Example tag implementation for CoinKeeper

types/result.go

@@ -2,7 +2,6 @@ package types
 
 import (
 	abci "github.com/tendermint/abci/types"
-	cmn "github.com/tendermint/tmlibs/common"
 )
 
 // Result is the union of ResponseDeliverTx and ResponseCheckTx.
@@ -31,7 +30,7 @@ type Result struct {
 	ValidatorUpdates []abci.Validator
 
 	// Tags are used for transaction indexing and pubsub.
-	Tags []cmn.KVPair
+	Tags Tags
 }
 
 // TODO: In the future, more codes may be OK.

types/tags.go

@@ -0,0 +1,31 @@
+package types
+
+import (
+	cmn "github.com/tendermint/tmlibs/common"
+)
+
+type Tag = cmn.KVPair
+
+type Tags = cmn.KVPairs
+
+// Append two lists of tags
+func AppendTags(a, b Tags) Tags {
+	return append(a, b...)
+}
+
+// New empty tags
+func EmptyTags() Tags {
+	return make(Tags, 0)
+}
+
+// Single tag to tags
+func SingleTag(t Tag) Tags {
+	return append(EmptyTags(), t)
+}
+
+// Make a tag from a key and a value
+func MakeTag(k string, v []byte) Tag {
+	return Tag{Key: []byte(k), Value: v}
+}
+
+// TODO: Deduplication?

types/tags_test.go

@@ -0,0 +1,30 @@
+package types
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAppendTags(t *testing.T) {
+	a := SingleTag(MakeTag("a", []byte("1")))
+	b := SingleTag(MakeTag("b", []byte("2")))
+	c := AppendTags(a, b)
+	require.Equal(t, c, Tags{MakeTag("a", []byte("1")), MakeTag("b", []byte("2"))})
+}
+
+func TestEmptyTags(t *testing.T) {
+	a := EmptyTags()
+	require.Equal(t, a, Tags{})
+}
+
+func TestSingleTag(t *testing.T) {
+	a := MakeTag("a", []byte("1"))
+	b := SingleTag(a)
+	require.Equal(t, b, Tags{MakeTag("a", []byte("1"))})
+}
+
+func TestMakeTag(t *testing.T) {
+	a := MakeTag("a", []byte("1"))
+	require.Equal(t, a, Tag{[]byte("a"), []byte("1")})
+}