/// <summary>
/// Creates a transducer <c>T(a, b) = sum_i Ti(a, b)</c>, where <c>Ti(a, b)</c> is an element of a given transducer collection.
/// </summary>
/// <param name="transducers">The transducers to sum.</param>
/// <returns>The created transducer.</returns>
public static TThis Sum(IEnumerable <TThis> transducers)
{
Argument.CheckIfNotNull(transducers, "transducers");
return(new TThis {
sequencePairToWeight = PairListAutomaton.Sum(transducers.Select(t => t.sequencePairToWeight))
});
}
/// <summary>
/// Creates a transducer <c>T'(a, b) = sum_{k=Kmin}^{Kmax} sum_{a1 a2 ... ak = a} sum_{b1 b2 ... bk = b} T(a1, b1)T(a2, b2)...T(ak, bk)</c>,
/// where <c>T(a, b)</c> is a given transducer, and <c>Kmin</c> and <c>Kmax</c> are the minimum
/// and the maximum number of factors in a sum term.
/// </summary>
/// <param name="transducer">The transducer.</param>
/// <param name="minTimes">The minimum number of factors in a sum term. Defaults to 1.</param>
/// <param name="maxTimes">An optional maximum number of factors in a sum term.</param>
/// <returns>The created transducer.</returns>
/// <remarks>
/// The result is the sum of Cauchy products of the given transducer with itself,
/// each product having a different number of factors.
/// </remarks>
public static TThis Repeat(TThis transducer, int minTimes = 1, int?maxTimes = null)
{
Argument.CheckIfNotNull(transducer, "transducer");
return(new TThis {
sequencePairToWeight = PairListAutomaton.Repeat(transducer.sequencePairToWeight, minTimes, maxTimes)
});
}
/// <summary>
/// Creates a transducer <c>T'(a, b) = T(a, b) + I[a = "", b = ""]</c>, where <c>T(a, b)</c> is a given transducer.
/// </summary>
/// <param name="transducer">The transducer <c>U(a, b)</c>.</param>
/// <returns>The created transducer.</returns>
public static TThis Optional(TThis transducer)
{
Argument.CheckIfNotNull(transducer, "transducer");
var emptySequence = new List <Pair <Option <TSrcElement>, Option <TDestElement> > >();
return(Sum(
transducer,
new TThis {
sequencePairToWeight = PairListAutomaton.ConstantOnLog(0.0, emptySequence)
}));
}
/// <summary>
/// Creates a transducer <c>T(a, b) = f(a) I[b = ""]</c>, where <c>f(a)</c> is a given automaton.
/// </summary>
/// <param name="srcAutomaton">The automaton defining weights for the first transducer argument.</param>
/// <returns>The created transducer.</returns>
public static TThis Consume(TSrcAutomaton srcAutomaton)
{
Argument.CheckIfNotNull(srcAutomaton, nameof(srcAutomaton));
return(new TThis
{
sequencePairToWeight = srcAutomaton.ApplyFunction <
List <(Option <TSrcElement>, Option <TDestElement>)>,
(Option <TSrcElement>, Option <TDestElement>),
TPairDistribution,
ListManipulator <List <(Option <TSrcElement>, Option <TDestElement>)>, (Option <TSrcElement>, Option <TDestElement>)>,
PairListAutomaton>(
(dist, weight, group) => ValueTuple.Create(
dist.HasValue
? Option.Some(ImmutablePairDistributionBase <TSrcElement, TSrcElementDistribution, TDestElement, TDestElementDistribution, TPairDistribution> .FromFirst(dist))
: Option.None,
weight))
});
