Support fuzzy term matching in streaming search

Uses a DFA-based matcher for max edits in {1, 2} and falls back
to the legacy non-DFA matcher for all other values (including 0).

Currently only supports fuzzy matching across the full field
string, i.e. there's no implicit tokenization or whitespace
removal. This matches the semantics we currently have for fuzzy
search over attributes in a non-streaming case

1 files changed, 2 insertions, 0 deletions

diff --git a/searchlib/src/vespa/searchlib/query/streaming/queryterm.h b/searchlib/src/vespa/searchlib/query/streaming/queryterm.h
index cd2bdd7eaec..ed9af969aa2 100644
--- a/searchlib/src/vespa/searchlib/query/streaming/queryterm.h
+++ b/searchlib/src/vespa/searchlib/query/streaming/queryterm.h
@@ -11,6 +11,7 @@
 
 namespace search::streaming {
 
+class FuzzyTerm;
 class NearestNeighborQueryNode;
 class MultiTerm;
 class RegexpTerm;
@@ -95,6 +96,7 @@ public:
     virtual NearestNeighborQueryNode* as_nearest_neighbor_query_node() noexcept;
     virtual MultiTerm* as_multi_term() noexcept;
     virtual RegexpTerm* as_regexp_term() noexcept;
+    virtual FuzzyTerm* as_fuzzy_term() noexcept;
 protected:
     using QueryNodeResultBaseContainer = std::unique_ptr<QueryNodeResultBase>;
     string                       _index;