From 7c08c6bb76498f05b512ef09b4129a75496ec620 Mon Sep 17 00:00:00 2001
From: Andreas Rumpf <rumpf_a@web.de>
Date: Wed, 16 Aug 2017 19:42:16 +0200
Subject: [PATCH] first version; wip

---
 experiments/nextgen.nim    | 181 +++++++++++++++++++++++++++++++++++++
 experiments/scrollapp.nims |   1 -
 src/karax.nim              |  32 ++++++-
 src/vdom.nim               |   3 +-
 4 files changed, 212 insertions(+), 5 deletions(-)
 create mode 100644 experiments/nextgen.nim
 delete mode 100644 experiments/scrollapp.nims

diff --git a/experiments/nextgen.nim b/experiments/nextgen.nim
new file mode 100644
index 0000000..eb94658
--- /dev/null
+++ b/experiments/nextgen.nim
@@ -0,0 +1,181 @@
+
+import kdom, jdict, jstrutils
+
+type
+  Message = enum
+    Unchanged
+    Changed
+    Mark
+    Inserted
+    Deleted
+
+  State = object
+    stale: int
+    outdated: bool
+    phantom: bool
+
+type
+  ReactiveBase* = ref object of RootObj ## everything that is a "reactive"
+                                        ## value derives from that
+    sinks*: seq[proc(msg: Message, pos: int)]
+  Reactive*[T] = ref object of ReactiveBase
+    value*: T
+
+  RString* = Reactive[cstring]
+#  RTime* = Reactive[Time]
+  RInt* = Reactive[int]
+
+  RBool* = Reactive[bool]
+
+  RSeq*[T] = ref object of ReactiveBase
+    s: seq[T]
+    L: RInt
+
+proc addSink[T](x: Reactive[T]; sink: proc(msg: Message; pos: int)) =
+  x.sinks.add sink
+
+proc broadcast(x: ReactiveBase, msg: Message; pos = 0) =
+  for s in x.sinks: s(msg, pos)
+
+var toTrack: proc (msg: Message; pos: int) = nil
+
+proc now[T](x: Reactive[T]): T =
+  if toTrack != nil:
+    x.addSink toTrack
+  result = x.value
+
+proc `:=`[T](x: Reactive[T], f: proc(): T) =
+  var state: State
+
+  toTrack = proc(msg: Message; pos: int) =
+    if not state.phantom:
+      case msg.kind:
+      of Changed, Unchanged:
+        state.outdated = state.outdated or (msg.kind == Changed)
+        dec state.stale
+        if state.stale == 0:
+          if state.outdated:
+            var t = f()
+            let thisChanged = if x.value != t: Changed else: Unchanged
+            x.value = t
+            x.broadcast(thisChanged, pos)
+            state.outdated = false
+          else:
+            x.broadcast(Unchanged, pos)
+      of Mark:
+        if state.stale == 0:
+          x.broadcast(msg, pos)
+        inc state.stale
+      of Inserted, Deleted:
+        dec state.stale
+        if state.stale == 0:
+          x.broadcast(msg, pos)
+          #state.phantom = true
+
+  x.value = f()
+  toTrack = nil
+
+proc `<-`[T](x: Reactive[T], val: T) =
+  if x.value != val:
+    x.value = val
+    x.broadcast(Mark)
+    x.broadcast(Changed)
+
+proc changed*(x: ReactiveBase) =
+  x.broadcast(Mark)
+  x.broadcast(Changed)
+
+proc subscribe[T](x: Reactive[T], f: proc(x: T)) =
+  let reactor = proc (msg: Message, pos: int) =
+    case msg:
+    of Mark: discard
+    of Changed, Unchanged: f(x.value)
+    of Inserted, Deleted: discard
+  x.addSink reactor
+
+template lift1(op: untyped) =
+  proc op[T](a: Reactive[T]): (proc(): T) =
+    result = proc(): T = op(a.now)
+
+template lift2(op: untyped) =
+  proc op[T](a, b: Reactive[T]): (proc(): T) =
+    result = proc(): T = op(a.now, b.now)
+
+lift1 `not`
+lift2 `&`
+
+proc newReactive[T](x: T): Reactive[T] =
+  result = Reactive[T](value: x)
+
+proc rstr(x: cstring): RString =
+  result = RString(value: x)
+
+proc newRSeq*[T](len: int): RSeq[T] =
+  result = RSeq[T](s: newSeq[T](len), L: newReactive[int](0))
+
+proc newRSeq*[T](data: seq[T]): RSeq[T] =
+  result = RSeq[T](s: newSeq[T](data.len), L: newReactive[int](0))
+  for i in 0..high(data):
+    result.s[i] = data[i]
+
+proc `[]=`[T](x: RSeq[T]; index: int; v: T) =
+  x.s[index] = v
+
+proc `[]`[T](x: RSeq[T]; index: int): T = x.s[index]
+
+proc insert*[T](x: RSeq[T]; y: T; position = 0) =
+  x.s.insert(y, position)
+  x.broadcast(Mark)
+  x.broadcast(Inserted, position)
+
+proc delete*[T](x: RSeq[T]; position = 0) =
+  x.s.delete(position)
+  x.broadcast(Mark)
+  x.broadcast(Deleted, position)
+
+proc map[T, U](x: RSeq[T], f: proc(x: T): U): RSeq[U] =
+  let xl = x.L.value
+  let res = newRSeq[U](xl)
+  for i in 0..<xl:
+    res.s[i] := proc(): U = f(x[i].now)
+
+  let reactor = proc (msg: Message, pos: int) =
+    case msg:
+    of Mark, Changed, Unchanged: discard "nothing to do"
+    of Inserted:
+      res.insert(f(x[pos]), pos)
+    of Deleted:
+      res.delete(pos)
+  x.addSink reactor
+  result = res
+
+type
+  User = ref object
+    firstname, lastname: cstring
+
+var gu = newReactive(User(firstname: "Some", lastname: "Body"))
+
+proc renderUser(u: Reactive[User]): Node =
+  result = document.createElement("button")
+  result.appendChild document.createTextNode(u.now.firstname & " " & u.now.lastname)
+  result.addEventListener "click", proc (ev: Event) =
+    gu <- User(firstname: "Another", lastname: "Guy")
+
+proc replaceById(id: cstring; newTree: Node) =
+  let x = document.getElementById(id)
+  x.parentNode.replaceChild(newTree, x)
+  newTree.id = id
+
+template track(r: ReactiveBase; a, b: Node) =
+  r.addSink proc(m: Message; pos: int) =
+    if m == Changed:
+      a.parentNode.replaceChild(b, a)
+
+proc main(): Node =
+  result = renderUser(gu)
+  track gu, result, renderUser(gu)
+
+proc init(ev: Event) =
+  replaceById("ROOT", main())
+
+window.onload = init
diff --git a/experiments/scrollapp.nims b/experiments/scrollapp.nims
deleted file mode 100644
index 532b206..0000000
--- a/experiments/scrollapp.nims
+++ /dev/null
@@ -1 +0,0 @@
---path: "../src"
diff --git a/src/karax.nim b/src/karax.nim
index 5cee5cf..b0b7761 100644
--- a/src/karax.nim
+++ b/src/karax.nim
@@ -37,6 +37,7 @@ type
     patchLenV: int
     runCount: int
     components: seq[ComponentPair]
+    surpressRedraws*: bool
     when defined(stats):
       recursion: int
 
@@ -117,7 +118,7 @@ proc applyEvents(n: VNode; kxi: KaraxInstance) =
   for i in 0..<len(n.events):
     n.events[i][2] = wrapEvent(dest, n, n.events[i][0], n.events[i][1])
 
-proc vnodeToDom(n: VNode; kxi: KaraxInstance): Node =
+proc vnodeToDom*(n: VNode; kxi: KaraxInstance): Node =
   if n.kind == VNodeKind.text:
     result = document.createTextNode(n.text)
     attach n
@@ -134,6 +135,7 @@ proc vnodeToDom(n: VNode; kxi: KaraxInstance): Node =
     return result
   elif n.kind == VNodeKind.component:
     let x = VComponent(n)
+    if x.realDomImpl != nil: return x.realDomImpl(x)
     if x.onAttachImpl != nil: x.onAttachImpl(x)
     assert x.renderImpl != nil
     if x.expanded == nil:
@@ -465,7 +467,11 @@ proc applyComponents(kxi: KaraxInstance) =
     let newNode = kxi.components[i].newNode
     when defined(karaxDebug):
       echo "Processing component ", newNode.text, " changed impl set ", x.changedImpl != nil
-    if x.changedImpl != nil and x.changedImpl(x, newNode):
+    if x.realDomImpl != nil:
+      let current = kxi.components[i].current
+      let parent = kxi.components[i].parent
+      kxi.addPatch(pkReplace, parent, current, x)
+    elif x.changedImpl != nil and x.changedImpl(x, newNode):
       when defined(karaxDebug):
         echo "Component ", newNode.text, " did change"
       let current = kxi.components[i].current
@@ -507,6 +513,14 @@ when defined(stats):
     result = m + 1
     inc total
 
+proc runDiff*(kxi: KaraxInstance; oldNode, newNode: VNode) =
+  let olddom = oldNode.dom
+  discard diff(newNode, oldNode, nil, olddom, kxi)
+  applyComponents(kxi)
+  applyPatch(kxi)
+  if kxi.currentTree == oldNode:
+    kxi.currentTree = newNode
+
 proc dodraw(kxi: KaraxInstance) =
   if kxi.renderer.isNil: return
   let newtree = kxi.renderer()
@@ -576,6 +590,18 @@ proc setRenderer*(renderer: proc (): VNode, root: cstring = "ROOT",
   kxi = result
   window.onload = init
 
+proc setInitializer*(renderer: proc (): VNode, root: cstring = "ROOT",
+                    clientPostRenderCallback: proc () = nil): KaraxInstance {.discardable.} =
+  ## Setup Karax. Usually the return value can be ignored.
+  result = KaraxInstance(rootId: root, renderer: renderer,
+                        postRenderCallback: clientPostRenderCallback,
+                        patches: newSeq[Patch](60),
+                        patchesV: newSeq[PatchV](30),
+                        components: @[],
+                        surpressRedraws: true)
+  kxi = result
+  window.onload = init
+
 proc addEventHandler*(n: VNode; k: EventKind; action: EventHandler;
                       kxi: KaraxInstance = kxi) =
   ## Implements the foundation of Karax's event management.
@@ -585,7 +611,7 @@ proc addEventHandler*(n: VNode; k: EventKind; action: EventHandler;
   ## a ``redraw``.
   proc wrapper(ev: Event; n: VNode) =
     action(ev, n)
-    redraw(kxi)
+    if not kxi.surpressRedraws: redraw(kxi)
   addEventListener(n, k, wrapper)
 
 proc setOnHashChange*(action: proc (hashPart: cstring)) =
diff --git a/src/vdom.nim b/src/vdom.nim
index f31d6d6..d055b50 100644
--- a/src/vdom.nim
+++ b/src/vdom.nim
@@ -133,6 +133,7 @@ type
     updatedImpl*: proc(self, newInstance: VComponent)
     onAttachImpl*: proc(self: VComponent)
     onDetachImpl*: proc(self: VComponent)
+    realDomImpl*: proc(self: VComponent): kdom.Node
     version*: int         ## Update this to trigger a redraw by karax. Usually you
                           ## should call 'markDirty' instead which is an alias for
                           ## 'inc version'.
@@ -185,7 +186,7 @@ proc getDebugId(): int =
   gid
 
 template newComponent*[T](t: typeDesc[T];
-                 render: (proc(self: VComponent): VNode) not nil,
+                 render: (proc(self: VComponent): VNode) = nil,
                  onAttach: proc(self: VComponent) = nil,
                  onDetach: proc(self: VComponent) = nil,
                  changed: (proc(self, newInstance: VComponent): bool) = defaultChangedImpl,