From 911d297136a41484b4d67df98c3fd1866a4479d1 Mon Sep 17 00:00:00 2001
From: Ed J <mohawk2@users.noreply.github.com>
Date: Sat, 17 Feb 2018 04:17:56 +0000
Subject: [PATCH] memoise wrapper values

---
 src/type/wrappers.js | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/type/wrappers.js b/src/type/wrappers.js
index 8ebec67729..99edc9ae2e 100644
--- a/src/type/wrappers.js
+++ b/src/type/wrappers.js
@@ -34,12 +34,19 @@ declare class GraphQLList<+T: GraphQLType> {
   // Note: constructors cannot be used for covariant types. Drop the "new".
   constructor(ofType: any): void;
 }
+const listCache = new WeakMap();
 // eslint-disable-next-line no-redeclare
 export function GraphQLList(ofType) {
   if (this instanceof GraphQLList) {
     this.ofType = assertType(ofType);
   } else {
-    return new GraphQLList(ofType);
+    const cachedValue = listCache.get(ofType);
+    if (cachedValue !== undefined) {
+      return cachedValue;
+    }
+    const newValue = new GraphQLList(ofType);
+    listCache.set(ofType, newValue);
+    return newValue;
   }
 }
 
@@ -75,12 +82,19 @@ declare class GraphQLNonNull<+T: GraphQLNullableType> {
   // Note: constructors cannot be used for covariant types. Drop the "new".
   constructor(ofType: any): void;
 }
+const nnCache = new WeakMap();
 // eslint-disable-next-line no-redeclare
 export function GraphQLNonNull(ofType) {
   if (this instanceof GraphQLNonNull) {
     this.ofType = assertNullableType(ofType);
   } else {
-    return new GraphQLNonNull(ofType);
+    const cachedValue = nnCache.get(ofType);
+    if (cachedValue !== undefined) {
+      return cachedValue;
+    }
+    const newValue = new GraphQLNonNull(ofType);
+    nnCache.set(ofType, newValue);
+    return newValue;
   }
 }