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

---
 README.md       |  6 ++----
 src/lapi.js     | 21 ++++++++++++++++++++-
 src/ldblib.js   | 13 +++++++++++--
 tests/ldblib.js | 45 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 78 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index 47c80bf..e32f8f5 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,6 @@
     - [ ] lua_getstack
     - [ ] lua_getupvalue
     - [ ] lua_isboolean
-    - [ ] lua_iscfunction
     - [ ] lua_islightuserdata
     - [ ] lua_isuserdata
     - [ ] lua_pcallk
@@ -48,7 +47,6 @@
     - [ ] lua_setallocf
     - [ ] lua_sethook
     - [ ] lua_tocfunction
-    - [ ] lua_upvaluejoin
 - [ ] Auxiliary library
     - [x] ...
     - [ ] luaL_addsize
@@ -94,10 +92,10 @@
         - [x] debug.setupvalue
         - [x] debug.setuservalue
         - [x] debug.traceback
+        - [x] debug.upvalueid
+        - [x] debug.upvaluejoin
         - [ ] debug.gethook
         - [ ] debug.sethook
-        - [ ] debug.upvalueid
-        - [ ] debug.upvaluejoin
 - [ ] Run [Lua test suite](https://github.com/lua/tests)
 - [ ] DOM API binding
 
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
diff --git a/tests/ldblib.js b/tests/ldblib.js
index 30a3eb6..7dd35c3 100644
--- a/tests/ldblib.js
+++ b/tests/ldblib.js
@@ -157,6 +157,51 @@ test('debug.upvalueid', function (t) {
 });
 
 
+test('debug.upvaluejoin', function (t) {
+    let luaCode = `
+        local upvalue1 = "upvalue1"
+        local upvalue2 = "upvalue2"
+
+        local l1 = function()
+            return upvalue1
+        end
+
+        local l2 = function()
+            return upvalue2
+        end
+
+        debug.upvaluejoin(l1, 1, l2, 1)
+
+        return l1()
+    `, L;
+    
+    t.plan(3);
+
+    t.doesNotThrow(function () {
+
+        L = lauxlib.luaL_newstate();
+
+        linit.luaL_openlibs(L);
+
+        lauxlib.luaL_loadstring(L, lua.to_luastring(luaCode));
+
+    }, "Lua program loaded without error");
+
+    t.doesNotThrow(function () {
+
+        lapi.lua_call(L, 0, -1);
+
+    }, "Lua program ran without error");
+
+    t.strictEqual(
+        lapi.lua_tojsstring(L, -1),
+        "upvalue2",
+        "Correct element(s) on the stack"
+    );
+
+});
+
+
 test('debug.traceback (with a global)', function (t) {
     let luaCode = `
         local trace
-- 
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