From fd613ef1da5e3eeb10d13351ccf217e33b30b1dd Mon Sep 17 00:00:00 2001
From: Benoit Giannangeli <giann008@gmail.com>
Date: Fri, 14 Apr 2017 08:18:27 +0200
Subject: debug.upvaluejoin

---
 src/lapi.js   | 21 ++++++++++++++++++++-
 src/ldblib.js | 13 +++++++++++--
 2 files changed, 31 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/lapi.js b/src/lapi.js
index b41cfbe..caafc0a 100644
--- a/src/lapi.js
+++ b/src/lapi.js
@@ -719,6 +719,11 @@ const lua_typename = function(L, t) {
     return ltm.ttypename(t);
 };
 
+const lua_iscfunction = function(L, idx) {
+    let o = index2addr(L, idx);
+    return o.ttislcf(o) || o.ttisCclosure();
+};
+
 const lua_isnil = function(L, n) {
     return lua_type(L, n) === CT.LUA_TNIL;
 };
@@ -933,7 +938,8 @@ const getupvalref = function(L, fidx, n, pf) {
     assert(1 <= n && n <= f.p.upvalues.length, "invalid upvalue index");
     return {
         closure: f,
-        upval: f.upvals[n - 1]
+        upval: f.upvals[n - 1],
+        upvalOff: n - 1
     };
 };
 
@@ -955,6 +961,17 @@ const lua_upvalueid = function(L, fidx, n) {
     }
 };
 
+const lua_upvaluejoin = function(L, fidx1, n1, fidx2, n2) {
+    let ref1 = getupvalref(L, fidx1, n1);
+    let ref2 = getupvalref(L, fidx2, n2);
+    let up1 = ref1.upvalOff;
+    let up2 = ref2.upval;
+    let f1 = ref1.closure;
+
+    f1.upvals[up1] = up2;
+    up2.u.open.touched = true; // TODO: useful
+};
+
 // This functions are only there for compatibility purposes
 const lua_gc = function () {};
 
@@ -993,6 +1010,7 @@ module.exports.lua_gettop            = lua_gettop;
 module.exports.lua_getupvalue        = lua_getupvalue;
 module.exports.lua_getuservalue      = lua_getuservalue;
 module.exports.lua_insert            = lua_insert;
+module.exports.lua_iscfunction       = lua_iscfunction;
 module.exports.lua_isfunction        = lua_isfunction;
 module.exports.lua_isinteger         = lua_isinteger;
 module.exports.lua_isnil             = lua_isnil;
@@ -1061,5 +1079,6 @@ module.exports.lua_touserdata        = lua_touserdata;
 module.exports.lua_type              = lua_type;
 module.exports.lua_typename          = lua_typename;
 module.exports.lua_upvalueid         = lua_upvalueid;
+module.exports.lua_upvaluejoin       = lua_upvaluejoin;
 module.exports.lua_version           = lua_version;
 module.exports.lua_xmove             = lua_xmove;
diff --git a/src/ldblib.js b/src/ldblib.js
index 9fc6ce6..27aca96 100644
--- a/src/ldblib.js
+++ b/src/ldblib.js
@@ -248,13 +248,21 @@ const checkupval = function(L, argf, argnup) {
     return nup;
 };
 
-
 const db_upvalueid = function(L) {
    let n = checkupval(L, 1, 2);
    lapi.lua_pushlightuserdata(L, lapi.lua_upvalueid(L, 1, n));
    return 1;
 };
 
+const db_upvaluejoin = function(L) {
+    let n1 = checkupval(L, 1, 2);
+    let n2 = checkupval(L, 3, 4);
+    lauxlib.luaL_argcheck(L, !lapi.lua_iscfunction(L, 1), 1, lua.to_luastring("Lua function expected"));
+    lauxlib.luaL_argcheck(L, !lapi.lua_iscfunction(L, 3), 3, lua.to_luastring("Lua function expected"));
+    lapi.lua_upvaluejoin(L, 1, n1, 3, n2);
+    return 0;
+};
+
 const db_traceback = function(L) {
     let thread = getthread(L);
     let L1 = thread.thread;
@@ -281,7 +289,8 @@ const dblib = {
     "setupvalue":   db_setupvalue,
     "setuservalue": db_setuservalue,
     "traceback":    db_traceback,
-    "upvalueid":    db_upvalueid
+    "upvalueid":    db_upvalueid,
+    "upvaluejoin":  db_upvaluejoin
 };
 
 // Only with Node
-- 
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