Change API.

Remove Aspects for Filters.

README.md

@@ -9,8 +9,9 @@ Component Systems, here is some
 Copy paste tiny.lua into your source folder.
 
 ## Overview ##
-Tiny-ecs has four important types: Worlds, Aspects, Systems, and Entities.
+Tiny-ecs has four important types: Worlds, Filters, Systems, and Entities.
-Entities, however, can be any lua table.
+Entities, however, can be any lua table, and Filters are just functions that
+take an Entity as a parameter.
 
 ### Entities ###
 Entities are simply lua tables of data that gets processed by Systems. Entities
@@ -24,32 +25,25 @@ and Entities. In typical use, only one World is used at a time.
 
 ### Systems ###
 Systems in tiny-ecs describe how to update Entities. Systems select certain Entities
-using an aspect, and then only update those select Entities. Systems have three
+using a Filter, and then only update those select Entities. Some Systems don't
-parts: a one-time update function, a per Entity update function, and an Aspect.
+update Entities, and instead just act as function callbacks every update. Tiny-ecs
-The one-time update function is called once per World update, and the per Entity
+provides functions for creating Systems easily.
-update function is called once per Entity per World update. The Aspect is used
-to select which Entities the System will update.
 
-### Aspects ###
+### Filters ###
-Aspects are used to select Entities by the presence or absence of specific
+Filters are used to select Entities. Filters can be any lua function, but
-Components. If an Entity contains all Components required by an Aspect, and
+tiny-ecs provides some functions for generating common ones, like selecting
-doesn't contain Components that are excluded by the Aspect, it is said to match
+only Entities that have all required components.
-the Aspect. Aspects can also be composed into more complicated Aspects that
-are equivalent to the union of all sub-Aspects.
 
 ## Example ##
 ```lua
 local tiny = require("tiny")
 
-local personAspect = tiny.Aspect({"name", "mass", "phrase"})
+local talkingSystem = tiny.processingSystem(
-
+    tiny.requireAll("name", "mass", "phrase"),
-local talkingSystem = tiny.System(
-    nil,
     function (p, delta)
         p.mass = p.mass + delta * 3
         print(p.name .. ", who weighs " .. p.mass .. " pounds, says, \"" .. p.phrase .. "\"")
-    end,
+    end
-    personAspect
 )
 
 local joe = {
@@ -59,7 +53,7 @@ local joe = {
     hairColor = "brown"
 }
 
-local world = tiny.World(talkingSystem, joe)
+local world = tiny.newWorld(talkingSystem, joe)
 
 for i = 1, 20 do
     world:update(1)

spec/tiny_spec.lua

@@ -1,9 +1,5 @@
 local tiny = require "tiny"
 
-local World = tiny.World
-local Aspect = tiny.Aspect
-local System = tiny.System
-
 -- Taken from answer at http://stackoverflow.com/questions/640642/how-do-you-copy-a-lua-table-by-value
 local function deep_copy(o, seen)
   seen = seen or {}
@@ -39,7 +35,8 @@ local entityTemplate2 = {
     vel = {x = -1, y = 0},
     name = "E2",
     size = 10,
-    description = "It does not go to 11."
+    description = "It does not go to 11.",
+    onlyTen = true
 }
 
 local entityTemplate3 = {
@@ -47,12 +44,13 @@ local entityTemplate3 = {
     vel = {x = 0, y = 3},
     name = "E3",
     size = 8,
-    description = "The smallest entity."
+    description = "The smallest entity.",
+    littleMan = true
 }
 
 describe('tiny-ecs:', function()
 
-    describe('Aspect:', function()
+    describe('Filters:', function()
 
         local entity1, entity2, entity3
 
@@ -62,21 +60,22 @@ describe('tiny-ecs:', function()
             entity3 = deep_copy(entityTemplate3)
         end)
 
-        it("Correctly match Aspects and Entities", function()
+        it("Default Filters", function()
 
-            local atap = Aspect({"spinalTap"})
+            local ftap = tiny.requireAll("spinalTap")
-            local avel = Aspect({"vel"})
+            local fvel = tiny.requireAll("vel")
-            local axform = Aspect({"xform"})
+            local fxform = tiny.requireAll("xform")
-            local aall = Aspect({})
+            local fall = tiny.requireOne("spinalTap", "onlyTen", "littleMan")
-            local aboth = Aspect.compose(atap, axform)
-            local amove = Aspect.compose(axform, avel)
 
-            assert.truthy(atap:matches(entity1))
+            assert.truthy(fall(entity1))
-            assert.falsy(atap:matches(entity2))
+            assert.truthy(ftap(entity1))
-            assert.truthy(axform:matches(entity1))
+            assert.falsy(ftap(entity2))
-            assert.truthy(axform:matches(entity2))
+            assert.truthy(fxform(entity1))
-            assert.truthy(aboth:matches(entity1))
+            assert.truthy(fxform(entity2))
-            assert.falsy(aboth:matches(entity2))
+
+            assert.truthy(fall(entity1))
+            assert.truthy(fall(entity2))
+            assert.truthy(fall(entity3))
 
         end)
 
@@ -86,20 +85,19 @@ describe('tiny-ecs:', function()
 
         local world, entity1, entity2, entity3
 
-        local moveSystem = System(
+        local moveSystem = tiny.processingSystem(
-            nil,
+            tiny.requireAll("xform", "vel"),
             function(e, dt)
                 local xform = e.xform
                 local vel = e.vel
                 local x, y = xform.x, xform.y
                 local xvel, yvel = vel.x, vel.y
                 xform.x, xform.y = x + xvel * dt, y + yvel * dt
-            end,
+            end
-            Aspect({"xform", "vel"})
         )
 
         local timePassed = 0
-        local oneTimeSystem = System(
+        local oneTimeSystem = tiny.emptySystem(
             function(dt)
                 timePassed = timePassed + dt
             end
@@ -109,7 +107,7 @@ describe('tiny-ecs:', function()
             entity1 = deep_copy(entityTemplate1)
             entity2 = deep_copy(entityTemplate2)
             entity3 = deep_copy(entityTemplate3)
-            world = World(moveSystem, oneTimeSystem, entity1, entity2, entity3)
+            world = tiny.newWorld(moveSystem, oneTimeSystem, entity1, entity2, entity3)
             timePassed = 0
         end)
 

tiny.lua

@@ -12,13 +12,12 @@ local ipairs = ipairs
 local setmetatable = setmetatable
 local getmetatable = getmetatable
 
--- Simplified class implementation with no inheritance or polymorphism.
+-- Simple class implementation with no inheritance or polymorphism.
-local function class(name)
+local function class()
     local c = {}
     local mt = {}
     setmetatable(c, mt)
     c.__index = c
-    c.name = name
     function mt.__call(_, ...)
         local newobj = {}
         setmetatable(newobj, c)
@@ -30,159 +29,14 @@ local function class(name)
     return c
 end
 
-local World = class("World")
-local Aspect = class("Aspect")
-local System = class("System")
-
-tiny.World = World
-tiny.Aspect = Aspect
-tiny.System = System
-
------ Aspect -----
-
--- Aspect(required, excluded, oneRequired)
-
--- Creates an Aspect. Aspects are used to select which Entities are inlcuded
--- in each system. An Aspect has three fields, namely all required Components,
--- all excluded Components, and Components of which a system requires only one.
--- If an Entitiy has all required Components, none of the excluded Components,
--- and at least one of the oneRequired Components, it matches the Aspects.
--- This method expects at least one and up to three lists of strings, the names
--- of components. If no arguments are supplied, the Aspect will not match any
--- Entities. Will not mutate supplied arguments.
-function Aspect:init(required, excluded, oneRequired)
-
-    local r, e, o = {}, {}, {}
-    self[1], self[2], self[3] = r, e, o
-
-    -- Check for empty Aspect
-    if not required and not oneRequired then
-        self[4] = true
-        return
-    end
-    self[4] = false
-
-    local excludeSet, requiredSet = {}, {}
-
-    -- Iterate through excluded Components
-    for _, v in ipairs(excluded or {}) do
-        tinsert(e, v)
-        excludeSet[v] = true
-    end
-
-    -- Iterate through required Components
-    for _, v in ipairs(required or {}) do
-        if excludeSet[v] then -- If Comp. is required and excluded, empty Aspect
-            self[1], self[2], self[3], self[4] = {}, {}, {}, true
-            return
-        else
-            tinsert(r, v)
-            requiredSet[v] = true
-        end
-    end
-
-    -- Iterate through one-required Components
-    for _, v in ipairs(oneRequired or {}) do
-        if requiredSet[v] then -- If one-required Comp. is also required,
-            -- don't need one required Components
-            self[3] = {}
-            return
-        end
-        if not excludeSet[v] then
-            tinsert(o, v)
-        end
-    end
-end
-
--- Aspect.compose(...)
-
--- Composes multiple Aspects into one Aspect. The resulting Aspect will match
--- any Entity that matches all sub Aspects.
-function Aspect.compose(...)
-
-    local newa = {{}, {}, {}}
-
-    for _, a in ipairs{...} do
-
-        if a[4] then -- Aspect must be empty Aspect
-            return Aspect()
-        end
-
-        for i = 1, 3 do
-            for _, c in ipairs(a[i]) do
-                tinsert(newa[i], c)
-            end
-        end
-
-    end
-
-    return Aspect(newa[1], newa[2], newa[3])
-end
-
--- Aspect:matches(entity)
-
--- Returns boolean indicating if an Entity matches the Aspect.
-function Aspect:matches(entity)
-
-    -- Aspect is the empty Aspect
-    if self[4] then return false end
-
-    local rs, es, os = self[1], self[2], self[3]
-
-    -- Assert Entity has all required Components
-    for i = 1, #rs do
-        local r = rs[i]
-        if entity[r] == nil then return false end
-    end
-
-    -- Assert Entity has no excluded Components
-    for i = 1, #es do
-        local e = es[i]
-        if entity[e] ~= nil then return false end
-    end
-
-    -- if Aspect has at least one Component in the one-required
-    -- field, assert that the Entity has at least one of these.
-    if #os >= 1 then
-        for i = 1, #os do
-            local o = os[i]
-            if entity[o] ~= nil then return true end
-        end
-        return false
-    end
-
-    return true
-end
-
-function Aspect:__tostring()
-    if self[4] then
-        return "TinyAspect<>"
-    else
-        return "TinyAspect<Required: {" ..
-        tconcat(self[1], ", ") ..
-        "}, Excluded: {" ..
-        tconcat(self[2], ", ") ..
-        "}, One Req.: {" ..
-        tconcat(self[3], ", ") ..
-        "}>"
-    end
-end
-
 -- --- System --- --
+local System = class()
 
--- System(preupdate, update, [aspect, addCallback, removeCallback])
+-- Initializes a System.
-
+function System:init(preupdate, filter, update, add, remove)
--- Creates a new System with the given aspect and update callback. The update
--- callback should be a function of one parameter, an entity. If no aspect is
--- provided the empty Aspect, which matches no Entity, is used. Preupdate is a
--- function of no arguments that is called once per system update before the
--- entities are updated. The add and remove callbacks are optional functions
--- that are called when entities are added or removed from the system. They
--- should each take one argument - an Entity.
-function System:init(preupdate, update, aspect, add, remove)
     self.preupdate = preupdate
     self.update = update
-    self.aspect = aspect or Aspect()
+    self.filter = filter
     self.add = add
     self.remove = remove
 end
@@ -192,16 +46,15 @@ function System:__tostring()
     self.preupdate ..
     ", update: " ..
     self.update ..
-    ", aspect: " ..
+    ", filter: " ..
-    self.aspect ..
+    self.filter ..
     ">"
 end
 
 -- --- World --- --
+local World = class()
 
--- World(...)
+-- Initializes a World.
-
--- Creates a new World with the given Systems and Entities in order.
 function World:init(...)
 
     -- Table of Entities to status
@@ -252,7 +105,7 @@ end
 
 -- Adds Entities and Systems to the World. New objects will enter the World the
 -- next time World:update(dt) is called. Also call this method when an Entity
--- has had its Components changed, such that it matches different Aspects.
+-- has had its Components changed, such that it matches different Filters.
 function World:add(...)
     local args = {...}
     local status = self.status
@@ -275,11 +128,12 @@ end
 function World:remove(...)
     local args = {...}
     local status = self.status
+    local entities = self.entities
     local systemsToRemove = self.systemsToRemove
     for _, obj in ipairs(args) do
         if getmetatable(obj) == System then
             tinsert(systemsToRemove, obj)
-        else -- Assume obj is an Entity
+        elseif entities[obj] then -- Assume obj is an Entity
             status[obj] = "remove"
         end
     end
@@ -360,9 +214,11 @@ function World:manageSystems()
             systemIndices[sys] = #systems
             activeSystems[sys] = true
 
-            local a = sys.aspect
+            local a = sys.filter
+            if a then
                 for e in pairs(entities) do
-                es[e] = a:matches(e) and true or nil
+                    es[e] = a(e) and true or nil
+                end
             end
 
             deltaSystemCount = deltaSystemCount + 1
@@ -391,19 +247,22 @@ function World:manageEntities()
         if s == "add" then
             deltaEntityCount = deltaEntityCount + 1
             for sys, es in pairs(systemEntities) do
-                local matches = sys.aspect:matches(e) and true or nil
+                local filter = sys.filter
+                if filter then
+                    local matches = filter(e) and true or nil
                     local addCallback = sys.add
                     if addCallback and matches and not es[e] then
                         addCallback(e)
                     end
                     es[e] = matches
                 end
+            end
         elseif s == "remove" then
             deltaEntityCount = deltaEntityCount - 1
             entities[e] = nil
             for sys, es in pairs(systemEntities) do
                 local removec = sys.remove
-                if removec then
+                if es[e] and removec then
                     removec(e)
                 end
                 es[e] = nil
@@ -467,4 +326,62 @@ function World:setSystemActive(system, active)
     self.activeSystem[system] = active and true or nil
 end
 
+-- --- Top Level module functions --- --
+
+--- Creates a new tiny-ecs World.
+function tiny.newWorld(...)
+    return World(...)
+end
+
+--- Makes a Filter that filters Entities with specified Components.
+-- An Entity must have all Components to match the filter.
+function tiny.requireAll(...)
+    local components = {...}
+    local len = #components
+    return function(e)
+        local c
+        for i = 1, len do
+            c = components[i]
+            if e[c] == nil then
+                return false
+            end
+        end
+        return true
+    end
+end
+
+--- Makes a Filter that filters Entities with specified Components.
+-- An Entity must have at least one specified Component to match the filter.
+function tiny.requireOne(...)
+    local components = {...}
+    local len = #components
+    return function(e)
+        local c
+        for i = 1, len do
+            c = components[i]
+            if e[c] ~= nil then
+                return true
+            end
+        end
+        return false
+    end
+end
+
+--- Creates a System that doesn't update any Entities, but executes a callback
+-- once per update.
+function tiny.emptySystem(callback)
+    return System(callback)
+end
+
+--- Creates a System that processes Entities every update. Also provides
+-- optional callbacks for when Entities are added or removed from the System.
+function tiny.processingSystem(filter, entityCallback, onAdd, onRemove)
+    return System(nil, filter, entityCallback, onAdd, onRemove)
+end
+
+--- Creates a System.
+function tiny.system(callback, filter, entityCallback, onAdd, onRemove)
+    return System(callback, filter, entityCallback, onAdd, onRemove)
+end
+
 return tiny