src/function.cpp

   1 // Copyright Daniel Wallin 2008. Use, modification and distribution is
   2 // subject to the Boost Software License, Version 1.0. (See accompanying
   3 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   4
   5 #define LUABIND_BUILDING
   6
   7 #include <luabind/make_function.hpp>
   8
   9 namespace luabind { namespace detail {
  10
  11 namespace
  12 {
  13
  14   int function_destroy(lua_State* L)
  15   {
  16       function_object* fn = *(function_object**)lua_touserdata(L, 1);
  17       delete fn;
  18       return 0;
  19   }
  20
  21   void push_function_metatable(lua_State* L)
  22   {
  23       lua_pushstring(L, "luabind.function");
  24       lua_rawget(L, LUA_REGISTRYINDEX);
  25
  26       if (lua_istable(L, -1))
  27           return;
  28
  29       lua_pop(L, 1);
  30
  31       lua_newtable(L);
  32
  33       lua_pushstring(L, "__gc");
  34       lua_pushcclosure(L, &function_destroy, 0);
  35       lua_rawset(L, -3);
  36
  37       lua_pushstring(L, "luabind.function");
  38       lua_pushvalue(L, -2);
  39       lua_rawset(L, LUA_REGISTRYINDEX);
  40   }
  41
  42   // A pointer to this is used as a tag value to identify functions exported
  43   // by luabind.
  44   int function_tag = 0;
  45
  46 } // namespace unnamed
  47
  48 LUABIND_API bool is_luabind_function(lua_State* L, int index)
  49 {
  50     if (!lua_getupvalue(L, index, 2))
  51         return false;
  52     bool result = lua_touserdata(L, -1) == &function_tag;
  53     lua_pop(L, 1);
  54     return result;
  55 }
  56
  57 namespace
  58 {
  59
  60   inline bool is_luabind_function(object const& obj)
  61   {
  62       obj.push(obj.interpreter());
  63       bool result = detail::is_luabind_function(obj.interpreter(), -1);
  64       lua_pop(obj.interpreter(), 1);
  65       return result;
  66   }
  67
  68 } // namespace unnamed
  69
  70 LUABIND_API void add_overload(
  71     object const& context, char const* name, object const& fn)
  72 {
  73     function_object* f = *touserdata<function_object*>(getupvalue(fn, 1));
  74     f->name = name;
  75
  76     if (object overloads = context[name])
  77     {
  78         if (is_luabind_function(overloads) && is_luabind_function(fn))
  79         {
  80             f->next = *touserdata<function_object*>(getupvalue(overloads, 1));
  81             f->keepalive = overloads;
  82         }
  83     }
  84
  85     context[name] = fn;
  86 }
  87
  88 LUABIND_API object make_function_aux(lua_State* L, int arity, function_object* impl)
  89 {
  90     void* storage = lua_newuserdata(L, sizeof(function_object*));
  91     push_function_metatable(L);
  92     *(function_object**)storage = impl;
  93     lua_setmetatable(L, -2);
  94
  95     lua_pushlightuserdata(L, &function_tag);
  96     lua_pushcclosure(L, impl->entry, 2);
  97     stack_pop pop(L, 1);
  98
  99     return object(from_stack(L, -1));
 100 }
 101
 102 void invoke_context::format_error(
 103     lua_State* L, function_object const* overloads) const
 104 {
 105     char const* function_name =
 106         overloads->name.empty() ? "<unknown>" : overloads->name.c_str();
 107
 108     if (candidate_index == 0)
 109     {
 110         lua_pushstring(L, "No matching overload found, candidates:\n");
 111         int count = 0;
 112         for (function_object const* f = overloads; f != 0; f = f->next)
 113         {
 114             if (count != 0)
 115                 lua_pushstring(L, "\n");
 116             f->format_signature(L, function_name);
 117             ++count;
 118         }
 119         lua_concat(L, count * 2);
 120     }
 121     else
 122     {
 123         // Ambiguous
 124         lua_pushstring(L, "Ambiguous, candidates:\n");
 125         for (int i = 0; i < candidate_index; ++i)
 126         {
 127             if (i != 0)
 128                 lua_pushstring(L, "\n");
 129             candidates[i]->format_signature(L, function_name);
 130         }
 131         lua_concat(L, candidate_index * 2);
 132     }
 133 }
 134
 135 }} // namespace luabind::detail
 136