WIP

src/patch_promise.js

@@ -1,78 +1,37 @@
 export const patch_promise = window => {
 
-  if(window.Promise.Original != null) {
+  if(window.Promise.__patched) {
     // already patched
     return
   }
 
-  class PromiseRecordChildren extends Promise {
-    then(on_resolve, on_reject) {
-      let children = window.get_children()
-      if(children == null) {
-        children = []
-        window.set_children(children)
-      }
-      return super.then(
-        on_resolve == null
-          ? null
-          : value => {
-              window.set_children(children)
-              return on_resolve(value)
-            },
+  const _then = Promise.prototype.then
 
-        on_reject == null
-          ? null
-          : error => {
-            window.set_children(children)
-            return on_reject(error)
+  Promise.prototype.then = function then(on_resolve, on_reject) {
+    let children = window.get_children()
+    if(children == null) {
+      children = []
+      window.set_children(children)
+    }
+
+    const make_callback = cb => cb == null
+      ? null
+      : value => {
+          const current = window.get_children()
+          window.set_children(children)
+          try {
+            return cb(value)
+          } finally {
+            window.set_children(current)
           }
-      )
-    }
-  }
-
-  class PromiseWithStatus extends window.Promise {
-    constructor(fn) {
-      let status 
-      let is_constructor_finished = false
-      const p = new PromiseRecordChildren(
-        (resolve, reject) => {
-          fn(
-            (value) => {
-              if(value instanceof window.Promise.Original) {
-                value
-                  .then(v => {
-                    p.status = {ok: true, value: v}
-                    resolve(v)
-                  })
-                  .catch(e => {
-                    p.status = {ok: false, error: e}
-                    reject(e)
-                  })
-              } else {
-                status = {ok: true, value}
-                if(is_constructor_finished) {
-                  p.status = status
-                }
-                resolve(value)
-              }
-            },
-            (error) => {
-              status = {ok: false, error}
-              if(is_constructor_finished) {
-                p.status = status
-              }
-              reject(error)
-            },
-          )
         }
-      )
-      is_constructor_finished = true
-      p.status = status
-      return p
-    }
+
+    return _then.call(
+      this,
+      make_callback(on_resolve),
+      make_callback(on_reject),
+    )
   }
 
-  PromiseWithStatus.Original = window.Promise
-
-  window.Promise = PromiseWithStatus
+  window.Promise.__patched = true
 }