feat(method): add method utilities

README.md

@@ -199,6 +199,39 @@ assertEquals(isResponse({}), false);
 assertEquals(isResponse(null), false);
 ```
 
+## isSafeMethod
+
+Whether the method is safe method or not.
+
+Defined in
+[RFC 9110, 9.2.1. Safe Methods](https://www.rfc-editor.org/rfc/rfc9110.html#name-safe-methods).
+
+```ts
+import { isSafeMethod } from "https://deno.land/x/http_utils@$VERSION/mod.ts";
+import { assert } from "https://deno.land/std@$VERSION/testing/asserts.ts";
+
+assert(isSafeMethod("GET"));
+assert(isSafeMethod("HEAD"));
+assert(isSafeMethod("OPTIONS"));
+assert(isSafeMethod("TRACE"));
+```
+
+## isIdempotentMethod
+
+Whether the method is idempotent method or not.
+
+Defined in
+[RFC 9110, 9.2.2 Idempotent Methods](https://www.rfc-editor.org/rfc/rfc9110.html#name-idempotent-methods).
+
+```ts
+import { isIdempotentMethod } from "https://deno.land/x/http_utils@$VERSION/mod.ts";
+import { assert } from "https://deno.land/std@$VERSION/testing/asserts.ts";
+
+assert(isIdempotentMethod("GET"));
+assert(isIdempotentMethod("PUT"));
+assert(isIdempotentMethod("DELETE"));
+```
+
 ## License
 
 Copyright © 2023-present [httpland](https://github.com/httpland).

dev_deps.ts

@@ -1,4 +1,5 @@
-export * from "https://deno.land/std@0.159.0/testing/bdd.ts";
+export { describe, it } from "https://deno.land/std@0.178.0/testing/bdd.ts";
+export { assertEquals } from "https://deno.land/std@0.178.0/testing/asserts.ts";
 import {
   defineExpect,
   jestMatcherMap,

method.ts

@@ -25,3 +25,52 @@ export const enum Method {
 
 /** HTTP request method. */
 export type HttpMethod = Uppercase<keyof typeof Method>;
+
+/** HTTP method that is read-only.
+ * @see [RFC 9110, 9.2.1. Safe Methods](https://www.rfc-editor.org/rfc/rfc9110.html#name-safe-methods)
+ */
+export type SafeMethod =
+  | Method.Get
+  | Method.Head
+  | Method.Options
+  | Method.Trace;
+
+/** HTTP method that is idempotent.
+ * @see [RFC 9110, 9.2.2 Idempotent Methods](https://www.rfc-editor.org/rfc/rfc9110.html#name-idempotent-methods)
+ */
+export type IdempotentMethod = Method.Put | Method.Delete | SafeMethod;
+
+/** Whether the method is {@link SafeMethod} or not.
+ *
+ * @example
+ * ```ts
+ * import { isSafeMethod } from "https://deno.land/x/http_utils@$VERSION/mod.ts";
+ * import { assert } from "https://deno.land/std@$VERSION/testing/asserts.ts";
+ *
+ * assert(isSafeMethod("GET"));
+ * assert(isSafeMethod("HEAD"));
+ * assert(isSafeMethod("OPTIONS"));
+ * assert(isSafeMethod("TRACE"));
+ * ```
+ */
+export function isSafeMethod(method: string): method is SafeMethod {
+  return ([Method.Get, Method.Head, Method.Options, Method.Trace] as string[])
+    .includes(method);
+}
+
+/** Whether the method is {@link IdempotentMethod} or not.
+ *
+ * @example
+ * ```ts
+ * import { isIdempotentMethod } from "https://deno.land/x/http_utils@$VERSION/mod.ts";
+ * import { assert } from "https://deno.land/std@$VERSION/testing/asserts.ts";
+ *
+ * assert(isIdempotentMethod("GET"));
+ * assert(isIdempotentMethod("PUT"));
+ * assert(isIdempotentMethod("DELETE"));
+ * ```
+ */
+export function isIdempotentMethod(method: string): method is IdempotentMethod {
+  return isSafeMethod(method) ||
+    ([Method.Put, Method.Delete] as string[]).includes(method);
+}

method_test.ts

@@ -0,0 +1,54 @@
+import { assertEquals, describe, Fn, it } from "./dev_deps.ts";
+import { isIdempotentMethod, isSafeMethod } from "./method.ts";
+
+describe("isSafeMethod", () => {
+  it("should pass cases", () => {
+    const table: Fn<typeof isSafeMethod>[] = [
+      ["", false],
+      ["get", false],
+      ["head", false],
+      ["post", false],
+      ["put", false],
+      ["POST", false],
+      ["PUT", false],
+      ["DELETE", false],
+      ["CONNECT", false],
+      ["PATCH", false],
+
+      ["GET", true],
+      ["HEAD", true],
+      ["OPTIONS", true],
+      ["TRACE", true],
+    ];
+
+    table.forEach(([method, expected]) => {
+      assertEquals(isSafeMethod(method), expected);
+    });
+  });
+});
+
+describe("isIdempotentMethod", () => {
+  it("should pass cases", () => {
+    const table: Fn<typeof isIdempotentMethod>[] = [
+      ["", false],
+      ["get", false],
+      ["head", false],
+      ["post", false],
+      ["put", false],
+      ["POST", false],
+      ["CONNECT", false],
+      ["PATCH", false],
+
+      ["GET", true],
+      ["HEAD", true],
+      ["OPTIONS", true],
+      ["TRACE", true],
+      ["PUT", true],
+      ["DELETE", true],
+    ];
+
+    table.forEach(([method, expected]) => {
+      assertEquals(isIdempotentMethod(method), expected);
+    });
+  });
+});

mod.ts

@@ -12,4 +12,11 @@ export {
   parseFieldValue,
 } from "./headers.ts";
 export { equalsResponse, isResponse, safeResponse } from "./responses.ts";
-export { type HttpMethod, Method } from "./method.ts";
+export {
+  type HttpMethod,
+  type IdempotentMethod,
+  isIdempotentMethod,
+  isSafeMethod,
+  Method,
+  type SafeMethod,
+} from "./method.ts";