made ipairs respect __index metamethod

Author: matthias314

README.rst

@@ -19,7 +19,8 @@ GopherLua: VM and compiler for Lua in Go.
 |
 
 
-GopherLua is a Lua5.1(+ `goto` statement in Lua5.2) VM and compiler written in Go. GopherLua has a same goal
+GopherLua is a Lua 5.1 (+ `goto` statement from Lua 5.2 and `ipairs` as in Lua 5.3)
+VM and compiler written in Go. GopherLua has a same goal
 with Lua: **Be a scripting language with extensible semantics** . It provides
 Go APIs that allow you to easily embed a scripting language to your Go host
 programs.
@@ -835,6 +836,7 @@ Miscellaneous notes
 - GopherLua has a function to set an environment variable : ``os.setenv(name, value)``
 - GopherLua support ``goto`` and ``::label::`` statement in Lua5.2.
     - `goto` is a keyword and not a valid variable name.
+- GopherLua respects the `__index` metamethod in `ipairs` as in Lua 5.3.
 
 ----------------------------------------------------------------
 Standalone interpreter

_glua-tests/vm.lua

@@ -15,6 +15,15 @@ assert(#tbl == 10)
 setmetatable(tbl, nil)
 assert(#tbl == 3)
 
+setmetatable(tbl, {__index = function(t, i)
+  return i <= 5 and -i or nil
+end})
+local s = 0
+for _, x in ipairs(tbl) do
+  s = s+x
+end
+assert(s == -3) -- == 1+2+3-4-5
+
 local ok, msg = pcall(function()
   return 1 < "hoge"
 end)

baselib.go

@@ -133,16 +133,17 @@ func baseGetMetatable(L *LState) int {
 }
 
 func ipairsaux(L *LState) int {
-	tb := L.CheckTable(1)
+	tb := L.Get(1)
 	i := L.CheckInt(2)
 	i++
-	v := tb.RawGetInt(i)
+	li := LNumber(i)
+	v := L.getField(tb, li)
 	if v == LNil {
 		return 0
 	} else {
 		L.Pop(1)
-		L.Push(LNumber(i))
-		L.Push(LNumber(i))
+		L.Push(li)
+		L.Push(li)
 		L.Push(v)
 		return 2
 	}