protected internal override float PhraseFreq()
{
// sort list with pq
pq.Clear();
for (PhrasePositions pp = first; pp != null; pp = pp.next)
{
pp.FirstPosition();
pq.Add(pp); // build pq from list
}
PqToList(); // rebuild list from pq
// for counting how many times the exact phrase is found in current document,
// just count how many times all PhrasePosition's have exactly the same position.
int freq = 0;
do
{
// find position w/ all terms
while (first.position < last.position)
{
// scan forward in first
do
{
if (!first.NextPosition())
{
return(freq);
}
}while (first.position < last.position);
FirstToLast();
}
freq++; // all equal: a match
}while (last.NextPosition());
return(freq);
}
/// <summary> Init PhrasePositions in place.
/// There is a one time initialization for this scorer:
/// <br/>- Put in repeats[] each pp that has another pp with same position in the doc.
/// <br/>- Also mark each such pp by pp.repeats = true.
/// <br/>Later can consult with repeats[] in termPositionsDiffer(pp), making that check efficient.
/// In particular, this allows to score queries with no repetitions with no overhead due to this computation.
/// <br/>- Example 1 - query with no repetitions: "ho my"~2
/// <br/>- Example 2 - query with repetitions: "ho my my"~2
/// <br/>- Example 3 - query with repetitions: "my ho my"~2
/// <br/>Init per doc w/repeats in query, includes propagating some repeating pp's to avoid false phrase detection.
/// </summary>
/// <returns> end (max position), or -1 if any term ran out (i.e. done)
/// </returns>
/// <throws> IOException </throws>
private int InitPhrasePositions()
{
int end = 0;
// no repeats at all (most common case is also the simplest one)
if (checkedRepeats && repeats == null)
{
// build queue from list
pq.Clear();
for (PhrasePositions pp = first; pp != null; pp = pp.next)
{
pp.FirstPosition();
if (pp.position > end)
{
end = pp.position;
}
pq.Add(pp); // build pq from list
}
return(end);
}
// position the pp's
for (PhrasePositions pp = first; pp != null; pp = pp.next)
{
pp.FirstPosition();
}
// one time initializatin for this scorer
if (!checkedRepeats)
{
checkedRepeats = true;
// check for repeats
HashMap <PhrasePositions, object> m = null;
for (PhrasePositions pp = first; pp != null; pp = pp.next)
{
int tpPos = pp.position + pp.offset;
for (PhrasePositions pp2 = pp.next; pp2 != null; pp2 = pp2.next)
{
int tpPos2 = pp2.position + pp2.offset;
if (tpPos2 == tpPos)
{
if (m == null)
{
m = new HashMap <PhrasePositions, object>();
}
pp.repeats = true;
pp2.repeats = true;
m[pp] = null;
m[pp2] = null;
}
}
}
if (m != null)
{
repeats = m.Keys.ToArray();
}
}
// with repeats must advance some repeating pp's so they all start with differing tp's
if (repeats != null)
{
for (int i = 0; i < repeats.Length; i++)
{
PhrasePositions pp = repeats[i];
PhrasePositions pp2;
while ((pp2 = TermPositionsDiffer(pp)) != null)
{
if (!pp2.NextPosition())
{
// out of pps that do not differ, advance the pp with higher offset
return(-1); // ran out of a term -- done
}
}
}
}
// build queue from list
pq.Clear();
for (PhrasePositions pp = first; pp != null; pp = pp.next)
{
if (pp.position > end)
{
end = pp.position;
}
pq.Add(pp); // build pq from list
}
if (repeats != null)
{
tmpPos = new PhrasePositions[pq.Size()];
}
return(end);
}
