/// <summary>
/// Expert: like <seealso cref="Util#getByOutput(FST, long)"/> except reusing
/// BytesReader, initial and scratch Arc, and result.
/// </summary>
public static IntsRef GetByOutput(FST <long?> fst, long targetOutput, FST <long?> .BytesReader @in, FST <long?> .Arc <long?> arc, FST <long?> .Arc <long?> scratchArc, IntsRef result)
{
long output = arc.Output.Value;
int upto = 0;
//System.out.println("reverseLookup output=" + targetOutput);
while (true)
{
//System.out.println("loop: output=" + output + " upto=" + upto + " arc=" + arc);
if (arc.Final)
{
long finalOutput = output + arc.NextFinalOutput.Value;
//System.out.println(" isFinal finalOutput=" + finalOutput);
if (finalOutput == targetOutput)
{
result.Length = upto;
//System.out.println(" found!");
return(result);
}
else if (finalOutput > targetOutput)
{
//System.out.println(" not found!");
return(null);
}
}
if (FST <long?> .TargetHasArcs(arc))
{
//System.out.println(" targetHasArcs");
if (result.Ints.Length == upto)
{
result.Grow(1 + upto);
}
fst.ReadFirstRealTargetArc(arc.Target, arc, @in);
if (arc.BytesPerArc != 0)
{
int low = 0;
int high = arc.NumArcs - 1;
int mid = 0;
//System.out.println("bsearch: numArcs=" + arc.numArcs + " target=" + targetOutput + " output=" + output);
bool exact = false;
while (low <= high)
{
mid = (int)((uint)(low + high) >> 1);
@in.Position = arc.PosArcsStart;
@in.SkipBytes(arc.BytesPerArc * mid);
var flags = (sbyte)@in.ReadByte();
fst.ReadLabel(@in);
long minArcOutput;
if ((flags & FST <long> .BIT_ARC_HAS_OUTPUT) != 0)
{
long arcOutput = fst.Outputs.Read(@in).Value;
minArcOutput = output + arcOutput;
}
else
{
minArcOutput = output;
}
if (minArcOutput == targetOutput)
{
exact = true;
break;
}
else if (minArcOutput < targetOutput)
{
low = mid + 1;
}
else
{
high = mid - 1;
}
}
if (high == -1)
{
return(null);
}
else if (exact)
{
arc.ArcIdx = mid - 1;
}
else
{
arc.ArcIdx = low - 2;
}
fst.ReadNextRealArc(arc, @in);
result.Ints[upto++] = arc.Label;
output += arc.Output.Value;
}
else
{
FST <long?> .Arc <long?> prevArc = null;
while (true)
{
//System.out.println(" cycle label=" + arc.label + " output=" + arc.output);
// this is the min output we'd hit if we follow
// this arc:
long minArcOutput = output + arc.Output.Value;
if (minArcOutput == targetOutput)
{
// Recurse on this arc:
//System.out.println(" match! break");
output = minArcOutput;
result.Ints[upto++] = arc.Label;
break;
}
else if (minArcOutput > targetOutput)
{
if (prevArc == null)
{
// Output doesn't exist
return(null);
}
else
{
// Recurse on previous arc:
arc.CopyFrom(prevArc);
result.Ints[upto++] = arc.Label;
output += arc.Output.Value;
//System.out.println(" recurse prev label=" + (char) arc.label + " output=" + output);
break;
}
}
else if (arc.Last)
{
// Recurse on this arc:
output = minArcOutput;
//System.out.println(" recurse last label=" + (char) arc.label + " output=" + output);
result.Ints[upto++] = arc.Label;
break;
}
else
{
// Read next arc in this node:
prevArc = scratchArc;
prevArc.CopyFrom(arc);
//System.out.println(" after copy label=" + (char) prevArc.label + " vs " + (char) arc.label);
fst.ReadNextRealArc(arc, @in);
}
}
}
}
else
{
//System.out.println(" no target arcs; not found!");
return(null);
}
}
}
