feat: parseAsTuple (#1036)

Author: I-3B

packages/nuqs/src/parsers.test.ts

@@ -16,7 +16,8 @@ import {
   parseAsString,
   parseAsStringEnum,
   parseAsStringLiteral,
-  parseAsTimestamp
+  parseAsTimestamp,
+  parseAsTuple
 } from './parsers'
 import {
   isParserBijective,
@@ -299,6 +300,25 @@ describe('parsers', () => {
       isParserBijective(parser, 'not-an-array', ['a', 'b'])
     ).toThrow()
   })
+  it.only('parseAsTuple', () => {
+    const parser = parseAsTuple([parseAsInteger, parseAsString, parseAsBoolean])
+    expect(parser.parse('1,a,false,will-ignore')).toStrictEqual([1, 'a', false])
+    expect(parser.parse('not-a-number,a,true')).toBeNull()
+    expect(parser.parse('1,a')).toBeNull()
+    // @ts-expect-error - Tuple length is less than 2
+    expect(() => parseAsTuple([parseAsInteger])).toThrow()
+    expect(parser.serialize([1, 'a', true])).toBe('1,a,true')
+    // @ts-expect-error - Tuple length mismatch
+    expect(() => parser.serialize([1, 'a'])).toThrow()
+    expect(testParseThenSerialize(parser, '1,a,true')).toBe(true)
+    expect(testSerializeThenParse(parser, [1, 'a', true] as const)).toBe(true)
+    expect(isParserBijective(parser, '1,a,true', [1, 'a', true] as const)).toBe(
+      true
+    )
+    expect(() =>
+      isParserBijective(parser, 'not-a-tuple', [1, 'a', true] as const)
+    ).toThrow()
+  })
 
   it('parseServerSide with default (#384)', () => {
     const p = parseAsString.withDefault('default')
@@ -351,4 +371,14 @@ describe('parsers/equality', () => {
     expect(eq([], ['foo'])).toBe(false)
     expect(eq(['foo'], ['bar'])).toBe(false)
   })
+  it.only('parseAsTuple', () => {
+    const eq = parseAsTuple([parseAsInteger, parseAsBoolean]).eq!
+    expect(eq([1, true], [1, true])).toBe(true)
+    expect(eq([1, true], [1, false])).toBe(false)
+    expect(eq([1, true], [2, true])).toBe(false)
+    // @ts-expect-error - Tuple length mismatch
+    expect(eq([1, true], [1])).toBe(false)
+    // @ts-expect-error - Tuple length mismatch
+    expect(eq([1], [1])).toBe(false)
+  })
 })

packages/nuqs/src/parsers.ts

@@ -465,6 +465,78 @@ export function parseAsArrayOf<ItemType>(
   })
 }
 
+type ParserTuple<T extends readonly unknown[]> = {
+  [K in keyof T]: ParserBuilder<T[K]>
+} & { length: 2 | 3 | 4 | 5 | 6 | 7 | 8 }
+
+/**
+ * Parse a comma-separated tuple with type-safe positions.
+ * Items are URI-encoded for safety, so they may not look nice in the URL.
+ * allowed tuple length is 2-8.
+ *
+ * @param itemParsers Tuple of parsers for each position in the tuple
+ * @param separator The character to use to separate items (default ',')
+ */
+export function parseAsTuple<T extends any[]>(
+  itemParsers: ParserTuple<T>,
+  separator = ','
+): ParserBuilder<T> {
+  const encodedSeparator = encodeURIComponent(separator)
+  if (itemParsers.length < 2 || itemParsers.length > 8) {
+    throw new Error(
+      `Tuple length must be between 2 and 8, got ${itemParsers.length}`
+    )
+  }
+  return createParser<T>({
+    parse: query => {
+      if (query === '') {
+        return null
+      }
+      const parts = query.split(separator)
+      if (parts.length < itemParsers.length) {
+        return null
+      }
+      // iterating by parsers instead of parts, any additional parts are ignored.
+      const result = itemParsers.map(
+        (parser, index) =>
+          safeParse(
+            parser.parse,
+            parts[index]!.replaceAll(encodedSeparator, separator),
+            `[${index}]`
+          ) as T[number] | null
+      )
+      return result.some(x => x === null) ? null : (result as T)
+    },
+    serialize: (values: T) => {
+      if (values.length !== itemParsers.length) {
+        throw new Error(
+          `Tuple length mismatch: expected ${itemParsers.length}, got ${values.length}`
+        )
+      }
+      return values
+        .map((value, index) => {
+          const parser = itemParsers[index]!
+          const str = parser.serialize ? parser.serialize(value) : String(value)
+          return str.replaceAll(separator, encodedSeparator)
+        })
+        .join(separator)
+    },
+    eq(a: T, b: T) {
+      if (a === b) {
+        return true
+      }
+      if (a.length !== b.length || a.length !== itemParsers.length) {
+        return false
+      }
+      return a.every((value, index) => {
+        const parser = itemParsers[index]!
+        const itemEq = parser.eq ?? ((x, y) => x === y)
+        return itemEq(value, b[index])
+      })
+    }
+  })
+}
+
 type inferSingleParserType<Parser> = Parser extends ParserBuilder<
   infer Value
 > & {