1 files changed, 56 insertions, 5 deletions
diff --git a/scripts/context/lua/mtxrun.lua b/scripts/context/lua/mtxrun.lua
index d3e50e00e..ae0ee162f 100644
--- a/scripts/context/lua/mtxrun.lua
+++ b/scripts/context/lua/mtxrun.lua
@@ -525,7 +525,55 @@ local concat, sort, insert, remove = table.concat, table.sort, table.insert, tab
 local format, find, gsub, lower, dump, match = string.format, string.find, string.gsub, string.lower, string.dump, string.match
 local getmetatable, setmetatable = getmetatable, setmetatable
 local type, next, tostring, tonumber, ipairs = type, next, tostring, tonumber, ipairs
-local unpack = unpack or table.unpack
+
+-- Starting with version 5.2 Lua no longer provide ipairs, which makes
+-- sense. As we already used the for loop and # in most places the
+-- impact on ConTeXt was not that large; the remaining ipairs already
+-- have been replaced. In a similar fashio we also hardly used pairs.
+--
+-- Just in case, we provide the fallbacks as discussed in Programming
+-- in Lua (http://www.lua.org/pil/7.3.html):
+
+if not ipairs then
+
+    -- for k, v in ipairs(t) do                ... end
+    -- for k=1,#t            do local v = t[k] ... end
+
+    local function iterate(a,i)
+        i = i + 1
+        local v = a[i]
+        if v ~= nil then
+            return i, v --, nil
+        end
+    end
+
+    function ipairs(a)
+        return iterate, a, 0
+    end
+
+end
+
+if not pairs then
+
+    -- for k, v in pairs(t) do ... end
+    -- for k, v in next, t  do ... end
+
+    function pairs(t)
+        return next, t -- , nil
+    end
+
+end
+
+-- Also, unpack has been moved to the table table, and for compatiility
+-- reasons we provide both now.
+
+if not table.unpack then
+    table.unpack = _G.unpack
+elseif not unpack then
+    _G.unpack = table.unpack
+end
+
+-- extra functions, some might go (when not used)
 
 function table.strip(tab)
     local lst = { }
@@ -712,7 +760,7 @@ end
 table.fastcopy = fastcopy
 table.copy     = copy
 
--- rougly: copy-loop : unpack : sub == 0.9 : 0.4 : 0.45 (so in critical apps, use unpack)
+-- roughly: copy-loop : unpack : sub == 0.9 : 0.4 : 0.45 (so in critical apps, use unpack)
 
 function table.sub(t,i,j)
     return { unpack(t,i,j) }
@@ -735,7 +783,7 @@ function table.one_entry(t) -- obolete, use inline code instead
     return n and not next(t,n)
 end
 
---~ function table.starts_at(t) -- obsolete, not nice
+--~ function table.starts_at(t) -- obsolete, not nice anyway
 --~     return ipairs(t,1)(t,0)
 --~ end
 
@@ -1374,6 +1422,7 @@ function table.insert_after_value(t,value,extra)
 end
 
 
+
 end -- of closure
 
 do -- create closure to overcome 200 locals limit
@@ -6974,8 +7023,10 @@ local function reverse(collected)
 end
 
 local function attribute(collected,name)
-    local at = collected and collected[1].at
-    return at and at[name]
+    if collected and #collected > 0 then
+        local at = collected[1].at
+        return at and at[name]
+    end
 end
 
 local function att(id,name)