/// <summary>
/// Runs the lexer's DFA to match a terminal in the input ahead
/// </summary>
/// <param name="index">The current start index in the input text</param>
/// <returns>The matching DFA state and length</returns>
internal TokenMatch RunDFA(int index)
{
if (text.IsEnd(index))
{
// At the end of input
// The only terminal matched at state index 0 is $
return(new TokenMatch(0, 0));
}
TokenMatch result = new TokenMatch(0);
int state = 0;
int i = index;
while (state != Automaton.DEAD_STATE)
{
AutomatonState stateData = automaton.GetState(state);
// Is this state a matching state ?
if (stateData.TerminalsCount != 0)
{
result = new TokenMatch(state, i - index);
}
// No further transition => exit
if (stateData.IsDeadEnd)
{
break;
}
// At the end of the buffer
if (text.IsEnd(i))
{
break;
}
char current = text.GetValue(i);
i++;
// Try to find a transition from this state with the read character
state = stateData.GetTargetBy(current);
}
return(result);
}
/// <summary>
/// Runs this matcher
/// </summary>
/// <returns>The solution</returns>
public TokenMatch Run()
{
heads = new List <Head>();
insertions = new int[16];
insertionsCount = 0;
matchHead = new Head(0);
matchLength = 0;
int offset = 0;
bool atEnd = text.IsEnd(originIndex + offset);
char current = atEnd ? '\0' : text.GetValue(originIndex + offset);
if (atEnd)
{
InspectAtEnd(matchHead, offset);
}
else
{
Inspect(matchHead, offset, current);
}
while (heads.Count != 0)
{
offset++;
atEnd = text.IsEnd(originIndex + offset);
current = atEnd ? '\0' : text.GetValue(originIndex + offset);
List <Head> temp = new List <Head>(heads);
heads.Clear();
foreach (Head head in temp)
{
if (atEnd)
{
InspectAtEnd(head, offset);
}
else
{
Inspect(head, offset, current);
}
}
}
return(matchLength == 0 ? OnFailure() : OnSuccess());
}