Function NormaliseSubtypes

src/train_cmd.cpp:960–981

* Normalise the sub types of the parts in this chain. * @param chain the chain to normalise. */

 * @param chain the chain to normalise.
 */
static void NormaliseSubtypes(Train *chain)
{
	/* Nothing to do */
	if (chain == nullptr) return;

	/* We must be the first in the chain. */
	assert(chain->Previous() == nullptr);

	/* Set the appropriate bits for the first in the chain. */
	if (chain->IsWagon()) {
		chain->SetFreeWagon();
	} else {
		assert(chain->IsEngine());
		chain->SetFrontEngine();
	}

	/* Now clear the bits for the rest of the chain */
	for (Train *t = chain->Next(); t != nullptr; t = t->Next()) {
		t->ClearFreeWagon();
		t->ClearFrontEngine();
	}
}

/**
 * Check/validate whether we may actually build a new train.