implemented frontend including separate message system; started to implement backend

yjs-poll/node_modules/lib0/iterator.js

@@ -0,0 +1,61 @@
+/**
+ * Utility module to create and manipulate Iterators.
+ *
+ * @module iterator
+ */
+
+/**
+ * @template T,R
+ * @param {Iterator<T>} iterator
+ * @param {function(T):R} f
+ * @return {IterableIterator<R>}
+ */
+export const mapIterator = (iterator, f) => ({
+  [Symbol.iterator] () {
+    return this
+  },
+  // @ts-ignore
+  next () {
+    const r = iterator.next()
+    return { value: r.done ? undefined : f(r.value), done: r.done }
+  }
+})
+
+/**
+ * @template T
+ * @param {function():IteratorResult<T>} next
+ * @return {IterableIterator<T>}
+ */
+export const createIterator = next => ({
+  /**
+   * @return {IterableIterator<T>}
+   */
+  [Symbol.iterator] () {
+    return this
+  },
+  // @ts-ignore
+  next
+})
+
+/**
+ * @template T
+ * @param {Iterator<T>} iterator
+ * @param {function(T):boolean} filter
+ */
+export const iteratorFilter = (iterator, filter) => createIterator(() => {
+  let res
+  do {
+    res = iterator.next()
+  } while (!res.done && !filter(res.value))
+  return res
+})
+
+/**
+ * @template T,M
+ * @param {Iterator<T>} iterator
+ * @param {function(T):M} fmap
+ */
+export const iteratorMap = (iterator, fmap) => createIterator(() => {
+  const { done, value } = iterator.next()
+  return { done, value: done ? undefined : fmap(value) }
+})