From 6d6c2a6d20c42ec0198b245f26cea0d08d615c08 Mon Sep 17 00:00:00 2001
From: Vladislav Mamon <norskeld@gmail.com>
Date: Mon, 4 Jul 2022 17:17:23 +0500
Subject: [PATCH] feat(parsers/oneOf): add `oneOf` parser

---
 src/parsers.ts       |  1 +
 src/parsers/oneOf.ts | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+)
 create mode 100644 src/parsers/oneOf.ts

diff --git a/src/parsers.ts b/src/parsers.ts
index 850b6a3..16b9513 100644
--- a/src/parsers.ts
+++ b/src/parsers.ts
@@ -6,6 +6,7 @@ export * from './parsers/float'
 export * from './parsers/integer'
 export * from './parsers/letter'
 export * from './parsers/nothing'
+export * from './parsers/oneOf'
 export * from './parsers/regexp'
 export * from './parsers/rest'
 export * from './parsers/run'
diff --git a/src/parsers/oneOf.ts b/src/parsers/oneOf.ts
new file mode 100644
index 0000000..906a01c
--- /dev/null
+++ b/src/parsers/oneOf.ts
@@ -0,0 +1,26 @@
+import { type Parser } from '../state'
+
+export function oneOf(chars: string): Parser<string> {
+  const charset = [...chars]
+
+  return {
+    parse(input, pos) {
+      const nextPos = pos + 1
+      const char = input.substring(pos, nextPos)
+
+      if (charset.includes(char)) {
+        return {
+          isOk: true,
+          pos: nextPos,
+          value: char
+        }
+      }
+
+      return {
+        isOk: false,
+        pos,
+        expected: `one of: ${charset.join(', ')}`
+      }
+    }
+  }
+}