/// <summary>
/// Finds largest term accepted by this Automaton, that's
/// <= the provided input term. The result is placed in
/// output; it's fine for output and input to point to
/// the same BytesRef. The returned result is either the
/// provided output, or null if there is no floor term
/// (ie, the provided input term is before the first term
/// accepted by this Automaton).
/// </summary>
public virtual BytesRef Floor(BytesRef input, BytesRef output)
{
output.Offset = 0;
//if (DEBUG) System.out.println("CA.floor input=" + input.utf8ToString());
int state = RunAutomaton.InitialState;
// Special case empty string:
if (input.Length == 0)
{
if (RunAutomaton.IsAccept(state))
{
output.Length = 0;
return(output);
}
else
{
return(null);
}
}
IList <int> stack = new List <int>();
int idx = 0;
while (true)
{
int label = input.Bytes[input.Offset + idx] & 0xff;
int nextState = RunAutomaton.Step(state, label);
//if (DEBUG) System.out.println(" cycle label=" + (char) label + " nextState=" + nextState);
if (idx == input.Length - 1)
{
if (nextState != -1 && RunAutomaton.IsAccept(nextState))
{
// Input string is accepted
if (idx >= output.Bytes.Length)
{
output.Grow(1 + idx);
}
output.Bytes[idx] = (sbyte)label;
output.Length = input.Length;
//if (DEBUG) System.out.println(" input is accepted; return term=" + output.utf8ToString());
return(output);
}
else
{
nextState = -1;
}
}
if (nextState == -1)
{
// Pop back to a state that has a transition
// <= our label:
while (true)
{
Transition[] transitions = SortedTransitions[state];
if (transitions.Length == 0)
{
Debug.Assert(RunAutomaton.IsAccept(state));
output.Length = idx;
//if (DEBUG) System.out.println(" return " + output.utf8ToString());
return(output);
}
else if (label - 1 < transitions[0].Min_Renamed)
{
if (RunAutomaton.IsAccept(state))
{
output.Length = idx;
//if (DEBUG) System.out.println(" return " + output.utf8ToString());
return(output);
}
// pop
if (stack.Count == 0)
{
//if (DEBUG) System.out.println(" pop ord=" + idx + " return null");
return(null);
}
else
{
state = stack[stack.Count - 1];
stack.RemoveAt(stack.Count - 1);
idx--;
//if (DEBUG) System.out.println(" pop ord=" + (idx+1) + " label=" + (char) label + " first trans.min=" + (char) transitions[0].min);
label = input.Bytes[input.Offset + idx] & 0xff;
}
}
else
{
//if (DEBUG) System.out.println(" stop pop ord=" + idx + " first trans.min=" + (char) transitions[0].min);
break;
}
}
//if (DEBUG) System.out.println(" label=" + (char) label + " idx=" + idx);
return(AddTail(state, output, idx, label));
}
else
{
if (idx >= output.Bytes.Length)
{
output.Grow(1 + idx);
}
output.Bytes[idx] = (sbyte)label;
stack.Add(state);
state = nextState;
idx++;
}
}
}
