buildClientSchema: build enum type value maps lazily (#4424)

The option of passing a thunk was made available by: #4018 .

Always passing the thunk helps contribute to a "lazy" build process, which gives the following performance boost:

![image](https://github.com/user-attachments/assets/569b9b79-e6d9-44b6-b073-045d2df72c3c)

Lazy evaluation results in bad names for enum values not being checked until `type.getValues()` is called, similar to how bad names for fields are not checked until `type.getFields()` is called. Explicit validation validates enum value names just as with field names.

Author: yaacovCR

src/type/__tests__/definition-test.ts

@@ -794,15 +794,15 @@ describe('Type System: Enums', () => {
   });
 
   it('rejects an Enum type with incorrectly named values', () => {
-    expect(
-      () =>
-        new GraphQLEnumType({
-          name: 'SomeEnum',
-          values: {
-            'bad-name': {},
-          },
-        }),
-    ).to.throw('Names must only contain [_a-zA-Z0-9] but "bad-name" does not.');
+    const enumType = new GraphQLEnumType({
+      name: 'SomeEnum',
+      values: {
+        'bad-name': {},
+      },
+    });
+    expect(() => enumType.getValues()).to.throw(
+      'Names must only contain [_a-zA-Z0-9] but "bad-name" does not.',
+    );
   });
 });
 

src/type/definition.ts

@@ -1563,7 +1563,7 @@ export class GraphQLEnumType /* <T> */ implements GraphQLSchemaElement {
 
   private _values:
     | ReadonlyArray<GraphQLEnumValue /* <T> */>
-    | (() => GraphQLEnumValueConfigMap);
+    | (() => ReadonlyArray<GraphQLEnumValue>) /* <T> */;
 
   private _valueLookup: ReadonlyMap<any /* T */, GraphQLEnumValue> | null;
   private _nameLookup: ObjMap<GraphQLEnumValue> | null;
@@ -1576,13 +1576,7 @@ export class GraphQLEnumType /* <T> */ implements GraphQLSchemaElement {
     this.astNode = config.astNode;
     this.extensionASTNodes = config.extensionASTNodes ?? [];
 
-    this._values =
-      typeof config.values === 'function'
-        ? config.values
-        : Object.entries(config.values).map(
-            ([valueName, valueConfig]) =>
-              new GraphQLEnumValue(this, valueName, valueConfig),
-          );
+    this._values = defineEnumValues.bind(undefined, this, config.values);
     this._valueLookup = null;
     this._nameLookup = null;
   }
@@ -1593,10 +1587,7 @@ export class GraphQLEnumType /* <T> */ implements GraphQLSchemaElement {
 
   getValues(): ReadonlyArray<GraphQLEnumValue /* <T> */> {
     if (typeof this._values === 'function') {
-      this._values = Object.entries(this._values()).map(
-        ([valueName, valueConfig]) =>
-          new GraphQLEnumValue(this, valueName, valueConfig),
-      );
+      this._values = this._values();
     }
     return this._values;
   }
@@ -1722,6 +1713,18 @@ export class GraphQLEnumType /* <T> */ implements GraphQLSchemaElement {
   }
 }
 
+function defineEnumValues(
+  parentEnum: GraphQLEnumType,
+  values: ThunkObjMap<GraphQLEnumValueConfig /* <T> */>,
+): ReadonlyArray<GraphQLEnumValue> {
+  const valueMap = resolveObjMapThunk(values);
+
+  return Object.entries(valueMap).map(
+    ([valueName, valueConfig]) =>
+      new GraphQLEnumValue(parentEnum, valueName, valueConfig),
+  );
+}
+
 function didYouMeanEnumValue(
   enumType: GraphQLEnumType,
   unknownValueStr: string,