Get matched terms from Lucene query

Question

Given a Lucene search query like: +(letter:A letter:B letter:C) +(style:Capital), how can I tell which of the three letters actually matched any given document?

Answer 1

As answer given by @L.B, Here is the converted code of JAVA which works for me:

void GetHitTerms(Query query,IndexSearcher searcher,int docId,List hitTerms,Listrest) throws IOException
    {
        if(query instanceof TermQuery )
        {
            if (searcher.explain(query, docId).isMatch())
                hitTerms.add(((TermQuery) query).getTerm());
            else
                rest.add(((TermQuery) query).getTerm());
            return;
        }

            if(query instanceof BooleanQuery )
            {
                for (BooleanClause clause : (BooleanQuery)query) {
                    GetHitTerms(clause.getQuery(), searcher, docId,hitTerms,rest);
            }
            return;
        }

        if (query instanceof MultiTermQuery)
        {
            if (!(query instanceof FuzzyQuery)) //FuzzQuery doesn't support SetRewriteMethod
                ((MultiTermQuery)query).setRewriteMethod(MultiTermQuery.SCORING_BOOLEAN_QUERY_REWRITE);

            GetHitTerms(query.rewrite(searcher.getIndexReader()), searcher, docId,hitTerms,rest);
        }
    }