refactor(auto-reply): share directive arg parsing

src/auto-reply/reply/directive-parsing.ts

@@ -0,0 +1,40 @@
+export function skipDirectiveArgPrefix(raw: string): number {
+  let i = 0;
+  const len = raw.length;
+  while (i < len && /\s/.test(raw[i])) {
+    i += 1;
+  }
+  if (raw[i] === ":") {
+    i += 1;
+    while (i < len && /\s/.test(raw[i])) {
+      i += 1;
+    }
+  }
+  return i;
+}
+
+export function takeDirectiveToken(
+  raw: string,
+  startIndex: number,
+): { token: string | null; nextIndex: number } {
+  let i = startIndex;
+  const len = raw.length;
+  while (i < len && /\s/.test(raw[i])) {
+    i += 1;
+  }
+  if (i >= len) {
+    return { token: null, nextIndex: i };
+  }
+  const start = i;
+  while (i < len && !/\s/.test(raw[i])) {
+    i += 1;
+  }
+  if (start === i) {
+    return { token: null, nextIndex: i };
+  }
+  const token = raw.slice(start, i);
+  while (i < len && /\s/.test(raw[i])) {
+    i += 1;
+  }
+  return { token, nextIndex: i };
+}