And faster seek implementation.

Author: imotov

src/query/exist_query.rs

@@ -119,8 +119,7 @@ impl ExistsDocSet {
 
 impl DocSet for ExistsDocSet {
     fn advance(&mut self) -> DocId {
-        self.doc += 1;
-        self.find_next()
+        self.seek(self.doc + 1)
     }
 
     fn size_hint(&self) -> u32 {
@@ -130,17 +129,25 @@ impl DocSet for ExistsDocSet {
     fn doc(&self) -> DocId {
         self.doc
     }
+
+    #[inline(always)]
+    fn seek(&mut self, target: DocId) -> DocId {
+        self.doc = target;
+        self.find_next()
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use std::net::Ipv6Addr;
+    use std::ops::Bound;
 
     use common::DateTime;
     use time::OffsetDateTime;
 
     use crate::collector::Count;
     use crate::query::exist_query::ExistsQuery;
+    use crate::query::{BooleanQuery, RangeQuery};
     use crate::schema::{Facet, FacetOptions, Schema, FAST, INDEXED, STRING, TEXT};
     use crate::{doc, Index, Searcher};
 
@@ -179,6 +186,27 @@ mod tests {
         assert_eq!(count_existing_fields(&searcher, "multi")?, 10);
         assert_eq!(count_existing_fields(&searcher, "never")?, 0);
 
+        // exercise seek
+        let query = BooleanQuery::intersection(vec![
+            Box::new(RangeQuery::new_u64_bounds(
+                "all".to_string(),
+                Bound::Included(50),
+                Bound::Unbounded,
+            )),
+            Box::new(ExistsQuery::new_exists_query("even".to_string())),
+        ]);
+        assert_eq!(searcher.search(&query, &Count)?, 25);
+
+        let query = BooleanQuery::intersection(vec![
+            Box::new(RangeQuery::new_u64_bounds(
+                "all".to_string(),
+                Bound::Included(0),
+                Bound::Excluded(50),
+            )),
+            Box::new(ExistsQuery::new_exists_query("odd".to_string())),
+        ]);
+        assert_eq!(searcher.search(&query, &Count)?, 25);
+
         Ok(())
     }