From 367b8d64eb002fc1dd36bdf0d20df805034be55b Mon Sep 17 00:00:00 2001
From: SegaraRai <SegaraRai@users.noreply.github.com>
Date: Mon, 13 Jan 2025 11:34:49 +0900
Subject: [PATCH] feat: caching

---
 .changeset/wild-files-repair.md |  5 +++
 src/factory.ts                  | 58 ++++++++++++++++++++++++++++-----
 src/prisma.ts                   | 18 ++++++----
 3 files changed, 66 insertions(+), 15 deletions(-)
 create mode 100644 .changeset/wild-files-repair.md

diff --git a/.changeset/wild-files-repair.md b/.changeset/wild-files-repair.md
new file mode 100644
index 0000000..42794aa
--- /dev/null
+++ b/.changeset/wild-files-repair.md
@@ -0,0 +1,5 @@
+---
+"fraci": minor
+---
+
+Add caching feature.
diff --git a/src/factory.ts b/src/factory.ts
index 24350bb..2cead4d 100644
--- a/src/factory.ts
+++ b/src/factory.ts
@@ -37,23 +37,63 @@ export interface FraciOptions<D extends string, L extends string> {
   maxRetries?: number;
 }
 
+export type FraciCache = Map<string, unknown> & { __fraci__: never };
+
+/**
+ * Create cache.
+ *
+ * @returns Cache
+ */
+export function createFraciCache(): FraciCache {
+  return new Map() as FraciCache;
+}
+
+function withCache<T>(
+  cache: FraciCache | undefined,
+  key: string,
+  fn: () => T
+): T {
+  if (!cache) {
+    return fn();
+  }
+
+  let value = cache.get(key) as T | undefined;
+  if (value === undefined) {
+    value = fn();
+    cache.set(key, value);
+  }
+
+  return value;
+}
+
 /**
  * Create fractional indexing utility.
  *
  * @param options Options
+ * @param cache Cache (optional)
  * @returns Fractional indexing utility
  */
-export function fraci<D extends string, L extends string, X>({
-  digitBase,
-  lengthBase,
-  maxLength = DEFAULT_MAX_LENGTH,
-  maxRetries = DEFAULT_MAX_RETRIES,
-}: FraciOptions<D, L>): Fraci<D, L, X> {
+export function fraci<D extends string, L extends string, X>(
+  {
+    digitBase,
+    lengthBase,
+    maxLength = DEFAULT_MAX_LENGTH,
+    maxRetries = DEFAULT_MAX_RETRIES,
+  }: FraciOptions<D, L>,
+  cache?: FraciCache
+): Fraci<D, L, X> {
   type F = FractionalIndex<D, L, X>;
 
-  const [digBaseForward, digBaseReverse] = createDigitBaseMap(digitBase);
-  const [lenBaseForward, lenBaseReverse] =
-    createIntegerLengthBaseMap(lengthBase);
+  const [digBaseForward, digBaseReverse] = withCache(
+    cache,
+    `D${digitBase}`,
+    createDigitBaseMap.bind(null, digitBase)
+  );
+  const [lenBaseForward, lenBaseReverse] = withCache(
+    cache,
+    `L${lengthBase}`,
+    createIntegerLengthBaseMap.bind(null, lengthBase)
+  );
   const smallestInteger = getSmallestInteger(digBaseForward, lenBaseForward);
 
   return {
diff --git a/src/prisma.ts b/src/prisma.ts
index a5c4422..a61cc09 100644
--- a/src/prisma.ts
+++ b/src/prisma.ts
@@ -3,6 +3,7 @@
 import { Prisma, PrismaClient } from "@prisma/client/extension.js";
 import type { PrismaClientKnownRequestError } from "@prisma/client/runtime/library.js";
 import {
+  createFraciCache,
   DEFAULT_MAX_LENGTH,
   DEFAULT_MAX_RETRIES,
   fraci,
@@ -360,6 +361,8 @@ export function fraciExtension<Options extends FraciExtensionOptions>({
   maxRetries = DEFAULT_MAX_RETRIES,
 }: Options) {
   return Prisma.defineExtension((client) => {
+    const cache = createFraciCache();
+
     type HelperValue = FraciForPrisma<any, any, any, any, any>;
 
     const helperMap = new Map<string, HelperValue>();
@@ -376,12 +379,15 @@ export function fraciExtension<Options extends FraciExtensionOptions>({
         );
       }
 
-      const helper = fraci({
-        digitBase,
-        lengthBase,
-        maxLength,
-        maxRetries,
-      });
+      const helper = fraci(
+        {
+          digitBase,
+          lengthBase,
+          maxLength,
+          maxRetries,
+        },
+        cache
+      );
 
       const indicesForAfter = async (
         cursor: any,