Function tryEmitRustUnion

scripts/codegen/rust.ts:287–394

(
	schema: JSONSchema7,
	parentTypeName: string,
	jsonPropName: string,
	ctx: RustCodegenCtx,
)

}

function tryEmitRustUnion(
	schema: JSONSchema7,
	parentTypeName: string,
	jsonPropName: string,
	ctx: RustCodegenCtx,
): string | null {
	const variants = getUnionVariants(schema);
	if (!variants) return null;

	const nonNull = variants.filter((variant) => variant.type !== "null");
	if (nonNull.length <= 1) return null;

	const enumName =
		(typeof schema.title === "string" && schema.title) ||
		parentTypeName + toPascalCase(jsonPropName);

	const resolvedVariants: RustUnionVariant[] = [];
	for (let i = 0; i < nonNull.length; i++) {
		const variant = nonNull[i];
		if (variant.$ref && typeof variant.$ref === "string") {
			const resolved = resolveRef(variant.$ref, ctx.definitions);
			if (resolved && !isObjectSchema(resolved)) return null;
			resolvedVariants.push({
				schema: (resolved ?? variant) as JSONSchema7,
				typeName: rustRefTypeName(variant.$ref, ctx.definitions),
			});
			continue;
		}

		const resolved =
			resolveObjectSchema(variant, ctx.definitions) ??
			resolveSchema(variant, ctx.definitions) ??
			variant;
		if (!isObjectSchema(resolved)) return null;
		const discriminatorValue = Object.values(resolved.properties ?? {}).find(
			(prop) => typeof prop === "object" && (prop as JSONSchema7).const !== undefined,
		) as JSONSchema7 | undefined;
		const typeName =
			(typeof resolved.title === "string" && resolved.title) ||
			(discriminatorValue?.const !== undefined
				? `${enumName}${toPascalCase(String(discriminatorValue.const))}`
				: `${enumName}Variant${i + 1}`);

		resolvedVariants.push({
			schema: resolved as JSONSchema7,
			typeName,
		});
	}

	const discriminator = findRustDiscriminator(resolvedVariants);
	const isAllowedUnionType = ctx.allowedUnionTypeNames.has(enumName);
	if (discriminator) {
		if (
			ctx.unionDiscriminatorProperties &&
			!ctx.unionDiscriminatorProperties.has(discriminator) &&
			!isAllowedUnionType
		) {
			return null;