Refactor: Add Promise-Based API

lib/i2c.js

@@ -1,7 +1,18 @@
 const wire = require('../build/Release/i2c');
 const { EventEmitter } = require('events');
+const util = require('util');
+
 const tick = setImmediate || process.nextTick;
 
+//
+// Add promisify to the wire object so we can use async/await
+//
+for (const key in wire) {
+  if (typeof wire[key] === 'function') {
+    wire[`${key}Async`] = util.promisify(wire[key]);
+  }
+}
+
 class i2c extends EventEmitter {
 
   constructor(address, options) {
@@ -31,11 +42,10 @@ class i2c extends EventEmitter {
       console.log(`Error: ${err}`);
     });
 
-    this.open(this.options.device, (err) => {
-      if (!err) {
-        this.setAddress(this.address);
-      }
-    });
+    (async () => {
+      await this.openAsync(this.options.device);
+      this.setAddress(this.address);
+    })().catch((err) => this.emit('error', err));
   }
 
   scan(callback) {
@@ -141,6 +151,51 @@ class i2c extends EventEmitter {
       }
     });
   }
+
+  async scanAsync() {
+    const data = await wire.scanAsync();
+    return data.filter((num) => num >= 0);
+  }
+
+  async openAsync(device) {
+    return wire.openAsync(device);
+  }
+
+  async writeAsync(buf) {
+    this.setAddress(this.address);
+    if (!Buffer.isBuffer(buf)) {
+      buf = Buffer.from(buf);
+    }
+    return wire.writeAsync(buf);
+  }
+
+  async writeByteAsync(byte) {
+    this.setAddress(this.address);
+    return wire.writeByteAsync(byte);
+  }
+
+  async writeBytesAsync(cmd, buf) {
+    this.setAddress(this.address);
+    if (!Buffer.isBuffer(buf)) {
+      buf = Buffer.from(buf);
+    }
+    return wire.writeBlockAsync(cmd, buf);
+  }
+
+  async readAsync(len) {
+    this.setAddress(this.address);
+    return wire.readAsync(len);
+  }
+
+  async readByteAsync() {
+    this.setAddress(this.address);
+    return wire.readByteAsync();
+  }
+
+  async readBytesAsync(cmd, len) {
+    this.setAddress(this.address);
+    return wire.readBlockAsync(cmd, len, null);
+  }
 }
 
 module.exports = i2c;