Initial commit

ui/stream/subscribe.js

@@ -0,0 +1,114 @@
+// Sshwifty - A Web SSH client
+//
+// Copyright (C) 2019 Rui NI <nirui@gmx.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import Exception from "./exception.js";
+
+const typeReject = 0;
+const typeResolve = 1;
+
+export class Subscribe {
+  /**
+   * constructor
+   *
+   */
+  constructor() {
+    this.res = null;
+    this.rej = null;
+    this.pending = [];
+  }
+
+  /**
+   * Returns how many resolve/reject in the pending
+   */
+  pendings() {
+    return (
+      this.pending.length + (this.rej !== null || this.res !== null ? 1 : 0)
+    );
+  }
+
+  /**
+   * Resolve the subscribe waiter
+   *
+   * @param {any} d Resolve data which will be send to the subscriber
+   */
+  resolve(d) {
+    if (this.res === null) {
+      this.pending.push([typeResolve, d]);
+
+      return;
+    }
+
+    this.res(d);
+  }
+
+  /**
+   * Reject the subscribe waiter
+   *
+   * @param {any} e Error message that will be send to the subscriber
+   *
+   */
+  reject(e) {
+    if (this.rej === null) {
+      this.pending.push([typeReject, e]);
+
+      return;
+    }
+
+    this.rej(e);
+  }
+
+  /**
+   * Waiting and receive subscribe data
+   *
+   * @returns {Promise<any>} Data receiver
+   *
+   */
+  subscribe() {
+    if (this.pending.length > 0) {
+      let p = this.pending.shift();
+
+      switch (p[0]) {
+        case typeReject:
+          throw p[1];
+
+        case typeResolve:
+          return p[1];
+
+        default:
+          throw new Exception("Unknown pending type", false);
+      }
+    }
+
+    let self = this;
+
+    return new Promise((resolve, reject) => {
+      self.res = d => {
+        self.res = null;
+        self.rej = null;
+
+        resolve(d);
+      };
+
+      self.rej = e => {
+        self.res = null;
+        self.rej = null;
+
+        reject(e);
+      };
+    });
+  }
+}