Update to version 1.1-6.

Remove useless code in world metatable
Make tiny.world(...) return newworld, ...

rockspecs/tiny-ecs-1.1-6.rockspec

@@ -0,0 +1,24 @@
+package = "tiny-ecs"
+version = "1.1-6"
+source = {
+    url = "git://github.com/bakpakin/tiny-ecs",
+    tag = "1.1-6"
+}
+description = {
+    summary = "Entity Component System for Lua.",
+    detailed = [[
+        Pure Lua implementation of an easy to use, compact, fast, and flexible
+        Entity Component System. Works well with Object Orientation.
+    ]],
+    homepage = "https://github.com/bakpakin/tiny-ecs",
+    license = "MIT"
+}
+dependencies = {
+    "lua >= 5.1"
+}
+build = {
+    type = "builtin",
+    modules = {
+        tiny = "tiny.lua"
+    }
+}

spec/tiny_spec.lua

@@ -211,8 +211,8 @@ describe('tiny-ecs:', function()
             world:update(1)
             world:setSystemIndex(moveSystem, 2)
             world:update(1)
-            assert.equals(2, world:getSystemIndex(moveSystem))
+            assert.equals(2, moveSystem.index)
-            assert.equals(1, world:getSystemIndex(oneTimeSystem))
+            assert.equals(1, oneTimeSystem.index)
         end)
 
         it("Sorts Entities in Sorting Systems", function()

tiny.lua

@@ -23,7 +23,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 -- @author Calvin Rose
 -- @license MIT
 -- @copyright 2015
-local tiny = { _VERSION = "1.1-5" }
+local tiny = { _VERSION = "1.1-6" }
 
 -- Local versions of standard lua functions
 local tinsert = table.insert
@@ -206,12 +206,15 @@ end
 --   * The `active` flag is whether or not the System is updated automatically.
 -- Inactive Systems should be updated manually or not at all via
 -- `system:update(dt)`. Defaults to true.
---   * The 'entities' field is an ordered list of Entities in the System. This
+--   * The `entities` field is an ordered list of Entities in the System. This
 -- list can be used to quickly iterate through all Entities in a System.
 --   * The `interval` field is an optional field that makes Systems update at
 -- certain intervals using buffered time, regardless of World update frequency.
 -- For example, to make a System update once a second, set the System's interval
 -- to 1.
+--   * The `index` field is the System's index in the World. Lower indexed
+-- Systems are processed before higher indices. The `index` is a read only
+-- field; to set the `index`, use `tiny.setSystemIndex(world, system)`.
 --   * The `indices` field is a table of Entity keys to their indices in the
 -- `entities` list. Most Systems can ignore this.
 --   * The `modified` flag is an indicator if the System has been modified in
@@ -342,7 +345,8 @@ end
 local worldMetaTable
 
 --- Creates a new World.
--- Can optionally add default Systems and Entities.
+-- Can optionally add default Systems and Entities. Returns the new World along
+-- with default Entities and Systems.
 function tiny.world(...)
     local ret = {
 
@@ -361,44 +365,43 @@ function tiny.world(...)
         -- Set of Entities
         entities = {},
 
-        -- Number of Entities in World.
+        -- Number of Entities in World
         entityCount = 0,
 
-        -- List of System Data. A data element is a table with 4
+        -- List of Systems
-        -- keys: system, indices, entities, and active.
+        systems = {}
-        systems = {},
-
-        -- Table of Systems to System Indices
-        systemIndices = {}
     }
 
     tiny_add(ret, ...)
     tiny_manageSystems(ret)
     tiny_manageEntities(ret)
 
-    return setmetatable(ret, worldMetaTable)
+    return setmetatable(ret, worldMetaTable), ...
 end
 
 --- Adds an Entity to the world.
 -- Also call this on Entities that have changed Components such that they
--- match different Filters.
+-- match different Filters. Returns the Entity.
 function tiny.addEntity(world, entity)
     local e2a = world.entitiesToAdd
     e2a[#e2a + 1] = entity
     if world.entities[entity] then
         tiny_removeEntity(world, entity)
     end
+    return entity
 end
 tiny_addEntity = tiny.addEntity
 
---- Adds a System to the world.
+--- Adds a System to the world. Returns the System.
 function tiny.addSystem(world, system)
     local s2a = world.systemsToAdd
     s2a[#s2a + 1] = system
+    return system
 end
 tiny_addSystem = tiny.addSystem
 
---- Shortcut for adding multiple Entities and Systems to the World.
+--- Shortcut for adding multiple Entities and Systems to the World. Returns all
+-- added Entities and Systems.
 function tiny.add(world, ...)
     local obj
     for i = 1, select("#", ...) do
@@ -411,24 +414,28 @@ function tiny.add(world, ...)
             end
         end
     end
+    return ...
 end
 tiny_add = tiny.add
 
---- Removes an Entity to the World.
+--- Removes an Entity to the World. Returns the Entity.
 function tiny.removeEntity(world, entity)
     local e2r = world.entitiesToRemove
     e2r[#e2r + 1] = entity
+    return entity
 end
 tiny_removeEntity = tiny.removeEntity
 
---- Removes a System from the world.
+--- Removes a System from the world. Returns the System.
 function tiny.removeSystem(world, system)
     local s2r = world.systemsToRemove
     s2r[#s2r + 1] = system
+    return system
 end
 tiny_removeSystem = tiny.removeSystem
 
---- Shortcut for removing multiple Entities and Systems from the World.
+--- Shortcut for removing multiple Entities and Systems from the World. Returns
+-- all rmeove Systems and Entities
 function tiny.remove(world, ...)
     local obj
     for i = 1, select("#", ...) do
@@ -441,6 +448,7 @@ function tiny.remove(world, ...)
             end
         end
     end
+    return ...
 end
 tiny_remove = tiny.remove
 
@@ -453,7 +461,6 @@ function tiny_manageSystems(world)
             return
         end
 
-        local systemIndices = world.systemIndices
         local entities = world.entities
         local systems = world.systems
         local system, index, filter
@@ -462,8 +469,8 @@ function tiny_manageSystems(world)
         -- Remove Systems
         for i = 1, #s2r do
             system = s2r[i]
-            index = systemIndices[system]
+            index = system.index
-            if index then
+            if system.world == world then
                 onRemove = system.onRemove
                 if onRemove then
                     entityList = system.entities
@@ -471,10 +478,9 @@ function tiny_manageSystems(world)
                         onRemove(system, entityList[j])
                     end
                 end
-                systemIndices[system] = nil
                 tremove(systems, index)
                 for j = index, #systems do
-                    systemIndices[systems[j]] = j
+                    systems[j].index = j
                 end
             end
             s2r[i] = nil
@@ -483,12 +489,13 @@ function tiny_manageSystems(world)
             system.world = nil
             system.entities = nil
             system.indices = nil
+            system.index = nil
         end
 
         -- Add Systems
         for i = 1, #s2a do
             system = s2a[i]
-            if not systemIndices[system] then
+            if systems[system.index] ~= system then
                 entityList = {}
                 entityIndices = {}
                 system.entities = entityList
@@ -499,7 +506,7 @@ function tiny_manageSystems(world)
                 system.modified = true
                 system.world = world
                 index = #systems + 1
-                systemIndices[system] = index
+                system.index = index
                 systems[index] = system
 
                 -- Try to add Entities
@@ -673,26 +680,24 @@ function tiny.getSystemCount(world)
     return #(world.systems)
 end
 
---- Gets the index of a System in the World. Lower indexed Systems are processed
+--- Gets the index of the System in the World.
--- before higher indexed systems.
+-- A simpler alternative is `system.index`.
 function tiny.getSystemIndex(world, system)
-    return world.systemIndices[system]
+    return system.index
 end
 
 --- Sets the index of a System in the World, and returns the old index. Changes
 -- the order in which they Systems processed, because lower indexed Systems are
--- processed first.
+-- processed first. Returns the old system.index.
 function tiny.setSystemIndex(world, system, index)
-    local systemIndices = world.systemIndices
+    local oldIndex = system.index
-    local oldIndex = systemIndices[system]
     local systems = world.systems
-    local system = systems[oldIndex]
 
     tremove(systems, oldIndex)
     tinsert(systems, index, system)
 
     for i = oldIndex, index, index >= oldIndex and 1 or -1 do
-        systemIndices[systems[i]] = i
+        systems[i].index = i
     end
 
     return oldIndex