Add merge command

1 files changed, 85 insertions, 0 deletions

diff --git a/walk/walk.go b/walk/walk.go
index 3fba62f..e66feff 100644
--- a/walk/walk.go
+++ b/walk/walk.go
@@ -148,3 +148,88 @@ func (item WalkItem) Debug() string {
 	builder.WriteString(item.Value.Debug())
 	return builder.String()
 }
+
+func Merge(first Value, second Value) []Value {
+	switch first := first.(type) {
+	case NullValue:
+		return []Value {first, second}
+	case BoolValue:
+		return []Value {first, second}
+	case NumberValue:
+		return []Value {first, second}
+	case StringValue:
+		return []Value {first, second}
+	case ArrayValue:
+		secondArr, isArr := second.(ArrayValue)
+		if !isArr {
+			return []Value {first, second}
+		}
+
+		if len(first) == 0 {
+			return []Value {second}
+		}
+
+		if len(secondArr) == 0 {
+			return []Value {first}
+		}
+
+		var res ArrayValue
+		for _, el := range first[:len(first) - 1] {
+			res = append(res, el)
+		}
+		midFirst := first[len(first) - 1]
+		midSecond := secondArr[0]
+		if midFirst.Index == midSecond.Index {
+			for _, el := range Merge(midFirst.Value, midSecond.Value) {
+				res = append(res, ArrayElement {
+					Index: midFirst.Index,
+					Value: el,
+				})
+			}
+		} else {
+			res = append(res, midFirst, midSecond)
+		}
+		for _, el := range secondArr[1:] {
+			res = append(res, el)
+		}
+
+		return []Value {res}
+	case MapValue:
+		secondMap, isMap := second.(MapValue)
+		if !isMap {
+			return []Value {first, second}
+		}
+
+		if len(first) == 0 {
+			return []Value {second}
+		}
+
+		if len(secondMap) == 0 {
+			return []Value {first}
+		}
+
+		var res MapValue
+		for _, el := range first[:len(first) - 1] {
+			res = append(res, el)
+		}
+		midFirst := first[len(first) - 1]
+		midSecond := secondMap[0]
+		if midFirst.Key == midSecond.Key {
+			for _, el := range Merge(midFirst.Value, midSecond.Value) {
+				res = append(res, MapElement {
+					Key: midFirst.Key,
+					Value: el,
+				})
+			}
+		} else {
+			res = append(res, midFirst, midSecond)
+		}
+		for _, el := range secondMap[1:] {
+			res = append(res, el)
+		}
+
+		return []Value {res}
+	default:
+		panic("first is invalid value type")
+	}
+}