[LUCENE-7878] QueryParser AND default operator and MultiWords synonyms failed if keywords exactly matches a synonym

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 6.5.1, 6.6, 7.0
• Fix Version/s: 6.6.1, 6.7, 7.0
• Component/s: core/queryparser
• Labels: multi-word query-parser synonyms

Environment

1.8.0_131-b11 on Mac OS X

• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Emmanuel Keller
• Created: 14/Jun/17 10:52
• Updated: 28/Aug/22 15:16
• Resolved: 16/Jun/17 14:12

Description

This issue is about using the QueryParser with MultiWordsSynonyms.

To reproduce the bug:

• Use AND as default operator
• Use a query string which exactly matches one synonym.

In short, the part of the query which handle the synonym lookup should keep a "OR" relation between the synonyms, but it is translated as a "AND".

If I parse: "guinea pig" which is a synonym of "cavy":

Using default OR, I get something correct:
"(+guinea +pig) cavy"

Note: I should probably better have ((+guinea +pic) cavy)

Using AND as default operator, I get something wrong:
+(+guinea +pig) +cavy

I was expected:
+((+guinea +pig) cavy)

The relation between "guinea pig" and "cavy" is now a AND. It should be still a OR because it is a synonym clause.

To help understanding. If now I parse "guinea pig world"
And I get the expected result:
+((+guinea +pig) cavy) +world

The relation between "guinea pig" and "cavy" is a OR as expected (it is a synonym), and the relation with "world" is AND as expected by the default operator.

Here is the additional unit test for, I hope it is pretty self-explanatory:
org.apache.lucene.queryparser.classic.TestQueryParser

public void testDefaultOperatorWhenKeywordsMatchesExactlyOneSynonym() throws ParseException {
    // Using the default OR operator
    QueryParser smart = new QueryParser("field", new Analyzer1());
    smart.setSplitOnWhitespace(false);
    smart.setDefaultOperator(Operator.OR);
    assertEquals("(+guinea +pig) cavy", smart.parse("guinea pig").toString("field"));

    // Using the default AND operator
    smart = new QueryParser("field", new Analyzer1());
    smart.setSplitOnWhitespace(false);
    smart.setDefaultOperator(Operator.AND);
    assertEquals("+((+guinea +pig) cavy) +world", smart.parse("guinea pig world").toString("field"));

    // Using the default AND operator
    smart = new QueryParser("field", new Analyzer1());
    smart.setSplitOnWhitespace(false);
    smart.setDefaultOperator(Operator.AND);
    assertEquals("+((+guinea +pig) cavy)", smart.parse("guinea pig").toString("field"));
  }