/// <summary>
/// Compares the spacing (as represented by grouping) of using directives in
/// two lists. Returns null if they are the same, and otherwise returns a
/// description of the first line at which to either remove or insert space
/// to bring the list closer into line with the required spacing. (This presumes
/// that the order is already correct.)
/// </summary>
/// <param name="requiredGroups">The required order and spacing, where
/// spacing is denoted by grouping.</param>
/// <param name="currentGroups">The current order and spacing.</param>
/// <returns>Null if the spacing matches. Otherwise, a <see cref="SpaceChange"/>
/// describing where to add or remove a blank line.</returns>
public static SpaceChange GetNextModification(
IEnumerable<IEnumerable<UsingDirective>> requiredGroups,
IEnumerable<IEnumerable<UsingDirective>> currentGroups)
{
var requiredByGroup = requiredGroups
.SelectMany((items, groupIndex) => items.Select(item => groupIndex));
var currentByGroup = currentGroups
.SelectMany((items, groupIndex) => items.Select(item => groupIndex));
var itemsByGroup = requiredByGroup.Zip(currentByGroup, (required, actual) => new { required, actual });
int index = 0;
foreach (var groupIndices in itemsByGroup)
{
if (groupIndices.actual < groupIndices.required)
{
return SpaceChange.Insert(index);
}
if (groupIndices.actual > groupIndices.required)
{
return SpaceChange.Remove(index);
}
index += 1;
}
return null;
}
/// <summary>
/// Given a set of using directives which are already in the correct order, determines
/// where to remove or add a blank line to bring them one step closer to the correct
/// spacing. This method should be called repeatedly (applying each update that it
/// generates between each call) until it returns null to indicate that the order
/// is correct.
/// </summary>
/// <param name="requiredOrderByGroups">The correct order and spacing (e.g., as
/// determined by a call to <see cref="FlattenImportsAndDetermineOrderAndSpacing"/>).</param>
/// <param name="items">The directives as they are currently ordered and spaced.</param>
/// <returns>Null if the directives are already in the correct order. Otherwise,
/// a <see cref="SpaceChange"/> describing where to add or remove a blank line.</returns>
public static SpaceChange GetNextSpacingModification(
List <List <UsingDirective> > requiredOrderByGroups,
List <UsingDirectiveOrSpace> items)
{
SpaceChange nextChange = null;
if (requiredOrderByGroups != null)
{
var importsByGroup = new List <List <UsingDirective> >();
foreach (UsingDirectiveOrSpace item in items)
{
if (importsByGroup.Count == 0)
{
importsByGroup.Add(new List <UsingDirective>());
}
List <UsingDirective> currentGroup = importsByGroup[importsByGroup.Count - 1];
if (item.IsBlankLine)
{
if (currentGroup.Count > 0)
{
importsByGroup.Add(new List <UsingDirective>());
}
}
else
{
currentGroup.Add(item.Directive);
}
}
nextChange = SpacingChecker.GetNextModification(
requiredOrderByGroups,
importsByGroup);
}
return(nextChange);
}