init

12 files changed, 1569 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d1c2910
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.o
+libnerv.so
+build/
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..0202a2a
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "luajit-2.0"]
+	path = luajit-2.0
+	url = http://luajit.org/git/luajit-2.0.git
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..659774c
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,18 @@
+.PHONY: all clean
+OBJS := oop_example.o nerv.o luaT.o
+INCLUDE := -I luajit-2.0/build/include/luajit-2.0/ -DLUA_USE_APICHECK
+LDFLAGS := -L luajit-2.0/build/lib/ -llua -lm
+OBJ_DIR := build/objs
+OBJS := $(addprefix $(OBJ_DIR)/,$(OBJS))
+all: libnerv.so
+$(OBJS): $(OBJ_DIR)
+$(OBJ_DIR):
+	-mkdir -p $(OBJ_DIR)
+$(OBJ_DIR)/%.o: %.c
+	gcc -c -o $@ $< $(INCLUDE) -fPIC
+$(OBJ_DIR)/luaT.o:
+	gcc -c -o $@ luaT/luaT.c $(INCLUDE) -fPIC
+libnerv.so: $(OBJS)
+	gcc -shared -o $(OBJ_DIR)/$@ $(OBJS)
+clean:
+	-rm -rf $(OBJ_DIR)
diff --git a/install.sh b/install.sh
new file mode 100755
index 0000000..3b0f423
--- /dev/null
+++ b/install.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+PREFIX="${PWD}/build"
+LUAJIT_SRC='luajit-2.0/'
+LUAJIT_PREFIX="${PREFIX}/luaJIT"
+(cd "$LUAJIT_SRC"; make && make PREFIX="$LUAJIT_PREFIX" install)
diff --git a/luaT/README.md b/luaT/README.md
new file mode 100644
index 0000000..6e9cf0d
--- /dev/null
+++ b/luaT/README.md
@@ -0,0 +1,239 @@
+<a name="luat.dok"/>
+# Lua Torch C API #
+
+luaT provides an API to interface Lua and C in Torch packages. It defines a
+concept of _classes_ to Lua for Torch, and provides a mechanism to easily
+handle these Lua classes from C.
+
+It additionally provides few functions that `luaL` should have defined, and
+defines several functions similar to `luaL` ones for better type error printing when using
+`luaT` classes.
+
+<a name="luat.memory.dok"/>
+## Memory functions ##
+
+Classical memory allocation functions which generate a Lua error in case of
+problem.
+
+<a name="luaT_alloc"/>
+### void* luaT_alloc(lua_State *L, long size) ###
+
+Allocates `size` bytes, and return a pointer on the allocated
+memory. A Lua error will be generated if running out of memory.
+
+<a name="luaT_realloc"/>
+### void* luaT_realloc(lua_State *L, void *ptr, long size) ###
+
+Realloc `ptr` to `size` bytes. `ptr` must have been previously
+allocated with [luaT_alloc](#luaT_alloc) or
+[luaT_realloc](#luaT_realloc), or the C `malloc` or `realloc`
+functions. A Lua error will be generated if running out of memory.
+
+<a name="luaT_free"/>
+### void luaT_free(lua_State *L, void *ptr) ###
+
+Free memory allocated at address `ptr`. The memory must have been
+previously allocated with [luaT_alloc](#luaT_alloc) or
+[luaT_realloc](#luaT_realloc), or the C `malloc` or `realloc`
+functions.
+
+<a name="luat.classcreate"/>
+## Class creation and basic handling ##
+
+A `luaT` class is basically either a Lua _table_ or _userdata_ with
+an appropriate _metatable_. This appropriate metatable is created with
+[luaT_newmetatable](#luaT_newmetatable). Contrary to luaL userdata
+functions, luaT mechanism handles inheritance. If the class inherit from
+another class, then the metatable will itself have a metatable
+corresponding to the _parent metatable_: the metatables are cascaded
+according to the class inheritance. Multiple inheritance is not supported.
+
+<a name="luat.operatoroverloading"/>
+### Operator overloading ###
+
+The metatable of a `luaT` object contains `Lua` operators like
+`__index`, `__newindex`, `__tostring`, `__add`
+(etc...). These operators will respectively look for `__index__`,
+`__newindex__`, `__tostring__`, `__add__` (etc...) in the
+metatable. If found, the corresponding function or value will be returned,
+else a Lua error will be raised.
+
+If one wants to provide `__index__` or `__newindex__` in the
+metaclass, these operators must follow a particular scheme:
+
+  * `__index__` must either return a value _and_ `true` or return `false` only. In the first case, it means `__index__` was able to handle the given argument (for e.g., the type was correct). The second case means it was not able to do anything, so `__index` in the root metatable can then try to see if the metaclass contains the required value.
+
+  * `__newindex__` must either return `true` or `false`. As for `__index__`, `true` means it could handle the argument and `false` not. If not, the root metatable `__newindex` will then raise an error if the object was a userdata, or apply a rawset if the object was a Lua table.
+
+Other metaclass operators like `__tostring__`, `__add__`, etc... do not have any particular constraint.
+
+<a name="luat_newmetatable"/>
+### const char* luaT_newmetatable(lua_State *L, const char *tname, const char *parenttname, lua_CFunction constructor, lua_CFunction destructor, lua_CFunction factory) ###
+
+This function creates a new metatable, which is the Lua way to define a new
+object class. As for `luaL_newmetatable`, the metatable is registered in
+the Lua registry table, with the key `tname`. In addition, `tname` is
+also registered in the Lua registry, with the metatable as key (the
+typename of a given object can be thus easily retrieved).
+
+The class name `tname` must be of the form `modulename.classname`. The module name
+If not NULL, `parenttname` must be a valid typename corresponding to the
+parent class of the new class.
+
+If not NULL, `constructor`, a function `new` will be added to the metatable, pointing to this given function. The constructor might also
+be called through `modulename.classname()`, which is an alias setup by `luaT_metatable`.
+
+If not NULL, `destructor` will be called when garbage collecting the object.
+
+If not NULL, `factory` must be a Lua C function creating an empty object
+instance of the class. This functions are used in Torch for serialization.
+
+Note that classes can be partly defined in C and partly defined in Lua:
+once the metatable is created in C, it can be filled up with additional
+methods in Lua.
+
+The return value is the value returned by [luaT_typenameid](#luat_typenameid).
+
+<a name="luat_pushmetatable"/>
+### int luaT_pushmetatable(lua_State *L, const name *tname) ###
+
+Push the metatable with type name `tname` on the stack, it `tname` is a
+valid Torch class name (previously registered with luaT_newmetatable).
+
+On success, returns 1. If `tname` is invalid, nothing is pushed and it
+returns 0.
+
+<a name="luat_typenameid"/>
+### const char* luaT_typenameid(lua_State *L, const char *tname) ###
+
+If `tname` is a valid Torch class name, then returns a unique string (the
+contents will be the same than `tname`) pointing on the string registered
+in the Lua registry. This string is thus valid as long as Lua is
+running. The returned string shall not be freed.
+
+If `tname` is an invalid class name, returns NULL.
+
+<a name="luat_typename"/>
+### const char* luaT_typename(lua_State *L, int ud) ###
+
+Returns the typename of the object at index `ud` on the stack. If it is
+not a valid Torch object, returns NULL.
+
+<a name="luat_pushudata"/>
+### void luaT_pushudata(lua_State *L, void *udata, const char *tname) ###
+
+Given a C structure `udata`, push a userdata object on the stack with
+metatable corresponding to `tname`. Obviously, `tname` must be a valid
+Torch name registered with [luaT_newmetatable](#luat_newmetatable).
+
+<a name="luat_toudata"/>
+### void *luaT_toudata(lua_State *L, int ud, const char *tname) ###
+
+Returns a pointer to the original C structure previously pushed on the
+stack with [luaT_pushudata](#luat_pushudata), if the object at index
+`ud` is a valid Torch class name. Returns NULL otherwise.
+
+<a name="luat_isudata"/>
+### int luaT_isudata(lua_State *L, int ud, const char *tname) ###
+
+Returns 1 if the object at index `ud` on the stack is a valid Torch class name `tname`.
+Returns 0 otherwise.
+
+<a name="luat_getfield"/>
+### Checking fields of a table ###
+
+This functions check that the table at the given index `ud` on the Lua
+stack has a field named `field`, and that it is of the specified type.
+These function raises a Lua error on failure.
+
+<a name="luat_getfieldcheckudata"/>
+## void *luaT_getfieldcheckudata(lua_State *L, int ud, const char *field, const char *tname) ##
+
+Checks that the field named `field` of the table at index `ud` is a
+Torch class name `tname`.  Returns the pointer of the C structure
+previously pushed on the stack with [luaT_pushudata](#luat_pushudata) on
+success. The function raises a Lua error on failure.
+
+<a name="luat_getfieldchecklightudata"/>
+## void *luaT_getfieldchecklightudata(lua_State *L, int ud, const char *field) ##
+
+Checks that the field named `field` of the table at index `ud` is a
+lightuserdata.  Returns the lightuserdata pointer on success. The function
+raises a Lua error on failure.
+
+<a name="luat_getfieldcheckint"/>
+## int luaT_getfieldcheckint(lua_State *L, int ud, const char *field) ##
+
+Checks that the field named `field` of the table at index `ud` is an
+int. Returns the int value pointer on success. The function raises a Lua
+error on failure.
+
+<a name="luat_getfieldcheckstring"/>
+## const char* luaT_getfieldcheckstring(lua_State *L, int ud, const char *field) ##
+
+Checks that the field named `field` of the table at index `ud` is a
+string. Returns a pointer to the string on success. The function raises a
+Lua error on failure.
+
+<a name="luat_getfieldcheckboolean"/>
+## int luaT_getfieldcheckboolean(lua_State *L, int ud, const char *field) ##
+
+Checks that the field named `field` of the table at index `ud` is a
+boolean. On success, returns 1 if the boolean is `true`, 0 if it is
+`false`. The function raises a Lua error on failure.
+
+<a name="luat_getfieldchecktable"/>
+## void luaT_getfieldchecktable(lua_State *L, int ud, const char *field) ##
+
+Checks that the field named `field` of the table at index `ud` is a
+table. On success, push the table on the stack. The function raises a Lua
+error on failure.
+
+<a name="luat_typerror"/>
+### int luaT_typerror(lua_State *L, int ud, const char *tname) ###
+
+Raises a `luaL_argerror` (and returns its value), claiming that the
+object at index `ud` on the stack is not of type `tname`. Note that
+this function does not check the type, it only raises an error.
+
+<a name="luat_checkboolean"/>
+### int luaT_checkboolean(lua_State *L, int ud) ###
+
+Checks that the value at index `ud` is a boolean. On success, returns 1
+if the boolean is `true`, 0 if it is `false`. The function raises a Lua
+error on failure.
+
+<a name="luat_optboolean"/>
+### int luaT_optboolean(lua_State *L, int ud, int def) ###
+
+Checks that the value at index `ud` is a boolean. On success, returns 1
+if the boolean is `true`, 0 if it is `false`. If there is no value at
+index `ud`, returns `def`. In any other cases, raises an error.
+
+<a name="luat_registeratname"/>
+### void luaT_registeratname(lua_State *L, const struct luaL_Reg *methods, const char *name) ###
+
+This function assume a table is on the stack. It creates a table field
+`name` in the table (if this field does not exist yet), and fill up
+`methods` in this table field.
+
+<a name="luat_classrootname"/>
+### const char *luaT_classrootname(const char *tname) ###
+
+Assuming `tname` is of the form `modulename.classname`, returns
+`classname`. The returned value shall not be freed. It is a pointer
+inside `tname` string.
+
+<a name="luat_classmodulename"/>
+### const char *luaT_classmodulename(const char *tname) ###
+
+Assuming `tname` is of the form `modulename.classname`, returns
+`modulename`. The returned value shall not be freed. It is valid until the
+next call to `luaT_classrootname`.
+
+<a name="luat_stackdump"/>
+### void luaT_stackdump(lua_State *L) ###
+
+This function print outs the state of the Lua stack. It is useful for debug
+purposes.
+
diff --git a/luaT/luaT.c b/luaT/luaT.c
new file mode 100644
index 0000000..7b85ce3
--- /dev/null
+++ b/luaT/luaT.c
@@ -0,0 +1,1079 @@
+#include <stdlib.h>
+#include <string.h>
+
+#include "luaT.h"
+
+void* luaT_alloc(lua_State *L, long size)
+{
+  void *ptr;
+
+  if(size == 0)
+    return NULL;
+
+  if(size < 0)
+    luaL_error(L, "$ Torch: invalid memory size -- maybe an overflow?");
+
+  ptr = malloc(size);
+  if(!ptr)
+    luaL_error(L, "$ Torch: not enough memory: you tried to allocate %dGB. Buy new RAM!", size/1073741824);
+
+  return ptr;
+}
+
+void* luaT_realloc(lua_State *L, void *ptr, long size)
+{
+  if(!ptr)
+    return(luaT_alloc(L, size));
+
+  if(size == 0)
+  {
+    luaT_free(L, ptr);
+    return NULL;
+  }
+
+  if(size < 0)
+    luaL_error(L, "$ Torch: invalid memory size -- maybe an overflow?");
+
+  ptr = realloc(ptr, size);
+  if(!ptr)
+    luaL_error(L, "$ Torch: not enough memory: you tried to reallocate %dGB. Buy new RAM!", size/1073741824);
+  return ptr;
+}
+
+void luaT_free(lua_State *L, void *ptr)
+{
+  free(ptr);
+}
+
+void luaT_stackdump(lua_State *L)
+{
+  int i;
+  const char *tname = NULL;
+  int top = lua_gettop(L);
+  for(i = 1; i <= top; i++)
+  {
+    int t = lua_type(L, i);
+    printf("%3d. ", i);
+    switch(t)
+    {
+      case LUA_TSTRING:
+        printf("'%s'", lua_tostring(L,i));
+        break;
+      case LUA_TBOOLEAN:
+        printf(lua_toboolean(L, i) ? "true" : "false");
+        break;
+      case LUA_TNUMBER:
+        printf("%g", lua_tonumber(L,i));
+        break;
+      case LUA_TUSERDATA:
+        tname = luaT_typename(L, i);
+        printf("userdata %lx [%s]", (long)lua_topointer(L, i), (tname ? tname : "not a Torch object"));
+        break;
+      case 10:
+        tname = luaT_typename(L, i);
+        printf("cdata %lx [%s]", (long)lua_topointer(L, i), (tname ? tname : "not a Torch object"));
+        break;
+      case LUA_TTABLE:
+        lua_pushvalue(L, i);
+        lua_rawget(L, LUA_REGISTRYINDEX);
+        if(lua_isstring(L, -1))
+          tname = lua_tostring(L, -1); /*luaT_typenameid(L, lua_tostring(L, -1)); */
+        else
+          tname = NULL;
+        lua_pop(L, 1);
+        if(tname)
+          printf("metatable [%s]", tname);
+        else
+        {
+          tname = luaT_typename(L, i);
+          printf("table %lx [%s]", (long)lua_topointer(L, i), (tname ? tname : "not a Torch object"));
+        }
+        break;
+      default:
+        printf("Lua object type: %s", lua_typename(L,t));
+        break;
+    }
+    printf("\n");
+  }
+  printf("---------------------------------------------\n");
+}
+
+/* metatable operator methods */
+static int luaT_mt__index(lua_State *L);
+static int luaT_mt__newindex(lua_State *L);
+static int luaT_mt__tostring(lua_State *L);
+static int luaT_mt__add(lua_State *L);
+static int luaT_mt__sub(lua_State *L);
+static int luaT_mt__mul(lua_State *L);
+static int luaT_mt__div(lua_State *L);
+static int luaT_mt__mod(lua_State *L);
+static int luaT_mt__pow(lua_State *L);
+static int luaT_mt__unm(lua_State *L);
+static int luaT_mt__concat(lua_State *L);
+static int luaT_mt__len(lua_State *L);
+static int luaT_mt__eq(lua_State *L);
+static int luaT_mt__lt(lua_State *L);
+static int luaT_mt__le(lua_State *L);
+static int luaT_mt__call(lua_State *L);
+
+/* Constructor-metatable methods */
+static int luaT_cmt__call(lua_State *L);
+static int luaT_cmt__newindex(lua_State *L);
+
+const char* luaT_newmetatable(lua_State *L, const char *tname, const char *parenttname,
+                              lua_CFunction constructor, lua_CFunction destructor, lua_CFunction factory)
+{
+  lua_pushcfunction(L, luaT_lua_newmetatable);
+  lua_pushstring(L, tname);
+  (parenttname ? lua_pushstring(L, parenttname) : lua_pushnil(L));
+  (constructor ? lua_pushcfunction(L, constructor) : lua_pushnil(L));
+  (destructor ? lua_pushcfunction(L, destructor) : lua_pushnil(L));
+  (factory ? lua_pushcfunction(L, factory) : lua_pushnil(L));
+  lua_call(L, 5, 1);
+  return luaT_typenameid(L, tname);
+}
+
+int luaT_pushmetatable(lua_State *L, const char *tname)
+{
+  lua_getfield(L, LUA_REGISTRYINDEX, tname);
+  if(lua_isnil(L, -1))
+  {
+    lua_pop(L, 1);
+    return 0;
+  }
+  return 1;
+}
+
+const char *luaT_typenameid(lua_State *L, const char *tname)
+{
+  if(luaT_pushmetatable(L, tname))
+  {
+    const char *tnameid = NULL;
+    lua_rawget(L, LUA_REGISTRYINDEX);
+    if(lua_isstring(L, -1))
+      tnameid = lua_tostring(L, -1);
+    lua_pop(L, 1); /* the string/nil */
+    return tnameid;
+  }
+  return NULL;
+}
+
+static const char cdataname[] = ""
+  "local _, ffi = pcall(require, 'ffi')\n"
+  "if ffi then\n"
+  "  local id2name = {}\n"
+  "  return function(cdata, name)\n"
+  "    local id = tonumber(ffi.typeof(cdata))\n"
+  "    if id then\n"
+  "      if name then\n"
+  "        id2name[id] = name\n"
+  "        return name\n"
+  "      else\n"
+  "        return rawget(id2name, id)\n"
+  "      end\n"
+  "    end\n"
+  "    return nil\n"
+  "  end\n"
+  "else\n"
+  "  return function() end\n"
+  "end\n";
+
+static const char* luaT_cdataname(lua_State *L, int ud, const char *tname)
+{
+  lua_pushstring(L, "__cdataname");
+  lua_rawget(L, LUA_REGISTRYINDEX);
+  if(lua_isnil(L,-1))
+  {
+    lua_pop(L, 1);
+
+    if(luaL_dostring(L, cdataname)) /* did something go wrong? */
+      luaL_error(L, "internal error (could not load cdataname): %s", lua_tostring(L, -1));
+
+    lua_pushstring(L, "__cdataname");
+    lua_pushvalue(L, -2);
+    lua_rawset(L, LUA_REGISTRYINDEX);
+  }
+  if(!lua_isfunction(L, -1)) /* should not happen */
+    luaL_error(L, "internal error (cdataname is not a function)");
+
+  lua_pushvalue(L, ud);
+  if(tname)
+    lua_pushstring(L, tname);
+  if(lua_pcall(L, (tname ? 2 : 1), 1, 0))
+    luaL_error(L, "internal error (cdataname): %s", lua_tostring(L, -1));
+
+  tname = lua_tostring(L, -1);
+  lua_pop(L, 1);
+
+  return tname;
+}
+
+const char* luaT_typename(lua_State *L, int ud)
+{
+  if(lua_type(L, ud) == 10)
+    return luaT_cdataname(L, ud, NULL);
+  else if(lua_getmetatable(L, ud))
+  {
+    const char *tname = NULL;
+    lua_rawget(L, LUA_REGISTRYINDEX);
+    if(lua_isstring(L, -1))
+      tname = lua_tostring(L, -1);
+    lua_pop(L, 1); /* the string/nil */
+    return tname;
+  }
+  return NULL;
+}
+
+void luaT_pushudata(lua_State *L, void *udata, const char *tname)
+{
+  if(udata)
+  {
+    void **udata_p = lua_newuserdata(L, sizeof(void*));
+    *udata_p = udata;
+    if(!luaT_pushmetatable(L, tname))
+      luaL_error(L, "Torch internal problem: cannot find metatable for type <%s>", tname);
+    lua_setmetatable(L, -2);
+  }
+  else
+    lua_pushnil(L);
+}
+
+void *luaT_toudata(lua_State *L, int ud, const char *tname)
+{
+  void **p = lua_touserdata(L, ud);
+  if(p != NULL) /* value is a userdata? */
+  {
+    if(!luaT_pushmetatable(L, tname))
+      luaL_error(L, "Torch internal problem: cannot find metatable for type <%s>", tname);
+
+    /* initialize the table we want to get the metatable on */
+    /* note that we have to be careful with indices, as we just inserted stuff */
+    lua_pushvalue(L, (ud < 0 ? ud - 1 : ud));
+    while(lua_getmetatable(L, -1)) /* get the next metatable */
+    {
+      lua_remove(L, -2); /* remove the previous metatable [or object, if first time] */
+      if(lua_rawequal(L, -1, -2))
+      {
+        lua_pop(L, 2);  /* remove the two metatables */
+        return *p;
+      }
+    }
+    lua_pop(L, 2); /* remove the two metatables */
+  }
+  return NULL;
+}
+
+int luaT_isudata(lua_State *L, int ud, const char *tname)
+{
+  if(luaT_toudata(L, ud, tname))
+    return 1;
+  else
+    return 0;
+}
+
+void *luaT_checkudata(lua_State *L, int ud, const char *tname)
+{
+  void *p = luaT_toudata(L, ud, tname);
+  if(!p)
+    luaT_typerror(L, ud, tname);
+  return p;
+}
+
+void *luaT_getfieldcheckudata(lua_State *L, int ud, const char *field, const char *tname)
+{
+  void *p;
+  lua_getfield(L, ud, field);
+  if(lua_isnil(L, -1))
+    luaL_error(L, "bad argument #%d (field %s does not exist)", ud, field);
+  p = luaT_toudata(L, -1, tname);
+  if(!p)
+    luaL_error(L, "bad argument #%d (field %s is not a %s)", ud, field, tname);
+  return p;
+}
+
+void *luaT_getfieldchecklightudata(lua_State *L, int ud, const char *field)
+{
+  void *p;
+  lua_getfield(L, ud, field);
+  if(lua_isnil(L, -1))
+    luaL_error(L, "bad argument #%d (field %s does not exist)", ud, field);
+
+  if(!lua_islightuserdata(L, -1))
+    luaL_error(L, "bad argument #%d (field %s is not a light userdata)", ud, field);
+
+  p = lua_touserdata(L, -1);
+
+  return p;
+}
+
+double luaT_getfieldchecknumber(lua_State *L, int ud, const char *field)
+{
+  lua_getfield(L, ud, field);
+  if(lua_isnil(L, -1))
+    luaL_error(L, "bad argument #%d (field %s does not exist)", ud, field);
+  if(!lua_isnumber(L, -1))
+    luaL_error(L, "bad argument #%d (field %s is not a number)", ud, field);
+  return lua_tonumber(L, -1);
+}
+
+int luaT_getfieldcheckint(lua_State *L, int ud, const char *field)
+{
+  lua_getfield(L, ud, field);
+  if(lua_isnil(L, -1))
+    luaL_error(L, "bad argument #%d (field %s does not exist)", ud, field);
+  if(!lua_isnumber(L, -1))
+    luaL_error(L, "bad argument #%d (field %s is not a number)", ud, field);
+  return (int)lua_tonumber(L, -1);
+}
+
+const char* luaT_getfieldcheckstring(lua_State *L, int ud, const char *field)
+{
+  lua_getfield(L, ud, field);
+  if(lua_isnil(L, -1))
+    luaL_error(L, "bad argument #%d (field %s does not exist)", ud, field);
+  if(!lua_isstring(L, -1))
+    luaL_error(L, "bad argument #%d (field %s is not a string)", ud, field);
+  return lua_tostring(L, -1);
+}
+
+int luaT_getfieldcheckboolean(lua_State *L, int ud, const char *field)
+{
+  lua_getfield(L, ud, field);
+  if(lua_isnil(L, -1))
+    luaL_error(L, "bad argument #%d (field %s does not exist)", ud, field);
+  if(!lua_isboolean(L, -1))
+    luaL_error(L, "bad argument #%d (field %s is not a boolean)", ud, field);
+  return lua_toboolean(L, -1);
+}
+
+void luaT_getfieldchecktable(lua_State *L, int ud, const char *field)
+{
+  lua_getfield(L, ud, field);
+  if(lua_isnil(L, -1))
+    luaL_error(L, "bad argument #%d (field %s does not exist)", ud, field);
+  if(!lua_istable(L, -1))
+    luaL_error(L, "bad argument #%d (field %s is not a table)", ud, field);
+}
+
+/**** type checks as in luaL ****/
+int luaT_typerror(lua_State *L, int ud, const char *tname)
+{
+  const char *msg;
+  const char *tnameud = luaT_typename(L, ud);
+
+  if(!tnameud)
+    tnameud = lua_typename(L, ud);
+
+  msg = lua_pushfstring(L, "%s expected, got %s",
+                        tname,
+                        (tnameud ? tnameud : "unknown object"));
+
+  return luaL_argerror(L, ud, msg);
+}
+
+int luaT_checkboolean(lua_State *L, int ud)
+{
+  if(!lua_isboolean(L, ud))
+    luaT_typerror(L, ud, lua_typename(L, LUA_TBOOLEAN));
+  return lua_toboolean(L, ud);
+}
+
+int luaT_optboolean(lua_State *L, int ud, int def)
+{
+  if(lua_isnoneornil(L,ud))
+    return def;
+
+  return luaT_checkboolean(L, ud);
+}
+
+void luaT_registeratname(lua_State *L, const struct luaL_Reg *methods, const char *name)
+{
+  int idx = lua_gettop(L);
+
+  luaL_checktype(L, idx, LUA_TTABLE);
+  lua_pushstring(L, name);
+  lua_rawget(L, idx);
+
+  if(lua_isnil(L, -1))
+  {
+    lua_pop(L, 1);
+    lua_pushstring(L, name);
+    lua_newtable(L);
+    lua_rawset(L, idx);
+
+    lua_pushstring(L, name);
+    lua_rawget(L, idx);
+  }
+
+  luaL_register(L, NULL, methods);
+  lua_pop(L, 1);
+}
+
+
+/* utility functions */
+const char *luaT_classrootname(const char *tname)
+{
+  int i;
+  int sz = strlen(tname);
+
+  for(i = 0; i < sz; i++)
+  {
+    if(tname[i] == '.')
+      return tname+i+1;
+  }
+  return tname;
+}
+
+/* module_name must be a buffer at least as big as tname 
+ * return true if the class is part of a module */
+int luaT_classmodulename(const char *tname, char *module_name)
+{
+  char chars[] = {'.', '\0'};
+  size_t n;
+  n = strcspn(tname, chars);
+  strncpy(module_name, tname, n);
+  module_name[n] = '\0';
+  return tname[n] == '.';
+}
+
+/* Lua only functions */
+int luaT_lua_newmetatable(lua_State *L)
+{
+  const char* tname = luaL_checkstring(L, 1);
+  char module_name[256];
+  int is_in_module = 0;
+  is_in_module = luaT_classmodulename(tname, module_name);
+
+  lua_settop(L, 5);
+  luaL_argcheck(L, lua_isnoneornil(L, 2) || lua_isstring(L, 2), 2, "parent class name or nil expected");
+  luaL_argcheck(L, lua_isnoneornil(L, 3) || lua_isfunction(L, 3), 3, "constructor function or nil expected");
+  luaL_argcheck(L, lua_isnoneornil(L, 4) || lua_isfunction(L, 4), 4, "destructor function or nil expected");
+  luaL_argcheck(L, lua_isnoneornil(L, 5) || lua_isfunction(L, 5), 5, "factory function or nil expected");
+
+  if(is_in_module)
+    lua_getfield(L, LUA_GLOBALSINDEX, module_name);
+  else
+    lua_pushvalue(L, LUA_GLOBALSINDEX);
+  if(!lua_istable(L, 6))
+    luaL_error(L, "while creating metatable %s: bad argument #1 (%s is an invalid module name)", tname, module_name);
+
+  /* we first create the new metaclass if we have to */
+  if(!luaT_pushmetatable(L, tname))
+  {
+    /* create the metatable */
+    lua_newtable(L);
+
+    /* registry[name] = metatable */
+    lua_pushvalue(L, -1);
+    lua_setfield(L, LUA_REGISTRYINDEX, tname);
+
+    /* registry[metatable] = tname */
+    lua_pushvalue(L, -1);
+    lua_pushstring(L, tname);
+    lua_rawset(L, LUA_REGISTRYINDEX);
+
+    /* __index handling */
+    lua_pushcfunction(L, luaT_mt__index);
+    lua_setfield(L, -2, "__index");
+
+    /* __newindex handling */
+    lua_pushcfunction(L, luaT_mt__newindex);
+    lua_setfield(L, -2, "__newindex");
+
+    /* __typename contains the typename */
+    lua_pushstring(L, tname);
+    lua_setfield(L, -2, "__typename");
+
+    /* __metatable is self */
+    lua_pushvalue(L, -1);
+    lua_setfield(L, -2, "__metatable");
+
+    /* by default, __version equals 1 */
+    lua_pushnumber(L, 1);
+    lua_setfield(L, -2, "__version");
+
+    /* assign default operator functions */
+    lua_pushcfunction(L, luaT_mt__tostring);
+    lua_setfield(L, -2, "__tostring");
+
+    lua_pushcfunction(L, luaT_mt__add);
+    lua_setfield(L, -2, "__add");
+
+    lua_pushcfunction(L, luaT_mt__sub);
+    lua_setfield(L, -2, "__sub");
+
+    lua_pushcfunction(L, luaT_mt__mul);
+    lua_setfield(L, -2, "__mul");
+
+    lua_pushcfunction(L, luaT_mt__div);
+    lua_setfield(L, -2, "__div");
+
+    lua_pushcfunction(L, luaT_mt__mod);
+    lua_setfield(L, -2, "__mod");
+
+    lua_pushcfunction(L, luaT_mt__pow);
+    lua_setfield(L, -2, "__pow");
+
+    lua_pushcfunction(L, luaT_mt__unm);
+    lua_setfield(L, -2, "__unm");
+
+    lua_pushcfunction(L, luaT_mt__concat);
+    lua_setfield(L, -2, "__concat");
+
+    lua_pushcfunction(L, luaT_mt__len);
+    lua_setfield(L, -2, "__len");
+
+    lua_pushcfunction(L, luaT_mt__eq);
+    lua_setfield(L, -2, "__eq");
+
+    lua_pushcfunction(L, luaT_mt__lt);
+    lua_setfield(L, -2, "__lt");
+
+    lua_pushcfunction(L, luaT_mt__le);
+    lua_setfield(L, -2, "__le");
+
+    lua_pushcfunction(L, luaT_mt__call);
+    lua_setfield(L, -2, "__call");
+  }
+
+  /* we assign the parent class if necessary */
+  if(!lua_isnoneornil(L, 2))
+  {
+    if(lua_getmetatable(L, -1))
+      luaL_error(L, "class %s has been already assigned a parent class\n", tname);
+    else
+    {
+      const char* parenttname = luaL_checkstring(L, 2);
+      if(!luaT_pushmetatable(L, parenttname))
+        luaL_error(L, "bad argument #2 (invalid parent class name %s)", parenttname);
+      lua_setmetatable(L, -2);
+    }
+  }
+
+  /* register the destructor function  */
+  if(!lua_isnoneornil(L, 4))
+  {
+    /* does it exists already? */
+    lua_pushstring(L, "__gc");
+    lua_rawget(L, -2);
+
+    if(lua_isnil(L, -1))
+    {
+      lua_pop(L, 1); /* pop nil */
+      lua_pushstring(L, "__gc");
+      lua_pushvalue(L, 4);
+      lua_rawset(L, -3);
+    }
+    else
+      luaL_error(L, "%s has been already assigned a destructor", tname);
+  }
+
+  /* register the factory function  */
+  if(!lua_isnoneornil(L, 5))
+  {
+    /* does it exists already? */
+    lua_pushstring(L, "__factory");
+    lua_rawget(L, -2);
+
+    if(lua_isnil(L, -1))
+    {
+      lua_pop(L, 1); /* pop nil */
+      lua_pushstring(L, "__factory");
+      lua_pushvalue(L, 5);
+      lua_rawset(L, -3);
+    }
+    else
+      luaL_error(L, "%s has been already assigned a factory", tname);
+  }
+
+  /******** Constructor table and metatable ********/
+  lua_pushstring(L, "__constructor");
+  lua_rawget(L, -2);
+  if(lua_isnil(L, -1))
+  {
+    lua_pop(L, 1);                        /* pop nil */
+    lua_newtable(L);                      /* fancy table */
+    lua_newtable(L);                      /* fancy metatable */
+
+    lua_pushvalue(L, -3);                 /* metatable */
+    lua_setfield(L, -2, "__index");       /* so we can get the methods */
+
+    lua_pushcfunction(L, luaT_cmt__newindex);
+    lua_setfield(L, -2, "__newindex");    /* so we add new methods */
+
+    lua_pushcfunction(L, luaT_cmt__call);
+    lua_setfield(L, -2, "__call");        /* so we can create, we are here for only that */
+
+    lua_pushvalue(L, -3);
+    lua_setfield(L, -2, "__metatable");   /* redirect to metatable with methods */
+
+    lua_setmetatable(L, -2);              /* constructor metatable is ... this fancy metatable */
+
+    /* set metatable[__constructor] = constructor-metatable */
+    lua_pushstring(L, "__constructor");
+    lua_pushvalue(L, -2);
+    lua_rawset(L, -4);
+  }
+
+  /* register the constructor function  */
+  if(!lua_isnoneornil(L, 3))
+  {
+    /* get constructor metatable */
+    lua_getmetatable(L, -1);
+
+    /* does it exists already? */
+    lua_pushstring(L, "__new");
+    lua_rawget(L, -2);
+
+    if(lua_isnil(L, -1))
+    {
+      lua_pop(L, 1); /* pop nil */
+      lua_pushstring(L, "__new");
+      lua_pushvalue(L, 3);
+      lua_rawset(L, -3);
+
+      /* set "new" in the metatable too */
+      lua_pushstring(L, "new");
+      lua_pushvalue(L, 3);
+      lua_rawset(L, -5);
+    }
+    else
+      luaL_error(L, "%s has been already assigned a constructor", tname);
+
+    /* pop constructor metatable */
+    lua_pop(L, 1);
+  }
+
+  /* module.name = constructor metatable */
+  lua_setfield(L, 6, luaT_classrootname(tname));
+
+  return 1; /* returns the metatable */
+}
+
+/* Lua only utility functions */
+
+/* add any custom type, provided the object has a metatable */
+int luaT_lua_metatype(lua_State *L)
+{
+  if( (lua_gettop(L) != 2) && (lua_gettop(L) != 3) )
+    luaL_error(L, "expecting: string table [ctype]");
+
+  luaL_checkstring(L, 1);
+  luaL_checktype(L, 2, LUA_TTABLE);
+
+  if(lua_gettop(L) == 3)
+  {
+    if(!luaT_cdataname(L, 3, lua_tostring(L, 1)))
+      luaL_error(L, "could not register cdata type -- missing ffi library?");
+  }
+
+  /* registry[name] = metatable */
+  lua_pushvalue(L, 1);
+  lua_pushvalue(L, 2);
+  lua_rawset(L, LUA_REGISTRYINDEX);
+
+  /* registry[metatable] = tname */
+  lua_pushvalue(L, 2);
+  lua_pushvalue(L, 1);
+  lua_rawset(L, LUA_REGISTRYINDEX);
+
+  return 0;
+}
+
+/* return a userdata from a C pointer */
+/* you are better to know what you are doing */
+int luaT_lua_pushudata(lua_State *L)
+{
+  void *udata = NULL;
+  const char *tname = luaL_checkstring(L, 2);
+
+  if(lua_type(L,