FLAG);

  slot = fxNextHostFunctionProperty(the, slot, mxCallback(fx_trace_right), 1, mxID(_right), XS_DONT_ENUM_FLAG);

    mxPull(mxTraceFunction);

#if mxNative  

  fxBuildHostFunction(the, mxCallback(fx_Native), 1, mxID(_Native));

  mxPull(mxNativeConstructor);

  fxBuildHostFunction(the, mxCallback(fx_native), 1, mxID(_native));

  mxPull(mxNativeFunction);

#endif  

  fxNewHostFunction(the, mxCallback(fxThrowTypeError), 0, XS_NO_ID, XS_NO_ID);

  mxThrowTypeErrorFunction = *the->stack;

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

  slot->flag |= XS_DONT_PATCH_FLAG;

  slot = slot->next;

  while (slot) {

    slot->flag |= XS_DONT_DELETE_FLAG | XS_DONT_SET_FLAG;

    slot = slot->next;

  }

  mxPop();

}

txSlot* fxNewGlobalInstance(txMachine* the)

{

  txSlot* instance;

  txSlot* property;

  txSize size = fxMultiplyChunkSizes(the, XS_INTRINSICS_COUNT, sizeof(txSlot*));

  instance = fxNewSlot(the);

  instance->flag = XS_EXOTIC_FLAG;

  instance->kind = XS_INSTANCE_KIND;

  instance->value.instance.garbage = C_NULL;

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

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

  the->stack->kind = XS_REFERENCE_KIND;

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

  property->value.table.address = (txSlot**)fxNewChunk(the, size);

  c_memset(property->value.table.address, 0, size);

  property->value.table.length = XS_INTRINSICS_COUNT;

  property->flag = XS_INTERNAL_FLAG;

  property->ID = XS_GLOBAL_BEHAVIOR;

  property->kind = XS_GLOBAL_KIND;

  return instance;

}

txBoolean fxGlobalDeleteProperty(txMachine* the, txSlot* instance, txID id, txIndex index) 

{

  txBoolean result = fxOrdinaryDeleteProperty(the, instance, id, index);

  if ((XS_SYMBOL_ID_COUNT <= id) && (id < XS_INTRINSICS_COUNT) && result) {

    txSlot* globals = instance->next;

    globals->value.table.address[id] = C_NULL;

  }

  return result;

}

txSlot* fxGlobalGetProperty(txMachine* the, txSlot* instance, txID id, txIndex index, txFlag flag) 

{

  txSlot* result = C_NULL;

  if ((XS_SYMBOL_ID_COUNT <= id) && (id < XS_INTRINSICS_COUNT)) {

    txSlot* globals = instance->next;

    result = globals->value.table.address[id];

    if (!result) {

      result = fxOrdinaryGetProperty(the, instance, id, index, flag);

      globals->value.table.address[id] = result;

    }

  }

  if (!result)

    result = fxOrdinaryGetProperty(the, instance, id, index, flag);

  return result;

}

txSlot* fxGlobalSetProperty(txMachine* the, txSlot* instance, txID id, txIndex index, txFlag flag) 

{

  txSlot* result = C_NULL;

  if ((XS_SYMBOL_ID_COUNT <= id) && (id < XS_INTRINSICS_COUNT)) {

    txSlot* globals = instance->next;

    result = globals->value.table.address[id];

    if (!result) {

      result = fxOrdinarySetProperty(the, instance, id, index, flag);

      globals->value.table.address[id] = result;

    }

  }

  if (!result)

    result = fxOrdinarySetProperty(the, instance, id, index, flag);

  return result;

}

void fx_decodeURI(txMachine* the)

{

  if (mxArgc < 1)

    mxSyntaxError("no URI parameter");

  fxDecodeURI(the, (txString)gxURIReservedSet);

}

void fx_decodeURIComponent(txMachine* the)

{

  if (mxArgc < 1)

    mxSyntaxError("no URI Component parameter");

  fxDecodeURI(the, (txString)gxURIEmptySet);

}

void fx_encodeURI(txMachine* the)

{

  if (mxArgc < 1)

    mxSyntaxError("no URI parameter");

  fxEncodeURI(the, (txString)gxURIReservedAndUnescapedSet);

}

void fx_encodeURIComponent(txMachine* the)

{

  if (mxArgc < 1)

    mxSyntaxError("no URI Component parameter");

  fxEncodeURI(the, (txString)gxURIUnescapedSet);

}

void fx_escape(txMachine* the)

{

  static const char ICACHE_RODATA_ATTR gxSet[128] = {

    /* 0 1 2 3 4 5 6 7 8 9 A B C D E F */

     0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 0x                    */

     0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 1x                    */

     0,0,0,0,0,0,0,0,0,0,1,1,0,1,1,1, /* 2x   !"#$%&'()*+,-./  */

     1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0, /* 3x  0123456789:;<=>?  */

     1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, /* 4x  @ABCDEFGHIJKLMNO  */

     1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,1, /* 5X  PQRSTUVWXYZ[\]^_  */

     0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, /* 6x  `abcdefghijklmno  */

     1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0  /* 7X  pqrstuvwxyz{|}~   */

  };

  txString src;

  txInteger length;

  txInteger c;

  txString dst;

  if (mxArgc < 1) {

    mxResult->value.string = mxUndefinedString.value.string;

    mxResult->kind = mxUndefinedString.kind;

    return;

  }

  src = fxToString(the, mxArgv(0));

  length = 0;

  while (((src = mxStringByteDecode(src, &c))) && (c != C_EOF)) {

    if ((c < 128) && c_read8(gxSet + (int)c))

      length = fxAddChunkSizes(the, length, 1);

    else if (c < 256)

      length = fxAddChunkSizes(the, length, 3);

    else if (c < 0x10000)

      length = fxAddChunkSizes(the, length, 6);

    else

      length = fxAddChunkSizes(the, length, 12);

  }

  length = fxAddChunkSizes(the, length, 1);

  if (length == (src - mxArgv(0)->value.string)) {

    mxResult->value.string = mxArgv(0)->value.string;

    mxResult->kind = mxArgv(0)->kind;

    return;

  }

  mxResult->value.string = fxNewChunk(the, length);

  mxResult->kind = XS_STRING_KIND;

  src = mxArgv(0)->value.string;

  dst = mxResult->value.string;

  while (((src = mxStringByteDecode(src, &c))) && (c != C_EOF)) {

    if ((c < 128) && c_read8(gxSet + (int)c))

      *dst++ = (char)c;

    else if (c < 256) {

      *dst++ = '%';

      dst = fxStringifyHexEscape(dst, c);

    }

    else {

      *dst++ = '%'; 

      *dst++ = 'u'; 

      dst = fxStringifyUnicodeEscape(dst, c, '%');

    }

  }

  *dst = 0;

}

void fx_eval(txMachine* the)

{

  txStringStream aStream;

  txSlot* realm;

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

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

  realm = mxModuleInstanceInternal(module)->value.module.realm;

  if (mxArgc < 1)

    return;

  if (!mxIsStringPrimitive(mxArgv(0))) {

    *mxResult = *mxArgv(0);

    return;

  }

  aStream.slot = mxArgv(0);

  aStream.offset = 0;

  aStream.size = mxStringLength(fxToString(the, mxArgv(0)));

  fxRunScript(the, fxParseScript(the, &aStream, fxStringGetter, mxProgramFlag | mxEvalFlag), mxRealmGlobal(realm), C_NULL, mxRealmClosures(realm)->value.reference, C_NULL, module);

  mxPullSlot(mxResult);

}

void fx_Native(txMachine* the)

{

  mxSyntaxError("invalid Native");

}

void fx_native(txMachine* the)

{

  mxSyntaxError("invalid native");

}

void fx_trace(txMachine* the)

{

//@@#ifdef mxDebug

  int i;

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

    fxToString(the, mxArgv(i));

    fxReport(the, "%s", mxArgv(i)->value.string);

  }

//#endif

}

void fx_trace_aux(txMachine* the, txInteger flags)

{

  txSlot* conversation = C_NULL;

  void* message = C_NULL;

  txInteger length = 0;

  if (mxArgc > 1) {

    conversation = mxArgv(1);

    fxToString(the, conversation);

  }

  if ((mxArgc > 0) && (mxArgv(0)->kind == XS_REFERENCE_KIND)) {

    txSlot* slot = mxArgv(0)->value.reference->next;

    if (slot && (slot->kind == XS_ARRAY_BUFFER_KIND)) {

      txSlot* bufferInfo = slot->next;

      length = bufferInfo->value.bufferInfo.length;

      message = slot->value.arrayBuffer.address;

      flags |= XS_BUBBLE_BINARY;

    }

    else if (slot && (slot->kind == XS_HOST_KIND)) {

      txSlot* bufferInfo = slot->next;

      if (bufferInfo && (bufferInfo->kind == XS_BUFFER_INFO_KIND)) {

        length = bufferInfo->value.bufferInfo.length;

        message = slot->value.host.data;

        flags |= XS_BUBBLE_BINARY;

      }

    }

  }

  if (!message)

    message = fxToString(the, mxArgv(0));

  fxBubble(the, flags, message, length, (conversation) ? conversation->value.string : C_NULL);

}

void fx_trace_center(txMachine* the)

{

  fx_trace_aux(the, XS_NO_FLAG);

}

void fx_trace_left(txMachine* the)

{

  fx_trace_aux(the, XS_BUBBLE_LEFT);

}

void fx_trace_right(txMachine* the)

{

  fx_trace_aux(the, XS_BUBBLE_RIGHT);

}

void fx_unescape(txMachine* the)

{

  txString src;

  txInteger length;

  char c;

  txInteger d;

  txString dst;

  if (mxArgc < 1) {

    mxResult->value.string = mxUndefinedString.value.string;

    mxResult->kind = mxUndefinedString.kind;

    return;

  }

  src = fxToString(the, mxArgv(0));

  length = 0;

  while ((c = c_read8(src++))) {

    if (c == '%') {

      c = c_read8(src++);

      if (c == 'u') {

        if (fxParseUnicodeEscape(&src, &d, 0, '%'))

          length += mxStringByteLength(d);

        else

          length += 2;

      }

      else {

        src--;

        if (fxParseHexEscape(&src, &d))

          length += mxStringByteLength(d);

        else

          length += 1;

      }

    }

    else

      length += 1;

  }   

  length += 1;

  if (length == (src - mxArgv(0)->value.string)) {

    mxResult->value.string = mxArgv(0)->value.string;

    mxResult->kind = mxArgv(0)->kind;

    return;

  }

  mxResult->value.string = fxNewChunk(the, length);

  mxResult->kind = XS_STRING_KIND;

  src = mxArgv(0)->value.string;

  dst = mxResult->value.string;

  while ((c = c_read8(src++))) {

    if (c == '%') {

      c = c_read8(src++);

      d = 0;

      if (c == 'u') {

        if (fxParseUnicodeEscape(&src, &d, 0, '%'))

          dst = mxStringByteEncode(dst, d);

        else {

          *dst++ = '%';

          *dst++ = 'u';

        }

      }

      else {

        src--;

        if (fxParseHexEscape(&src, &d))

          dst = mxStringByteEncode(dst, d);

        else

          *dst++ = '%';

      }

    }

    else

      *dst++ = (txU1)c;

  }

  *dst = 0;

}

void fxDecodeURI(txMachine* the, txString theSet)

{

  txString src;

  txInteger length;

  txInteger c, d;

  const txUTF8Sequence *sequence;

  txInteger size;

  txString dst;

  src = fxToString(the, mxArgv(0));

  length = 0;

  while ((c = c_read8(src++))) {

    if (c == '%') {

      if (!fxParseHexEscape(&src, &d))

        mxURIError("invalid URI");

      if ((d < 128) && c_read8(theSet + d))

        length += 3;

      else {

        for (sequence = gxUTF8Sequences; sequence->size; sequence++) {

          if ((d & sequence->cmask) == sequence->cval)

            break;

        }

        if (!sequence->size)

          mxURIError("invalid URI");

        size = sequence->size - 1;

        while (size > 0) {

          c = c_read8(src++);

          if (c != '%')

            mxURIError("invalid URI");

          if (!fxParseHexEscape(&src, &c))

            mxURIError("invalid URI");

          if ((c & 0xC0) != 0x80)

            mxURIError("invalid URI");

          d = (d << 6) | (c & 0x3F);

          size--;

        }

        d &= sequence->lmask;

        if (sequence != gxUTF8Sequences) {

          if ((sequence[-1].lmask >= (txU4)d) || ((d >= 0xD800) & (d <= 0xDFFF)) || (d >= 0x110000))

            mxURIError("invalid URI");

        }

        length += mxStringByteLength(d);

      }

    }

    else

      length += 1;

  }    

  length += 1;

  if (length == (src - mxArgv(0)->value.string)) {

    mxResult->value.string = mxArgv(0)->value.string;

    mxResult->kind = mxArgv(0)->kind;

    return;

  }

  mxResult->value.string = fxNewChunk(the, length);

  mxResult->kind = XS_STRING_KIND;

  src = mxArgv(0)->value.string;

  dst = mxResult->value.string;

  while ((c = c_read8(src++))) {

    if (c == '%') {

      fxParseHexEscape(&src, &d);

      if ((d < 128) && c_read8(theSet + d)) {

        *dst++ = c_read8(src - 3);

        *dst++ = c_read8(src - 2);

        *dst++ = c_read8(src - 1);

      }

      else {

        for (sequence = gxUTF8Sequences; sequence->size; sequence++) {

          if ((d & sequence->cmask) == sequence->cval)

            break;

        }

        size = sequence->size - 1;

        while (size > 0) {

          src++;

          fxParseHexEscape(&src, &c);

          d = (d << 6) | (c & 0x3F);

          size--;

        }

        d &= sequence->lmask;

        dst = mxStringByteEncode(dst, d);

      }

    }

    else

      *dst++ = c;

  }

  *dst = 0;

}

void fxEncodeURI(txMachine* the, txString theSet)

{

  txString src;

  txInteger length;

  txInteger c;

  txString dst;

  src = fxToString(the, mxArgv(0));

  length = 0;

  while (((src = mxStringByteDecode(src, &c))) && (c != C_EOF)) {

    if (c < 0x80) {

      if (c_read8(theSet + c))

        length += 1;

      else

        length += 3;

    }

    else if (c < 0x800)

      length += 6;

    else if ((0xD800 <= c) && (c <= 0xDFFF))

      mxURIError("invalid string");

    else if (c < 0x10000)

      length += 9;

    else

      length += 12;

  }

  length += 1;

  if (length == (src - mxArgv(0)->value.string)) {

    mxResult->value.string = mxArgv(0)->value.string;

    mxResult->kind = mxArgv(0)->kind;

    return;

  }

  mxResult->value.string = fxNewChunk(the, length);

  mxResult->kind = XS_STRING_KIND;

  src = mxArgv(0)->value.string;

  dst = mxResult->value.string;

  while (((src = mxStringByteDecode(src, &c))) && (c != C_EOF)) {

    if (c < 0x80) {

      if (c_read8(theSet + c))

        *dst++ = (char)c;

      else {

        *dst++ = '%';

        dst = fxStringifyHexEscape(dst, c);

      }

    }

    else if (c < 0x800) {

      *dst++ = '%';

      dst = fxStringifyHexEscape(dst, 0xC0 | (c >> 6));

      *dst++ = '%';

      dst = fxStringifyHexEscape(dst, 0x80 | (c & 0x3F));

    }

    else if (c < 0x10000) {

      *dst++ = '%';

      dst = fxStringifyHexEscape(dst, 0xE0 | (c >> 12));

      *dst++ = '%';

      dst = fxStringifyHexEscape(dst, 0x80 | ((c >> 6) & 0x3F));

      *dst++ = '%';

      dst = fxStringifyHexEscape(dst, 0x80 | (c & 0x3F));

    }

    else {

      *dst++ = '%';

      dst = fxStringifyHexEscape(dst, 0xF0 | (c >> 18));

      *dst++ = '%';

      dst = fxStringifyHexEscape(dst, 0x80 | ((c >> 12) & 0x3F));

      *dst++ = '%';

      dst = fxStringifyHexEscape(dst, 0x80 | ((c >> 6) & 0x3F));

      *dst++ = '%';

      dst = fxStringifyHexEscape(dst, 0x80 | (c & 0x3F));

    }

  }

  *dst = 0;

}