luaxx.hpp

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/* vim: set et sw=3 tw=0 fo=croqlaw cino=t0:
 *
 * Luaxx, the C++ Lua wrapper library.
 * Copyright (c) 2006-2008 Matthew Nicholson
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy 
 * of this software and associated documentation files (the "Software"), to 
 * deal in the Software without restriction, including without limitation the 
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 
 * sell copies of the Software, and to permit persons to whom the Software is 
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in 
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 
 * IN THE SOFTWARE. 
 */

#ifndef LUAXX_H
#define LUAXX_H

#include <lua.hpp>
#include <string>
#include <vector>
#include <new>
#include <exception>

namespace lua
{
   class exception : public std::exception {
      public:
         exception() : std::exception() { }
         explicit exception(const char* desc) : std::exception(), description(desc) { }
         virtual ~exception() throw() { }
         virtual const char* what() const throw() {
            return description.c_str();
         }
      private:
         std::string description;
   };

   class runtime_error : public exception {
      public:
         runtime_error() : exception() { }
         explicit runtime_error(const char* desc) : exception(desc) { }
         virtual ~runtime_error() throw() { }
   };

   class syntax_error : public exception {
      public:
         syntax_error() : exception() { }
         explicit syntax_error(const char* desc) : exception(desc) { }
         virtual ~syntax_error() throw() { }
   };

   class file_error : public exception {
      public:
         file_error() : exception() { }
         explicit file_error(const char* desc) : exception(desc) { }
         virtual ~file_error() throw() { }
   };

   class bad_alloc : public exception, std::bad_alloc {
      public:
         bad_alloc() : lua::exception(), std::bad_alloc() { }
         explicit bad_alloc(const char* desc) : lua::exception(desc), std::bad_alloc() { }
         virtual ~bad_alloc() throw() { }
   };
   
   class bad_conversion : public exception {
      public:
         bad_conversion() : exception() { }
         explicit bad_conversion(const char* desc) : exception(desc) { }
         virtual ~bad_conversion() throw() { }
   };

   class table { };
   class nil { };
   class function { };
   class userdata { };
   class lightuserdata { };

   typedef lua_CFunction cfunction;  
   typedef lua_Integer integer;      
   typedef lua_Number number;        
   typedef lua_Reader reader;        
   const int multiret = LUA_MULTRET; 

   class state {
      public:
         state();
         state(lua_State* L);
         ~state();

         operator lua_State*();

         state& push();
         state& push(nil);
         state& push(bool boolean);
         template<typename T> state& push(T number);
         state& push(const char* s, size_t length);
         state& push(const char* s);
         state& push(const std::string& s);
         state& push(cfunction f);
         state& push(table);
         state& push(void* p);
         template<typename T> state& pushlightuserdata(T p);
         
         template<typename T> state& to(T& number, int index = -1);
         template<typename T> state& touserdata(T& p, int index = -1);

         template<typename T> T as(T default_value, int index = -1);
         template<typename T> T as(int index = -1);

         template<typename T> bool is(int index = -1);

         state& check(int narg);
#if lua_Integer != int
         state& check(int& i, int narg);
#endif
         state& check(integer& i, int narg);
#if lua_Integer != long
         state& check(long& l, int narg);
#endif
         state& check(std::string& s, int narg);
         state& check(number& n, int narg);

         template<typename msg_t> void error(msg_t message);
#if 0
         template<> void error(const std::string& message);
#endif

         state& pcall(int nargs = 0, int nresults = 0, int on_error = 0);
         state& call(int nargs = 0, int nresults = 0);
         
         state& checkstack(int size);
         state& settop(int index);
         int gettop();
         int size();
         bool empty();
         
         state& insert(int index);
         state& replace(int index);
         state& remove(int index);
         state& pop(int elements = 1);

         state& pushvalue(int index);

         state& newtable();
         bool newmetatable(const std::string& tname);
         template<typename userdata_t> userdata_t* newuserdata();
         void* newuserdata(size_t nbytes);

         state& gettable(int index = -2);
         state& getfield(const std::string& k, int index = -1);
         state& settable(int index = -3);
         state& setfield(const std::string& k, int index = -2);
         state& getmetatable(const std::string& tname);
         bool getmetatable(int index);

         bool next(int index = -2);

         state& getglobal(const std::string& name);
         state& setglobal(const std::string& name);

         state& loadfile(const std::string& filename);
         state& loadstring(const std::string& s);

         template<typename iterator_t> state& load(iterator_t begin, iterator_t end);

         size_t objlen(int index = -1);

      private:
         lua_State* L;
         bool managed;
         
         // make lua::states non copyable
         state(const state&);              
         state& operator = (const state&); 

         int throw_error(int code);
   };

   // template functions
   
   template<typename T>
   state& state::push(T number) {
      lua_pushnumber(L, number);
      return *this;
   }

   template<typename T>
   state& state::pushlightuserdata(T p) {
      lua_pushlightuserdata(L, p);
      return *this;
   }

   template<typename T>
   bool state::is(int index) {
      return lua_isnumber(L, index);
   }

   template<typename T>
   state& state::to(T& number, int index) {
      if (lua_isnumber(L, index))
         number = static_cast<T>(lua_tonumber(L, index));
      else
         throw bad_conversion("Cannot convert non 'number' value to number");

      return *this;
   }
   
   template<typename T>
   state& state::touserdata(T& p, int index) {
      if (lua_isuserdata(L, index))
         p = reinterpret_cast<T>(lua_touserdata(L, index));
      else
         throw bad_conversion("Cannot convert non 'userdata' or 'lightuserdata' value to userdata");

      return *this;
   }
   
   template<typename T>
   T state::as(T default_value, int index) {
      if (lua_isnumber(L, index))
         return static_cast<T>(lua_tonumber(L, index));
      else
         return default_value;
   }

   template<typename T>
   T state::as(int index) {
      if (lua_isnumber(L, index))
         return static_cast<T>(lua_tonumber(L, index));
      else
         throw bad_conversion("Cannot convert non 'number' value to number");
   }
   
   template<typename userdata_t>
   userdata_t* state::newuserdata() {
      return reinterpret_cast<userdata_t*>(lua_newuserdata(L, sizeof(userdata_t)));
   }

   template<typename msg_t>
   void state::error(msg_t message) {
      push(message);
      lua_error(L);
   }

   template<typename iterator_t>
   state& state::load(iterator_t begin, iterator_t end) {
      // convert the data to characters
      std::vector<char> chunk(begin, end);
      
      // Here we use the address of the first element of our vector.  
      // This works because the data in std::vectors is contiguous.
      throw_error(luaL_loadbuffer(L, &(*chunk.begin()), chunk.size(), NULL));
      return *this;
   }


   // template specializations
   template<> state& state::to(bool& boolean, int index);
   template<> state& state::to(std::string& string, int index);

   template<> bool state::as(bool default_value, int index);
   template<> std::string state::as(std::string default_value, int index);
   template<> bool state::as(int index);
   template<> std::string state::as(int index);

   template<> bool state::is<nil>(int index);
   template<> bool state::is<bool>(int index);
   template<> bool state::is<std::string>(int index);
   template<> bool state::is<table>(int index);
   template<> bool state::is<cfunction>(int index);
   template<> bool state::is<function>(int index);
   template<> bool state::is<userdata>(int index);
   template<> bool state::is<lightuserdata>(int index);
  

   // inline functions
   
   inline state::operator lua_State*() {
      return L;
   }

   inline int state::throw_error(int code) {
      std::string error;

      // below, we package lua errors into exceptions
      switch (code) {
         case 0:
            break;
         case LUA_ERRSYNTAX:
            to(error).pop();
            throw syntax_error(error.c_str());
         case LUA_ERRMEM:
            to(error).pop();
            throw bad_alloc(error.c_str());
         case LUA_ERRRUN:
            to(error).pop();
            throw runtime_error(error.c_str());
         case LUA_ERRFILE:
            to(error).pop();
            throw file_error(error.c_str());
         default:
            to(error).pop();
            throw exception(error.c_str());
      }
      return code;
   }
   
}

#endif

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