From b58bd5a12e511d9d6059c04b2fe86036b9f218df Mon Sep 17 00:00:00 2001
From: Bruce Hill <bitbucket@bruce-hill.com>
Date: Fri, 9 Feb 2018 19:03:10 -0800
Subject: [PATCH] Cleanup and compressing methods/metamethods into the same
 thing.

---
 limmutable.c | 53 +++++++++++++++++++---------------------------------
 test.lua     | 20 ++++++++++++++++++--
 2 files changed, 37 insertions(+), 36 deletions(-)

diff --git a/limmutable.c b/limmutable.c
index e6e4c4c..8125c60 100644
--- a/limmutable.c
+++ b/limmutable.c
@@ -100,15 +100,11 @@ static int Lcreate_instance(lua_State *L)
         // Stack: [inst, buckets]
         lua_createtable(L, 1, 0);
         // Stack: [inst, buckets, bucket]
-        // TODO: share bucket metatables
-        lua_createtable(L, 0, 1);
-        // Stack: [inst, buckets, bucket, bucket_mt]
-        lua_pushstring(L, "k");
-        lua_setfield(L, -2, "__mode");
+        lua_pushlightuserdata(L, (void*)Lcreate_instance);
+        lua_gettable(L, LUA_REGISTRYINDEX);
         // Stack: [inst, buckets, bucket, {'__mode'='k'}]
         lua_setmetatable(L, -2);
         // Stack: [inst, buckets, bucket]
-
         lua_pushvalue(L, -1);
         // Stack: [inst, buckets, bucket, bucket]
         lua_rawseti(L, -3, hash);
@@ -376,6 +372,7 @@ static const luaL_Reg R[] =
 {
     { "__len", Llen},
     { "__index", Lindex},
+    { "__tostring", Ltostring},
     { "__ipairs", Lipairs},
     { "__pairs", Lpairs},
     { "from_table", Lfrom_table},
@@ -384,21 +381,24 @@ static const luaL_Reg R[] =
 
 static int Lmake_class(lua_State *L)
 {
-    // args: fields, [methods, [metamethods]]
+    // args: fields, [methods/metamethods]
     int n_args = lua_gettop(L);
 
     // CLS = {}
     lua_newtable(L);
     // Stack: [CLS]
-    lua_pushcfunction(L, Ltostring);
-    lua_setfield(L, -2, "__tostring");
+    // Populate CLS.__len, CLS.__index, CLS.__pairs, etc.
+    luaL_register(L,NULL,R);
 
-    // If metamethods were passed in, copy them over
-    if (n_args > 2) {
+    // If methods were passed in, copy them over, overwriting defaults if desired
+    if (n_args >= 2) {
+        // Stack: [CLS]
         lua_pushnil(L);
         // Stack: [CLS, nil]
-        while (lua_next(L, 3) != 0) {
+        while (lua_next(L, 2) != 0) {
+            // Stack: [CLS, method_name, method_value]
             lua_pushvalue(L, -2);
+            // Stack: [CLS, method_name, method_value, method_name]
             lua_pushvalue(L, -2);
             // Stack: [CLS, method_name, method_value, method_name, method_value]
             lua_settable(L, -5);
@@ -406,9 +406,10 @@ static int Lmake_class(lua_State *L)
             lua_pop(L, 1);
             // Stack: [CLS, method_name]
         }
+        // Stack: [CLS]
     }
 
-    // CLS.buckets = {}
+    // Stack: [CLS]
     lua_newtable(L);
     // Stack: [CLS, CLS.buckets]
     lua_setfield(L, -2, "__instances");
@@ -435,27 +436,6 @@ static int Lmake_class(lua_State *L)
     lua_setfield(L, -2, "__indices");
     // Stack: [CLS]
 
-    // If methods were passed in, copy them over
-    if (n_args > 1) {
-        // Stack: [
-        lua_pushnil(L);
-        // Stack: [CLS, nil]
-        while (lua_next(L, 2) != 0) {
-            // Stack: [CLS, method_name, method_value]
-            lua_pushvalue(L, -2);
-            lua_pushvalue(L, -2);
-            // Stack: [CLS, method_name, method_value, method_name, method_value]
-            lua_settable(L, -5);
-            // Stack: [CLS, method_name, method_value]
-            lua_pop(L, 1);
-            // Stack: [CLS, method_name]
-        }
-    }
-    // Stack: [CLS]
-
-    // Populate __len, __eq, __index, new, etc.
-    luaL_register(L,NULL,R);
-
     // setmetatable(CLS, {__new=CLS.new})
     lua_createtable(L, 0, 1);
     lua_pushcfunction(L, Lcreate_instance);
@@ -468,6 +448,11 @@ static int Lmake_class(lua_State *L)
 
 LUALIB_API int luaopen_immutable(lua_State *L)
 {
+    lua_pushlightuserdata(L, (void*)Lcreate_instance);
+    lua_createtable(L, 0, 1);
+    lua_pushstring(L, "k");
+    lua_setfield(L, -2, "__mode");
+    lua_settable(L, LUA_REGISTRYINDEX);
     lua_pushcfunction(L, Lmake_class);
     return 1;
 }
diff --git a/test.lua b/test.lua
index e58a98c..10a8711 100644
--- a/test.lua
+++ b/test.lua
@@ -47,7 +47,6 @@ test("Creating class", function()
         len2=function(self)
             return self.x*self.x + self.y*self.y
         end,
-    }, {
         __add=function(self, other)
             local cls = getmetatable(self)
             return cls(self.x+other.x, self.y+other.y)
@@ -110,12 +109,29 @@ end)
 collectgarbage()
 collectgarbage()
 
+test("Testing garbage collection", function()
+    local collected = false
+    local GCSnooper = immutable({}, {
+        __gc=function(self)
+            collected = true
+        end,
+    })
+    local g = GCSnooper()
+    collectgarbage()
+    collectgarbage()
+    assert(not collected)
+    g = nil
+    collectgarbage()
+    collectgarbage()
+    assert(collected)
+end)
+
+
 test("Testing similar class", function()
     local FooVec = immutable({"x","y"}, {
         len2=function(self)
             return self.x*self.x + self.y*self.y
         end,
-    }, {
         __add=function(self, other)
             local cls = getmetatable(self)
             return cls(self.x+other.x, self.y+other.y)