add hash-sum

utils/hash-sum.ts

@@ -0,0 +1,71 @@
+function pad(hash: string, len: number): string {
+  while (hash.length < len) {
+    hash = "0" + hash;
+  }
+  return hash;
+}
+
+function fold(hash: number, text: string): number {
+  let i: number;
+  let chr: number;
+  let len: number;
+  if (text.length === 0) {
+    return hash;
+  }
+  for (i = 0, len = text.length; i < len; i++) {
+    chr = text.charCodeAt(i);
+    hash = (hash << 5) - hash + chr;
+    hash |= 0; // Convert to 32bit integer
+  }
+  return hash < 0 ? hash * -2 : hash;
+}
+
+function foldObject(hash: number, o: any, seen: any[]): number {
+  return Object.keys(o).sort().reduce(foldKey, hash);
+  function foldKey(hash: number, key: string): number {
+    return foldValue(hash, o[key], key, seen);
+  }
+}
+
+function foldValue(
+  input: number,
+  value: any,
+  key: string,
+  seen: any[]
+): number {
+  let hash = fold(fold(fold(input, key), toString(value)), typeof value);
+  if (value === null) {
+    return fold(hash, "null");
+  }
+  if (value === undefined) {
+    return fold(hash, "undefined");
+  }
+  if (typeof value === "object" || typeof value === "function") {
+    if (seen.indexOf(value) !== -1) {
+      return fold(hash, "[Circular]" + key);
+    }
+    seen.push(value);
+
+    const objHash = foldObject(hash, value, seen);
+
+    if (!("valueOf" in value) || typeof value.valueOf !== "function") {
+      return objHash;
+    }
+
+    try {
+      return fold(objHash, String(value.valueOf()));
+    } catch (err: any) {
+      return fold(objHash, "[valueOf exception]" + (err.stack || err.message));
+    }
+  }
+  return fold(hash, value.toString());
+}
+
+function toString(o: any): string {
+  return Object.prototype.toString.call(o);
+}
+
+export function hashSum(o: any): string {
+  return pad(foldValue(0, o, "", []).toString(16), 8);
+}
+