* Make ToV2, FromV2 converters for Patch and PayloadPatch;
* Add unit-tests.

Signed-off-by: Airat Arifullin <a.arifullin@yadro.com>

@@ -0,0 +13,4 @@
+
+var (
+	ErrOffsetExceedsSize         = errors.New("patch offset exceeds object size")
+	ErrEmptyPayloadPatch         = errors.New("patch must contain payload")

@@ -0,0 +39,4 @@
+// HeaderProvider is the interface that provides a method to get an original's object header.
+type HeaderProvider interface {
+	// GetObjectHeader gets an original's object header.
+	GetObjectHeader(ctx context.Context, addr oid.Address) (*objectSDK.Object, error)

@@ -0,0 +48,4 @@
+	// ReadRange reads an original object payload by the given range.
+	// The method returns io.Reader over the data range only. This means if the data is read out,
+	// then ReadRange has to be invoked to provide reader over the next range.
+	ReadRange(ctx context.Context, addr oid.Address, rng *objectSDK.Range) io.Reader

@@ -0,0 +81,4 @@
+	}
+}
+
+func (p *patcher) ApplyPatch(ctx context.Context, currPatch *objectSDK.Patch) bool {

@@ -0,0 +83,4 @@
+
+func (p *patcher) ApplyPatch(ctx context.Context, currPatch *objectSDK.Patch) bool {
+	if currPatch == nil {
+		return true

@@ -0,0 +161,4 @@
+
+	rdr := p.rangeProvider.ReadRange(ctx, p.addr, rng)
+	for {
+		remain := make([]byte, 1024)

@@ -0,0 +194,4 @@
+
+		rdr := p.rangeProvider.ReadRange(ctx, p.addr, rng)
+		for {
+			orig := make([]byte, 1024)

@@ -0,0 +238,4 @@
+	}
+
+	var mergedAttrs []objectSDK.Attribute
+	for key, value := range attrMap {

@@ -0,0 +316,4 @@
+				},
+			},
+			patchPayloads: []*objectSDK.PayloadPatch{
+				nil,

@@ -0,0 +198,4 @@
+			var n int
+			n, err = rdr.Read(orig)
+			if err != nil {
+				if err == io.EOF {

@@ -0,0 +53,4 @@
+
+var _ RangeProvider = (*mockRangeProvider)(nil)
+
+func (m *mockRangeProvider) ReadRange(_ context.Context, addr oid.Address, rng *objectSDK.Range) io.Reader {

@@ -0,0 +81,4 @@
+	}
+}
+
+func (p *patcher) ApplyAttributesPatch(ctx context.Context, newAttrs []objectSDK.Attribute, replaceAttrs bool) error {

@@ -0,0 +128,4 @@
+	rng.SetOffset(p.currOffset)
+	rng.SetLength(p.originalPayloadSize - p.currOffset)
+
+	rdr := p.rangeProvider.ReadRange(ctx, rng)

@@ -0,0 +453,4 @@
+			require.NoError(t, err)
+			require.Equal(t, test.patched, patchedObject.Payload())
+
+			// attrOfPatchedObject := patchedObject.Attributes()

@@ -0,0 +116,4 @@
+		p.firstPayloadPatchCall = false
+	}()
+
+	if !p.attrPatchAlreadyApplied {

@@ -0,0 +121,4 @@
+	}
+
+	if payloadPatch == nil {
+		if p.firstPayloadPatchCall {

@@ -0,0 +25,4 @@
+// PatchApplier is the interface that provides method to apply header and payload patches.
+type PatchApplier interface {
+	// ApplyAttributesPatch applies the patch only for the object's attributes.
+	// This method must be ALWAYS invoked first as attribute patch must income ONLY with the first patch

@@ -0,0 +49,4 @@
+	// ReadRange reads an original object payload by the given range.
+	// The method returns io.Reader over the data range only. This means if the data is read out,
+	// then ReadRange has to be invoked to provide reader over the next range.
+	ReadRange(ctx context.Context, rng *objectSDK.Range) io.Reader

@@ -0,0 +119,4 @@
+	if replaceAttrs {
+		p.hdr.SetAttributes(newAttrs...)
+	} else if len(newAttrs) > 0 {
+		mergedAttrs := mergeAttributes(newAttrs, p.hdr.Attributes())

@@ -0,0 +157,4 @@
+
+	// copy remaining originial payload
+	if err := p.copyRange(ctx, rng); err != nil {
+		return PatchRes{}, fmt.Errorf("copy payload error: %w", err)

@@ -0,0 +219,4 @@
+}
+
+func mergeAttributes(newAttrs, oldAttrs []objectSDK.Attribute) []objectSDK.Attribute {
+	attrMap := make(map[string]string)

@@ -0,0 +556,4 @@
+			require.NoError(t, err)
+			require.Equal(t, test.patched, patchedObject.Payload())
+
+			newAttrs := append([]objectSDK.Attribute{}, test.patches[0].NewAttributes...)

@@ -0,0 +49,4 @@
+			var attr1, attr2 Attribute
+			attr1.SetKey("key1")
+			attr1.SetValue("val1")
+			attr1.SetKey("key2")

@@ -0,0 +362,4 @@
+			},
+			originalObjectPayload:   []byte("0123456789qwertyuiopasdfghjklzxcvbnm"),
+			patchedPayload:          []byte("inserted at the beginning0123456789qwertyuiopasdfghjklzxcvbnm"),
+			expectedPayloadPatchErr: ErrPayloadPatchIsNil,