/**
* Creates a {@link MiddlemanType#AGGREGATING_MIDDLEMAN aggregating} middleman.
*
* @param owner the owner of the action that will be created; must not be null
* @param purpose the purpose for which this middleman is created. This should be a string which
* is suitable for use as a filename. A single rule may have many middlemen with distinct
* purposes.
* @param inputs the set of artifacts for which the created artifact is to be the middleman.
* @param middlemanDir the directory in which to place the middleman.
* @return null iff {@code inputs} is empty; the single element of {@code inputs} if there's only
* one; a new aggregating middleman for the {@code inputs} otherwise
*/
public Artifact createAggregatingMiddleman(
ActionOwner owner, String purpose, Iterable<Artifact> inputs, Root middlemanDir) {
if (hasExactlyOneInput(inputs)) { // Optimization: No middleman for just one input.
return Iterables.getOnlyElement(inputs);
}
Pair<Artifact, Action> result =
createMiddleman(
owner,
Label.print(owner.getLabel()),
purpose,
inputs,
middlemanDir,
MiddlemanType.AGGREGATING_MIDDLEMAN);
return result == null ? null : result.getFirst();
}
