move utils code; fix sprintf; implement enc/dec

utils.js

@@ -0,0 +1,23 @@
+const matchy = /%[0-9.-]*([a-z])/g;
+const replacy = /(?<pre>.*?)%(?<num>[0-9.-]+)*(?<formatter>[a-z])/gs;
+
+export const placeholderTypes = (str) => {
+  // '%-16s, line %4d, %-16s:ret=%d,broadcast lan_seach to %s:%.3f!!!!'
+  // =>
+  // [ 's', 'd', 's', 'd', 's', 'f' ]
+  return [...str.matchAll(matchy)].map((m) => m[1]);
+};
+export const sprintf = (str, values) => {
+  // '%-16s, line %4d, %-16s:ret=%d,broadcast lan_seach to %s:%.3f!!!!' +
+  // ["asd", 20, ...]
+  // =>
+  // asd, line 20, ...
+  const matches = str.matchAll(replacy);
+  return [...matches]
+    .map((m, idx) => {
+      const cur = values[idx];
+      const val = m.groups.formatter == "x" ? `0x${cur.toString(16)}` : cur.toString();
+      return m.groups.pre + val;
+    })
+    .join("");
+};