src/dedo.go: Add separate read and read-write ROCursorI and RWCursorI types

2 files changed, 71 insertions, 41 deletions

diff --git a/src/dedo.go b/src/dedo.go
index f308b71..4a27286 100644
--- a/src/dedo.go
+++ b/src/dedo.go
@@ -62,27 +62,38 @@ import (
 
 
 
-type CursorI interface{
+type baseCursorI interface{
 	First() ([]byte, []byte)
 	Last()  ([]byte, []byte)
 	Next()  ([]byte, []byte)
 	Prev()  ([]byte, []byte)
 	Seek([]byte) ([]byte, []byte)
+}
+
+type ROCursorI interface{
+	baseCursorI
+}
+
+type RWCursorI interface{
+	baseCursorI
 	Delete() error
 }
 
-type ROBucketI interface{
+type baseBucketI interface{
 	Get([]byte) []byte
-	Cursor() CursorI
 	ForEach(func([]byte, []byte) error) error
+}
+
+type ROBucketI interface{
+	baseBucketI
 	ROBucket([]byte) (ROBucketI, error)
+	ROCursor() ROCursorI
 }
 
 type RWBucketI interface{
-	Get([]byte) []byte
-	Cursor() CursorI
-	ForEach(func([]byte, []byte) error) error
+	baseBucketI
 	RWBucket([]byte) (RWBucketI, error)
+	RWCursor() RWCursorI
 	Put([]byte, []byte) error
 	Delete([]byte) error
 	CreateBucket([]byte) (RWBucketI, error)
@@ -92,23 +103,23 @@ type RWBucketI interface{
 	NextSequence() (uint64, error)
 }
 
+type baseOperationI interface{
+	WriteTo(io.Writer) (int64, error)
+	Check() <-chan error
+}
+
 type SnapshotI interface{
+	baseOperationI
 	ROBucket([]byte) (ROBucketI, error)
-	Cursor() CursorI
+	ROCursor() ROCursorI
 	ROForEach(func([]byte, ROBucketI) error) error
-
-	WriteTo(io.Writer) (int64, error)
-	Check() <-chan error
 }
 
 type TransactionI interface{
+	baseOperationI
 	RWBucket([]byte) (RWBucketI, error)
-	Cursor() CursorI
+	RWCursor() RWCursorI
 	RWForEach(func([]byte, RWBucketI) error) error
-
-	WriteTo(io.Writer) (int64, error)
-	Check() <-chan error
-
 	CreateBucket           ([]byte) (RWBucketI, error)
 	CreateBucketIfNotExists([]byte) (RWBucketI, error)
 	DeleteBucket([]byte) error
@@ -648,7 +659,11 @@ func bucketCursor(b *bucketT) *cursorT {
 	}
 }
 
-func (b *bucketT) Cursor() CursorI {
+func (b *bucketT) ROCursor() ROCursorI {
+	return bucketCursor(b)
+}
+
+func (b *bucketT) RWCursor() RWCursorI {
 	return bucketCursor(b)
 }
 
@@ -979,7 +994,7 @@ func bucketForEach(b *bucketT, fn func(k, v []byte) error) error {
 	if b.tx.db == nil {
 		return ErrTxClosed
 	}
-	c := b.Cursor()
+	c := bucketCursor(b)
 	for k, v := c.First(); k != nil; k, v = c.Next() {
 		err := fn(k, v)
 		if err != nil {
@@ -1914,7 +1929,14 @@ func (bucket *inMemoryValueT) DeleteBucket(name []byte) error {
 	return nil
 }
 
-func (bucket *inMemoryValueT) Cursor() CursorI {
+func (bucket *inMemoryValueT) ROCursor() ROCursorI {
+	return &inMemoryCursorT{
+		bucket:   bucket,
+		iterator: bucket.data.Iterator(),
+	}
+}
+
+func (bucket *inMemoryValueT) RWCursor() RWCursorI {
 	return &inMemoryCursorT{
 		bucket:   bucket,
 		iterator: bucket.data.Iterator(),
@@ -1926,7 +1948,7 @@ func (bucket *inMemoryValueT) ForEach(fn func([]byte, []byte) error) error {
 		return ErrTxClosed
 	}
 
-	cursor := bucket.Cursor()
+	cursor := bucket.ROCursor()
 	for key, value := cursor.First(); key != nil; key, value = cursor.Next() {
 		err := fn(key, value)
 		if err != nil {
@@ -2003,7 +2025,11 @@ func (tx *inMemoryTxT) CreateBucketIfNotExists(name []byte) (RWBucketI, error) {
 	return nil, nil // FIXME
 }
 
-func (tx *inMemoryTxT) Cursor() CursorI {
+func (tx *inMemoryTxT) ROCursor() ROCursorI {
+	return nil // FIXME
+}
+
+func (tx *inMemoryTxT) RWCursor() RWCursorI {
 	return nil // FIXME
 }
 
@@ -3823,7 +3849,11 @@ func txCursor(tx *transactionT) *cursorT {
 	return bucketCursor(&tx.root)
 }
 
-func (tx *transactionT) Cursor() CursorI {
+func (tx *transactionT) ROCursor() ROCursorI {
+	return txCursor(tx)
+}
+
+func (tx *transactionT) RWCursor() RWCursorI {
 	return txCursor(tx)
 }
 
diff --git a/tests/dedo.go b/tests/dedo.go
index bce24b5..d0489ee 100644
--- a/tests/dedo.go
+++ b/tests/dedo.go
@@ -656,7 +656,7 @@ func TestBucket_Get_Capacity(t *testing.T) {
 
 	// Retrieve value and attempt to append to it.
 	err = db.Update(func(tx TransactionI) error {
-		k, v := g.Must(tx.RWBucket([]byte("bucket"))).Cursor().First()
+		k, v := g.Must(tx.RWBucket([]byte("bucket"))).RWCursor().First()
 
 		// Verify capacity.
 		if len(k) != cap(k) {
@@ -1009,7 +1009,7 @@ func TestBucket_Delete_FreelistOverflow(t *testing.T) {
 	// Delete all of them in one large transaction
 	err := db.Update(func(tx TransactionI) error {
 		b := g.Must(tx.RWBucket([]byte("0")))
-		c := b.Cursor()
+		c := b.RWCursor()
 		for k, _ := c.First(); k != nil; k, _ = c.Next() {
 			err := c.Delete()
 			if err != nil {
@@ -2224,7 +2224,7 @@ func TestCursor_Seek(t *testing.T) {
 	}
 
 	err = db.View(func(snapshot SnapshotI) error {
-		c := g.Must(snapshot.ROBucket([]byte("widgets"))).Cursor()
+		c := g.Must(snapshot.ROBucket([]byte("widgets"))).ROCursor()
 
 		// Exact match should go to the key.
 		k, v := c.Seek([]byte("bar"))
@@ -2308,7 +2308,7 @@ func TestCursor_Delete(t *testing.T) {
 	}
 
 	err = db.Update(func(tx TransactionI) error {
-		c := g.Must(tx.RWBucket([]byte("widgets"))).Cursor()
+		c := g.Must(tx.RWBucket([]byte("widgets"))).RWCursor()
 		bound := make([]byte, 8)
 		binary.BigEndian.PutUint64(bound, uint64(count/2))
 		for
@@ -2370,7 +2370,7 @@ func TestCursor_Seek_Large(t *testing.T) {
 	}
 
 	err = db.View(func(snapshot SnapshotI) error {
-		c := g.Must(snapshot.ROBucket([]byte("widgets"))).Cursor()
+		c := g.Must(snapshot.ROBucket([]byte("widgets"))).ROCursor()
 		for i := 0; i < count; i++ {
 			seek := make([]byte, 8)
 			binary.BigEndian.PutUint64(seek, uint64(i))
@@ -2422,7 +2422,7 @@ func TestCursor_EmptyBucket(t *testing.T) {
 	}
 
 	err = db.View(func(snapshot SnapshotI) error {
-		c := g.Must(snapshot.ROBucket([]byte("widgets"))).Cursor()
+		c := g.Must(snapshot.ROBucket([]byte("widgets"))).ROCursor()
 		k, v := c.First()
 		if k != nil {
 			t.Fatalf("unexpected key: %v", k)
@@ -2452,7 +2452,7 @@ func TestCursor_EmptyBucketReverse(t *testing.T) {
 	}
 
 	err = db.View(func(snapshot SnapshotI) error {
-		c := g.Must(snapshot.ROBucket([]byte("widgets"))).Cursor()
+		c := g.Must(snapshot.ROBucket([]byte("widgets"))).ROCursor()
 		k, v := c.Last()
 		if k != nil {
 			t.Fatalf("unexpected key: %v", k)
@@ -2506,7 +2506,7 @@ func TestCursor_Iterate_Leaf(t *testing.T) {
 	}
 	defer func() { _ = tx.rollback() }()
 
-	c := g.Must(tx.RWBucket([]byte("widgets"))).Cursor()
+	c := g.Must(tx.ROBucket([]byte("widgets"))).ROCursor()
 
 	k, v := c.First()
 	if !bytes.Equal(k, []byte("bar")) {
@@ -2588,7 +2588,7 @@ func TestCursor_LeafRootReverse(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	c := g.Must(tx.ROBucket([]byte("widgets"))).Cursor()
+	c := g.Must(tx.ROBucket([]byte("widgets"))).ROCursor()
 	k, v := c.Last()
 	if !bytes.Equal(k, []byte("foo")) {
 		t.Fatalf("unexpected key: %v", k)
@@ -2663,7 +2663,7 @@ func TestCursor_Restart(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	c := g.Must(tx.ROBucket([]byte("widgets"))).Cursor()
+	c := g.Must(tx.ROBucket([]byte("widgets"))).ROCursor()
 
 	k, _ := c.First()
 	if !bytes.Equal(k, []byte("bar")) {
@@ -2726,7 +2726,7 @@ func TestCursor_First_EmptyPages(t *testing.T) {
 			}
 		}
 
-		c := b.Cursor()
+		c := b.RWCursor()
 		var n int
 		for k, _ := c.First(); k != nil; k, _ = c.Next() {
 			n++
@@ -2780,7 +2780,7 @@ func TestCursor_QuickCheck(t *testing.T) {
 			t.Fatal(err)
 		}
 
-		c := g.Must(tx.ROBucket([]byte("widgets"))).Cursor()
+		c := g.Must(tx.ROBucket([]byte("widgets"))).ROCursor()
 		for
 				k, v := c.First();
 				k != nil && index < len(items);
@@ -2855,7 +2855,7 @@ func TestCursor_QuickCheck_Reverse(t *testing.T) {
 			t.Fatal(err)
 		}
 
-		c := g.Must(tx.ROBucket([]byte("widgets"))).Cursor()
+		c := g.Must(tx.ROBucket([]byte("widgets"))).ROCursor()
 		for
 				k, v := c.Last();
 				k != nil && index < len(items);
@@ -2925,7 +2925,7 @@ func TestCursor_QuickCheck_BucketsOnly(t *testing.T) {
 
 	err = db.View(func(snapshot SnapshotI) error {
 		names := []string{}
-		c := g.Must(snapshot.ROBucket([]byte("widgets"))).Cursor()
+		c := g.Must(snapshot.ROBucket([]byte("widgets"))).ROCursor()
 		for k, v := c.First(); k != nil; k, v = c.Next() {
 			names = append(names, string(k))
 			if v != nil {
@@ -2979,7 +2979,7 @@ func TestCursor_QuickCheck_BucketsOnly_Reverse(t *testing.T) {
 
 	err = db.View(func(snapshot SnapshotI) error {
 		names := []string{}
-		c := g.Must(snapshot.ROBucket([]byte("widgets"))).Cursor()
+		c := g.Must(snapshot.ROBucket([]byte("widgets"))).ROCursor()
 		for k, v := c.Last(); k != nil; k, v = c.Prev() {
 			names = append(names, string(k))
 			if v != nil {
@@ -3031,7 +3031,7 @@ func ExampleCursor() {
 		}
 
 		// Create a cursor for iteration.
-		c := b.Cursor()
+		c := b.RWCursor()
 
 		// Iterate over items in sorted key order. This starts from the
 		// first key/value pair and updates the k/v variables to the
@@ -3093,7 +3093,7 @@ func ExampleCursor_reverse() {
 		}
 
 		// Create a cursor for iteration.
-		c := b.Cursor()
+		c := b.RWCursor()
 
 		// Iterate over items in reverse sorted key order. This starts
 		// from the last key/value pair and updates the k/v variables to
@@ -4283,7 +4283,7 @@ func ExampleDB_Begin_ReadOnly() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	c := g.Must(tx.ROBucket([]byte("widgets"))).Cursor()
+	c := g.Must(tx.ROBucket([]byte("widgets"))).ROCursor()
 	for k, v := c.First(); k != nil; k, v = c.Next() {
 		fmt.Printf("%s likes %s\n", k, v)
 	}
@@ -4499,7 +4499,7 @@ func validateBatchBench(b *testing.B, db *WDB) {
 			}
 		}
 		// should be empty now
-		c := bucket.Cursor()
+		c := bucket.RWCursor()
 		for k, v := c.First(); k != nil; k, v = c.Next() {
 			b.Errorf("unexpected key: %x = %q", k, v)
 		}
@@ -5808,7 +5808,7 @@ func TestTx_Cursor(t *testing.T) {
 			t.Fatal(err)
 		}
 
-		c := tx.Cursor()
+		c := tx.RWCursor()
 		k, v := c.First()
 		if !bytes.Equal(k, []byte("widgets")) {
 			t.Fatalf("unexpected key: %v", k)