From dc69636f7243303e6f845ce9eaeb705be17deca1 Mon Sep 17 00:00:00 2001
From: bakpakin <calsrose@gmail.com>
Date: Sat, 25 Apr 2015 21:37:04 +0800
Subject: [PATCH] Fix reordering of Systems.

---
 spec/tiny_spec.lua | 8 ++++++++
 tiny.lua           | 9 +++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/spec/tiny_spec.lua b/spec/tiny_spec.lua
index 23bba4b..4cc9efa 100644
--- a/spec/tiny_spec.lua
+++ b/spec/tiny_spec.lua
@@ -197,6 +197,14 @@ describe('tiny-ecs:', function()
             assert.equals(3, world:getEntityCount())
         end)
 
+        it("Reorder Systems", function()
+            world:update(1)
+            world:setSystemIndex(moveSystem, 2)
+            world:update(1)
+            assert.equals(2, world:getSystemIndex(moveSystem))
+            assert.equals(1, world:getSystemIndex(oneTimeSystem))
+        end)
+
     end)
 
 end)
diff --git a/tiny.lua b/tiny.lua
index 0116070..3e6c1b6 100644
--- a/tiny.lua
+++ b/tiny.lua
@@ -540,11 +540,16 @@ end
 -- @param system
 -- @param index
 function tiny.setSystemIndex(world, system, index)
-    local oldIndex = world.systemIndices[system]
+    local systemIndices = world.systemIndices
+    local oldIndex = systemIndices[system]
     local systems = world.systems
+
     tremove(systems, oldIndex)
     tinsert(systems, index, system)
-    world.systemIndices[system] = index
+
+    for i = oldIndex, index, index >= oldIndex and 1 or -1 do
+        systemIndices[systems[i]] = i
+    end
 end
 
 --- Activates Systems in the World.