/// <summary>
/// Executes the "|" operator by creating a state from which we can
/// choose to move to either first NFA or the second
/// </summary>
/// <param name="operandStack">The operand stack to execute the operator on</param>
public void Execute(Stack<NFAFragment> operandStack)
{
//Get the two operands
NFAFragment nfa2 = operandStack.Pop();
NFAFragment nfa1 = operandStack.Pop();
//The new NFA fragment starts with a split state
//The unbound states in it are those of both nfa1 and nfa2
NFAFragment newNFA = new NFAFragment();
newNFA.startState = new NFASplitState(nfa1.startState, nfa2.startState);
newNFA.unboundStates = nfa1.unboundStates;
newNFA.unboundStates.AddRange(nfa2.unboundStates);
//Put the resultant NFA back
operandStack.Push(newNFA);
}
/// <summary>
/// Compiles the given regular expression
/// </summary>
/// <param name="regExp">The regular expression to parse</param>
public Regex(string regExp)
{
//Initialisation
textView = regExp;
try
{
//Preprocess the regular expression and compile it into an NFA
resNFA = NFABuilder.CreateNFA(regExp);
}
catch (IndexOutOfRangeException)
{
//Exception while creating the NFA, the regular expression must be invalid
throw new RegexCompileException();
}
catch (InvalidOperationException)
{
throw new RegexCompileException();
}
}