Use types.Null instead of nil

.github/workflows/go.yml

@@ -127,7 +127,7 @@ jobs:
           git config user.name ferretdb-bot
           git config user.email ferretdb-bot@ferretdb.io
           git add --all .
-          git commit --message 'Update corpus'
+          git diff-index --quiet HEAD || git commit --message 'Update corpus'
           git fetch
           git rebase origin/main
           git push

internal/bson/array.go

@@ -22,7 +22,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// Array represents BSON Array data type.
+// Array represents BSON Array type.
 type Array types.Array
 
 func (a *Array) bsontype() {}

internal/bson/array_test.go

@@ -39,7 +39,7 @@ var arrayTestCases = []testCase{{
 		int32(42),
 		int64(42),
 		"foo",
-		nil,
+		types.Null,
 	)),
 	b: testutil.MustParseDumpFile("testdata", "array_all.hex"),
 }, {

internal/bson/bool.go

@@ -20,7 +20,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// Bool represents BSON Bool data type.
+// Bool represents BSON Boolean type.
 type Bool bool
 
 func (b *Bool) bsontype() {}

internal/bson/bson.go

@@ -57,8 +57,8 @@ func fromBSON(v bsontype) any {
 		return bool(*v)
 	case *DateTime:
 		return time.Time(*v)
-	case nil:
-		return nil
+	case *nullType:
+		return types.Null
 	case *Regex:
 		return types.Regex(*v)
 	case *Int32:
@@ -93,8 +93,8 @@ func toBSON(v any) bsontype {
 		return pointer.To(Bool(v))
 	case time.Time:
 		return pointer.To(DateTime(v))
-	case nil:
-		return nil
+	case types.NullType:
+		return pointer.To(nullType(v))
 	case types.Regex:
 		return pointer.To(Regex(v))
 	case int32:

internal/bson/cstring.go

@@ -20,7 +20,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// CString represents BSON CString data type.
+// CString represents BSON zero-terminated UTF-8 string type.
 type CString string
 
 func (cstr *CString) bsontype() {}

internal/bson/datetime.go

@@ -23,7 +23,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// DateTime represents BSON DateTime data type.
+// DateTime represents BSON UTC datetime type.
 type DateTime time.Time
 
 func (dt DateTime) String() string {

internal/bson/document.go

@@ -39,7 +39,7 @@ type document interface {
 	Keys() []string
 }
 
-// Document represents BSON Document data type.
+// Document represents BSON Document type.
 type Document struct {
 	m    map[string]any
 	keys []string
@@ -204,7 +204,8 @@ func (doc *Document) ReadFrom(r *bufio.Reader) error {
 			doc.m[string(ename)] = time.Time(v)
 
 		case tagNull:
-			doc.m[string(ename)] = nil
+			// skip calling ReadFrom that does nothing
+			doc.m[string(ename)] = types.Null
 
 		case tagRegex:
 			var v Regex
@@ -352,11 +353,12 @@ func (doc Document) MarshalBinary() ([]byte, error) {
 				return nil, lazyerrors.Error(err)
 			}
 
-		case nil:
+		case types.NullType:
 			bufw.WriteByte(byte(tagNull))
 			if err := ename.WriteTo(bufw); err != nil {
 				return nil, lazyerrors.Error(err)
 			}
+			// skip calling WriteTo that does nothing
 
 		case types.Regex:
 			bufw.WriteByte(byte(tagRegex))

internal/bson/double.go

@@ -23,7 +23,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// Double represents BSON Double data type.
+// Double represents BSON 64-bit binary floating point type.
 type Double float64
 
 func (d *Double) bsontype() {}

internal/bson/int32.go

@@ -22,7 +22,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// Int32 represents BSON Int32 data type.
+// Int32 represents BSON 32-bit integer type.
 type Int32 int32
 
 func (i *Int32) bsontype() {}

internal/bson/int64.go

@@ -22,7 +22,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// Int64 represents BSON Int64 data type.
+// Int64 represents BSON 64-bit integer type.
 type Int64 int64
 
 func (i *Int64) bsontype() {}

internal/bson/null.go

@@ -0,0 +1,46 @@
+// Copyright 2021 FerretDB Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package bson
+
+import (
+	"bufio"
+
+	"github.com/FerretDB/FerretDB/internal/types"
+)
+
+// nullType represents BSON Null type.
+type nullType types.NullType
+
+func (*nullType) bsontype() {}
+
+// ReadFrom implements bsontype interface.
+func (*nullType) ReadFrom(r *bufio.Reader) error {
+	return nil
+}
+
+// WriteTo implements bsontype interface.
+func (nullType) WriteTo(w *bufio.Writer) error {
+	return nil
+}
+
+// MarshalBinary implements bsontype interface.
+func (nullType) MarshalBinary() ([]byte, error) {
+	return nil, nil
+}
+
+// check interfaces
+var (
+	_ bsontype = (*nullType)(nil)
+)

internal/bson/objectid.go

@@ -22,7 +22,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// ObjectID represents BSON ObjectID data type.
+// ObjectID represents BSON ObjectId type.
 type ObjectID types.ObjectID
 
 func (obj *ObjectID) bsontype() {}

internal/bson/regex.go

@@ -22,7 +22,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// Regex represents BSON Regex data type.
+// Regex represents BSON Regular expression type.
 type Regex types.Regex
 
 func (regex *Regex) bsontype() {}

internal/bson/string.go

@@ -23,7 +23,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// String represents BSON String data type.
+// String represents BSON UTF-8 string type.
 type String string
 
 func (str *String) bsontype() {}

internal/bson/timestamp.go

@@ -23,7 +23,7 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// Timestamp represents BSON Timestamp data type.
+// Timestamp represents BSON Timestamp type.
 type Timestamp types.Timestamp
 
 func (ts *Timestamp) bsontype() {}

internal/fjson/array.go

@@ -22,14 +22,14 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// fjsonArray represents BSON fjsonArray data type.
-type fjsonArray types.Array
+// arrayType represents BSON Array type.
+type arrayType types.Array
 
 // fjsontype implements fjsontype interface.
-func (a *fjsonArray) fjsontype() {}
+func (a *arrayType) fjsontype() {}
 
 // UnmarshalJSON implements fjsontype interface.
-func (a *fjsonArray) UnmarshalJSON(data []byte) error {
+func (a *arrayType) UnmarshalJSON(data []byte) error {
 	if bytes.Equal(data, []byte("null")) {
 		panic("null data")
 	}
@@ -57,12 +57,12 @@ func (a *fjsonArray) UnmarshalJSON(data []byte) error {
 		}
 	}
 
-	*a = fjsonArray(*ta)
+	*a = arrayType(*ta)
 	return nil
 }
 
 // MarshalJSON implements fjsontype interface.
-func (a *fjsonArray) MarshalJSON() ([]byte, error) {
+func (a *arrayType) MarshalJSON() ([]byte, error) {
 	var buf bytes.Buffer
 	buf.WriteByte('[')
 
@@ -91,5 +91,5 @@ func (a *fjsonArray) MarshalJSON() ([]byte, error) {
 
 // check interfaces
 var (
-	_ fjsontype = (*fjsonArray)(nil)
+	_ fjsontype = (*arrayType)(nil)
 )

internal/fjson/array_test.go

@@ -21,8 +21,8 @@ import (
 	"github.com/FerretDB/FerretDB/internal/types"
 )
 
-func convertArray(a *types.Array) *fjsonArray {
-	res := fjsonArray(*a)
+func convertArray(a *types.Array) *arrayType {
+	res := arrayType(*a)
 	return &res
 }
 
@@ -38,7 +38,7 @@ var arrayTestCases = []testCase{{
 		int32(42),
 		int64(42),
 		"foo",
-		nil,
+		types.Null,
 	)),
 	j: `[[],{"$b":"Qg==","s":128},true,{"$d":1627378542123},{"$k":[]},{"$f":42.13},42,{"$l":"42"},"foo",null]`,
 }, {
@@ -49,13 +49,13 @@ var arrayTestCases = []testCase{{
 
 func TestArray(t *testing.T) {
 	t.Parallel()
-	testJSON(t, arrayTestCases, func() fjsontype { return new(fjsonArray) })
+	testJSON(t, arrayTestCases, func() fjsontype { return new(arrayType) })
 }
 
 func FuzzArray(f *testing.F) {
-	fuzzJSON(f, arrayTestCases, func() fjsontype { return new(fjsonArray) })
+	fuzzJSON(f, arrayTestCases, func() fjsontype { return new(arrayType) })
 }
 
 func BenchmarkArray(b *testing.B) {
-	benchmark(b, arrayTestCases, func() fjsontype { return new(fjsonArray) })
+	benchmark(b, arrayTestCases, func() fjsontype { return new(arrayType) })
 }

internal/fjson/binary.go

@@ -22,19 +22,19 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// fjsonBinary represents BSON fjsonBinary data type.
-type fjsonBinary types.Binary
+// binaryType represents BSON Binary data type.
+type binaryType types.Binary
 
 // fjsontype implements fjsontype interface.
-func (bin *fjsonBinary) fjsontype() {}
+func (bin *binaryType) fjsontype() {}
 
 type binaryJSON struct {
 	B []byte `json:"$b"`
 	S byte   `json:"s"`
 }
 
 // UnmarshalJSON implements fjsontype interface.
-func (bin *fjsonBinary) UnmarshalJSON(data []byte) error {
+func (bin *binaryType) UnmarshalJSON(data []byte) error {
 	if bytes.Equal(data, []byte("null")) {
 		panic("null data")
 	}
@@ -58,7 +58,7 @@ func (bin *fjsonBinary) UnmarshalJSON(data []byte) error {
 }
 
 // MarshalJSON implements fjsontype interface.
-func (bin *fjsonBinary) MarshalJSON() ([]byte, error) {
+func (bin *binaryType) MarshalJSON() ([]byte, error) {
 	res, err := json.Marshal(binaryJSON{
 		B: bin.B,
 		S: byte(bin.Subtype),
@@ -71,5 +71,5 @@ func (bin *fjsonBinary) MarshalJSON() ([]byte, error) {
 
 // check interfaces
 var (
-	_ fjsontype = (*fjsonBinary)(nil)
+	_ fjsontype = (*binaryType)(nil)
 )

internal/fjson/binary_test.go

@@ -22,29 +22,29 @@ import (
 
 var binaryTestCases = []testCase{{
 	name: "foo",
-	v: &fjsonBinary{
+	v: &binaryType{
 		Subtype: types.BinaryUser,
 		B:       []byte("foo"),
 	},
 	j: `{"$b":"Zm9v","s":128}`,
 }, {
 	name: "empty",
-	v: &fjsonBinary{
+	v: &binaryType{
 		Subtype: types.BinaryGeneric,
 		B:       []byte{},
 	},
 	j:      `{"$b":""}`,
 	canonJ: `{"$b":"","s":0}`,
 }, {
 	name: "invalid subtype",
-	v: &fjsonBinary{
+	v: &binaryType{
 		Subtype: 0xff,
 		B:       []byte{},
 	},
 	j: `{"$b":"","s":255}`,
 }, {
 	name: "extra JSON fields",
-	v: &fjsonBinary{
+	v: &binaryType{
 		Subtype: types.BinaryUser,
 		B:       []byte("foo"),
 	},
@@ -59,13 +59,13 @@ var binaryTestCases = []testCase{{
 
 func TestBinary(t *testing.T) {
 	t.Parallel()
-	testJSON(t, binaryTestCases, func() fjsontype { return new(fjsonBinary) })
+	testJSON(t, binaryTestCases, func() fjsontype { return new(binaryType) })
 }
 
 func FuzzBinary(f *testing.F) {
-	fuzzJSON(f, binaryTestCases, func() fjsontype { return new(fjsonBinary) })
+	fuzzJSON(f, binaryTestCases, func() fjsontype { return new(binaryType) })
 }
 
 func BenchmarkBinary(b *testing.B) {
-	benchmark(b, binaryTestCases, func() fjsontype { return new(fjsonBinary) })
+	benchmark(b, binaryTestCases, func() fjsontype { return new(binaryType) })
 }