/// <summary>
/// Generates all repeating compositions with the specified parameters.
/// </summary>
/// <param name="compositionParameters">The parameters of the compositions to generate.</param>
/// <returns>An <see cref="IEnumerable{T}"/> containing the compositions that were generated.</returns>
/// <exception cref="ArgumentNullException"><paramref name="compositionParameters"/> is
/// <see langword="null"/>.</exception>
/// <exception cref="ArgumentException"><paramref name="compositionParameters"/> does not
/// have <see cref="CompositionParameters.Sum"/> a multiple of the number of repetitions of
/// this generator, or <paramref name="compositionParameters"/> does not have
/// <see cref="CompositionParameters.NumTerms"/> a multiple of the number of repetitions of
/// this generator.</exception>
/// <remarks>
/// <para>The compositions are generated in increasing lexicographical order.</para>
/// </remarks>
public IEnumerable <Composition> GenerateCompositions(CompositionParameters compositionParameters)
{
if (compositionParameters is null)
{
throw new ArgumentNullException(nameof(compositionParameters));
}
if (!compositionParameters.Sum.IsMultipleOf(numRepetitions))
{
throw new ArgumentException($"The sum ({compositionParameters.Sum}) is not a multiple " +
$"of the number of repetitions ({numRepetitions}).");
}
if (!compositionParameters.NumTerms.IsMultipleOf(numRepetitions))
{
throw new ArgumentException($"The number of terms ({compositionParameters.NumTerms}) " +
$"is not a multiple of the number of repetitions ({numRepetitions}).");
}
IEnumerable <Composition> Generate()
{
var exhaustiveGenerator = new ExhaustiveCompositionGenerator();
var parametersForNonRepeatingCompositions = new CompositionParameters(
compositionParameters.Sum / numRepetitions,
compositionParameters.NumTerms / numRepetitions);
foreach (var nonRepeatingComposition in exhaustiveGenerator.GenerateCompositions(parametersForNonRepeatingCompositions))
{
var repeatingTerms = Enumerable.Repeat(nonRepeatingComposition.Terms, numRepetitions).SelectMany(term => term);
var repeatingComposition = new Composition(repeatingTerms);
yield return(repeatingComposition);
}
}
return(Generate());
}
private IEnumerable <InteractiveLayeredQuiverGeneratorOutput> DoWork(
InteractiveLayeredQuiverGenerator interactiveQuiverGenerator,
CompositionParameters nextCompositionParameters,
ICompositionGenerator compositionGenerator)
{
if (nextCompositionParameters is null)
{
yield return(interactiveQuiverGenerator.EndGeneration());
yield break;
}
foreach (var composition in compositionGenerator.GenerateCompositions(nextCompositionParameters))
{
if (!interactiveQuiverGenerator.TrySupplyComposition(composition, out nextCompositionParameters))
{
continue;
}
foreach (var output in DoWork(interactiveQuiverGenerator, nextCompositionParameters, compositionGenerator))
{
yield return(output);
}
interactiveQuiverGenerator.UnsupplyLastComposition();
}
}
/// <summary>
/// Generates all compositions with the specified parameters.
/// </summary>
/// <param name="compositionParameters">The parameters of the compositions to generate.</param>
/// <returns>An <see cref="IEnumerable{T}"/> containing the compositions that were generated.</returns>
/// <exception cref="ArgumentNullException"><paramref name="compositionParameters"/> is
/// <see langword="null"/>.</exception>
/// <remarks>
/// <para>The compositions are generated in increasing lexicographical order.</para>
/// </remarks>
public IEnumerable <Composition> GenerateCompositions(CompositionParameters compositionParameters)
{
if (compositionParameters is null)
{
throw new ArgumentNullException(nameof(compositionParameters));
}
// If no terms, return the singleton collection of the empty composition.
if (compositionParameters.NumTerms == 0)
{
return(new Composition[] { new Composition() });
}
int numTermsLeft = compositionParameters.NumTerms;
var previousValues = new List <int>();
var previousValuesSum = 0;
int targetSum = compositionParameters.Sum;
return(DoWork(numTermsLeft, previousValues, previousValuesSum, targetSum));
}
