ClassDB is now in C++

luprex/syscpp/lpx-classdb.cpp

@@ -0,0 +1,131 @@
+#include "lpx-classdb.hpp"
+#include "lpx-table.hpp"
+
+// Get an entry from the class database.
+//
+//   DB, CLASSNAME
+//   if classname is already present, and is a table, return it.
+//   if classname is already present, and not a table, error.
+//   if classname is not present, create and initialize it.
+// 
+int lpx_classdb_get(lua_State *L) {
+    const int db = lua_gettop(L) - 1;
+    const int cname = lua_gettop(L);
+    
+    luaL_checktype(L, db, LUA_TTABLE);
+    luaL_checktype(L, cname, LUA_TSTRING);
+    lua_pushvalue(L, cname);
+    lua_rawget(L, db);
+    if (lua_istable(L, -1)) {
+        return 1;
+    } else if (!lua_isnil(L, -1)) {
+        lua_pushfstring(L, "%s is not a class", lua_tostring(L, cname));
+        lua_error(L);
+    }
+    lua_pop(L, 1);
+    lua_newtable(L);
+    int cls = lua_gettop(L);
+    lua_pushvalue(L, cname);
+    lua_pushvalue(L, cls);
+    lua_rawset(L, db);
+    lua_pushstring(L, "__index");
+    lua_pushvalue(L, cls);
+    lua_rawset(L, cls);
+    lua_pushstring(L, "__class");
+    lua_pushvalue(L, cname);
+    lua_rawset(L, cls);
+    lua_pushstring(L, "action");
+    lua_newtable(L);
+    lua_rawset(L, cls);
+
+    // Remove arguments, leaving new table on stack.
+    lua_replace(L, db);
+    lua_settop(L, db);
+    return 1;
+}
+
+// Curried version of classdb.get where db is stored in an upvalue.
+//
+static int lpx_classdb_class(lua_State *L) {
+    const int cname = lua_gettop(L);
+    lua_pushvalue(L, lua_upvalueindex(1));
+    lua_insert(L, cname);
+    return lpx_classdb_get(L);
+}
+
+int lpx_classdb_accessor(lua_State *L) {
+    const int db = lua_gettop(L);
+    luaL_checktype(L, db, LUA_TTABLE);
+    lua_pushcclosure(L, lpx_classdb_class, 1);
+    return 1;
+}
+
+// Reset a class database:
+//
+//   Clear out all classes.  Instead of replacing the class tables,
+//   it simply deletes all keys.  That way, if somebody has a pointer
+//   to a class, the pointer is not invalidated.
+//
+//   Caution: do not reset the global class database!
+//
+int lpx_classdb_reset(lua_State *L) {
+    const int db = lua_gettop(L);
+    luaL_checktype(L, db, LUA_TTABLE);
+    lua_pushnil(L);
+    while (lua_next(L, db) != 0) {
+        int cname = lua_gettop(L) - 1;
+        int cls = lua_gettop(L);
+        if (lua_istable(L, cls)) {
+            lua_pushstring(L, "action");
+            lua_rawget(L, cls);
+            int actn = lua_gettop(L);
+            if (lua_istable(L, actn)) {
+                lua_pushvalue(L, actn);
+                lpx_table_clear(L);
+            } else {
+                lua_pop(L, 1);
+                lua_newtable(L);
+            }
+            lua_pushvalue(L, cls);
+            lpx_table_clear(L);
+            lua_pushstring(L, "__index");
+            lua_pushvalue(L, cls);
+            lua_rawset(L, cls);
+            lua_pushstring(L, "__class");
+            lua_pushvalue(L, cname);
+            lua_rawset(L, cls);
+            lua_pushstring(L, "action");
+            lua_pushvalue(L, actn);
+            lua_rawset(L, cls);
+        }
+        lua_settop(L, cname);
+    }
+    // Remove arguments, leave nothing on stack.
+    lua_settop(L, db - 1);
+    return 0;
+}
+
+// Create the global function 'class'.
+//
+//   This version of 'class' creates classes in the global environment.
+//   Note that this is lua 5.1 specific.
+//
+static int lpx_create_global_class(lua_State *L) {
+    lua_pushstring(L, "class");
+    lua_pushvalue(L, LUA_GLOBALSINDEX);
+    lpx_classdb_accessor(L);
+    lua_rawset(L, LUA_GLOBALSINDEX);
+}
+
+static const struct luaL_Reg lpx_classdb_lib [] = {
+    {"get", lpx_classdb_get},
+    {"accessor", lpx_classdb_accessor},
+    {"reset", lpx_classdb_reset},
+    {NULL, NULL}  /* sentinel */
+};
+
+int luaopen_lpx_classdb(lua_State *L) {
+    luaL_openlib(L, "classdb", lpx_classdb_lib, 0);
+    lpx_create_global_class(L);
+    return 1;
+}