Move the document trait into a separate crate (#3035)

* add a default head method through eval
* remove the old document trait
* implement document for each platform
* pull out document into a dedicated crate to cut down on shared dependencies
---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

packages/document/src/ts/.gitignore

@@ -0,0 +1,3 @@
+# please dont accidentally run tsc and commit your js in this dir.
+*.js
+

packages/document/src/ts/eval.ts

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+// Handle communication between rust and evaluating javascript
+
+export class Channel {
+  pending: any[];
+  waiting: ((data: any) => void)[];
+
+  constructor() {
+    this.pending = [];
+    this.waiting = [];
+  }
+
+  send(data: any) {
+    // If there's a waiting callback, call it
+    if (this.waiting.length > 0) {
+      this.waiting.shift()(data);
+      return;
+    }
+    // Otherwise queue the data
+    this.pending.push(data);
+  }
+
+  async recv(): Promise<any> {
+    return new Promise((resolve, _reject) => {
+      // If data already exists, resolve immediately
+      if (this.pending.length > 0) {
+        resolve(this.pending.shift());
+        return;
+      }
+      // Otherwise queue the resolve callback
+      this.waiting.push(resolve);
+    });
+  }
+}
+
+export class WeakDioxusChannel {
+  inner: WeakRef<DioxusChannel>;
+
+  constructor(channel: DioxusChannel) {
+    this.inner = new WeakRef(channel);
+  }
+
+  // Send data from rust to javascript
+  rustSend(data: any) {
+    let channel = this.inner.deref();
+    if (channel) {
+      channel.rustSend(data);
+    }
+  }
+
+  // Receive data sent from javascript in rust
+  async rustRecv(): Promise<any> {
+    let channel = this.inner.deref();
+    if (channel) {
+      return await channel.rustRecv();
+    }
+  }
+}
+
+export abstract class DioxusChannel {
+  // Return a weak reference to this channel
+  weak(): WeakDioxusChannel {
+    return new WeakDioxusChannel(this);
+  }
+
+  // Send data from rust to javascript
+  abstract rustSend(data: any): void;
+
+  // Receive data sent from javascript in rust
+  abstract rustRecv(): Promise<any>;
+}

packages/document/src/ts/head.ts

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+// Helper functions for working with the document head
+
+function createElementInHead(
+  tag: string,
+  attributes: [string, string][],
+  children: string | null
+): void {
+  const element = document.createElement(tag);
+  for (const [key, value] of attributes) {
+    element.setAttribute(key, value);
+  }
+  if (children) {
+    element.appendChild(document.createTextNode(children));
+  }
+  document.head.appendChild(element);
+}
+
+// @ts-ignore
+window.createElementInHead = createElementInHead;