/// <summary>
/// Returns an empty template group.
/// </summary>
/// <param name="startingId">The lowest value for TemplateId in the group, which must be
/// greater than or equal to 0.</param>
public static ITemplateGroup CreateTemplateGroup(int startingId) {
Contract.Requires(startingId >= 0);
var group = new TemplateGroup();
// We consume startingId-1 so that the first id generator is equal to startingId
group.TemplateIdGenerator.Consume(startingId - 1);
return group;
}
/// <summary>
/// Merges a set of template groups together into one template group. An
/// InvalidOperationException is thrown if there are two templates with the same TemplateId.
/// </summary>
/// <param name="groups">The template groups to merge.</param>
/// <returns>A single template group that contains all of the templates within the given
/// groups.</returns>
/// <exception cref="InvalidOperationException">There were duplicate TemplateIds</exception>
public static ITemplateGroup MergeTemplateGroups(IEnumerable<ITemplateGroup> groups) {
// We store all of our templates in result.
var result = new TemplateGroup();
// ids verifies that every template has a unique TemplateId by checking for insertion
// failures (hash collisions) -- we could also use a SparseArray, but that could be
// * very* slow if the template groups go into the high ranges.
var ids = new HashSet<int>();
foreach (TemplateGroup templateGroup in groups.Cast<TemplateGroup>()) {
foreach (ITemplate template in templateGroup.Templates) {
int id = template.TemplateId;
// verify that we don't have any duplicate template ids
if (ids.Add(id) == false) {
throw new InvalidOperationException("Duplicate template with id=" + id);
}
// add the template to the result and consume its id
result.Templates.Add(template);
result.TemplateIdGenerator.Consume(id);
}
}
return result;
}
