Initial commit: Crypto trader application

frontend/node_modules/globby/stream-utils.js

@@ -0,0 +1,46 @@
+'use strict';
+const {Transform} = require('stream');
+
+class ObjectTransform extends Transform {
+	constructor() {
+		super({
+			objectMode: true
+		});
+	}
+}
+
+class FilterStream extends ObjectTransform {
+	constructor(filter) {
+		super();
+		this._filter = filter;
+	}
+
+	_transform(data, encoding, callback) {
+		if (this._filter(data)) {
+			this.push(data);
+		}
+
+		callback();
+	}
+}
+
+class UniqueStream extends ObjectTransform {
+	constructor() {
+		super();
+		this._pushed = new Set();
+	}
+
+	_transform(data, encoding, callback) {
+		if (!this._pushed.has(data)) {
+			this.push(data);
+			this._pushed.add(data);
+		}
+
+		callback();
+	}
+}
+
+module.exports = {
+	FilterStream,
+	UniqueStream
+};