/// <summary>
/// Expects a string similar to:
/// E={a|O,b|O},true
/// Indicating that two strings are legal in state E:
/// a, which maps to O, and b, which maps to O, as well as e being an accepting state.
///
/// Doesn't fully populate the State Object, and instead, returns a partially populated state object, with a list(tuple(string, statename) indicating the mapping states.
/// </summary>
/// <param name="s">the string to parse.</param>
/// <returns>A Tuple representing a <see cref="DeterministicState"/>, and list of tuple(string,string) describing the legal characters and state transformations of the <see cref="DeterministicState"/>, for secondary parsing.</returns>
private static Tuple <DeterministicState, List <Tuple <string, string> > > ParseStateLine(string s)
{
if (!s.Contains("="))
{
throw new Exception("Missing a '=' symbol on line '" + s + "'");
}
string stateName = s.Trim().Substring(0, s.Trim().IndexOf("=")).Trim();
string map = s.Substring(s.IndexOf('{') + 1, s.IndexOf('}') - s.IndexOf('{') - 1);
string isAcceptingUnparsed = s.Substring(s.IndexOf(",", s.IndexOf('}')) + 1).Trim();
DeterministicState retState = new DeterministicState
{
StateName = stateName,
IsAccepting = bool.Parse(isAcceptingUnparsed),
};
List <Tuple <string, string> > mapDef = new List <Tuple <string, string> >();
string[] splitMapDefsZero = map.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
foreach (string splitMapDef in splitMapDefsZero)
{
string trimmedSplitMaPdef = splitMapDef.Trim();
int pipeIndex = trimmedSplitMaPdef.Trim().IndexOf('|');
string val = trimmedSplitMaPdef.Substring(0, pipeIndex).Trim();
string mappedState = trimmedSplitMaPdef.Substring(pipeIndex + 1).Trim();
mapDef.Add(new Tuple <string, string>(val, mappedState));
}
return(new Tuple <DeterministicState, List <Tuple <string, string> > >(retState, mapDef));
}
/// <summary>
/// Evaluates whether two provided <see cref="DeterministicState"/>s are equal by value.
/// <para>Note: If every <see cref="DeterministicState"/> S in <paramref name="left"/> has a corresponding <see cref="DeterministicState"/> with an identical NAME in <paramref name="right"/>,
/// they are assumed to be equal, even if the states mapped are not actually the same by ref, or have differing definitions.</para>
/// </summary>
/// <param name="left">The left <see cref="DeterministicState"/> to compare.</param>
/// <param name="right">The right <see cref="DeterministicState"/> to compare.</param>
/// <returns><see langword="true"/> if <paramref name="left"/> equals <paramref name="right"/>, else, <see langword="false"/>.</returns>
public static bool ValueEquals(this DeterministicState left, DeterministicState right)
{
if (left.AreValueInequalByNullDisparity(right))
{
return(false);
}
if (object.ReferenceEquals(left, right))
{
return(true);
}
if (left.StateName != right.StateName ||
left.IsAccepting != right.IsAccepting ||
left.AcceptableStrings.AreValueInequalByNullDisparity(right.AcceptableStrings) ||
left.AcceptableStrings?.Count != right.AcceptableStrings?.Count)
{
return(false);
}
foreach (var keyPair in left.AcceptableStrings)
{
if (!right.AcceptableStrings.ContainsKey(keyPair.Key))
{
return(false);
}
}
return(true);
}
private static ParseStringResults EvalDFA(DFA dfa, string data)
{
ParseStringResults retVal = new ParseStringResults
{
Input = data,
CorrespondingAutomaton = dfa,
};
DeterministicState currState = null;
int digitsForLengthOfChars = CalculateDigits(data.Length);
if (dfa.StateLookup.ContainsKey("E"))
{
currState = dfa.DeterministicStateLookup["E"]; // always start with E.
}
else if (dfa.StateLookup.ContainsKey("q_0"))
{
currState = dfa.DeterministicStateLookup["q_0"]; // else, start with q_0.
}
else if (dfa.StateLookup.ContainsKey("Q_0"))
{
currState = dfa.DeterministicStateLookup["Q_0"]; // else, start with Q_0.
}
else if (dfa.StateLookup.ContainsKey("q0"))
{
currState = dfa.DeterministicStateLookup["q0"]; // else, start with q0.
}
else if (dfa.StateLookup.ContainsKey("Q0"))
{
currState = dfa.DeterministicStateLookup["Q0"]; // else, start with Q0.
}
else
{
retVal.ErrorMessage = "Please ensure your automaton has a starting edge named, in order, one of (E,q_0,Q_0,q0,Q0). The first edge by a matching name in the aforementioned tuple is assumed to be the starting edge.";
}
int idx = 0;
foreach (char c in data)
{
if (currState.AcceptableStrings.ContainsKey(c.ToString()))
{
DeterministicState nextState = currState.AcceptableStrings[c.ToString()];
retVal.EvalStatements.Add(string.Format(
"[{0}]: {1}[{2}] -> {3}",
idx.ToString().PadLeft(digitsForLengthOfChars, '0'),
currState.StateName,
c,
nextState.StateName));
currState = nextState;
}
else
{
retVal.ErrorMessage = string.Format("Illegal character at index {0}", idx);
retVal.IllegalCharIndex = idx;
retVal.Validated = false;
return(retVal);
}
idx++;
}
if (currState.IsAccepting)
{
retVal.Validated = true;
}
else
{
retVal.Validated = false;
retVal.ErrorMessage = string.Format(
"The Automaton did not end in an accepting state. The final state was {0}.",
currState.StateName);
retVal.IllegalCharIndex = retVal.Input.Length - 1;
}
return(retVal);
}
