Stable sorting of sequences of various types #470

Author: tonsky

CHANGELOG.md

@@ -1,3 +1,7 @@
+# WIP
+
+- Stable sorting of sequences of various types #470
+
 # 1.6.5 - May 3, 2024
 
 - Regression: fixed some OR queries broken in 1.6.4 #468 #469

src/datascript/db.cljc

@@ -438,11 +438,46 @@
   #?(:clj  (. clojure.lang.Util (hasheq x))
      :cljs (hash x)))
 
-(defn value-compare
-  ^long [x y]
+(declare+ ^number value-compare [x y])
+
+(defn- seq-compare [xs ys]
+  (let [cx (count xs)
+        cy (count ys)]
+    (cond
+      (< cx cy)
+      -1
+      
+      (> cx cy)
+      1
+      
+      :else
+      (loop [xs xs
+             ys ys]
+        (if (empty? xs)
+          0
+          (let [x (first xs)
+                y (first ys)]
+            (cond
+              (and (nil? x) (nil? y))
+              (recur (next xs) (next ys))
+                
+              (nil? x)
+              -1
+                
+              (nil? y)
+              1
+                
+              :else
+              (let [v (value-compare x y)]
+                (if (= v 0)
+                  (recur (next xs) (next ys))
+                  v)))))))))
+
+(defn+ ^number value-compare [x y]
   (try
     (cond
       (= x y) 0
+      (and (sequential? x) (sequential? y)) (seq-compare x y)
       #?@(:clj  [(instance? Number x)       (clojure.lang.Numbers/compare x y)])
       #?@(:clj  [(instance? Comparable x)   (.compareTo ^Comparable x y)]
           :cljs [(satisfies? IComparable x) (-compare x y)])

test/datascript/test/index.cljc

@@ -63,7 +63,25 @@
             (d/datoms db :avet :name "Ivan")))
 
       (is (thrown-msg? "Attribute :name should be marked as :db/index true"
-            (d/datoms db :avet :name "Ivan" 1))))))
+            (d/datoms db :avet :name "Ivan" 1))))
+    
+    (testing "Sequence compare issue-470"
+      (let [db (-> (d/empty-db {:path {:db/index true}})
+                 (d/db-with [{:db/id 1 :path [1 2]}
+                             {:db/id 2 :path [1 2 3]}]))]
+        (are [value result] (= result (mapv :e (d/datoms db :avet :path value)))
+          [1]                 []
+          [1 1]               []
+          [1 2]               [1]
+          (list 1 2)          [1]
+          (butlast [1 2 3])   [1]
+          [1 3]               []
+          [1 2 2]             []
+          [1 2 3]             [2]
+          (list 1 2 3)        [2]
+          (butlast [1 2 3 4]) [2]
+          [1 2 4]             []
+          [1 2 3 4]           [])))))
 
 (deftest test-datom
   (let [dvec #(when % (vector (:e %) (:a %) (:v %)))