Snippets draft 1, a lot too much complex.

Author: glorieux-f

common/src/java/com/github/oeuvres/alix/lucene/spans/HistoListener.java

@@ -17,7 +17,9 @@ public HistoListener(final HistoNum histo)
     {
         this.histo = Objects.requireNonNull(histo);
         histo.valueSpans = new int[histo.length()];
+        histo.valueDocs = new int[histo.length()];
         histo.cols().add(Col.SPANS);
+        histo.cols().add(Col.DOCS);
     }
 
     @Override
@@ -37,6 +39,7 @@ public void endDoc(final int spanCount)
     {
         if (histoIndex < 0) return;
         histo.valueSpans[histoIndex] += spanCount;
+        if (spanCount > 0) histo.valueDocs[histoIndex]++;
     }