public SymbolTuple(NonTerminalSymbol target, TerminalSymbol terminalSymbol, NonTerminalSymbol nonTerminalSymbol)
{
if (target == null)
{
throw new ArgumentNullException(nameof(target));
}
Target = target;
NonTerminalSymbol = nonTerminalSymbol;
TerminalSymbol = terminalSymbol;
}
private SymbolTuple GetSymbolTuple(GrammarType grammarType, Chain chain, NonTerminalSymbol ruleTarget, NonTerminalSymbol finalTarget = null)
{
int state = 0;
Symbol otherSymbol = null;
NonTerminalSymbol nonTerminalSymbol = null;
TerminalSymbol terminalSymbol = null;
foreach (Symbol symbol in Enumerate(chain, grammarType))
{
switch (state)
{
case 0:
otherSymbol = symbol;
state = 1;
break;
case 1:
nonTerminalSymbol = otherSymbol.As <NonTerminalSymbol>();
if (nonTerminalSymbol == null)
{
throw new InvalidOperationException("Expected non terminal symbol.");
}
terminalSymbol = symbol.As <TerminalSymbol>();
if (terminalSymbol == null)
{
throw new InvalidOperationException("Expected terminal symbol.");
}
state = 2;
break;
default:
throw new InvalidOperationException("Expected 2 or less symbols.");
}
}
switch (state)
{
case 0:
if (ruleTarget != Target && finalTarget != null)
{
throw new InvalidOperationException("Expected that rule target equals to grammar target.");
}
return(new SymbolTuple(ruleTarget, null, null));
case 1:
nonTerminalSymbol = finalTarget != null ? finalTarget : otherSymbol.As <NonTerminalSymbol>();
terminalSymbol = otherSymbol.As <TerminalSymbol>();
if (terminalSymbol == null && nonTerminalSymbol == null)
{
throw new InvalidOperationException(string.Format("The symbol type is not supported symbol type: {0}.", otherSymbol));
}
if (finalTarget != null && terminalSymbol == null)
{
throw new InvalidOperationException("One symbol chain must contain terminal symbol.");
}
goto case 2;
case 2:
default:
return(new SymbolTuple(ruleTarget, terminalSymbol, nonTerminalSymbol));
}
}