Add support for "-" JSON index to db operations

sources/Data/Database/Database.uc

@@ -104,6 +104,8 @@ public function DBReadTask ReadData(
  *
  *  @param  pointer JSON pointer to the location in the database, where `data`
  *      should be written (as a JSON value).
+ *      This JSON pointer can make use of "-" index for JSON arrays that allows
+ *      appending data at their end.
  *      `none` is always treated as an invalid JSON pointer.
  *  @param  data    Data that needs to be written at the specified location
  *      inside the database. For method to succeed this object needs to have
@@ -273,6 +275,9 @@ public function DBKeysTask GetDataKeys(JSONPointer pointer)
  *  @param  pointer     JSON pointer to the location in the database, where
  *      data should be incremented (by `increment`).
  *      `none` is always treated as an invalid JSON pointer.
+ *      This JSON pointer can make use of "-" index for JSON arrays that allows
+ *      to add `none` value at the end of that array and then "increment" it
+ *      with `increment` parameter.
  *  @param  increment   JSON-compatible value to be used as an increment for
  *      the data at the specified location inside the database.
  *  @return Task object that corresponds to this `IncrementData()` call.

sources/Data/Database/Local/DBRecord.uc

@@ -135,6 +135,7 @@ var private config array<StorageItem> storage;
 
 var private const int       LATIN_LETTERS_AMOUNT;
 var private const int       LOWER_A_CODEPOINT, UPPER_A_CODEPOINT;
+var private const string    JSONPOINTER_NEW_ARRAY_ELEMENT;
 
 /**
  *      Since `DBRecord` represents JSON array or object, we can use
@@ -422,16 +423,18 @@ public final function bool SaveObject(
         return false;
     }
     directContainer = pointer.record;
+    itemKey = __().text.ToString(jsonPointer.Pop(true));
     if (directContainer.isJSONArray)
     {
         index = jsonPointer.PopNumeric(true);
+        if (index < 0 && itemKey == JSONPOINTER_NEW_ARRAY_ELEMENT) {
+            index = directContainer.GetStorageLength();
+        }
         if (index < 0) {
             return false;
         }
     }
-    else
+    else {
-    {
-        itemKey = __().text.ToString(jsonPointer.Pop(true));
         index = directContainer.FindItem(itemKey);
     }
     directContainer.SetItem(index, ConvertObjectToItem(newItem), itemKey);
@@ -624,16 +627,18 @@ public final function Database.DBQueryResult IncrementObject(
         return DBR_InvalidPointer;
     }
     directContainer = pointer.record;
+    itemKey = __().text.ToString(jsonPointer.Pop(true));
     if (directContainer.isJSONArray)
     {
         index = jsonPointer.PopNumeric(true);
+        if (index < 0 && itemKey == JSONPOINTER_NEW_ARRAY_ELEMENT) {
+            index = directContainer.GetStorageLength();
+        }
         if (index < 0) {
             return DBR_InvalidPointer;
         }
     }
-    else
+    else {
-    {
-        itemKey = __().text.ToString(jsonPointer.Pop(true));
         index = directContainer.FindItem(itemKey);
     }
     if (directContainer.IncrementItem(index, object, itemKey)) {
@@ -752,6 +757,8 @@ private final function bool IncrementItem(
     }
     if (IncrementItemByObject(itemToIncrement, object))
     {
+        //  Increment object cannot overwrite existing `DBRecord` with
+        //  other value, so it's safe to skip cleaning check
         storage[index]      = itemToIncrement;
         storage[index].k    = itemName;
         return true;
@@ -1157,4 +1164,7 @@ defaultproperties
     LATIN_LETTERS_AMOUNT            = 26
     LOWER_A_CODEPOINT               = 97
     UPPER_A_CODEPOINT               = 65
+    //  JSON Pointers allow using "-" as an indicator that element must be
+    //  added at the end of the array
+    JSONPOINTER_NEW_ARRAY_ELEMENT   = "-"
 }

sources/Data/Database/Tests/TEST_LocalDatabase.uc

@@ -710,6 +710,7 @@ protected static function SubTest_WritingArrayIndicies(LocalDatabaseInstance db)
     db.WriteData(__().json.Pointer(P("")), templateObject);
     db.WriteData(__().json.Pointer(P("/A")), templateArray);
     db.WriteData(__().json.Pointer(P("/A/100")), __().box.int(-342));
+    db.WriteData(__().json.Pointer(P("/A/-")), __().box.int(95));
 
     Issue("Database allows writing data into negative JSON array indices.");
     writeTask = db.WriteData(__().json.Pointer(P("/A/-5")), __().box.int(1202));
@@ -717,12 +718,13 @@ protected static function SubTest_WritingArrayIndicies(LocalDatabaseInstance db)
     writeTask.TryCompleting();
 
     Issue("Database cannot extend stored JSON array's length by assigning to"
-        @ "the out-of-bounds index.");
+        @ "the out-of-bounds index or \"-\".");
     ReadFromDB(db, "/A");
     resultArray = DynamicArray(default.resultObject);
-    TEST_ExpectTrue(resultArray.GetLength() == 101);
+    TEST_ExpectTrue(resultArray.GetLength() == 102);
     TEST_ExpectNone(resultArray.GetItem(99));
     TEST_ExpectTrue(resultArray.GetInt(100) == -342);
+    TEST_ExpectTrue(resultArray.GetInt(101) == 95);
     TEST_ExpectTrue(resultArray.GetBool(0));
 }
 
@@ -1221,14 +1223,17 @@ protected static function SubTest_IncrementMissing(LocalDatabaseInstance db)
     task.connect = DBIncrementHandler;
     task.TryCompleting();
     TEST_ExpectTrue(default.resultType == DBR_Success);
-    task = db.IncrementData(__().json.Pointer(P("/B/A/1//10")), none);
+    db.IncrementData(__().json.Pointer(P("/B/A/1//10")), none);
+    task = db.IncrementData(__().json.Pointer(P("/B/A/1//-")),
+                            __().box.int(85));
     task.connect = DBIncrementHandler;
     task.TryCompleting();
     TEST_ExpectTrue(default.resultType == DBR_Success);
     db.CheckDataType(__().json.Pointer(P("/L"))).connect = DBCheckHandler;
     ReadFromDB(db, "/B/A/1/");
     TEST_ExpectTrue(default.resultDataType == JSON_Number);
-    TEST_ExpectTrue(DynamicArray(default.resultObject).GetLength() == 11);
+    TEST_ExpectTrue(DynamicArray(default.resultObject).GetLength() == 12);
+    TEST_ExpectTrue(DynamicArray(default.resultObject).GetInt(11) == 85);
 }
 
 defaultproperties