src/cleanup.luau

@@ -13,3 +13,4 @@ local function cleanup(fn: () -> ())
 end
 
 return cleanup
+

src/graph.luau

@@ -3,34 +3,22 @@ if not game then script = require "test/relative-string" end
 local throw = require(script.Parent.throw)
 local flags = require(script.Parent.flags)
 
-export type Scope = {
-    parent: Scope | false,
-    cleanups: { () -> () } | false,
-    [number]: Scope -- children
-}
-
 export type StartNode<T> = {
     cache: T,
+    n: number,
     [number]: Node<T>
 }
 
 export type Node<T> = StartNode<T> & {
-    scope: Scope,
     effect:  (T) -> (),
+    cleanups: { () -> () } | false,
 }
 
--- flag used to detect when node reference capturing is active
-local reff = false
--- array of all nodes referenced since above flag was set
-local refs = {} :: { StartNode<unknown> }
-
-local scopes = { n = 0 } :: { [number]: Scope, n: number }
+local scopes = { n = 0 } :: { [number]: Node<any>, n: number }
 
 local WEAK_VALUES = { __mode = "v" }
 local EVALUATION_ERR = "error while evaluating source:\n\n"
 
-setmetatable(refs :: any, WEAK_VALUES)
-
 -- runs a given callback in a context that Luau does not allow yielding in
 local check_for_yield: <T...>(fn: (T...) -> unknown, T...) -> () do
     local t = { __mode = "kv" }
@@ -57,14 +45,32 @@ local check_for_yield: <T...>(fn: (T...) -> unknown, T...) -> () do
     end
 end
 
-local function get_scope(): Scope
+local function get_scope(): Node<unknown>
     return scopes[scopes.n]
 end
 
-local function open_scope(scope: Scope)
+local function add_child<T>(parent: Node<any>, child: Node<any>)
+    local n = parent.n + 1
+    parent.n = n
+    parent[n] = child
+end
+
+-- local function open_root_scope<T>(node: Node<T>)
+--     assert(not scopes[1])
+
+--     local n = scopes.n + 1
+--     scopes.n = n
+--     scopes[n] = node
+-- end
+
+local function open_scope<T>(node: Node<T>)
     local n = scopes.n + 1
     scopes.n = n
-    scopes[n] = scope
+    scopes[n] = node
+
+    -- local parent = scopes[n-1]
+    -- assert(parent)
+    -- add_child(parent, node)
 end
 
 local function close_scope()
@@ -73,124 +79,74 @@ local function close_scope()
     scopes[n] = nil
 end
 
-local function add_cleanup(scope: Scope, cleanup: () -> ())
-    if scope.cleanups then
-        table.insert(scope.cleanups, cleanup)
+local function add_cleanup<T>(node: Node<T>, cleanup: () -> ())
+    if node.cleanups then
+        table.insert(node.cleanups, cleanup)
     else
-        scope.cleanups = { cleanup }
+        node.cleanups = { cleanup }
     end
 end
 
-local function run_cleanups(scope: Scope)
-    if scope.cleanups then
-        for _, fn in next, scope.cleanups do
+local function run_cleanups<T>(node: Node<T>)
+    if node.cleanups then
+        for _, fn in next, node.cleanups do
             fn()
         end
-        table.clear(scope.cleanups)
+        table.clear(node.cleanups)
     end
 end
 
---[[
-
-Each node side-effect is registered with a corresponding weak key.
-This makes the lifetime of the side-effect tied to the key's.
-The main usecase of this is to tie a side-effect to an instance, while allowing
-the instance to be garbage collected even when the node still exists.
-
-The weak key is passed as an argument to its side-effect callback.
-
-]]
-
 local function run_effect<T>(node: Node<T>)
     node.effect(node.cache)
 end
 
-local function add_child(parent: StartNode<any>, child: Node<any>)
-    table.insert(parent, child)
-end
-
-local function add_children(parent: Node<any>, children: { Node<any> })
-    for _, child in next, children do
-        table.insert(parent, child)
-    end
-end
-
-local function destroy(scope: Scope)
-    run_cleanups(scope)
-    for _, child in ipairs(scope) do
+local function destroy<T>(node: Node<T>)
+    run_cleanups(node)
+    for _, child in ipairs(node) do
         destroy(child)
     end
 end
 
 -- runs node effects, recalculates descendants and runs descendant effects
 local function update<T>(node: StartNode<T>)
-    for _, child in ipairs(node) do
-        local scope = child.scope
-        assert(scope)
-        open_scope(scope :: Scope)
-        run_cleanups(scope :: Scope)
+    local children = { unpack(node) }
+    for i = 1, node.n do
+        node[i] = nil
+    end
+    node.n = 0
+
+    for _, child in children do
+        open_scope(child)
+        run_cleanups(child)
         run_effect(child)
-        update(child)
         close_scope()
+        update(child)
     end
 end
 
--- detect what nodes were referenced in the given callback and returns them in an array
-local function capture<T, U>(fn: (U?) -> T, arg: U?): ({ StartNode<unknown> }, T)
-    if reff then throw("recursive capture detected") end
-
-    table.clear(refs)
-    reff = true
-
-    local ok: boolean, result: T|string
-    
-    if arg == nil then
-        ok, result = pcall(fn)
-    else
-        ok, result = pcall(fn, arg)
-    end
-
-    reff = false
-
-    if not ok then throw(EVALUATION_ERR .. result :: string) end
-
-    return refs, result :: T
-end
-
-local function capture_parents<T, U>(child: Node<T>, fn: (U?) -> T, arg: U?): T
-    local refs, result = capture(fn, arg)
-
-    for _, parent in next, refs do
-        add_child(parent, child)
-    end
-
-    return result
-end
-
-local function track<T>(node: StartNode<T>)
-    if reff then table.insert(refs, node :: Node<any>) end
-end
-
-local function create_scope(): Scope
-    return {
-        parent = get_scope() or false,
-        cleanups = false
-    }
+local function track<T>(node: Node<T>)
+    add_child(node, get_scope())
 end
 
 local function create_node<T>(value: T): Node<T>
     return {
-        scope = create_scope(),
         cache = value,
         effect = function() end,
+        cleanups = false :: false,
+        n = 0
     }
 end
 
+local function get_children(node: Node<unknown>): { Node<unknown> }
+    return { unpack(node) }
+end
+
 local function create_start_node<T>(value: T): StartNode<T>
-    return { cache = value }
+    return { cache = value, n = 0 }
 end
 
 return table.freeze {
+    open_root_scope = open_root_scope,
     open_scope = open_scope,
     close_scope = close_scope,
     get_scope = get_scope,
@@ -200,11 +156,7 @@ return table.freeze {
     track = track,
     update = update,
     add_child = add_child,
-    add_children = add_children,
-    capture = capture,
-    capture_parents = capture_parents,
     create_node = create_node,
     create_start_node = create_start_node,
-    create_scope = create_scope,
-    refs = refs
+    get_children = get_children
 }

test/tests.luau

@@ -1,5 +1,7 @@
 local testkit = require("test/testkit")
-local TEST, CASE, CHECK, FINISH = testkit.test()
+local TEST, CASE, CHECK, FINISH, SKIP = testkit.test()
+
+SKIP"graph"
 
 local mock = require "test/mock"
 local Instance, Signal = mock.Instance, mock.Signal
@@ -29,40 +31,60 @@ TEST("graph", function()
     local graph = require "src/graph"
     local create_node = graph.create_node
     local track = graph.track
-    local capture = graph.capture
     local update = graph.update
     local add_child = graph.add_child
+    local open_root_scope = graph.open_root_scope
+    local open_scope = graph.open_scope
+    local close_scope = graph.close_scope
+    local get_children = graph.get_children
 
     do CASE "node creation"
         local node = create_node(1)
         CHECK(node.cache == 1)
     end
 
-    do CASE "capture nodes"
-        local node1 = create_node(nil)
-        local node2 = create_node(nil)
-        local captured = capture(function()
-            track(node1)
-            track(node2)
-            return nil
-        end)
-        CHECK(captured[1] == node1)
-        CHECK(captured[2] == node2)
+    do CASE "link nodes"
+        local a = create_node(nil)
+        local b = create_node(nil)
+        local c = create_node(nil)
+
+        open_scope(c)
+
+        track(a)
+        track(b)
+
+        close_scope()
+
+        CHECK(get_children(a)[1] == c)
+        CHECK(get_children(b)[1] == c)
     end
 
-    do CASE "linking nodes"
-        local parent = create_node(1)
-        local child = create_node(0)
+    do CASE "rerun linked nodes"
+        local a = create_node(nil)
+        local b = create_node(nil)
+        local c = create_node(nil)
 
-        add_child(parent, child)
+        local count = 0
 
-        local ran = false
-        child.effect = function()
-            ran = true
+        local function effect()
+            track(a)
+            track(b)
+            count += 1
         end
 
-        update(parent)
-        CHECK(ran)
+        c.effect = effect
+
+        open_scope(c)
+
+        effect()
+
+        close_scope()
+        
+        CHECK(count == 1)
+        update(a)
+        CHECK(count == 2)
+        update(b)
+        CHECK(count == 3)
     end
 
     -- todo: further tests
@@ -72,6 +94,10 @@ TEST("graph", function()
         gc()
         CHECK(not wref[1])
     end
+
+    do CASE "test"
+        local x = 1
+    end
 end)
 
 TEST("source()", wrap_root(function()