Adding upstream version 0.2.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

deepmerge.go

@@ -0,0 +1,48 @@
+package deepmerge
+
+import (
+	"errors"
+)
+
+var (
+	ErrKeyWithPrimitiveValueDefinedMoreThanOnce = errors.New("error due to parameter with value of primitive type: only maps and slices/arrays can be merged, which means you cannot have define the same key twice for parameters that are not maps or slices/arrays")
+)
+
+func DeepMerge(dst, src map[string]interface{}, config Config) error {
+	for srcKey, srcValue := range src {
+		if srcValueAsMap, ok := srcValue.(map[string]interface{}); ok { // handle maps
+			if dstValue, ok := dst[srcKey]; ok {
+				if dstValueAsMap, ok := dstValue.(map[string]interface{}); ok {
+					err := DeepMerge(dstValueAsMap, srcValueAsMap, config)
+					if err != nil {
+						return err
+					}
+					continue
+				}
+			} else {
+				dst[srcKey] = make(map[string]interface{})
+			}
+			err := DeepMerge(dst[srcKey].(map[string]interface{}), srcValueAsMap, config)
+			if err != nil {
+				return err
+			}
+		} else if srcValueAsSlice, ok := srcValue.([]interface{}); ok { // handle slices
+			if dstValue, ok := dst[srcKey]; ok {
+				if dstValueAsSlice, ok := dstValue.([]interface{}); ok {
+					// If both src and dst are slices, we'll copy the elements from that src slice over to the dst slice
+					dst[srcKey] = append(dstValueAsSlice, srcValueAsSlice...)
+					continue
+				}
+			}
+			dst[srcKey] = srcValueAsSlice
+		} else { // handle primitives
+			if config.PreventMultipleDefinitionsOfKeysWithPrimitiveValue {
+				if _, ok := dst[srcKey]; ok {
+					return ErrKeyWithPrimitiveValueDefinedMoreThanOnce
+				}
+			}
+			dst[srcKey] = srcValue
+		}
+	}
+	return nil
+}