Refactoring

src/functions/split.ts

@@ -0,0 +1,34 @@
+import { Transform } from "stream";
+import { StringDecoder } from "string_decoder";
+import { WithEncoding } from "./baseDefinitions";
+/**
+ * Return a ReadWrite stream that splits streamed chunks using the given separator
+ * @param separator Separator to split by, defaulting to "\n"
+ * @param options
+ * @param options.encoding Encoding written chunks are assumed to use
+ */
+export function split(
+    separator: string | RegExp = "\n",
+    options: WithEncoding = { encoding: "utf8" },
+): Transform {
+    let buffered = "";
+    const decoder = new StringDecoder(options.encoding);
+
+    return new Transform({
+        readableObjectMode: true,
+        transform(chunk: Buffer, encoding, callback) {
+            const asString = decoder.write(chunk);
+            const splitted = asString.split(separator);
+            if (splitted.length > 1) {
+                splitted[0] = buffered.concat(splitted[0]);
+                buffered = "";
+            }
+            buffered += splitted[splitted.length - 1];
+            splitted.slice(0, -1).forEach((part: string) => this.push(part));
+            callback();
+        },
+        flush(callback) {
+            callback(undefined, buffered + decoder.end());
+        },
+    });
+}