Wire fuzzy prefix matching support through the query stack

Adds `prefix:[true|false]` annotation support to the `fuzzy`
query operator in the YQL and JSON query languages. Fuzzy
prefix matching semantics are wired through to the matcher
implementations for both indexed and streaming search.

Example usage:

  {maxEditDistance:1,prefix:true}fuzzy("foo")

Will match `foo`, `foobar`, `foxtrot`, `zookeeper` and so on.

It can be combined with the existing prefix locking feature:

  {maxEditDistance:1,prefixLength:2,prefix:true}fuzzy("foo")

Which will match `foo`, `foobar`, `foxtrot` etc, but _not_
`zookeeper` since the locked prefix (`fo`) does not match.

Due to the complexities involved with extending the legacy binary
query stack representation, signalling prefix matching for the
fuzzy term is done by pragmatically adding a new, generic "prefix
matching" term-level flag. This is currently ignored for
everything except fuzzy query items.

Modernizing the query stack format to make it more extensible
(i.e. move encoding to Protobuf) is on the backlog...!

1 files changed, 11 insertions, 12 deletions

diff --git a/container-search/src/test/java/com/yahoo/search/searchers/ValidateFuzzySearcherTestCase.java b/container-search/src/test/java/com/yahoo/search/searchers/ValidateFuzzySearcherTestCase.java
index c4b8c9f2044..027152bfd69 100644
--- a/container-search/src/test/java/com/yahoo/search/searchers/ValidateFuzzySearcherTestCase.java
+++ b/container-search/src/test/java/com/yahoo/search/searchers/ValidateFuzzySearcherTestCase.java
@@ -55,14 +55,13 @@ public class ValidateFuzzySearcherTestCase {
         searcher = new ValidateFuzzySearcher();
     }
 
-    private String makeQuery(String attribute, String query, int maxEditDistance, int prefixLength) {
-        return "select * from sources * where " + attribute +
-                " contains ({maxEditDistance:" + maxEditDistance + ", prefixLength:" + prefixLength +"}" +
-                "fuzzy(\"" + query + "\"))";
+    private String makeQuery(String attribute, String query, int maxEditDistance, int prefixLength, boolean prefixMatch) {
+        return "select * from sources * where %s contains ({maxEditDistance:%d,prefixLength:%d,prefix:%b}fuzzy(\"%s\"))"
+                .formatted(attribute, maxEditDistance, prefixLength, prefixMatch, query);
     }
 
     private String makeQuery(String attribute, String query) {
-        return makeQuery(attribute, query, 2, 0);
+        return makeQuery(attribute, query, 2, 0, false);
     }
 
 
@@ -76,7 +75,7 @@ public class ValidateFuzzySearcherTestCase {
             if (validAttributes.contains(attribute)) {
                 assertNull(r.hits().getError());
             } else {
-                assertErrMsg("FUZZY(fuzzy,2,0) " + attribute + ":fuzzy field is not a string attribute", r);
+                assertErrMsg("FUZZY(fuzzy,2,0,false) " + attribute + ":fuzzy field is not a string attribute", r);
             }
         }
     }
@@ -85,28 +84,28 @@ public class ValidateFuzzySearcherTestCase {
     void testInvalidEmptyStringQuery() {
         String q = makeQuery("string_single", "");
         Result r = doSearch(searcher, q);
-        assertErrMsg("FUZZY(,2,0) string_single: fuzzy query must be non-empty", r);
+        assertErrMsg("FUZZY(,2,0,false) string_single: fuzzy query must be non-empty", r);
     }
 
     @Test
     void testInvalidQueryWrongMaxEditDistance() {
-        String q = makeQuery("string_single", "fuzzy", -1, 0);
+        String q = makeQuery("string_single", "fuzzy", -1, 0, false);
         Result r = doSearch(searcher, q);
-        assertErrMsg("FUZZY(fuzzy,-1,0) string_single:fuzzy has invalid maxEditDistance -1: Must be >= 0", r);
+        assertErrMsg("FUZZY(fuzzy,-1,0,false) string_single:fuzzy has invalid maxEditDistance -1: Must be >= 0", r);
     }
 
     @Test
     void testInvalidQueryWrongPrefixLength() {
-        String q = makeQuery("string_single", "fuzzy", 2, -1);
+        String q = makeQuery("string_single", "fuzzy", 2, -1, true);
         Result r = doSearch(searcher, q);
-        assertErrMsg("FUZZY(fuzzy,2,-1) string_single:fuzzy has invalid prefixLength -1: Must be >= 0", r);
+        assertErrMsg("FUZZY(fuzzy,2,-1,true) string_single:fuzzy has invalid prefixLength -1: Must be >= 0", r);
     }
 
     @Test
     void testInvalidQueryWrongAttributeName() {
         String q = makeQuery("wrong_name", "fuzzy");
         Result r = doSearch(searcher, q);
-        assertErrMsg("FUZZY(fuzzy,2,0) wrong_name:fuzzy field is not a string attribute", r);
+        assertErrMsg("FUZZY(fuzzy,2,0,false) wrong_name:fuzzy field is not a string attribute", r);
     }
 
     private static void assertErrMsg(String message, Result r) {