From e4c9580d20924a0db1ff7ed0d30da9b71dbb5066 Mon Sep 17 00:00:00 2001
From: daurnimator <quae@daurnimator.com>
Date: Mon, 22 May 2017 21:21:50 +1000
Subject: Introduce lvm.cvt2str

In future this could be configurable
---
 src/lapi.js   | 16 +++++++++++-----
 src/ldebug.js |  2 +-
 src/lvm.js    |  9 +++++++--
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/lapi.js b/src/lapi.js
index f06fc65..f7ef82e 100644
--- a/src/lapi.js
+++ b/src/lapi.js
@@ -667,8 +667,11 @@ const lua_toboolean = function(L, idx) {
 const lua_tolstring = function(L, idx) {
     let o = index2addr(L, idx);
 
-    if ((!o.ttisstring() && !o.ttisnumber()))
-        return null;
+    if (!o.ttisstring()) {
+        if (!lvm.cvt2str(o)) {  /* not convertible? */
+            return null;
+        }
+    }
 
     return o.ttisstring() ? o.svalue() : defs.to_luastring(`${o.value}`);
 };
@@ -678,8 +681,11 @@ const lua_tostring =  lua_tolstring;
 const lua_toljsstring = function(L, idx) {
     let o = index2addr(L, idx);
 
-    if ((!o.ttisstring() && !o.ttisnumber()))
-        return null;
+    if (!o.ttisstring()) {
+        if (!lvm.cvt2str(o)) {  /* not convertible? */
+            return null;
+        }
+    }
 
     return o.ttisstring() ? o.jsstring() : `${o.value}`;
 };
@@ -872,7 +878,7 @@ const lua_isnumber = function(L, idx) {
 
 const lua_isstring = function(L, idx) {
     let o = index2addr(L, idx);
-    return o.ttisstring() || o.ttisnumber();
+    return o.ttisstring() || lvm.cvt2str(o);
 };
 
 const lua_isuserdata = function(L, idx) {
diff --git a/src/ldebug.js b/src/ldebug.js
index 1862e55..74a04db 100644
--- a/src/ldebug.js
+++ b/src/ldebug.js
@@ -546,7 +546,7 @@ const luaG_typeerror = function(L, o, op) {
 };
 
 const luaG_concaterror = function(L, p1, p2) {
-    if (p1.ttisstring() || p1.ttisnumber()) p1 = p2;
+    if (p1.ttisstring() || lvm.cvt2str(p1)) p1 = p2;
     luaG_typeerror(L, p1, defs.to_luastring('concatenate', true));
 };
 
diff --git a/src/lvm.js b/src/lvm.js
index 4804cde..bd370a6 100644
--- a/src/lvm.js
+++ b/src/lvm.js
@@ -958,12 +958,16 @@ const luaV_shiftl = function(x, y) {
     }
 };
 
+const cvt2str = function(o) {
+    return o.ttisnumber();
+};
+
 const tostring = function(L, i) {
     let o = L.stack[i];
 
     if (o.ttisstring()) return true;
 
-    if (o.ttisnumber() && !isNaN(o.value)) {
+    if (cvt2str(o) && !isNaN(o.value)) {
         L.stack[i] = new lobject.TValue(CT.LUA_TLNGSTR, lstring.luaS_bless(L, defs.to_luastring(`${o.value}`)));
         return true;
     }
@@ -985,7 +989,7 @@ const luaV_concat = function(L, total) {
         let top = L.top;
         let n = 2; /* number of elements handled in this pass (at least 2) */
 
-        if (!(L.stack[top-2].ttisstring() || L.stack[top-2].ttisnumber()) || !tostring(L, top - 1)) {
+        if (!(L.stack[top-2].ttisstring() || cvt2str(L.stack[top-2])) || !tostring(L, top - 1)) {
             ltm.luaT_trybinTM(L, L.stack[top-2], L.stack[top-1], top-2, ltm.TMS.TM_CONCAT);
             delete L.stack[top - 1];
         } else if (isemptystr(L.stack[top-1])) {
@@ -1090,6 +1094,7 @@ module.exports.RB                = RB;
 module.exports.RC                = RC;
 module.exports.RKB               = RKB;
 module.exports.RKC               = RKC;
+module.exports.cvt2str           = cvt2str;
 module.exports.dojump            = dojump;
 module.exports.donextjump        = donextjump;
 module.exports.forlimit          = forlimit;
-- 
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