GODRIVER-2719 Remove unnecessary errors from bson.Encoder/bson.Decoder. (#1525)

Author: qingyang-hu

bson/bson_test.go

@@ -184,11 +184,10 @@ func TestMapCodec(t *testing.T) {
 				mapRegistry := NewRegistry()
 				mapRegistry.RegisterKindEncoder(reflect.Map, mapCodec)
 				buf := new(bytes.Buffer)
-				vw, err := bsonrw.NewBSONValueWriter(buf)
-				assert.Nil(t, err)
+				vw := bsonrw.NewValueWriter(buf)
 				enc := NewEncoder(vw)
 				enc.SetRegistry(mapRegistry)
-				err = enc.Encode(mapObj)
+				err := enc.Encode(mapObj)
 				assert.Nil(t, err, "Encode error: %v", err)
 				str := buf.String()
 				assert.True(t, strings.Contains(str, tc.key), "expected result to contain %v, got: %v", tc.key, str)

bson/bsoncodec/default_value_decoders_test.go

@@ -2427,7 +2427,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 				buildDocument(bsoncore.AppendNullElement(nil, "bar")),
 			),
 		)
-		dvr := bsonrw.NewBSONDocumentReader(b)
+		dvr := bsonrw.NewValueReader(b)
 		dr, err := dvr.ReadDocument()
 		noerr(t, err)
 		_, vr, err := dr.ReadElement()
@@ -2488,7 +2488,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 		noerr(t, err)
 		doc, err = bsoncore.AppendDocumentEnd(doc, idx)
 		noerr(t, err)
-		dvr := bsonrw.NewBSONDocumentReader(doc)
+		dvr := bsonrw.NewValueReader(doc)
 		noerr(t, err)
 		dr, err := dvr.ReadDocument()
 		noerr(t, err)
@@ -3132,7 +3132,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 		t.Run("Decode", func(t *testing.T) {
 			for _, tc := range testCases {
 				t.Run(tc.name, func(t *testing.T) {
-					vr := bsonrw.NewBSONDocumentReader(tc.b)
+					vr := bsonrw.NewValueReader(tc.b)
 					reg := buildDefaultRegistry()
 					vtype := reflect.TypeOf(tc.value)
 					dec, err := reg.LookupDecoder(vtype)
@@ -3181,7 +3181,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 
 		for _, tc := range testCases {
 			t.Run(tc.name, func(t *testing.T) {
-				vr := bsonrw.NewBSONDocumentReader(tc.b)
+				vr := bsonrw.NewValueReader(tc.b)
 				reg := buildDefaultRegistry()
 				vtype := reflect.TypeOf(tc.value)
 				dec, err := reg.LookupDecoder(vtype)
@@ -3403,7 +3403,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 		})
 		t.Run("top level document", func(t *testing.T) {
 			data := bsoncore.BuildDocument(nil, bsoncore.AppendDoubleElement(nil, "pi", 3.14159))
-			vr := bsonrw.NewBSONDocumentReader(data)
+			vr := bsonrw.NewValueReader(data)
 			want := primitive.D{{"pi", 3.14159}}
 			var got interface{}
 			val := reflect.ValueOf(&got).Elem()
@@ -3451,7 +3451,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 			}
 			for _, tc := range testCases {
 				var got interface{}
-				vr := bsonrw.NewBSONDocumentReader(doc)
+				vr := bsonrw.NewValueReader(doc)
 				val := reflect.ValueOf(&got).Elem()
 
 				err := defaultEmptyInterfaceCodec.DecodeValue(DecodeContext{Registry: tc.registry}, vr, val)
@@ -3487,7 +3487,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 			}
 
 			var got primitive.D
-			vr := bsonrw.NewBSONDocumentReader(doc)
+			vr := bsonrw.NewValueReader(doc)
 			val := reflect.ValueOf(&got).Elem()
 			err := defaultSliceCodec.DecodeValue(DecodeContext{Registry: reg}, vr, val)
 			noerr(t, err)
@@ -3577,7 +3577,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 				// DecodeValue error when decoding into a primitive.D.
 				"primitive.D slice",
 				primitive.D{},
-				bsonrw.NewBSONDocumentReader(docBytes),
+				bsonrw.NewValueReader(docBytes),
 				emptyInterfaceErrorRegistry,
 				defaultSliceCodec,
 				docEmptyInterfaceErr,
@@ -3600,7 +3600,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 				// the decodeD helper function.
 				"primitive.D array",
 				[1]primitive.E{},
-				bsonrw.NewBSONDocumentReader(docBytes),
+				bsonrw.NewValueReader(docBytes),
 				emptyInterfaceErrorRegistry,
 				ValueDecoderFunc(dvd.ArrayDecodeValue),
 				docEmptyInterfaceErr,
@@ -3623,7 +3623,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 				// DecodeValue error when decoding into a map.
 				"map",
 				map[string]interface{}{},
-				bsonrw.NewBSONDocumentReader(docBytes),
+				bsonrw.NewValueReader(docBytes),
 				emptyInterfaceErrorRegistry,
 				defaultMapCodec,
 				docEmptyInterfaceErr,
@@ -3632,7 +3632,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 				// DecodeValue error when decoding into a struct.
 				"struct - DecodeValue error",
 				emptyInterfaceStruct{},
-				bsonrw.NewBSONDocumentReader(docBytes),
+				bsonrw.NewValueReader(docBytes),
 				emptyInterfaceErrorRegistry,
 				defaultTestStructCodec,
 				emptyInterfaceStructErr,
@@ -3643,15 +3643,15 @@ func TestDefaultValueDecoders(t *testing.T) {
 				// no decoder for strings.
 				"struct - no decoder found",
 				stringStruct{},
-				bsonrw.NewBSONDocumentReader(docBytes),
+				bsonrw.NewValueReader(docBytes),
 				NewRegistryBuilder().Build(),
 				defaultTestStructCodec,
 				stringStructErr,
 			},
 			{
 				"deeply nested struct",
 				outer{},
-				bsonrw.NewBSONDocumentReader(outerDoc),
+				bsonrw.NewValueReader(outerDoc),
 				nestedRegistry,
 				defaultTestStructCodec,
 				nestedErr,
@@ -3681,7 +3681,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 			type outer struct{ Foo inner }
 
 			dc := DecodeContext{Registry: buildDefaultRegistry()}
-			vr := bsonrw.NewBSONDocumentReader(outerBytes)
+			vr := bsonrw.NewValueReader(outerBytes)
 			val := reflect.New(reflect.TypeOf(outer{})).Elem()
 			err := defaultTestStructCodec.DecodeValue(dc, vr, val)
 
@@ -3714,7 +3714,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 			reg := rb.RegisterTypeMapEntry(bsontype.Boolean, reflect.TypeOf(mybool(true))).Build()
 
 			dc := DecodeContext{Registry: reg}
-			vr := bsonrw.NewBSONDocumentReader(docBytes)
+			vr := bsonrw.NewValueReader(docBytes)
 			val := reflect.New(tD).Elem()
 			err := defaultValueDecoders.DDecodeValue(dc, vr, val)
 			assert.Nil(t, err, "DDecodeValue error: %v", err)
@@ -3733,7 +3733,7 @@ func TestDefaultValueDecoders(t *testing.T) {
 
 			type myMap map[string]mybool
 			dc := DecodeContext{Registry: buildDefaultRegistry()}
-			vr := bsonrw.NewBSONDocumentReader(docBytes)
+			vr := bsonrw.NewValueReader(docBytes)
 			val := reflect.New(reflect.TypeOf(myMap{})).Elem()
 			err := defaultMapCodec.DecodeValue(dc, vr, val)
 			assert.Nil(t, err, "DecodeValue error: %v", err)

bson/bsoncodec/default_value_encoders_test.go

@@ -1770,8 +1770,7 @@ func TestDefaultValueEncoders(t *testing.T) {
 		for _, tc := range testCases {
 			t.Run(tc.name, func(t *testing.T) {
 				b := make(bsonrw.SliceWriter, 0, 512)
-				vw, err := bsonrw.NewBSONValueWriter(&b)
-				noerr(t, err)
+				vw := bsonrw.NewValueWriter(&b)
 				reg := buildDefaultRegistry()
 				enc, err := reg.LookupEncoder(reflect.TypeOf(tc.value))
 				noerr(t, err)
@@ -1821,8 +1820,7 @@ func TestDefaultValueEncoders(t *testing.T) {
 		for _, tc := range testCases {
 			t.Run(tc.name, func(t *testing.T) {
 				b := make(bsonrw.SliceWriter, 0, 512)
-				vw, err := bsonrw.NewBSONValueWriter(&b)
-				noerr(t, err)
+				vw := bsonrw.NewValueWriter(&b)
 				reg := buildDefaultRegistry()
 				enc, err := reg.LookupEncoder(reflect.TypeOf(tc.value))
 				noerr(t, err)

bson/bsoncodec/registry_examples_test.go

@@ -68,13 +68,10 @@ func ExampleRegistry_customEncoder() {
 	// Marshal the document as BSON. Expect that the int field is encoded to the
 	// same value and that the negatedInt field is encoded as the negated value.
 	buf := new(bytes.Buffer)
-	vw, err := bsonrw.NewBSONValueWriter(buf)
-	if err != nil {
-		panic(err)
-	}
+	vw := bsonrw.NewValueWriter(buf)
 	enc := bson.NewEncoder(vw)
 	enc.SetRegistry(reg)
-	err = enc.Encode(doc)
+	err := enc.Encode(doc)
 	if err != nil {
 		panic(err)
 	}
@@ -209,13 +206,10 @@ func ExampleRegistry_RegisterKindEncoder() {
 	// Marshal the document as BSON. Expect that all fields are encoded as BSON
 	// int64 (represented as "$numberLong" when encoded as Extended JSON).
 	buf := new(bytes.Buffer)
-	vw, err := bsonrw.NewBSONValueWriter(buf)
-	if err != nil {
-		panic(err)
-	}
+	vw := bsonrw.NewValueWriter(buf)
 	enc := bson.NewEncoder(vw)
 	enc.SetRegistry(reg)
-	err = enc.Encode(doc)
+	err := enc.Encode(doc)
 	if err != nil {
 		panic(err)
 	}

bson/bsonrw/extjson_writer.go

@@ -92,15 +92,11 @@ type extJSONValueWriter struct {
 }
 
 // NewExtJSONValueWriter creates a ValueWriter that writes Extended JSON to w.
-func NewExtJSONValueWriter(w io.Writer, canonical, escapeHTML bool) (ValueWriter, error) {
-	if w == nil {
-		return nil, errNilWriter
-	}
-
+func NewExtJSONValueWriter(w io.Writer, canonical, escapeHTML bool) ValueWriter {
 	// Enable newlines for all Extended JSON value writers created by NewExtJSONValueWriter. We
 	// expect these value writers to be used with an Encoder, which should add newlines after
 	// encoded Extended JSON documents.
-	return newExtJSONWriter(w, canonical, escapeHTML, true), nil
+	return newExtJSONWriter(w, canonical, escapeHTML, true)
 }
 
 func newExtJSONWriter(w io.Writer, canonical, escapeHTML, newlines bool) *extJSONValueWriter {

bson/bsonrw/extjson_writer_test.go

@@ -8,7 +8,7 @@ package bsonrw
 
 import (
 	"fmt"
-	"io/ioutil"
+	"io"
 	"reflect"
 	"strings"
 	"testing"
@@ -139,7 +139,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 				t.Fatalf("fn must have one return value and it must be an error.")
 			}
 			params := make([]reflect.Value, 1, len(tc.params)+1)
-			ejvw := newExtJSONWriter(ioutil.Discard, true, true, false)
+			ejvw := newExtJSONWriter(io.Discard, true, true, false)
 			params[0] = reflect.ValueOf(ejvw)
 			for _, param := range tc.params {
 				params = append(params, reflect.ValueOf(param))
@@ -162,7 +162,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 	}
 
 	t.Run("WriteArray", func(t *testing.T) {
-		ejvw := newExtJSONWriter(ioutil.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true, false)
 		ejvw.push(mArray)
 		want := TransitionError{current: mArray, destination: mArray, parent: mTopLevel,
 			name: "WriteArray", modes: []mode{mElement, mValue}, action: "write"}
@@ -172,7 +172,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteCodeWithScope", func(t *testing.T) {
-		ejvw := newExtJSONWriter(ioutil.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true, false)
 		ejvw.push(mArray)
 		want := TransitionError{current: mArray, destination: mCodeWithScope, parent: mTopLevel,
 			name: "WriteCodeWithScope", modes: []mode{mElement, mValue}, action: "write"}
@@ -182,7 +182,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteDocument", func(t *testing.T) {
-		ejvw := newExtJSONWriter(ioutil.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true, false)
 		ejvw.push(mArray)
 		want := TransitionError{current: mArray, destination: mDocument, parent: mTopLevel,
 			name: "WriteDocument", modes: []mode{mElement, mValue, mTopLevel}, action: "write"}
@@ -192,7 +192,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteDocumentElement", func(t *testing.T) {
-		ejvw := newExtJSONWriter(ioutil.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true, false)
 		ejvw.push(mElement)
 		want := TransitionError{current: mElement,
 			destination: mElement,
@@ -206,7 +206,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteDocumentEnd", func(t *testing.T) {
-		ejvw := newExtJSONWriter(ioutil.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true, false)
 		ejvw.push(mElement)
 		want := fmt.Errorf("incorrect mode to end document: %s", mElement)
 		got := ejvw.WriteDocumentEnd()
@@ -215,7 +215,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteArrayElement", func(t *testing.T) {
-		ejvw := newExtJSONWriter(ioutil.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true, false)
 		ejvw.push(mElement)
 		want := TransitionError{current: mElement,
 			destination: mValue,
@@ -229,7 +229,7 @@ func TestExtJSONValueWriter(t *testing.T) {
 		}
 	})
 	t.Run("WriteArrayEnd", func(t *testing.T) {
-		ejvw := newExtJSONWriter(ioutil.Discard, true, true, false)
+		ejvw := newExtJSONWriter(io.Discard, true, true, false)
 		ejvw.push(mElement)
 		want := fmt.Errorf("incorrect mode to end array: %s", mElement)
 		got := ejvw.WriteArrayEnd()

bson/bsonrw/value_reader.go

@@ -92,9 +92,9 @@ type valueReader struct {
 	frame int64
 }
 
-// NewBSONDocumentReader returns a ValueReader using b for the underlying BSON
+// NewValueReader returns a ValueReader using b for the underlying BSON
 // representation. Parameter b must be a BSON Document.
-func NewBSONDocumentReader(b []byte) ValueReader {
+func NewValueReader(b []byte) ValueReader {
 	// TODO(skriptble): There's a lack of symmetry between the reader and writer, since the reader takes a []byte while the
 	// TODO writer takes an io.Writer. We should have two versions of each, one that takes a []byte and one that takes an
 	// TODO io.Reader or io.Writer. The []byte version will need to return a thing that can return the finished []byte since

bson/bsonrw/value_writer.go

@@ -95,8 +95,6 @@ func (bvwp *BSONValueWriterPool) Put(vw ValueWriter) (ok bool) {
 // allocating a 4GB slice.
 var maxSize = math.MaxInt32
 
-var errNilWriter = errors.New("cannot create a ValueWriter from a nil io.Writer")
-
 type errMaxDocumentSizeExceeded struct {
 	size int64
 }
@@ -188,15 +186,12 @@ func (vw *valueWriter) pop() {
 	}
 }
 
-// NewBSONValueWriter creates a ValueWriter that writes BSON to w.
+// NewValueWriter creates a ValueWriter that writes BSON to w.
 //
 // This ValueWriter will only write entire documents to the io.Writer and it
 // will buffer the document as it is built.
-func NewBSONValueWriter(w io.Writer) (ValueWriter, error) {
-	if w == nil {
-		return nil, errNilWriter
-	}
-	return newValueWriter(w), nil
+func NewValueWriter(w io.Writer) ValueWriter {
+	return newValueWriter(w)
 }
 
 func newValueWriter(w io.Writer) *valueWriter {