squirrel_helper.hpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD 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 General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#ifndef SQUIRREL_HELPER_HPP
#define SQUIRREL_HELPER_HPP
 
#include "squirrel.hpp"
#include "../string_func.h"
#include "../tile_type.h"
#include "../core/convertible_through_base.hpp"
#include "squirrel_helper_type.hpp"

template <class CL, ScriptType ST> SQInteger PushClassName(HSQUIRRELVM vm);

namespace SQConvert {
  template <typename T> struct Return;
 
  template <> struct Return<uint8_t>        { static inline int Set(HSQUIRRELVM vm, uint8_t res)       { sq_pushinteger(vm, (int32_t)res); return 1; } };
  template <> struct Return<uint16_t>       { static inline int Set(HSQUIRRELVM vm, uint16_t res)      { sq_pushinteger(vm, (int32_t)res); return 1; } };
  template <> struct Return<uint32_t>       { static inline int Set(HSQUIRRELVM vm, uint32_t res)      { sq_pushinteger(vm, (int32_t)res); return 1; } };
  template <> struct Return<int8_t>         { static inline int Set(HSQUIRRELVM vm, int8_t res)        { sq_pushinteger(vm, res); return 1; } };
  template <> struct Return<int16_t>        { static inline int Set(HSQUIRRELVM vm, int16_t res)       { sq_pushinteger(vm, res); return 1; } };
  template <> struct Return<int32_t>        { static inline int Set(HSQUIRRELVM vm, int32_t res)       { sq_pushinteger(vm, res); return 1; } };
  template <> struct Return<int64_t>        { static inline int Set(HSQUIRRELVM vm, int64_t res)       { sq_pushinteger(vm, res); return 1; } };
  template <> struct Return<TileIndex>    { static inline int Set(HSQUIRRELVM vm, TileIndex res)   { sq_pushinteger(vm, (int32_t)res.base()); return 1; } };
  template <> struct Return<bool>         { static inline int Set(HSQUIRRELVM vm, bool res)        { sq_pushbool   (vm, res); return 1; } };
  template <> struct Return<char *>       { /* Do not use char *, use std::optional<std::string> instead. */ };
  template <> struct Return<const char *> { /* Do not use const char *, use std::optional<std::string> instead. */ };
  template <> struct Return<HSQOBJECT>    { static inline int Set(HSQUIRRELVM vm, HSQOBJECT res)   { sq_pushobject(vm, res); return 1; } };
 
  template <typename T> requires std::is_enum_v<T> struct Return<T> {
    static inline int Set(HSQUIRRELVM vm, T res)
    {
      sq_pushinteger(vm, to_underlying(res));
      return 1;
    }
  };
 
  template <ConvertibleThroughBase T> struct Return<T> {
    static inline int Set(HSQUIRRELVM vm, T res)
    {
      sq_pushinteger(vm, res.base());
      return 1;
    }
  };
 
  template <> struct Return<std::optional<std::string>> {
    static inline int Set(HSQUIRRELVM vm, std::optional<std::string> res)
    {
      if (res.has_value()) {
        sq_pushstring(vm, res.value());
      } else {
        sq_pushnull(vm);
      }
      return 1;
    }
  };

  template <typename T> struct Param;
 
  template <> struct Param<uint8_t>        { static inline uint8_t       Get(HSQUIRRELVM vm, int index) { SQInteger     tmp; sq_getinteger    (vm, index, &tmp); return tmp; } };
  template <> struct Param<uint16_t>       { static inline uint16_t      Get(HSQUIRRELVM vm, int index) { SQInteger     tmp; sq_getinteger    (vm, index, &tmp); return tmp; } };
  template <> struct Param<uint32_t>       { static inline uint32_t      Get(HSQUIRRELVM vm, int index) { SQInteger     tmp; sq_getinteger    (vm, index, &tmp); return tmp; } };
  template <> struct Param<int8_t>         { static inline int8_t        Get(HSQUIRRELVM vm, int index) { SQInteger     tmp; sq_getinteger    (vm, index, &tmp); return tmp; } };
  template <> struct Param<int16_t>        { static inline int16_t       Get(HSQUIRRELVM vm, int index) { SQInteger     tmp; sq_getinteger    (vm, index, &tmp); return tmp; } };
  template <> struct Param<int32_t>        { static inline int32_t       Get(HSQUIRRELVM vm, int index) { SQInteger     tmp; sq_getinteger    (vm, index, &tmp); return tmp; } };
  template <> struct Param<int64_t>        { static inline int64_t       Get(HSQUIRRELVM vm, int index) { SQInteger     tmp; sq_getinteger    (vm, index, &tmp); return tmp; } };
  template <> struct Param<TileIndex>    { static inline TileIndex   Get(HSQUIRRELVM vm, int index) { SQInteger     tmp; sq_getinteger    (vm, index, &tmp); return TileIndex((uint32_t)(int32_t)tmp); } };
  template <> struct Param<bool>         { static inline bool        Get(HSQUIRRELVM vm, int index) { SQBool        tmp; sq_getbool       (vm, index, &tmp); return tmp != 0; } };
  template <> struct Param<const char *> { /* Do not use const char *, use std::string& instead. */ };
 
  template <typename T> requires std::is_enum_v<T> struct Param<T> {
    static inline T Get(HSQUIRRELVM vm, int index)
    {
      SQInteger tmp;
      sq_getinteger(vm, index, &tmp);
      return static_cast<T>(tmp);
    }
  };
 
  template <ConvertibleThroughBase T> struct Param<T> {
    static inline T Get(HSQUIRRELVM vm, int index)
    {
      SQInteger tmp;
      sq_getinteger(vm, index, &tmp);
      return T{static_cast<T::BaseType>(tmp)};
    }
  };
 
  template <> struct Param<const std::string &> {
    static inline const std::string Get(HSQUIRRELVM vm, int index)
    {
      /* Convert what-ever there is as parameter to a string */
      sq_tostring(vm, index);
 
      std::string_view view;
      sq_getstring(vm, -1, view);
      std::string result = StrMakeValid(view);
      sq_poptop(vm);
      return result;
    }
  };
 
  template <typename Titem>
  struct Param<Array<Titem> &&> {
    static inline Array<Titem> Get(HSQUIRRELVM vm, int index)
    {
      /* Sanity check of the size. */
      if (sq_getsize(vm, index) > UINT16_MAX) throw sq_throwerror(vm, "an array used as parameter to a function is too large");
 
      SQObject obj;
      sq_getstackobj(vm, index, &obj);
      sq_pushobject(vm, obj);
      sq_pushnull(vm);
 
      Array<Titem> data;
 
      while (SQ_SUCCEEDED(sq_next(vm, -2))) {
        data.emplace_back(Param<Titem>::Get(vm, -1));
        sq_pop(vm, 2);
      }
      sq_pop(vm, 2);
 
      return data;
    }
  };

  template <typename Tfunc> struct HelperT;

  template <typename Tretval, typename... Targs>
  struct HelperT<Tretval (*)(Targs...)> {
    static int SQCall(void *instance, Tretval(*func)(Targs...), HSQUIRRELVM vm)
    {
      return SQCall(instance, func, vm, std::index_sequence_for<Targs...>{});
    }
 
  private:
    template <size_t... i>
    static int SQCall(void *, Tretval(*func)(Targs...), [[maybe_unused]] HSQUIRRELVM vm, std::index_sequence<i...>)
    {
      if constexpr (std::is_void_v<Tretval>) {
        (*func)(
          Param<Targs>::Get(vm, 2 + i)...
        );
        return 0;
      } else {
        Tretval ret = (*func)(
          Param<Targs>::Get(vm, 2 + i)...
        );
        return Return<Tretval>::Set(vm, std::move(ret));
      }
    }
  };

  template <class Tcls, typename Tretval, typename... Targs>
  struct HelperT<Tretval(Tcls:: *)(Targs...)> {
    static int SQCall(Tcls *instance, auto func, HSQUIRRELVM vm)
    {
      return SQCall(instance, func, vm, std::index_sequence_for<Targs...>{});
    }
 
    static Tcls *SQConstruct(HSQUIRRELVM vm)
    {
      return SQConstruct(vm, std::index_sequence_for<Targs...>{});
    }
 
  private:
    template <size_t... i>
    static int SQCall(Tcls *instance, auto func, [[maybe_unused]] HSQUIRRELVM vm, std::index_sequence<i...>)
    {
      if constexpr (std::is_void_v<Tretval>) {
        (instance->*func)(
          Param<Targs>::Get(vm, 2 + i)...
        );
        return 0;
      } else {
        Tretval ret = (instance->*func)(
          Param<Targs>::Get(vm, 2 + i)...
        );
        return Return<Tretval>::Set(vm, std::move(ret));
      }
    }
 
    template <size_t... i>
    static Tcls *SQConstruct([[maybe_unused]] HSQUIRRELVM vm, std::index_sequence<i...>)
    {
      Tcls *inst = new Tcls(
        Param<Targs>::Get(vm, 2 + i)...
      );
 
      return inst;
    }
  };

  template <class Tcls, typename Tretval, typename... Targs>
  struct HelperT<Tretval(Tcls:: *)(Targs...) const> : HelperT<Tretval(Tcls:: *)(Targs...)> {};
 

  template <typename Tcls, typename Tmethod, ScriptType Ttype>
  inline SQInteger DefSQNonStaticCallback(HSQUIRRELVM vm)
  {
    /* Find the amount of params we got */
    int nparam = sq_gettop(vm);
    SQUserPointer ptr = nullptr;
    SQUserPointer real_instance = nullptr;
    HSQOBJECT instance;
 
    /* Get the 'SQ' instance of this class */
    Squirrel::GetInstance(vm, &instance);
 
    /* Protect against calls to a non-static method in a static way */
    sq_pushroottable(vm);
    PushClassName<Tcls, Ttype>(vm);
    sq_get(vm, -2);
    sq_pushobject(vm, instance);
    if (sq_instanceof(vm) != SQTrue) return sq_throwerror(vm, "class method is non-static");
    sq_pop(vm, 3);
 
    /* Get the 'real' instance of this class */
    sq_getinstanceup(vm, 1, &real_instance, nullptr);
    /* Get the real function pointer */
    sq_getuserdata(vm, nparam, &ptr, nullptr);
    if (real_instance == nullptr) return sq_throwerror(vm, "couldn't detect real instance of class for non-static call");
    /* Remove the userdata from the stack */
    sq_pop(vm, 1);
 
    try {
      /* Delegate it to a template that can handle this specific function */
      auto cls_instance = static_cast<Tcls *>(real_instance);
      auto method = *static_cast<Tmethod *>(ptr);
      return HelperT<Tmethod>::SQCall(cls_instance, method, vm);
    } catch (SQInteger &e) {
      return e;
    }
  }

  template <typename Tcls, typename Tmethod, ScriptType Ttype>
  inline SQInteger DefSQAdvancedNonStaticCallback(HSQUIRRELVM vm)
  {
    /* Find the amount of params we got */
    int nparam = sq_gettop(vm);
    SQUserPointer ptr = nullptr;
    SQUserPointer real_instance = nullptr;
    HSQOBJECT instance;
 
    /* Get the 'SQ' instance of this class */
    Squirrel::GetInstance(vm, &instance);
 
    /* Protect against calls to a non-static method in a static way */
    sq_pushroottable(vm);
    PushClassName<Tcls, Ttype>(vm);
    sq_get(vm, -2);
    sq_pushobject(vm, instance);
    if (sq_instanceof(vm) != SQTrue) return sq_throwerror(vm, "class method is non-static");
    sq_pop(vm, 3);
 
    /* Get the 'real' instance of this class */
    sq_getinstanceup(vm, 1, &real_instance, nullptr);
    /* Get the real function pointer */
    sq_getuserdata(vm, nparam, &ptr, nullptr);
    if (real_instance == nullptr) return sq_throwerror(vm, "couldn't detect real instance of class for non-static call");
    /* Remove the userdata from the stack */
    sq_pop(vm, 1);
 
    try {
      /* Call the function, which its only param is always the VM */
      auto cls_instance = static_cast<Tcls *>(real_instance);
      auto method = *static_cast<Tmethod *>(ptr);
      return static_cast<SQInteger>((cls_instance->*method)(vm));
    } catch (SQInteger &e) {
      return e;
    }
  }

  template <typename Tcls, typename Tmethod>
  inline SQInteger DefSQStaticCallback(HSQUIRRELVM vm)
  {
    /* Find the amount of params we got */
    int nparam = sq_gettop(vm);
    SQUserPointer ptr = nullptr;
 
    /* Get the real function pointer */
    sq_getuserdata(vm, nparam, &ptr, nullptr);
 
    try {
      /* Delegate it to a template that can handle this specific function */
      auto cls_instance = static_cast<Tcls *>(nullptr);
      auto method = *static_cast<Tmethod *>(ptr);
      return HelperT<Tmethod>::SQCall(cls_instance, method, vm);
    } catch (SQInteger &e) {
      return e;
    }
  }
 

  template <typename Tcls, typename Tmethod>
  inline SQInteger DefSQAdvancedStaticCallback(HSQUIRRELVM vm)
  {
    /* Find the amount of params we got */
    int nparam = sq_gettop(vm);
    SQUserPointer ptr = nullptr;
 
    /* Get the real function pointer */
    sq_getuserdata(vm, nparam, &ptr, nullptr);
    /* Remove the userdata from the stack */
    sq_pop(vm, 1);
 
    try {
      /* Call the function, which its only param is always the VM */
      auto method = *static_cast<Tmethod *>(ptr);
      return static_cast<SQInteger>((*method)(vm));
    } catch (SQInteger &e) {
      return e;
    }
  }

  template <typename Tcls>
  static SQInteger DefSQDestructorCallback(SQUserPointer p, SQInteger)
  {
    /* Remove the real instance too */
    if (p != nullptr) ((Tcls *)p)->Release();
    return 0;
  }

  template <typename Tcls, typename Tmethod>
  inline SQInteger DefSQConstructorCallback(HSQUIRRELVM vm)
  {
    try {
      /* Find the amount of params we got */
      int nparam = sq_gettop(vm);
 
      /* Create the real instance */
      Tcls *instance = HelperT<Tmethod>::SQConstruct(vm);
      sq_setinstanceup(vm, -nparam, instance);
      sq_setreleasehook(vm, -nparam, DefSQDestructorCallback<Tcls>);
      instance->AddRef();
      return 0;
    } catch (SQInteger &e) {
      return e;
    }
  }

  template <typename Tcls>
  inline SQInteger DefSQAdvancedConstructorCallback(HSQUIRRELVM vm)
  {
    try {
      /* Find the amount of params we got */
      int nparam = sq_gettop(vm);
 
      /* Create the real instance */
      Tcls *instance = new Tcls(vm);
      sq_setinstanceup(vm, -nparam, instance);
      sq_setreleasehook(vm, -nparam, DefSQDestructorCallback<Tcls>);
      instance->AddRef();
      return 0;
    } catch (SQInteger &e) {
      return e;
    }
  }
 
} // namespace SQConvert
 
#endif /* SQUIRREL_HELPER_HPP */