Update version to 0.0.2

Add System addition and removal
Changed implementation for Entity removal
Change README and example code

README.md

@@ -51,7 +51,7 @@ local talkingSystem = System(
         print("Talking system has started.")
     end,
     function (p, delta)
-        print(p.name .. ", who weighs " .. p.mass .. "pounds, says, " .. p.phrase)
+        print(p.name .. ", who weighs " .. p.mass .. " pounds, says, \"" .. p.phrase .. "\"")
     end,
     personAspect
 )
@@ -61,7 +61,7 @@ local world = World(talkingSystem)
 local joe = {
     name = "Joe",
     phrase = "I'm a plumber.",
-    mass = 150,
+    mass = 250,
     hairColor = "brown"
 }
 

jojo.lua

@@ -1,5 +1,5 @@
 local jojo = {
-    _VERSION = "0.0.1",
+    _VERSION = "0.0.2",
     _URL = "https://github.com/bakpakin/Jojo"
 }
 
@@ -30,6 +30,7 @@ jojo.Aspect = Aspect
 jojo.System = System
 
 local tinsert = table.insert
+local tremove = table.remove
 local tconcat = table.concat
 local pairs = pairs
 local ipairs = ipairs
@@ -216,6 +217,9 @@ function World:init(...)
     -- Table of Entity IDs to Entities
     self.entities = {}
 
+    -- Number of Entities in World.
+    self.entityCount = 0
+
     -- List of Systems
     self.systems = args
 
@@ -226,15 +230,54 @@ function World:init(...)
     -- Next available entity ID
     self.nextID = 0
 
-    -- Table of System indices to Sets of matching Entity IDs
+    -- Table of System IDs to Sets of matching Entity IDs
     local systemEntities = {}
     self.systemEntities = systemEntities
 
     for i, sys in ipairs(args) do
-        systemEntities[i] = {}
+        local id = sys.id
-        systemIndices[sys.id] = i
+        systemEntities[id] = {}
+        systemIndices[id] = i
     end
 
+    -- List of Systems to add next update
+    self.systemsToAdd = {}
+
+    -- List of System ids to remove next update
+    self.systemsToRemove = {}
+
+end
+
+function World:__tostring()
+    return "JojoWorld<systemCount: " ..
+    #self.systems ..
+    ", entityCount: " ..
+    #self.entityCount ..
+    ">"
+end
+
+-- World:addSystems(...)
+
+-- Appends Systems in order to the World. Systems will be added after the next
+-- call to World:update(dt)
+function World:addSystems(...)
+    local args = {...}
+    local systemsToAdd = self.systemsToAdd
+    for i, sys in ipairs(args) do
+        tinsert(systemsToAdd, sys)
+    end
+end
+
+-- World:freeSystems(...)
+
+-- Appends Systems in order to the World. Systems will be added after the next
+-- call to World:update(dt)
+function World:removeSystems(...)
+    local args = {...}
+    local systemsToRemove = self.systemsToRemove
+    for i, sys in ipairs(args) do
+        tinsert(systemsToRemove, sys)
+    end
 end
 
 -- World:add(...)
@@ -287,64 +330,87 @@ function World:update(dt)
 
     local statuses = self.status
     local systemEntities = self.systemEntities
+    local systemIndices = self.systemIndices
     local entities = self.entities
     local systems = self.systems
+    local systemsToAdd = self.systemsToAdd
+    local systemsToRemove = self.systemsToRemove
 
-    for eid, s in pairs(statuses) do
+    -- Remove all Systems queued for removal
-        if s == "add" then
+    for i = #systemsToRemove, 1, -1 do
-            local e = entities[eid]
+        -- Pop system off the remove stack
-            for sysid, eids in pairs(systemEntities) do
+        local sys = systemsToRemove[i]
-                local a = systems[sysid].aspect
+        systemsToRemove[i] = nil
+
+        local id = sys.id
+        local sysIndex = systemIndices[id]
+        tremove(systems, sysIndex)
+        systemEntities[id] = nil
+    end
+
+    -- Add Systems queued for addition
+    for i = 1, #systemsToAdd do
+        -- Pop system off the add queue
+        local sys = systemsToAdd[i]
+        systemsToAdd[i] = nil
+
+        -- Add system to world
+        local id = sys.id
+        local eids = {}
+        systemEntities[id] = eids
+        tinsert(systems, sys)
+        systemIndices[id] = #systems
+
+        local a = sys.aspect
+        for eid, e in pairs(entities) do
             eids[eid] = a:matches(e) and true or nil
         end
+    end
+
+    -- Kepp track of number of Entities in World
+    local deltaEntityCount = 0
+
+    -- Add, remove, or change Entities
+    for eid, s in pairs(statuses) do
+        local e = entities[eid]
+        if s == "add" then
+            deltaEntityCount = deltaEntityCount + 1
+            for sysID, eids in pairs(systemEntities) do
+                local a = systems[systemIndices[sysID]].aspect
+                eids[eid] = a:matches(e) and true or nil
+            end
+        elseif s == "remove" then
+            deltaEntityCount = deltaEntityCount - 1
+            entities[eid] = nil
+            for _, eids in pairs(systemEntities) do
+                eids[eid] = nil
+            end
+        end
         statuses[eid] = nil
     end
-    end
 
-    for sysid, s in ipairs(self.systems) do
+    -- Update Entity count
+    self.entityCount = self.entityCount + deltaEntityCount
+
+    --  Iterate through Systems IN ORDER
+    for _, s in ipairs(self.systems) do
+        if s.active then
 
             local preupdate = s.preupdate
-        local eids = systemEntities[sysid]
+            local update = s.update
-        local active = s.active
 
-        -- Preupdate
+            if preupdate then
-        if active and preupdate then
                 preupdate(dt)
             end
 
-        if active then -- Free freed entities and update the others.
+            if update then
-
+                local eids = systemEntities[s.id]
-            local u = s.update
-
                 for eid in pairs(eids) do
-                local status = statuses[eid]
+                    update(entities[eid], dt)
-                if status == "remove" then
-                    eids[eid] = nil
-                else
-                    u(entities[eid], dt)
                 end
             end
-
-        else -- Just free freed Entities
-
-            for eid in pairs(eids) do
-                if statuses[eid] == "remove" then
-                    eids[eid] = nil
         end
     end
-
-        end
-    end
-
-    -- Reset all statuses for next update
-    for eid, s in pairs(statuses) do
-        if s == "remove" then
-            entities[eid].id = nil
-            entities[eid] = nil
-        end
-        statuses[eid] = nil
-    end
-
 end
 
 return jojo

jojotest.lua

@@ -83,12 +83,20 @@ assert(e1.xform.x == 21, "e1.xform.x should be 21, but is " .. e1.xform.x)
 assert(e2.xform.x == -19, "e2.xform.x should be -19, but is " .. e2.xform.x)
 assert(e3.xform.y == 68, "e3.xform.y should be 68, but is " .. e3.xform.y)
 
+world:removeSystems(moves)
+world:update(1234567890)
+world:addSystems(moves)
+
 world:remove(e3, e2)
 world:update(20)
 assert(e1.xform.x == 41, "e1.xform.x should be 41, but is " .. e1.xform.x)
 assert(e2.xform.x == -19, "e2.xform.x should be -19, but is " .. e2.xform.x)
 assert(e3.xform.y == 68, "e3.xform.y should be 68, but is " .. e3.xform.y)
 
+world:removeSystems(moves)
+world:update(12345)
+world:addSystems(moves)
+
 world:add(e3, e2)
 world:update(19)
 world:remove(e3, e2)