Make ref.Ref a type of Value too.

"Fixes" #141.

clients/xml_importer/xml_importer.go

@@ -75,11 +75,7 @@ func main() {
 		ref, err := types.WriteValue(nomsObj, ds)
 		Chk.NoError(err)
 
-		// BUG 141
-		nomsObj, err = types.ReadValue(ref, ds)
-		Chk.NoError(err)
-
-		list = list.Append(nomsObj)
+		list = list.Append(types.Ref{ref})
 		return nil
 	})
 

types/future.go

@@ -38,3 +38,11 @@ func futureEqualsValue(f Future, v Value) bool {
 		return f.Ref() == v.Ref()
 	}
 }
+
+func futureFromValue(v Value) Future {
+	if r, ok := v.(Ref); ok {
+		return &unresolvedFuture{ref:r.Ref()}
+	} else {
+		return resolvedFuture{v}
+	}
+}

types/incremental_test.go

@@ -104,3 +104,30 @@ func TestIncrementalLoadMap(t *testing.T) {
 		return
 	})
 }
+
+func TestIncrementalAddRef(t *testing.T) {
+	assert := assert.New(t)
+	cs := &chunks.TestStore{}
+
+	expectedItem := UInt32(42)
+	ref, err := WriteValue(expectedItem, cs)
+	assert.NoError(err)
+
+	expected := NewList(Ref{ref})
+	ref, err = WriteValue(expected, cs)
+	actualVar, err := ReadValue(ref, cs)
+	assert.NoError(err)
+
+	assert.Equal(1, cs.Reads)
+	assert.True(expected.Equals(actualVar))
+
+	actual := actualVar.(List)
+	actualItem := actual.Get(0)
+	assert.Equal(2, cs.Reads)
+	assert.True(expectedItem.Equals(actualItem))
+
+	// do it again to make sure caching works.
+	actualItem = actual.Get(0)
+	assert.Equal(2, cs.Reads)
+	assert.True(expectedItem.Equals(actualItem))
+}

types/ref.go

@@ -0,0 +1,21 @@
+package types
+
+import (
+	"github.com/attic-labs/noms/ref"
+)
+
+type Ref struct {
+	R ref.Ref
+}
+
+func (r Ref) Equals(other Value) bool {
+	return r.R == other.Ref()
+}
+
+func (r Ref) Ref() ref.Ref {
+	return r.R
+}
+
+func (r Ref) Chunks() []Future {
+	return nil
+}

types/resolved_future.go

@@ -5,10 +5,6 @@ import (
 	"github.com/attic-labs/noms/ref"
 )
 
-func futureFromValue(v Value) Future {
-	return resolvedFuture{v}
-}
-
 type resolvedFuture struct {
 	val Value
 }