feat: discriminator

Author: kevinand11

src/api/index.ts

@@ -5,7 +5,7 @@ import { VBase } from './base'
 import { VBoolean } from './booleans'
 import { VCore } from './core'
 import { VFile } from './files'
-import { VAnd, VOr } from './junctions'
+import { VAnd, VDiscriminator, VOr } from './junctions'
 import { VNumber } from './numbers'
 import { VObject } from './objects'
 import { VMap, VRecord } from './records'
@@ -21,6 +21,7 @@ export const v = {
 	or: VBase.createType(VOr),
 	and: VBase.createType(VAnd),
 	string: VBase.createType(VString),
+	discriminate: VBase.createType(VDiscriminator),
 	number: VBase.createType(VNumber),
 	boolean: VBase.createType(VBoolean),
 	time: VBase.createType(VTime),

src/api/junctions.ts

@@ -31,4 +31,16 @@ export class VAnd<I> extends VCore<I> {
 			return isValid(v)
 		}))
 	}
+}
+
+export class VDiscriminator<D extends Record<string, VCore<any>>> extends VCore<ExtractI<D[keyof D]>> {
+	constructor (discriminator: (val: ExtractI<D[keyof D]>) => string, schemas: D, err = 'doesnt match any of the schema') {
+		super()
+		this.addTyping(makeRule<ExtractI<D[keyof D]>>((value) => {
+			const val = value as ExtractI<D[keyof D]>
+			const accessor = discriminator(val)
+			if (!schemas[accessor]) return isInvalid([err], val)
+			return schemas[accessor].parse(val)
+		}))
+	}
 }

tests/api/junctions.test.ts

@@ -23,4 +23,25 @@ describe('and', () => {
 		expect(rules.parse('').valid).toBe(false)
 		expect(rules.parse(false).valid).toBe(false)
 	})
+})
+
+describe('discriminate', () => {
+	test('discriminate', () => {
+		const rules = v.discriminate((v) => v, {
+			'ha': v.string(),
+			'make': v.string().has(4),
+		})
+		expect(rules.parse('ha').valid).toBe(true)
+		expect(rules.parse(2).valid).toBe(false)
+		expect(rules.parse('make').valid).toBe(true)
+		expect(rules.parse('made').valid).toBe(false)
+
+		const objectRules = v.discriminate((v) => v.status, {
+			'ha': v.object({ status: v.is('ha'), total: v.number().gt(10) }),
+			'name': v.object({ status: v.is('name'), flow: v.boolean() })
+		})
+		expect(objectRules.parse({ 'status': 'ha', total: 12 }).valid).toBe(true)
+		expect(objectRules.parse({ 'status': 'ha', total: 9 }).valid).toBe(false)
+		expect(objectRules.parse({ 'status': 'none' }).valid).toBe(false)
+	})
 })