More tag creation functions.

2 files changed, 32 insertions, 8 deletions

diff --git a/nbt/bigtest_test.go b/nbt/bigtest_test.go
index af6c573..a0f6e7a 100644
--- a/nbt/bigtest_test.go
+++ b/nbt/bigtest_test.go
@@ -253,11 +253,7 @@ func TestCreateBigtest(t *testing.T) {
 	comp["egg"] = makeNested("Eggbert", 0.5)
 	rootcomp["nested compound test"] = Tag{TAG_Compound, comp}
 
-	listlong := make([]interface{}, 5)
-	for i := 0; i < 5; i++ {
-		listlong[i] = int64(i + 11)
-	}
-	rootcomp["listTest (long)"] = Tag{TAG_List, TagList{TAG_Long, listlong}}
+	rootcomp["listTest (long)"] = NewListTag(TAG_Long, []int64{11, 12, 13, 14, 15})
 
 	listcomp := make([]interface{}, 2)
 	for i := 0; i < 2; i++ {
@@ -266,7 +262,7 @@ func TestCreateBigtest(t *testing.T) {
 		comp["created-on"] = NewLongTag(1264099775885)
 		listcomp[i] = comp
 	}
-	rootcomp["listTest (compound)"] = Tag{TAG_List, TagList{TAG_Compound, listcomp}}
+	rootcomp["listTest (compound)"] = NewListTag(TAG_Compound, listcomp)
 
 	data := make([]byte, 1000)
 	for n := 0; n < 1000; n++ {
diff --git a/nbt/create.go b/nbt/create.go
index d515c1b..b3ff3e8 100644
--- a/nbt/create.go
+++ b/nbt/create.go
@@ -1,5 +1,9 @@
 package nbt
 
+import (
+	"reflect"
+)
+
 func NewByteTag(v byte) Tag        { return Tag{TAG_Byte, v} }
 func NewShortTag(v int16) Tag      { return Tag{TAG_Short, v} }
 func NewIntTag(v int32) Tag        { return Tag{TAG_Int, v} }
@@ -10,5 +14,29 @@ func NewByteArrayTag(v []byte) Tag { return Tag{TAG_Byte_Array, v} }
 func NewStringTag(v string) Tag    { return Tag{TAG_String, v} }
 func NewIntArrayTag(v []int32) Tag { return Tag{TAG_Int_Array, v} }
 
-// func NewCompoundTag() Tag {return Tag{TAG_Compound, make(TagCompound)}}
-// func NewListTag
+// NewCompoundTag creates a new Tag with type TAG_Compound. Usually it is more convenient to make the TagCompound payload and then manually construct the Tag value, though.
+func NewCompoundTag() Tag { return Tag{TAG_Compound, make(TagCompound)} }
+
+// NewListTag creates a new Tag of type TAG_List with tag elems of type ltt.
+//
+// l must either be of type []interface{}, where the elements are payloads for ltt tags OR of type []T, where T is the payload type for ltt tags.
+//
+// YOU are responsible for this, this function will not check the correctness.
+// When given wrong data, this function will either panic, or writing the NBT data will later fail.
+func NewListTag(ltt TagType, l interface{}) Tag {
+	var elems []interface{}
+	if is, ok := l.([]interface{}); ok {
+		elems = is
+	} else {
+		val := reflect.ValueOf(l)
+
+		n := val.Len()
+		elems = make([]interface{}, n)
+
+		for i := 0; i < n; i++ {
+			elems[i] = val.Index(i).Interface()
+		}
+	}
+
+	return Tag{TAG_List, TagList{ltt, elems}}
+}