From 4c92ab044414d572b342c8d4482184b8e52865cf Mon Sep 17 00:00:00 2001
From: Klaus Basan <klaus.basan@klausbasan.de>
Date: Fri, 15 Jan 2016 02:15:46 +0100
Subject: [PATCH] refs #568, find max key value (useful when key is integer to
 find latest values)

---
 src/blackmisc/datastoreobjectlist.cpp | 31 +++++++++++++++++++++++++++
 src/blackmisc/datastoreobjectlist.h   |  6 ++++++
 2 files changed, 37 insertions(+)

diff --git a/src/blackmisc/datastoreobjectlist.cpp b/src/blackmisc/datastoreobjectlist.cpp
index 82e2d951e..52f85178f 100644
--- a/src/blackmisc/datastoreobjectlist.cpp
+++ b/src/blackmisc/datastoreobjectlist.cpp
@@ -30,6 +30,23 @@ namespace BlackMisc
         return this->container().findFirstByOrDefault(&OBJ::getDbKey, key, notFound);
     }
 
+    template <class OBJ, class CONTAINER, typename KEYTYPE>
+    OBJ IDatastoreObjectList<OBJ, CONTAINER, KEYTYPE>::maxKeyObject() const
+    {
+        if (this->container().isEmpty()) { return OBJ(); }
+        const OBJ max = *std::max_element(this->container().begin(), this->container().end(), [](const OBJ & obj1, const OBJ & obj2)
+        {
+            bool v1 = obj1.hasValidDbKey();
+            bool v2 = obj2.hasValidDbKey();
+            if (v1 && v2)
+            {
+                return obj1.getDbKey() < obj2.getDbKey();
+            }
+            return v2;
+        });
+        return max;
+    }
+
     template <class OBJ, class CONTAINER, typename KEYTYPE>
     void IDatastoreObjectList<OBJ, CONTAINER, KEYTYPE>::sortByKey()
     {
@@ -48,6 +65,20 @@ namespace BlackMisc
         return keys;
     }
 
+    template <class OBJ, class CONTAINER, typename KEYTYPE>
+    KEYTYPE IDatastoreObjectList<OBJ, CONTAINER, KEYTYPE>::getMaxKey(bool *ok) const
+    {
+        QList<KEYTYPE> keys(this->toDbKeyList());
+        if (keys.isEmpty())
+        {
+            if (ok) { *ok = false; }
+            return KEYTYPE();
+        }
+        KEYTYPE max = *std::max_element(keys.begin(), keys.end());
+        if (ok) { *ok = true; }
+        return max;
+    }
+
     template <class OBJ, class CONTAINER, typename KEYTYPE>
     int IDatastoreObjectList<OBJ, CONTAINER, KEYTYPE>::removeObjectsWithKeys(const QList<KEYTYPE> &keys)
     {
diff --git a/src/blackmisc/datastoreobjectlist.h b/src/blackmisc/datastoreobjectlist.h
index fcdcb0938..633656f0e 100644
--- a/src/blackmisc/datastoreobjectlist.h
+++ b/src/blackmisc/datastoreobjectlist.h
@@ -28,12 +28,18 @@ namespace BlackMisc
         //! Object with key, notFound otherwise
         OBJ findByKey(KEYTYPE key, const OBJ &notFound = OBJ()) const;
 
+        //! Object with max.key
+        OBJ maxKeyObject() const;
+
         //! Sort by timestamp
         void sortByKey();
 
         //! All keys as list
         QList<KEYTYPE> toDbKeyList() const;
 
+        //! Max.key value (making sense with integer key)
+        KEYTYPE getMaxKey(bool *ok = nullptr) const;
+
         //! Remove objects with key
         int removeObjectsWithKeys(const QList<KEYTYPE> &keys);