debug step mode

lualib-src/lua-debugchannel.c

@@ -181,12 +181,97 @@ lconnect(lua_State *L) {
 	return 1;
 }
 
+static const int HOOKKEY = 0;
+
+/*
+** Auxiliary function used by several library functions: check for
+** an optional thread as function's first argument and set 'arg' with
+** 1 if this argument is present (so that functions can skip it to
+** access their other arguments)
+*/
+static lua_State *getthread (lua_State *L, int *arg) {
+  if (lua_isthread(L, 1)) {
+    *arg = 1;
+    return lua_tothread(L, 1);
+  }
+  else {
+    *arg = 0;
+    return L;  /* function will operate over current thread */
+  }
+}
+
+/*
+** Call hook function registered at hook table for the current
+** thread (if there is one)
+*/
+static void hookf (lua_State *L, lua_Debug *ar) {
+  static const char *const hooknames[] =
+    {"call", "return", "line", "count", "tail call"};
+  lua_rawgetp(L, LUA_REGISTRYINDEX, &HOOKKEY);
+  lua_pushthread(L);
+  if (lua_rawget(L, -2) == LUA_TFUNCTION) {  /* is there a hook function? */
+    lua_pushstring(L, hooknames[(int)ar->event]);  /* push event name */
+    if (ar->currentline >= 0)
+      lua_pushinteger(L, ar->currentline);  /* push current line */
+    else lua_pushnil(L);
+    lua_call(L, 2, 1);  /* call hook function */
+	int yield = lua_toboolean(L, -1);
+	lua_pop(L,1);
+	if (yield) {
+		lua_yield(L, 0);
+	}
+  }
+}
+
+/*
+** Convert a string mask (for 'sethook') into a bit mask
+*/
+static int makemask (const char *smask, int count) {
+  int mask = 0;
+  if (strchr(smask, 'c')) mask |= LUA_MASKCALL;
+  if (strchr(smask, 'r')) mask |= LUA_MASKRET;
+  if (strchr(smask, 'l')) mask |= LUA_MASKLINE;
+  if (count > 0) mask |= LUA_MASKCOUNT;
+  return mask;
+}
+
+static int db_sethook (lua_State *L) {
+  int arg, mask, count;
+  lua_Hook func;
+  lua_State *L1 = getthread(L, &arg);
+  if (lua_isnoneornil(L, arg+1)) {  /* no hook? */
+    lua_settop(L, arg+1);
+    func = NULL; mask = 0; count = 0;  /* turn off hooks */
+  }
+  else {
+    const char *smask = luaL_checkstring(L, arg+2);
+    luaL_checktype(L, arg+1, LUA_TFUNCTION);
+    count = (int)luaL_optinteger(L, arg + 3, 0);
+    func = hookf; mask = makemask(smask, count);
+  }
+  if (lua_rawgetp(L, LUA_REGISTRYINDEX, &HOOKKEY) == LUA_TNIL) {
+    lua_createtable(L, 0, 2);  /* create a hook table */
+    lua_pushvalue(L, -1);
+    lua_rawsetp(L, LUA_REGISTRYINDEX, &HOOKKEY);  /* set it in position */
+    lua_pushstring(L, "k");
+    lua_setfield(L, -2, "__mode");  /** hooktable.__mode = "k" */
+    lua_pushvalue(L, -1);
+    lua_setmetatable(L, -2);  /* setmetatable(hooktable) = hooktable */
+  }
+  lua_pushthread(L1); lua_xmove(L1, L, 1);  /* key (thread) */
+  lua_pushvalue(L, arg + 1);  /* value (hook function) */
+  lua_rawset(L, -3);  /* hooktable[L1] = new Lua hook */
+  lua_sethook(L1, func, mask, count);
+  return 0;
+}
+
 int
 luaopen_debugchannel(lua_State *L) {
 	luaL_Reg l[] = {
 		{ "create", lcreate },	// for write
 		{ "connect", lconnect },	// for read
 		{ "release", lrelease },
+		{ "sethook", db_sethook },
 		{ NULL, NULL },
 	};
 	luaL_checkversion(L);