From 4dcb41f5e6a5792c194ad5524e63be16a02433ff Mon Sep 17 00:00:00 2001
From: Pritesh Nandgaonkar <prit91@fb.com>
Date: Thu, 9 May 2019 06:34:05 -0700
Subject: [PATCH] Iterative version of the serializer

Summary: Iterative version of the custom serializer. The recursive implementation led to call stack overflow for news feed surface in fb4a.

Reviewed By: danielbuechele

Differential Revision: D15251643

fbshipit-source-id: b8af921b1a4d85c52d4d45a7abf95a5bb5f283f7
---
 src/utils/serialization.js | 160 ++++++++++++++++++++++++++++++++-----
 1 file changed, 138 insertions(+), 22 deletions(-)

diff --git a/src/utils/serialization.js b/src/utils/serialization.js
index 6654f5f1f..8445b4e89 100644
--- a/src/utils/serialization.js
+++ b/src/utils/serialization.js
@@ -13,33 +13,149 @@ export function deserialize(str: string): Object {
   return deserializeObject(JSON.parse(str));
 }
 
+function processArray(
+  element: any,
+  array: [any],
+  stack: Array<any>,
+  dict: Map<any, any>,
+): {premature: boolean, outputArr: Array<any>} {
+  let outputArr = [];
+  let premature = false;
+  for (const item of array) {
+    if (!dict.has(item)) {
+      if (!(item instanceof Object)) {
+        dict.set(item, item);
+      } else {
+        stack.push(element);
+        stack.push(item);
+        premature = true;
+        break;
+      }
+    }
+    if (dict.has(item)) {
+      dict.set(item, dict.get(item));
+      outputArr.push(dict.get(item));
+    }
+  }
+  return {premature, outputArr};
+}
+
+function processKeyValuePair(
+  element: any,
+  key: any,
+  value: any,
+  stack: Array<any>,
+  dict: Map<any, any>,
+): {premature: boolean} {
+  let premature = false;
+  if (!dict.has(key)) {
+    if (!(key instanceof Object)) {
+      dict.set(key, key);
+    } else {
+      stack.push(element);
+      stack.push(key);
+      premature = true;
+      return {premature};
+    }
+  }
+  if (!dict.has(value)) {
+    if (!(value instanceof Object)) {
+      dict.set(value, value);
+    } else {
+      stack.push(element);
+      stack.push(value);
+      premature = true;
+    }
+  }
+  return {premature};
+}
+
 export function makeObjectSerializable(obj: any): any {
   if (!(obj instanceof Object)) {
     return obj;
   }
-  if (obj instanceof Map) {
-    return {
-      __flipper_object_type__: 'Map',
-      data: [...obj].map(makeObjectSerializable),
-    };
-  } else if (obj instanceof Set) {
-    return {
-      __flipper_object_type__: 'Set',
-      data: [...obj].map(makeObjectSerializable),
-    };
-  } else if (obj instanceof Date) {
-    return {
-      __flipper_object_type__: 'Date',
-      data: obj.toString(),
-    };
-  } else if (obj instanceof Array) {
-    return obj.map(makeObjectSerializable);
+  let stack = [obj];
+  const dict: Map<any, any> = new Map();
+  while (stack.length > 0) {
+    const element = stack.pop();
+    if (element instanceof Map) {
+      const arr = [];
+      let premature = false;
+      for (const item of [...element]) {
+        const key = item[0];
+        const value = item[1];
+        premature = processKeyValuePair(element, key, value, stack, dict)
+          .premature;
+        if (premature) {
+          break;
+        }
+        if (dict.has(key) && dict.has(value)) {
+          dict.set(item, [dict.get(key), dict.get(value)]);
+          arr.push([dict.get(key), dict.get(value)]);
+        }
+      }
+      if (premature) {
+        continue;
+      }
+      dict.set(element, {
+        __flipper_object_type__: 'Map',
+        data: arr,
+      });
+    } else if (element instanceof Set) {
+      const {premature, outputArr} = processArray(
+        element,
+        [...element],
+        stack,
+        dict,
+      );
+      if (premature) {
+        continue;
+      }
+      dict.set(element, {
+        __flipper_object_type__: 'Set',
+        data: outputArr,
+      });
+    } else if (element instanceof Date) {
+      dict.set(element, {
+        __flipper_object_type__: 'Date',
+        data: element.toString(),
+      });
+    } else if (element instanceof Array) {
+      const {premature, outputArr} = processArray(
+        element,
+        element,
+        stack,
+        dict,
+      );
+      if (premature) {
+        continue;
+      }
+      dict.set(element, outputArr);
+    } else if (element instanceof Object) {
+      const array = Object.entries(element);
+      let obj = {};
+      let premature = false;
+      for (const item of array) {
+        const key = item[0];
+        const value = item[1];
+        premature = processKeyValuePair(element, key, value, stack, dict)
+          .premature;
+        if (premature) {
+          break;
+        }
+        const serializedKey = dict.get(key);
+        const serializedValue = dict.get(value);
+        if (serializedValue && serializedKey) {
+          obj = {...obj, [serializedKey]: serializedValue};
+        }
+      }
+      if (premature) {
+        continue;
+      }
+      dict.set(element, obj);
+    }
   }
-
-  return Object.entries(obj).reduce(
-    (acc, [key, value]) => ({...acc, [key]: makeObjectSerializable(value)}),
-    {},
-  );
+  return dict.get(obj);
 }
 
 export function deserializeObject(obj: any): any {