[Xapian-tickets] [Xapian] #790: Operators |= and &= with Xapian::Query{}

[Xapian]

#790: Operators |= and &= with Xapian::Query{}
-------------------------------+--------------------
        Reporter:  dpa-xapian  |      Owner:  olly
            Type:  defect      |     Status:  new
        Priority:  normal      |  Milestone:  1.4.x
       Component:  Other       |    Version:  1.4.11
        Severity:  normal      |   Keywords:
      Blocked By:              |   Blocking:
Operating System:  All         |
-------------------------------+--------------------
 I do expect, that Xapian::Query{} constructs an empty query, that is the
 neutral element towards AND and OR operations.  Thus in:
 {{{
 std::vector<std::string> v {"A", "B"};
 Xapian::Query q1, q2, qOR {Xapian::Query::OP_OR, v.begin(), v.end()}, qAND
 {Xapian::Query::OP_OR, v.begin(), v.end()}
 }}}
 q1 |= qOR → q1.get_type() will be OR and the q1 terms will be A and B

 q2 &= qAND → q2.get_type() will be AND and the q2 terms will be A and B

 Instead q1.get_type() == q2.get_type() == LEAF_MATCH_NOTHING and contain
 no terms.

 Reproducer:

 {{{
 #include <stdio.h>
 #include <string>
 #include <xapian.h>
 void print_terms(const Xapian::Query& f, std::string s) {
   printf("%s: ", s.c_str());
   for (Xapian::TermIterator it = f.get_terms_begin();  it !=
 f.get_terms_end(); ++it)
     printf("%s ", (*it).c_str());
   printf(" get_type=%i\n", f.get_type());
 }

 int main() {
   std::vector<std::string> v {"abc", "def", "ghi"};
   Xapian::Query t;
   print_terms(t, "t");
   Xapian::Query q { Xapian::Query::OP_OR, v.begin(), v.end()};
   print_terms(q, "q");
   t &= q;
   print_terms(t, "t2");
   return 0;
 }

 -- actual result
 t:  get_type=103
 q: abc def ghi  get_type=1
 t2:  get_type=103

 -- expected result
 t:  get_type=103
 q: abc def ghi  get_type=1
 t2: abc def ghi get_type=1
 }}}

--
Ticket URL: <https://trac.xapian.org/ticket/790>
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