From de1100ff0583d648bdaf45003e78c0a1b8d160d5 Mon Sep 17 00:00:00 2001
From: Yaacov Rydzinski <yaacovCR@gmail.com>
Date: Wed, 2 Oct 2024 06:24:18 +0300
Subject: [PATCH] perf: optimize replaceVariables

---
 src/utilities/replaceVariables.ts | 73 +++++++++++++++++++++----------
 1 file changed, 51 insertions(+), 22 deletions(-)

diff --git a/src/utilities/replaceVariables.ts b/src/utilities/replaceVariables.ts
index 747931fab7..307c987a01 100644
--- a/src/utilities/replaceVariables.ts
+++ b/src/utilities/replaceVariables.ts
@@ -1,8 +1,11 @@
 import type { Maybe } from '../jsutils/Maybe.js';
 
-import type { ConstValueNode, ValueNode } from '../language/ast.js';
+import type {
+  ConstValueNode,
+  ObjectFieldNode,
+  ValueNode,
+} from '../language/ast.js';
 import { Kind } from '../language/kinds.js';
-import { visit } from '../language/visitor.js';
 
 import type { VariableValues } from '../execution/values.js';
 
@@ -21,9 +24,9 @@ export function replaceVariables(
   variableValues?: Maybe<VariableValues>,
   fragmentVariableValues?: Maybe<VariableValues>,
 ): ConstValueNode {
-  return visit(valueNode, {
-    Variable(node) {
-      const varName = node.name.value;
+  switch (valueNode.kind) {
+    case Kind.VARIABLE: {
+      const varName = valueNode.name.value;
       const scopedVariableValues = fragmentVariableValues?.sources[varName]
         ? fragmentVariableValues
         : variableValues;
@@ -36,23 +39,19 @@ export function replaceVariables(
       if (scopedVariableSource.value === undefined) {
         const defaultValue = scopedVariableSource.signature.defaultValue;
         if (defaultValue !== undefined) {
-          return defaultValue.literal;
+          return defaultValue.literal as ConstValueNode;
         }
       }
 
       return valueToLiteral(
         scopedVariableSource.value,
         scopedVariableSource.signature.type,
-      );
-    },
-    ObjectValue(node) {
-      return {
-        ...node,
-        // Filter out any fields with a missing variable.
-        fields: node.fields.filter((field) => {
-          if (field.value.kind !== Kind.VARIABLE) {
-            return true;
-          }
+      ) as ConstValueNode;
+    }
+    case Kind.OBJECT: {
+      const newFields: Array<ObjectFieldNode> = [];
+      for (const field of valueNode.fields) {
+        if (field.value.kind === Kind.VARIABLE) {
           const scopedVariableSource =
             fragmentVariableValues?.sources[field.value.name.value] ??
             variableValues?.sources[field.value.name.value];
@@ -61,11 +60,41 @@ export function replaceVariables(
             scopedVariableSource?.value === undefined &&
             scopedVariableSource?.signature.defaultValue === undefined
           ) {
-            return false;
+            continue;
           }
-          return true;
-        }),
-      };
-    },
-  }) as ConstValueNode;
+        }
+        const newFieldNodeValue = replaceVariables(
+          field.value,
+          variableValues,
+          fragmentVariableValues,
+        );
+        newFields.push({
+          ...field,
+          value: newFieldNodeValue,
+        });
+      }
+      return {
+        ...valueNode,
+        fields: newFields,
+      } as ConstValueNode;
+    }
+    case Kind.LIST: {
+      const newValues: Array<ValueNode> = [];
+      for (const value of valueNode.values) {
+        const newItemNodeValue = replaceVariables(
+          value,
+          variableValues,
+          fragmentVariableValues,
+        );
+        newValues.push(newItemNodeValue);
+      }
+      return {
+        ...valueNode,
+        values: newValues,
+      } as ConstValueNode;
+    }
+    default: {
+      return valueNode;
+    }
+  }
 }