Merge sort in setUnion (#603)

Author: redbaron

stdlib/std.jsonnet

@@ -1162,8 +1162,22 @@ limitations under the License.
     std.length(std.setInter([x], arr, keyF)) > 0,
 
   setUnion(a, b, keyF=id)::
-    // NOTE: order matters, values in `a` win due to sort being stable
-    std.set(a + b, keyF),
+    // NOTE: order matters, values in `a` win
+    local aux(a, b, i, j, acc) =
+      if i >= std.length(a) then
+        acc + b[j:]
+      else if j >= std.length(b) then
+        acc + a[i:]
+      else
+        local ak = keyF(a[i]);
+        local bk = keyF(b[j]);
+        if ak == bk then
+          aux(a, b, i + 1, j + 1, acc + [a[i]]) tailstrict
+        else if ak < bk then
+          aux(a, b, i + 1, j, acc + [a[i]]) tailstrict
+        else
+          aux(a, b, i, j + 1, acc + [b[j]]) tailstrict;
+    aux(a, b, 0, 0, []),
 
   setInter(a, b, keyF=id)::
     local aux(a, b, i, j, acc) =
@@ -1183,7 +1197,7 @@ limitations under the License.
       if i >= std.length(a) then
         acc
       else if j >= std.length(b) then
-        aux(a, b, i + 1, j, acc + [a[i]]) tailstrict
+        acc + a[i:]
       else
         if keyF(a[i]) == keyF(b[j]) then
           aux(a, b, i + 1, j + 1, acc) tailstrict

test_suite/error.equality_function.jsonnet.golden

@@ -1,3 +1,3 @@
 RUNTIME ERROR: cannot test equality of functions
-	std.jsonnet:1266:9-34	function <anonymous>
+	std.jsonnet:1280:9-34	function <anonymous>
 	error.equality_function.jsonnet:17:1-33	

test_suite/error.inside_equals_array.jsonnet.golden

@@ -1,7 +1,7 @@
 RUNTIME ERROR: foobar
 	error.inside_equals_array.jsonnet:18:18-32	thunk <array_element>
-	std.jsonnet:1246:29-33	thunk <b>
-	std.jsonnet:1246:21-33	function <anonymous>
-	std.jsonnet:1246:21-33	function <aux>
-	std.jsonnet:1249:15-31	function <anonymous>
-	std.jsonnet:1250:11-23	
+	std.jsonnet:1260:29-33	thunk <b>
+	std.jsonnet:1260:21-33	function <anonymous>
+	std.jsonnet:1260:21-33	function <aux>
+	std.jsonnet:1263:15-31	function <anonymous>
+	std.jsonnet:1264:11-23	

test_suite/error.inside_equals_object.jsonnet.golden

@@ -1,7 +1,7 @@
 RUNTIME ERROR: foobar
 	error.inside_equals_object.jsonnet:18:22-36	object <b>
-	std.jsonnet:1260:50-54	thunk <b>
-	std.jsonnet:1260:42-54	function <anonymous>
-	std.jsonnet:1260:42-54	function <aux>
-	std.jsonnet:1263:15-31	function <anonymous>
-	std.jsonnet:1264:11-23	
+	std.jsonnet:1274:50-54	thunk <b>
+	std.jsonnet:1274:42-54	function <anonymous>
+	std.jsonnet:1274:42-54	function <aux>
+	std.jsonnet:1277:15-31	function <anonymous>
+	std.jsonnet:1278:11-23	

test_suite/error.invariant.equality.jsonnet.golden

@@ -1,6 +1,6 @@
 RUNTIME ERROR: Object assertion failed.
 	error.invariant.equality.jsonnet:17:10-15	thunk <object_assert>
-	std.jsonnet:1260:42-46	thunk <a>
-	std.jsonnet:1260:42-54	function <anonymous>
-	std.jsonnet:1260:42-54	function <anonymous>
-	std.jsonnet:1264:11-23	
+	std.jsonnet:1274:42-46	thunk <a>
+	std.jsonnet:1274:42-54	function <anonymous>
+	std.jsonnet:1274:42-54	function <anonymous>
+	std.jsonnet:1278:11-23	

test_suite/error.obj_assert.fail1.jsonnet.golden

@@ -1,6 +1,6 @@
 RUNTIME ERROR: Object assertion failed.
 	error.obj_assert.fail1.jsonnet:20:23-29	thunk <object_assert>
-	std.jsonnet:1260:42-46	thunk <a>
-	std.jsonnet:1260:42-54	function <anonymous>
-	std.jsonnet:1260:42-54	function <anonymous>
-	std.jsonnet:1264:11-23	
+	std.jsonnet:1274:42-46	thunk <a>
+	std.jsonnet:1274:42-54	function <anonymous>
+	std.jsonnet:1274:42-54	function <anonymous>
+	std.jsonnet:1278:11-23	

test_suite/error.obj_assert.fail2.jsonnet.golden

@@ -1,6 +1,6 @@
 RUNTIME ERROR: foo was not equal to bar
 	error.obj_assert.fail2.jsonnet:20:32-65	thunk <object_assert>
-	std.jsonnet:1260:42-46	thunk <a>
-	std.jsonnet:1260:42-54	function <anonymous>
-	std.jsonnet:1260:42-54	function <anonymous>
-	std.jsonnet:1264:11-23	
+	std.jsonnet:1274:42-46	thunk <a>
+	std.jsonnet:1274:42-54	function <anonymous>
+	std.jsonnet:1274:42-54	function <anonymous>
+	std.jsonnet:1278:11-23