CLJ-2718 Fix bug in drop of repeat that goes to or past end of sequence

puredanger · puredanger · commit 09887382ac5f · 2022-12-07T15:49:46.000-06:00
diff --git a/src/jvm/clojure/lang/Repeat.java b/src/jvm/clojure/lang/Repeat.java
@@ -100,12 +100,15 @@ public Object reduce(IFn f, Object start){
 }
 
 public Sequential drop(int n) {
-    if(count > 1) {
-        return new Repeat(count-n, val);
-    } else if(count == INFINITE) {
+    if(count == INFINITE) {
         return this;
     } else {
-        return null;
+        long droppedCount = count-n;
+        if(droppedCount > 0) {
+            return new Repeat(droppedCount, val);
+        } else {
+            return null;
+        }
     }
 }
 
diff --git a/test/clojure/test_clojure/sequences.clj b/test/clojure/test_clojure/sequences.clj
@@ -1003,7 +1003,12 @@
       () '(1 2)
       [] [1 2]
       {} {:a 1 :b 2}
-      #{} #{1 2} ))
+      #{} #{1 2})
+
+  ; CLJ-2718
+  (is (= '(:a) (drop 1 (repeat 2 :a))))
+  (is (= () (drop 2 (repeat 2 :a))))
+  (is (= () (drop 3 (repeat 2 :a)))))
 
 (defspec longrange-equals-range 1000
   (prop/for-all [start gen/int

Original file line number	Diff line number	Diff line change
`@@ -100,12 +100,15 @@ public Object reduce(IFn f, Object start){`
`100`	`100`	`}`
`101`	`101`
`102`	`102`	`public Sequential drop(int n) {`
`103`		`- if(count > 1) {`
`104`		`- return new Repeat(count-n, val);`
`105`		`- } else if(count == INFINITE) {`
	`103`	`+ if(count == INFINITE) {`
`106`	`104`	`return this;`
`107`	`105`	`} else {`
`108`		`- return null;`
	`106`	`+ long droppedCount = count-n;`
	`107`	`+ if(droppedCount > 0) {`
	`108`	`+ return new Repeat(droppedCount, val);`
	`109`	`+ } else {`
	`110`	`+ return null;`
	`111`	`+ }`
`109`	`112`	`}`
`110`	`113`	`}`
`111`	`114`