private static bool FixSentinel(ref Signal signal, Dictionary<Guid, Signal> sentinels, Dictionary<Guid, Signal> signalReplacements)
{
bool ret = false;
while(sentinels.ContainsKey(signal.InstanceId)) // is a sentinel
{
ret = true;
Signal original = sentinels[signal.InstanceId];
Signal final;
if(signalReplacements.TryGetValue(original.InstanceId, out final) && !signal.Equals(final))
signal = final; // sentinel was replaced -> replace with replacement
else
signal = original; // sentinel was not replaced -> replace with original
}
return ret; // is not a sentinel
}
public override bool LeaveSignal(Signal signal, Port parent, bool again, bool root)
{
// ## POST-MANIPULATE (REPLACED) SIGNALS
Signal rep;
if(_signalRep.TryGetValue(signal.InstanceId, out rep))
_signalRep[signal.InstanceId] = _visitor.ManipulateSignal(signal, rep, !signal.Equals(rep));
else
_signalRep[signal.InstanceId] = _visitor.ManipulateSignal(signal, signal, false);
return base.LeaveSignal(signal, parent, again, root);
}
/// <summary>
/// Returns the coefficient factor in the monomial <see cref="signal"/>
/// </summary>
/// <returns>
/// Constant UndefinedSymbol if <see cref="signal"/> is not a single-variable monomial.
/// Otherwise the coefficient factor of the term.
/// </returns>
/// </returns>
/// <remarks><see cref="signal"/> is assumed to be automatic simplified.</remarks>
public static Signal MonomialCoefficient(Signal signal, Signal variable, out ValueStructure degree)
{
if(IsConstantAdditiveIdentity(signal))
{
degree = NegativeInfinitySymbol.Instance;
return signal;
}
if(IsAlwaysRational(signal))
{
degree = IntegerValue.Zero;
return signal;
}
Signal coeff = IntegerValue.ConstantOne(signal.Context);
if(signal.IsDrivenByPortEntity("Multiply", "Std") && signal.DrivenByPort.InputSignalCount == 2 && IsAlwaysRational(signal.DrivenByPort.InputSignals[0]))
{
coeff = signal.DrivenByPort.InputSignals[0];
signal = signal.DrivenByPort.InputSignals[1];
}
if(signal.Equals(variable))
{
degree = IntegerValue.One;
return coeff;
}
if(signal.IsDrivenByPortEntity("Power", "Std"))
{
Signal b = signal.DrivenByPort.InputSignals[0];
Signal e = signal.DrivenByPort.InputSignals[1];
if(b.Equals(variable) && Std.IsAlwaysPositiveInteger(e))
{
degree = e.Value;
return coeff;
}
}
degree = UndefinedSymbol.Instance;
return UndefinedSymbol.Constant(signal.Context);
}
/// <summary>
/// Evaluates the degree of the single-variable monomial <see cref="signal"/>.
/// </summary>
/// <returns>
/// <see cref="UndefinedSymbol"/> if <see cref="signal"/> is not a single-variable monomial.
/// <see cref="NegativeInfinitySymbol"/> if <see cref="signal"/> is zero.
/// Otherwise an <see cref="IntegerValue"/> representing the asked degree.
/// </returns>
/// <remarks><see cref="signal"/> is assumed to be automatic simplified.</remarks>
public static ValueStructure MonomialDegree(Signal signal, Signal variable)
{
if(IsConstantAdditiveIdentity(signal))
return NegativeInfinitySymbol.Instance;
if(IsAlwaysRational(signal))
return IntegerValue.Zero;
if(signal.IsDrivenByPortEntity("Multiply", "Std") && signal.DrivenByPort.InputSignalCount == 2 && IsAlwaysRational(signal.DrivenByPort.InputSignals[0]))
signal = signal.DrivenByPort.InputSignals[1];
if(signal.Equals(variable))
return IntegerValue.One;
if(signal.IsDrivenByPortEntity("Power", "Std"))
{
Signal b = signal.DrivenByPort.InputSignals[0];
Signal e = signal.DrivenByPort.InputSignals[1];
if(b.Equals(variable) && Std.IsAlwaysPositiveInteger(e))
return e.Value;
}
return UndefinedSymbol.Instance;
}
/// <summary>
/// Checks whether a signal is a single variable monomial, e.g. '2*x^3'
/// </summary>
/// <remarks><see cref="signal"/> is assumed to be automatic simplified</remarks>
public static bool IsMonomial(Signal signal, Signal variable)
{
if(IsAlwaysRational(signal))
return true;
if(signal.IsDrivenByPortEntity("Multiply", "Std") && signal.DrivenByPort.InputSignalCount == 2 && IsAlwaysRational(signal.DrivenByPort.InputSignals[0]))
signal = signal.DrivenByPort.InputSignals[1];
if(signal.Equals(variable))
return true;
if(signal.IsDrivenByPortEntity("Power", "Std"))
{
Signal b = signal.DrivenByPort.InputSignals[0];
Signal e = signal.DrivenByPort.InputSignals[1];
if(b.Equals(variable) && Std.IsAlwaysPositiveInteger(e))
return true;
}
return false;
}
private static IManipulationVisitor CreateSubstituteVisitor(Signal subject, Signal replacement)
{
return new BasicManipulationVisitor(
delegate(Port p)
{ // ## ESTIMATE PLAN
if(p.InputSignals.Contains(subject))
return ManipulationPlan.DoAlter;
else
return ManipulationPlan.CloneIfChildsAltered;
},
delegate(Port port, SignalSet manipulatedInputs, bool hasManipulatedInputs)
{ // ## MANIPULATE PORT
/* NOTE: manipulatedInputs could contain sentinels, that's why
* we use the original port inputs instead. */
ReadOnlySignalSet inputs = port.InputSignals;
for(int i = 0; i < inputs.Count; i++)
if(subject.Equals(inputs[i]))
manipulatedInputs[i] = replacement;
return port.CloneWithNewInputs(manipulatedInputs).OutputSignals;
},
delegate(Signal original, Signal replaced, bool isReplaced)
{ // ## POST-MANIPULATE SIGNAL
if(subject.Equals(replaced))
return replacement;
else
return replaced;
});
}
