Merge pull request #447 from willhite/empty-ref

Add IsEmpty() function on ref.Ref.

.gitignore

@@ -0,0 +1 @@
+noms.iml

chunks/chunk_store_test_common.go

@@ -72,7 +72,7 @@ func (suite *ChunkStoreTestSuite) TestChunkStoreChunkCloses() {
 
 func (suite *ChunkStoreTestSuite) TestChunkStoreRoot() {
 	oldRoot := suite.Store.Root()
-	suite.Equal(oldRoot, ref.Ref{})
+	suite.True(oldRoot.IsEmpty())
 
 	bogusRoot := ref.Parse("sha1-81c870618113ba29b6f2b396ea3a69c6f1d626c5") // sha1("Bogus, Dude")
 	newRoot := ref.Parse("sha1-907d14fb3af2b0d4f18c2d46abe8aedce17367bd")   // sha1("Hello, World")

chunks/http_store.go

@@ -193,7 +193,7 @@ func (c *HttpStore) postRefs(chs []Chunk) {
 func (c *HttpStore) requestRef(r ref.Ref, method string, body io.Reader) *http.Response {
 	url := *c.host
 	url.Path = constants.RefPath
-	if (r != ref.Ref{}) {
+	if !r.IsEmpty() {
 		url.Path = path.Join(url.Path, r.String())
 	}
 
@@ -270,7 +270,7 @@ func (c *HttpStore) requestRoot(method string, current, last ref.Ref) *http.Resp
 	u := *c.host
 	u.Path = constants.RootPath
 	if method == "POST" {
-		d.Exp.True(current != ref.Ref{})
+		d.Exp.False(current.IsEmpty())
 		params := url.Values{}
 		params.Add("last", last.String())
 		params.Add("current", current.String())

datas/datastore_common.go

@@ -49,14 +49,14 @@ func (ds *dataStoreCommon) doCommit(datasetID string, commit Commit) bool {
 	var currentDatasets MapOfStringToCommit
 	if ds.datasets != nil && currentRootRef == ds.datasets.Ref() {
 		currentDatasets = *ds.datasets
-	} else if currentRootRef != (ref.Ref{}) {
+	} else if !currentRootRef.IsEmpty() {
 		currentDatasets = *datasetsFromRef(currentRootRef, ds)
 	} else {
 		currentDatasets = NewMapOfStringToCommit()
 	}
 
 	// First commit in store is always fast-foward.
-	if currentRootRef != (ref.Ref{}) {
+	if !currentRootRef.IsEmpty() {
 		var currentHead Commit
 		currentHead, hasHead := currentDatasets.MaybeGet(datasetID)
 

datas/local_datastore.go

@@ -13,7 +13,7 @@ type LocalDataStore struct {
 
 func newLocalDataStore(cs chunks.ChunkStore) *LocalDataStore {
 	rootRef := cs.Root()
-	if rootRef == (ref.Ref{}) {
+	if rootRef.IsEmpty() {
 		return &LocalDataStore{dataStoreCommon{cs, nil}}
 	}
 
@@ -32,7 +32,7 @@ func (lds *LocalDataStore) CopyReachableChunksP(r, exclude ref.Ref, sink chunks.
 		return excludeRefs[r]
 	}
 
-	if exclude != (ref.Ref{}) {
+	if !exclude.IsEmpty() {
 		refChan := make(chan ref.Ref, 1024)
 		addRef := func(r ref.Ref) {
 			refChan <- r

datas/remote_datastore.go

@@ -22,7 +22,7 @@ type RemoteDataStore struct {
 
 func newRemoteDataStore(cs chunks.ChunkStore) *RemoteDataStore {
 	rootRef := cs.Root()
-	if rootRef == (ref.Ref{}) {
+	if rootRef.IsEmpty() {
 		return &RemoteDataStore{dataStoreCommon{cs, nil}}
 	}
 
@@ -46,7 +46,7 @@ func (lds *RemoteDataStore) CopyReachableChunksP(r, exclude ref.Ref, cs chunks.C
 
 	values := &url.Values{}
 	values.Add("all", "true")
-	if exclude != (ref.Ref{}) {
+	if !exclude.IsEmpty() {
 		values.Add("exclude", exclude.String())
 	}
 	u.RawQuery = values.Encode()

ref/ref.go

@@ -14,7 +14,8 @@ import (
 
 var (
 	// In the future we will allow different digest types, so this will get more complicated. For now sha1 is fine.
-	pattern = regexp.MustCompile("^sha1-([0-9a-f]{40})$")
+	pattern  = regexp.MustCompile("^sha1-([0-9a-f]{40})$")
+	emptyRef = Ref{}
 )
 
 type Sha1Digest [sha1.Size]byte
@@ -29,6 +30,10 @@ func (r Ref) Digest() Sha1Digest {
 	return r.digest
 }
 
+func (r Ref) IsEmpty() bool {
+	return r.digest == emptyRef.digest
+}
+
 func (r Ref) String() string {
 	return fmt.Sprintf("sha1-%s", hex.EncodeToString(r.digest[:]))
 }

ref/ref_test.go

@@ -68,3 +68,14 @@ func TestFromHash(t *testing.T) {
 	r := FromHash(h)
 	assert.Equal(t, "sha1-a9993e364706816aba3e25717850c26c9cd0d89d", r.String())
 }
+
+func TestIsEmpty(t *testing.T) {
+	r1 := Ref{}
+	assert.True(t, r1.IsEmpty())
+
+	r2 := Parse("sha1-0000000000000000000000000000000000000000")
+	assert.True(t, r2.IsEmpty())
+
+	r3 := Parse("sha1-a9993e364706816aba3e25717850c26c9cd0d89d")
+	assert.False(t, r3.IsEmpty())
+}

types/decode_noms_value.go

@@ -295,7 +295,7 @@ func (r *jsonArrayReader) readTypeRefAsValue(pkg *Package) TypeRef {
 		if ordinal == -1 {
 			namespace := r.readString()
 			name := r.readString()
-			d.Chk.Equal(ref.Ref{}, pkgRef, "Unresolved TypeRefs may not have a package ref")
+			d.Chk.True(pkgRef.IsEmpty(), "Unresolved TypeRefs may not have a package ref")
 			return MakeUnresolvedTypeRef(namespace, name)
 		}
 		return MakeTypeRef(pkgRef, ordinal)

types/get_ref.go

@@ -16,7 +16,7 @@ func getRefNoOverride(v Value) ref.Ref {
 }
 
 func ensureRef(r *ref.Ref, v Value) ref.Ref {
-	if *r == (ref.Ref{}) {
+	if r.IsEmpty() {
 		*r = getRef(v)
 	}
 	return *r