Add capture groups

Author: jehna

src/group.test.ts

@@ -0,0 +1,23 @@
+import group from "./group";
+import VerEx from "./verbalexpressions";
+import { anything } from "./constants";
+import { maybe } from "./maybe";
+
+describe("group", () => {
+  it("should export a function", () => {
+    expect(group).toBeInstanceOf(Function);
+  });
+
+  it("should add a capture gorup that to the expression", () => {
+    const exp = VerEx("foo", group("bar"), "baz");
+    const [, result] = exp.exec("foobarbaz");
+    expect(result).toEqual("bar");
+  });
+
+  it("should work with multiple arguments", () => {
+    const exp = VerEx(group("http", maybe("s")), "://", group(anything));
+    const [, protocol, domain] = exp.exec("https://google.com");
+    expect(protocol).toEqual("https");
+    expect(domain).toEqual("google.com");
+  });
+});

src/group.ts

@@ -0,0 +1,6 @@
+import { Expression } from "./types";
+import { compile } from "./verbalexpressions";
+
+export default function group(...inputs: Expression[]) {
+  return new RegExp(`(${compile(...inputs)})`);
+}