:bug: Fixed a bug where unordered patches would cause runtime errors.

2 files changed, 49 insertions, 13 deletions

diff --git a/src/lustre/internals/patch.gleam b/src/lustre/internals/patch.gleam
index 6efa63e..3e87b81 100644
--- a/src/lustre/internals/patch.gleam
+++ b/src/lustre/internals/patch.gleam
@@ -7,6 +7,7 @@ import gleam/int
 import gleam/json.{type Json}
 import gleam/list
 import gleam/option.{type Option, None, Some}
+import gleam/order.{type Order, Eq, Gt, Lt}
 import gleam/set.{type Set}
 import gleam/string
 import lustre/internals/constants
@@ -236,25 +237,38 @@ pub fn patch_to_json(patch: Patch(msg)) -> Json {
   }
 }
 
+import gleam/io
+
 pub fn element_diff_to_json(diff: ElementDiff(msg)) -> Json {
   json.preprocessed_array([
     json.preprocessed_array(
       list.reverse({
-        use array, key, element <- dict.fold(diff.created, [])
-        let json =
-          json.preprocessed_array([
-            json.string(key),
-            vdom.element_to_json(element),
-          ])
-
-        [json, ..array]
+        // Gleam's dictionaries are unordered, which is a bit of a problem for
+        // our runtime patching where we assume keys come in a stable order. To
+        // make our client code as fast as possible, we do the sort here rather
+        // than on the client.
+        dict.to_list(diff.created)
+        |> list.sort(fn(x, y) { key_sort(x.0, y.0) })
+        |> list.fold([], fn(array, patch) {
+          let #(key, element) = patch
+          io.debug(key)
+          let json =
+            json.preprocessed_array([
+              json.string(key),
+              vdom.element_to_json(element),
+            ])
+
+          [json, ..array]
+        })
       }),
     ),
     json.preprocessed_array({
-      use array, key <- set.fold(diff.removed, [])
-      let json = json.preprocessed_array([json.string(key)])
-
-      [json, ..array]
+      set.to_list(diff.removed)
+      |> list.sort(key_sort)
+      |> list.fold([], fn(array, key) {
+        let json = json.preprocessed_array([json.string(key)])
+        [json, ..array]
+      })
     }),
     json.preprocessed_array(
       list.reverse({
@@ -273,6 +287,28 @@ pub fn element_diff_to_json(diff: ElementDiff(msg)) -> Json {
   ])
 }
 
+fn key_sort(x: String, y: String) -> Order {
+  do_key_sort(string.split(x, "-"), string.split(y, "-"))
+}
+
+fn do_key_sort(xs: List(String), ys: List(String)) -> Order {
+  case xs, ys {
+    [], [] -> Eq
+    [], _ -> Lt
+    _, [] -> Gt
+    ["-", ..xs], ["-", ..ys] -> do_key_sort(xs, ys)
+    [x, ..xs], [y, ..ys] -> {
+      let assert Ok(x) = int.parse(x)
+      let assert Ok(y) = int.parse(y)
+
+      case int.compare(x, y) {
+        Eq -> do_key_sort(xs, ys)
+        order -> order
+      }
+    }
+  }
+}
+
 pub fn attribute_diff_to_json(diff: AttributeDiff(msg), key: String) -> Json {
   json.preprocessed_array([
     json.preprocessed_array({
diff --git a/src/lustre/server_component.gleam b/src/lustre/server_component.gleam
index 2b15314..6921e8f 100644
--- a/src/lustre/server_component.gleam
+++ b/src/lustre/server_component.gleam
@@ -109,7 +109,7 @@ pub fn script() -> Element(msg) {
   element("script", [attribute("type", "module")], [
     // <<INJECT RUNTIME>>
     element.text(
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+      "function w(t,e,i,o=!1){let s,a=[{prev:t,next:e,parent:t.parentNode}];for(;a.length;){let{prev:n,next:r,parent:l}=a.pop();if(r.subtree!==void 0&&(r=r.subtree()),r.content!==void 0)if(n)if(n.nodeType===Node.TEXT_NODE)n.textContent!==r.content&&(n.textContent=r.content),s??=n;else{let c=document.createTextNode(r.content);l.replaceChild(c,n),s??=c}else{let c=document.createTextNode(r.content);l.appendChild(c),s??=c}else if(r.tag!==void 0){let c=D({prev:n,next:r,dispatch:i,stack:a,isComponent:o});n?n!==c&&l.replaceChild(c,n):l.appendChild(c),s??=c}else r.elements!==void 0?x(r,c=>{a.unshift({prev:n,next:c,parent:l}),n=n?.nextSibling}):r.subtree!==void 0&&a.push({prev:n,next:r,parent:l})}return s}function J(t,e,i){let o=t.parentNode;for(let s of e[0]){let a=s[0].split(\"-\"),n=s[1],r=k(o,a),l;if(r!==null&&r!==o)l=w(r,n,i);else{let c=k(o,a.slice(0,-1)),u=document.createTextNode(\"\");c.appendChild(u),l=w(u,n,i)}a===\"0\"&&(t=l)}for(let s of e[1]){let 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     ),
   ])
 }