Add GetOrPut and GetAndDelete functions

Signed-off-by: m-murad <murad.kuka@gmail.com>

map.go

@@ -74,7 +74,7 @@ func (m *Map) Delete(key interface{}) bool {
 // UnorderedRange will range over the map in an unordered sequence.
 // This is same as ranging over a map using the "for range" syntax.
 // Parameter func f should not call any method of the Map, eg Get, Put, Delete, UnorderedRange, OrderedRange etc
-// It will cause a deadlock
+// It will cause a deadlock.
 func (m *Map) UnorderedRange(f func(key interface{}, value interface{})) {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
@@ -89,7 +89,7 @@ func (m *Map) UnorderedRange(f func(key interface{}, value interface{})) {
 // UnorderedRange completes in ~1.7 seconds,
 // OrderedRange completes in ~98 milli seconds.
 // Parameter func f should not call any method of the Map, eg Get, Put, Delete, UnorderedRange, OrderedRange etc
-// It will cause a deadlock
+// It will cause a deadlock.
 func (m *Map) OrderedRange(f func(key interface{}, value interface{})) {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
@@ -102,10 +102,43 @@ func (m *Map) OrderedRange(f func(key interface{}, value interface{})) {
 	}
 }
 
-// Length will return the length of Map
+// Length will return the length of Map.
 func (m *Map) Length() int {
 	m.mu.RLock()
 	defer m.mu.RUnlock()
 
 	return m.dll.Len()
 }
+
+// GetOrPut will return the existing value if the key exists in the Map.
+// If the key did not exist previously it will be added to the Map.
+// updated will be true if the key existed previously
+// otherwise it will be false if the key did not exist and was added to the Map.
+func (m *Map) GetOrPut(key interface{}, value interface{}) (finalValue interface{}, updated bool) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if e, exists := m.mp[key]; exists {
+		e.Value = mapElement{key: key, value: value}
+		return value, true
+	} else {
+		m.mp[key] = m.dll.PushFront(mapElement{key: key, value: value})
+		return value, false
+	}
+}
+
+// GetAndDelete will get the value saved against the given key.
+// deleted will be true if the key existed previously
+// otherwise it will be false.
+func (m *Map) GetAndDelete(key interface{}) (value interface{}, deleted bool) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if e, exists := m.mp[key]; exists {
+		m.dll.Remove(e)
+		delete(m.mp, key)
+		return e.Value, true
+	} else {
+		return nil, false
+	}
+}

map_test.go

@@ -163,3 +163,51 @@ func TestLength(t *testing.T) {
 		t.FailNow()
 	}
 }
+
+func TestGetOrPut(t *testing.T) {
+	m := initMap()
+
+	m.Put("a", 1)
+	m.Put("b", 2)
+	m.Put("c", 3)
+
+	if finalValue, updated := m.GetOrPut("a", 4); finalValue != 1 && !updated {
+		t.FailNow()
+	}
+
+	if finalValue, updated := m.GetOrPut("d", 4); finalValue != 4 && updated {
+		t.FailNow()
+	}
+
+	m.Delete("a")
+	if finalValue, updated := m.GetOrPut("a", 5); finalValue != 5 && updated {
+		t.FailNow()
+	}
+
+	m.Put("e", 5)
+	if finalValue, updated := m.GetOrPut("e", 6); finalValue != 5 && !updated {
+		t.FailNow()
+	}
+}
+
+func TestGetAndDelete(t *testing.T) {
+	m := initMap()
+
+	m.Put("a", 1)
+	m.Put("b", 2)
+	m.Put("c", 3)
+	m.Put("d", 4)
+
+	if value, deleted := m.GetAndDelete("a"); value != 1 && !deleted {
+		t.Fail()
+	}
+
+	if value, deleted := m.GetAndDelete("a"); value != nil && deleted {
+		t.Fail()
+	}
+
+	m.Put("a", 5)
+	if value, deleted := m.GetAndDelete("a"); value != 5 && !deleted {
+		t.Fail()
+	}
+}

readme.md

@@ -41,5 +41,11 @@ func main() {
 
     // Length will return the length of the Map.
     m.Length()
+
+    // GetOrPut will get the currect value if the key exists else it will save the new value
+    finalValue, updated := m.GetOrPut(key, value)
+
+    // GetAndDelete will get the value for the give key and deleted the key from the Map
+    value, deleted := m.GetAndDelete(key)
 }
 ```