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#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include "../common.h"
#define SQR(x) ((x) * (x))
const char *point_tname = "nerv.Point";
const char *better_point_tname = "nerv.BetterPoint";
typedef struct {
double x, y;
} Point;
static int point_norm (lua_State *L) {
Point *p = luaT_checkudata(L, 1, point_tname);
lua_pushnumber(L, sqrt(SQR(p->x) + SQR(p->y)));
return 1;
}
static int point_set_x (lua_State *L) {
Point *p = luaT_checkudata(L, 1, point_tname);
p->x = luaL_checknumber(L, 2);
return 0;
}
static int point_set_y (lua_State *L) {
Point *p = luaT_checkudata(L, 1, point_tname);
p->y = luaL_checknumber(L, 2);
return 0;
}
/* generic constructor */
void point_new_(Point *self, double x, double y) {
self->x = x;
self->y = y;
}
int point_new(lua_State *L) {
/* `_new` function should create the object itself */
Point *self = (Point *)malloc(sizeof(Point));
point_new_(self, luaL_checknumber(L, 1), luaL_checknumber(L, 2));
luaT_pushudata(L, self, point_tname);
fprintf(stderr, "[example] %s constructor is invoked\n",
point_tname);
return 1;
}
int point___init(lua_State *L) {
/* The difference between this function and `_new` function is that this
* one is called by subclass of Point implemented in Lua, although it
* basically does the same thing as `_new`. Also, it can read the empty
* object (table) from the stack. (In this example, the table is ignored.) */
Point *self = (Point *)malloc(sizeof(Point));
point_new_(self, luaL_checknumber(L, 2), luaL_checknumber(L, 3));
luaT_pushudata(L, self, point_tname);
fprintf(stderr, "[example] A subclass has invoked `__init`\n");
return 1;
}
static const luaL_Reg point_methods[] = {
{"set_x", point_set_x},
{"set_y", point_set_y},
{"__init", point___init},
{"norm", point_norm},
{NULL, NULL}
};
/* the subclass method overrides the one from baseclass */
static int better_point_norm (lua_State *L) {
Point *p = luaT_checkudata(L, 1, point_tname);
lua_pushnumber(L, fabs(p->x) + fabs(p->y));
return 1;
}
int better_point_new(lua_State *L) {
/* `_new` function should create the object itself */
Point *self = (Point *)malloc(sizeof(Point));
point_new_(self, luaL_checknumber(L, 1), luaL_checknumber(L, 2));
luaT_pushudata(L, self, better_point_tname);
fprintf(stderr, "[example] %s constructor is invoked\n",
better_point_tname);
return 1;
}
int better_point___init(lua_State *L) {
/* The difference between this function and `_new` function is that this
* one is called by subclass of Point implemented in Lua, although it
* basically does the same thing as `_new`. Also, it can read the empty
* object (table) from the stack. (In this example, the table is ignored.) */
Point *self = (Point *)malloc(sizeof(Point));
point_new_(self, luaL_checknumber(L, 2), luaL_checknumber(L, 3));
luaT_pushudata(L, self, better_point_tname);
fprintf(stderr, "[example] A subclass has invoked `__init`\n");
return 1;
}
static const luaL_Reg better_point_methods[] = {
{"norm", better_point_norm},
{"__init", better_point___init},
{NULL, NULL}
};
void nerv_point_init(lua_State *L) {
/* create a class and let luaT know */
luaT_newmetatable(L, point_tname, NULL, point_new, NULL, NULL);
/* register member functions */
luaL_register(L, NULL, point_methods);
/* keep the stack balanced, see `nerv.c` */
lua_pop(L, 1);
}
void nerv_better_point_init(lua_State *L) {
/* create a class and let luaT know */
luaT_newmetatable(L, better_point_tname, point_tname,
better_point_new, NULL, NULL);
/* register member functions */
luaL_register(L, NULL, better_point_methods);
/* keep the stack balanced, see `nerv.c` */
lua_pop(L, 1);
}
void nerv_example_init(lua_State *L) {
nerv_point_init(L);
nerv_better_point_init(L);
}
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