return includePaths;
        }
        return new PrefixedIncludePath(toDir(sourceDir), includePaths);
    }

    private static abstract class IncludePath {
        @Nullable
        abstract IncludeFile searchForDependency(String includePath, boolean quotedPath);
    }

    private static class PrefixedIncludePath extends IncludePath {
        private final DirectoryContents head;