Rewrite util.sortedpairs to avoid using coroutines

util.sortedpairs is used in luarocks loader since @6dc745a.
Openresty does not like coroutines being used from inside `require`,
resulting in "attempt to yield across C-call boundary" error.
New version of util.sortedpairs uses a prepared array of ordered keys
instead of coroutines.

Ref #620.

1 files changed, 43 insertions, 36 deletions

diff --git a/src/luarocks/util.lua b/src/luarocks/util.lua
index 532bea8b..c9fb7d63 100644
--- a/src/luarocks/util.lua
+++ b/src/luarocks/util.lua
@@ -357,52 +357,59 @@ local function default_sort(a, b)
    end
 end
 
--- The iterator function used internally by util.sortedpairs.
+--- A table iterator generator that returns elements sorted by key,
+-- to be used in "for" loops.
 -- @param tbl table: The table to be iterated.
--- @param sort_function function or nil: An optional comparison function
--- to be used by table.sort when sorting keys.
--- @see sortedpairs
-local function sortedpairs_iterator(tbl, sort_function)
-   local ks = util.keys(tbl)
-   if not sort_function or type(sort_function) == "function" then
-      table.sort(ks, sort_function or default_sort)
-      for _, k in ipairs(ks) do
-         coroutine.yield(k, tbl[k])
-      end
+-- @param sort_function function or table or nil: An optional comparison function
+-- to be used by table.sort when sorting keys, or an array listing an explicit order
+-- for keys. If a value itself is an array, it is taken so that the first element
+-- is a string representing the field name, and the second element is a priority table
+-- for that key, which is returned by the iterator as the third value after the key
+-- and the value.
+-- @return function: the iterator function.
+function util.sortedpairs(tbl, sort_function)
+   sort_function = sort_function or default_sort
+   local keys = util.keys(tbl)
+   local sub_orders = {}
+
+   if type(sort_function) == "function" then
+      table.sort(keys, sort_function)
    else
       local order = sort_function
-      local done = {}
-      for _, k in ipairs(order) do
-         local sub_order
-         if type(k) == "table" then
-            sub_order = k[2]
-            k = k[1]
+      local ordered_keys = {}
+      local all_keys = keys
+      keys = {}
+
+      for _, order_entry in ipairs(order) do
+         local key, sub_order
+         if type(order_entry) == "table" then
+            key = order_entry[1]
+            sub_order = order_entry[2]
+         else
+            key = order_entry
          end
-         if tbl[k] then
-            done[k] = true
-            coroutine.yield(k, tbl[k], sub_order)
+
+         if tbl[key] then
+            ordered_keys[key] = true
+            sub_orders[key] = sub_order
+            table.insert(keys, key)
          end
       end
-      table.sort(ks, default_sort)
-      for _, k in ipairs(ks) do
-         if not done[k] then
-            coroutine.yield(k, tbl[k])
+
+      table.sort(all_keys, default_sort)
+      for _, key in ipairs(all_keys) do
+         if not ordered_keys[key] then
+            table.insert(keys, key)
          end
       end
    end
-end
 
---- A table iterator generator that returns elements sorted by key,
--- to be used in "for" loops.
--- @param tbl table: The table to be iterated.
--- @param sort_function function or table or nil: An optional comparison function
--- to be used by table.sort when sorting keys, or an array listing an explicit order
--- for keys. If a value itself is an array, it is taken so that the first element
--- is a string representing the field name, and the second element is a priority table
--- for that key.
--- @return function: the iterator function.
-function util.sortedpairs(tbl, sort_function)
-   return coroutine.wrap(function() sortedpairs_iterator(tbl, sort_function) end)
+   local i = 1
+   return function()
+      local key = keys[i]
+      i = i + 1
+      return key, tbl[key], sub_orders[key]
+   end
 end
 
 function util.lua_versions()