/// <summary> Creates a collection of indices pointing in the specified collection. </summary>
/// <param name="collection"> The collection the resulting indices will point in. </param>
/// <param name="indices"> The indices to point at. Must be in range. </param>
public static Index <TElement>[] Range(IReadOnlyList <TElement> collection, params int[] indices)
{
Contract.Requires(collection != null);
Contract.Requires(indices != null);
Contract.RequiresForAll(indices, i => 0 <= i && i < collection.Count);
return(indices.Map(i => new Index <TElement>(i, collection)));
}
public ConcatenatedReadOnlyObservableCollection(params ObservableCollection <T>[] collections)
{
Contract.Requires(collections != null);
Contract.RequiresForAll(collections, Global.NotNull);
this.collections = collections;
foreach (var collection in collections)
{
collection.CollectionChanged += onCollectionCollectionChanged;
}
this.recomputeCount();
}
/// <summary> Gets whether the specified combination of occupations fills the entire specified length. Is public only to serve debugging purposes. </summary>
public static bool DoesCombinationFill(IEnumerable <IReadOnlyList <bool> > combination, Interval toFill)
{
Contract.Requires(!toFill.IsEmpty);
Contract.Requires(toFill.StartInclusive);
Contract.Requires(!toFill.EndInclusive);
Contract.Requires(combination != null);
Contract.RequiresForAll(combination, NotNull);
EnsureSingleEnumerationDEBUG(ref combination);
Contract.Requires(combination.Any(justAny => true));
Contract.Requires(combination.Select(combi => combi.Count).AreEqual());
//Contract.LazilyRequires(ref combination, occupation => occupation.Count == toFill.Length);//assumed the combinations are already shifted to start at the beginning of the specified interval
//an interval is filled if all bits up to length occur once in the combinations and no bits after length occur.
//that is the same as counting the bits and that they must equal length and that the indices of the bits are unique
BitArray filled = new BitArray(toFill.Length);
foreach (var occupation in combination)
{
Contract.Requires(occupation.Count >= toFill.Length);
for (int i = 0; i < filled.Length; i++)
{
if (filled[i])
{
if (occupation[i + toFill.Start])
{
return(false); // bit is doubly filled
}
}
else
{
filled[i] |= occupation[i + toFill.Start];
}
}
}
return(filled.IsFull());
}
/// <summary> Gets all combinations of options that fill the specified length. </summary>
/// <param name="options"> The option to fill the interval with. Each option holds the information of which spots it fills (from 0 to end.Length). </param>
/// <param name="toFill"> The interval to fill. </param>
/// <param name="initialFilling"> Specifies which indices are pre-filled. Specify null to indicate no pre-filling. </param>
public static IEnumerable <T[]> AllFillingIntervalCombinations <T>(this IReadOnlyList <T> options, Interval toFill, IReadOnlyList <bool> initialFilling = null) where T : IFillable
{
//TODO: redo this method, it is terribly inefficient (and the other overload as well)
//also immediately remove options that have overlap with the initial filling: or change design to ignore overlap with initial filling. Should that overlap then be full?
Contract.Requires(!toFill.IsEmpty);
Contract.Requires(toFill.StartInclusive);
Contract.Requires(!toFill.EndInclusive);
Contract.Requires(toFill.Start >= 0);
Contract.Requires(options != null);
Contract.RequiresForAll(options, option => option != null);
Contract.LazilyAssertForAll(options, option => option.Occupation.Count == toFill.End);
if (initialFilling != null && initialFilling.All())
{
return(EmptyCollection <T> .Array.ToSingleton());
}
var result = Enumerable.Range(1, options.Count)
.SelectMany(i => AllCombinations(options, i))
.Where(combination => DoesCombinationFill(combination.Select(element => element.Occupation).ConcatIfNotNull(initialFilling), toFill));
EnsureSingleEnumerationDEBUG(ref result);
return(result);
}
/// <summary> Determines whether this combination of fillings can fill the entire length, where some fillings may be expanded. </summary>
/// <returns> The specified combination with the gaps; or null if the entire length couldn't be filled (even with expansions). </returns>
private static CombinationWithGaps <T> CanCombinationFill <T>(IReadOnlyList <T> combination, IEnumerable <IReadOnlyList <bool> > combinationFilling, IReadOnlyList <bool> initialFilling, Interval toFill, CanExpandFillingDelegate <T> canExpand) where T : class, IFillable
{
//an interval is filled if all positions up to length occur once in the combinationFilling and no positions after length occur.
//if there are gaps, positions next to the gaps may be queried whether they are capable of filling the gaps. A gap may be multiple positions wide.
//a gap may not be filled by two partial expansions
//these restricions are imposed for simplicity: perhaps later in general any gap may be filled by any position, but that doesn't seem required for now
Contract.Requires(combination != null);
Contract.RequiresForAll(combination, selection => toFill.Contains(new Interval(selection.Occupation)), "combination selected outside of interval to fill");
Contract.Requires(!toFill.IsEmpty);
Contract.Requires(toFill.StartInclusive);
Contract.Requires(!toFill.EndInclusive);
int length = combination[0].Occupation.Count;
Func <int, T> getOptionThatFilledIndex = positionIndex =>
{
int i = combinationFilling.IndexOf(filling => positionIndex >= filling.Count ? false : filling[positionIndex]);
if (i == -1)
{
//in case the leaf at the specified position index was flagged 'alreadyBound'
Contract.Assert(initialFilling[positionIndex]);
return(null);
}
return(combination[i]);
};
SortedList <int> filledPositionIndices = combinationFilling.ConcatIfNotNull(initialFilling)
.SelectManySorted(elementFilling => elementFilling.IndicesOf(_ => _))
.ToSortedList(); //TODO: more lazily
if (containsDoubles(filledPositionIndices))
{
return(null);
}
List <Gap> gaps = findGaps(filledPositionIndices, toFill).ToList();
foreach (Gap gap in gaps)
{
T substitute = null;
//check whether the element to the left can fill the gap
if (gap.Start != 0)
{
var optionThatFilled = getOptionThatFilledIndex(gap.Start - 1);
if (optionThatFilled != null && canExpand(optionThatFilled, gap))
{
continue;
}
}
//check whether the element to the right can fill the gap
if (gap.End < length)
{
Contract.Assert(substitute == null, "gap is being filled from both sides"); //just place 'else' before 'if' above: but realize that this then makes filling from the left preferable
var optionThatFilled = getOptionThatFilledIndex(gap.End);
if (optionThatFilled != null && canExpand(optionThatFilled, gap))
{
continue;
}
}
//some gap could not be filled
return(null);
}
//all gaps were filled
return(new CombinationWithGaps <T>(combination, gaps));
}
