/// <summary>
/// Creates an automaton for validating the correctness of argument placeholders for a given argument.
/// </summary>
/// <param name="argToValidateIndex">The index of the argument to validate.</param>
/// <param name="argNames">The names of all arguments.</param>
/// <returns>The created automaton.</returns>
private static StringAutomaton GetArgumentValidatingAutomaton(int argToValidateIndex, IReadOnlyList <string> argNames)
{
Debug.Assert(
argNames != null && argNames.All(name => !string.IsNullOrEmpty(name)),
"A valid array of argument names must be provided.");
Debug.Assert(
argToValidateIndex >= 0 && argToValidateIndex < argNames.Count,
"The provided argument index must be a valid index in the argument name array.");
string argListKey = ArgumentListToDictionaryKey(argToValidateIndex, argNames);
StringAutomaton result;
if (ArgsToValidatingAutomaton.TryGetValue(argListKey, out result))
{
return(result);
}
// Accepts placeholder for the current argument
StringAutomaton checkBracesForCurrentArg = StringAutomaton.ConstantOn(1.0, "{" + argNames[argToValidateIndex] + "}");
StringAutomaton checkBracesForOtherArgs = DisallowBracesAutomaton.Clone();
if (argNames.Count > 1)
{
// Skips placeholders for every argument except the current one
StringAutomaton skipOtherArgs = StringAutomaton.ConstantOnElement(1.0, '{');
skipOtherArgs.AppendInPlace(StringAutomaton.ConstantOn(1.0, argNames.Where((arg, index) => index != argToValidateIndex)));
skipOtherArgs.AppendInPlace(StringAutomaton.ConstantOnElement(1.0, '}'));
// Accepts placeholders for arguments other than current, with arbitrary intermediate text
checkBracesForOtherArgs.AppendInPlace(skipOtherArgs);
checkBracesForOtherArgs = StringAutomaton.Repeat(checkBracesForOtherArgs, minTimes: 0);
checkBracesForOtherArgs.AppendInPlace(DisallowBracesAutomaton);
}
// Checks the placeholder for the current argument, then skips placeholders for other arguments
StringAutomaton validateArgumentThenOtherArguments = checkBracesForCurrentArg.Clone();
validateArgumentThenOtherArguments.AppendInPlace(checkBracesForOtherArgs);
if (!RequirePlaceholderForEveryArgument)
{
// Make this block optional
validateArgumentThenOtherArguments = StringAutomaton.Sum(
validateArgumentThenOtherArguments,
StringAutomaton.ConstantOn(1.0, string.Empty));
}
// Accepts placeholders for arguments other then current, then for the current argument, then again other placeholders
result = checkBracesForOtherArgs.Clone();
result.AppendInPlace(validateArgumentThenOtherArguments);
result.TryDeterminize();
ArgsToValidatingAutomaton[argListKey] = result;
return(result);
}
public void NonNormalizableLoop3()
{
StringAutomaton automaton = StringAutomaton.Zero();
automaton.Start.AddTransition('a', Weight.FromValue(2.0), automaton.Start);
automaton.Start.EndWeight = Weight.FromValue(5.0);
StringAutomaton copyOfAutomaton = automaton.Clone();
Assert.Throws <InvalidOperationException>(() => automaton.NormalizeValues());
Assert.False(copyOfAutomaton.TryNormalizeValues());
////Assert.Equal(f, copyOfF); // TODO: fix equality first
}
/// <summary>
/// Tests if the weights of all outgoing transitions sum to one for each state of a given automaton.
/// </summary>
/// <param name="automaton">The automaton.</param>
private static void AssertStochastic(StringAutomaton automaton)
{
StringAutomaton automatonClone = automaton.Clone();
automatonClone.RemoveDeadStates();
for (int i = 0; i < automatonClone.States.Count; ++i)
{
Weight weightSum = automatonClone.States[i].EndWeight;
for (int j = 0; j < automatonClone.States[i].Transitions.Count; ++j)
{
weightSum += automatonClone.States[i].Transitions[j].Weight;
}
Assert.Equal(0.0, weightSum.LogValue, 1e-6);
}
}
public void NonNormalizableLoop2()
{
StringAutomaton automaton = StringAutomaton.Zero();
var endState = automaton.Start.AddTransition('a', Weight.FromValue(2.0));
endState.EndWeight = Weight.FromValue(5.0);
endState.AddTransition('b', Weight.FromValue(0.1), automaton.Start);
endState.AddTransition('c', Weight.FromValue(0.05), automaton.Start);
endState.AddSelfTransition('!', Weight.FromValue(0.75));
StringAutomaton copyOfAutomaton = automaton.Clone();
Assert.Throws <InvalidOperationException>(() => copyOfAutomaton.NormalizeValues());
Assert.False(copyOfAutomaton.TryNormalizeValues());
////Assert.Equal(f, copyOfF); // TODO: fix equality first
}
public void NonNormalizableLoop4()
{
StringAutomaton automaton = StringAutomaton.Zero();
automaton.Start.AddSelfTransition('a', Weight.FromValue(0.1));
var branch1 = automaton.Start.AddTransition('a', Weight.FromValue(2.0));
branch1.AddSelfTransition('a', Weight.FromValue(2.0));
branch1.SetEndWeight(Weight.One);
var branch2 = automaton.Start.AddTransition('a', Weight.FromValue(2.0));
branch2.SetEndWeight(Weight.One);
StringAutomaton copyOfAutomaton = automaton.Clone();
Assert.Throws <InvalidOperationException>(() => automaton.NormalizeValues());
Assert.False(copyOfAutomaton.TryNormalizeValues());
////Assert.Equal(f, copyOfF); // TODO: fix equality first
}
public void NormalizeValuesWithNonTrivialLoop()
{
StringAutomaton automaton = StringAutomaton.Zero();
var endState = automaton.Start.AddTransition('a', Weight.FromValue(2.0));
endState.EndWeight = Weight.FromValue(5.0);
endState.AddTransition('b', Weight.FromValue(0.1), automaton.Start);
endState.AddTransition('c', Weight.FromValue(0.05), automaton.Start);
endState.AddSelfTransition('!', Weight.FromValue(0.5));
var normalizedAutomaton = automaton.Clone();
double logNormalizer = normalizedAutomaton.NormalizeValues();
Assert.Equal(Math.Log(50.0), logNormalizer, 1e-6);
Assert.Equal(Math.Log(50.0), GetLogNormalizerByGetValue(automaton), 1e-6);
Assert.Equal(Math.Log(50.0), GetLogNormalizerByGetValueWithTransducers(automaton), 1e-6);
AssertStochastic(normalizedAutomaton);
foreach (var str in new[] { "a!!", "abaca", "a!ba!!ca!!!!" })
{
Assert.False(double.IsNegativeInfinity(automaton.GetLogValue(str)));
Assert.Equal(automaton.GetLogValue(str), normalizedAutomaton.GetLogValue(str) + logNormalizer, 1e-6);
}
}