Function findRustDiscriminator

scripts/codegen/rust.ts:247–285

(variants: RustUnionVariant[])

}

function findRustDiscriminator(variants: RustUnionVariant[]): string | null {
	const first = variants[0]?.schema;
	if (!isObjectSchema(first) || !first.properties) return null;

	for (const [propName, propSchema] of Object.entries(first.properties).sort(
		([a], [b]) => a.localeCompare(b),
	)) {
		if (typeof propSchema !== "object") continue;
		if ((propSchema as JSONSchema7).const === undefined) continue;

		const values = new Set<string>();
		let isValid = true;
		for (const { schema } of variants) {
			if (!isObjectSchema(schema) || !schema.properties) {
				isValid = false;
				break;
			}
			const candidate = schema.properties[propName];
			if (typeof candidate !== "object") {
				isValid = false;
				break;
			}
			const value = (candidate as JSONSchema7).const;
			if (value === undefined) {
				isValid = false;
				break;
			}
			const key = String(value);
			if (values.has(key)) {
				isValid = false;
				break;
			}
			values.add(key);
		}
		if (isValid) return propName;
	}

	return null;
}

function tryEmitRustUnion(
	schema: JSONSchema7,