chore: Add format type text

cmd/oras/internal/display/handler.go

@@ -39,15 +39,15 @@ func NewPushHandler(out io.Writer, format option.Format, tty *os.File, verbose b
 	var statusHandler status.PushHandler
 	if tty != nil {
 		statusHandler = status.NewTTYPushHandler(tty)
-	} else if format.Type == "" {
+	} else if format.Type == option.FormatTypeText.Name {
 		statusHandler = status.NewTextPushHandler(out, verbose)
 	} else {
 		statusHandler = status.NewDiscardHandler()
 	}
 
 	var metadataHandler metadata.PushHandler
 	switch format.Type {
-	case "":
+	case option.FormatTypeText.Name:
 		metadataHandler = text.NewPushHandler(out)
 	case option.FormatTypeJSON.Name:
 		metadataHandler = json.NewPushHandler(out)
@@ -64,15 +64,15 @@ func NewAttachHandler(out io.Writer, format option.Format, tty *os.File, verbose
 	var statusHandler status.AttachHandler
 	if tty != nil {
 		statusHandler = status.NewTTYAttachHandler(tty)
-	} else if format.Type == "" {
+	} else if format.Type == option.FormatTypeText.Name {
 		statusHandler = status.NewTextAttachHandler(out, verbose)
 	} else {
 		statusHandler = status.NewDiscardHandler()
 	}
 
 	var metadataHandler metadata.AttachHandler
 	switch format.Type {
-	case "":
+	case option.FormatTypeText.Name:
 		metadataHandler = text.NewAttachHandler(out)
 	case option.FormatTypeJSON.Name:
 		metadataHandler = json.NewAttachHandler(out)
@@ -89,15 +89,15 @@ func NewPullHandler(out io.Writer, format option.Format, path string, tty *os.Fi
 	var statusHandler status.PullHandler
 	if tty != nil {
 		statusHandler = status.NewTTYPullHandler(tty)
-	} else if format.Type == "" {
+	} else if format.Type == option.FormatTypeText.Name {
 		statusHandler = status.NewTextPullHandler(out, verbose)
 	} else {
 		statusHandler = status.NewDiscardHandler()
 	}
 
 	var metadataHandler metadata.PullHandler
 	switch format.Type {
-	case "":
+	case option.FormatTypeText.Name:
 		metadataHandler = text.NewPullHandler(out)
 	case option.FormatTypeJSON.Name:
 		metadataHandler = json.NewPullHandler(out, path)
@@ -113,7 +113,7 @@ func NewPullHandler(out io.Writer, format option.Format, path string, tty *os.Fi
 func NewDiscoverHandler(out io.Writer, format option.Format, path string, rawReference string, desc ocispec.Descriptor, verbose bool) (metadata.DiscoverHandler, error) {
 	var handler metadata.DiscoverHandler
 	switch format.Type {
-	case option.FormatTypeTree.Name, "":
+	case option.FormatTypeTree.Name:
 		handler = tree.NewDiscoverHandler(out, path, desc, verbose)
 	case option.FormatTypeTable.Name:
 		handler = table.NewDiscoverHandler(out, rawReference, desc, verbose)
@@ -133,7 +133,7 @@ func NewManifestFetchHandler(out io.Writer, format option.Format, outputDescript
 	var contentHandler content.ManifestFetchHandler
 
 	switch format.Type {
-	case "":
+	case option.FormatTypeText.Name:
 		// raw
 		if outputDescriptor {
 			metadataHandler = descriptor.NewManifestFetchHandler(out, pretty)

cmd/oras/internal/display/handler_test.go

@@ -0,0 +1,44 @@
+/*
+Copyright The ORAS Authors.
+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 display
+
+import (
+	"os"
+	"testing"
+
+	"oras.land/oras/cmd/oras/internal/option"
+)
+
+func TestNewPushHandler(t *testing.T) {
+	_, _, err := NewPushHandler(os.Stdout, option.Format{Type: option.FormatTypeText.Name}, os.Stdout, false)
+	if err != nil {
+		t.Errorf("NewPushHandler() error = %v, want nil", err)
+	}
+}
+
+func TestNewAttachHandler(t *testing.T) {
+	_, _, err := NewAttachHandler(os.Stdout, option.Format{Type: option.FormatTypeText.Name}, os.Stdout, false)
+	if err != nil {
+		t.Errorf("NewAttachHandler() error = %v, want nil", err)
+	}
+}
+
+func TestNewPullHandler(t *testing.T) {
+	_, _, err := NewPullHandler(os.Stdout, option.Format{Type: option.FormatTypeText.Name}, "", os.Stdout, false)
+	if err != nil {
+		t.Errorf("NewPullHandler() error = %v, want nil", err)
+	}
+}

cmd/oras/internal/option/format.go

@@ -64,26 +64,41 @@ var (
 		Name:  "tree",
 		Usage: "Get referrers recursively and print in tree format",
 	}
+	FormatTypeText = &FormatType{
+		Name:  "text",
+		Usage: "Print in text format",
+	}
 )
 
 // Format contains input and parsed options for formatted output flags.
 type Format struct {
 	FormatFlag   string
 	Type         string
 	Template     string
-	AllowedTypes []*FormatType
+	allowedTypes []*FormatType
+	defaultType  *FormatType
+}
+
+// SetTypes sets the default format type and allowed format types.
+func (f *Format) SetTypes(defaultType *FormatType, allowedTypes ...*FormatType) {
+	f.defaultType = defaultType
+	f.allowedTypes = append(allowedTypes, defaultType)
 }
 
-// ApplyFlag implements FlagProvider.ApplyFlag.
+// ApplyFlags implements FlagProvider.ApplyFlag.
 func (opts *Format) ApplyFlags(fs *pflag.FlagSet) {
 	buf := bytes.NewBufferString("[Experimental] Format output using a custom template:")
 	w := tabwriter.NewWriter(buf, 0, 0, 2, ' ', 0)
-	for _, t := range opts.AllowedTypes {
+	for _, t := range opts.allowedTypes {
 		_, _ = fmt.Fprintf(w, "\n'%s':\t%s", t.Name, t.Usage)
 	}
-	w.Flush()
+	_ = w.Flush()
+	defaultTypeName := FormatTypeText.Name
+	if opts.defaultType != nil {
+		defaultTypeName = opts.defaultType.Name
+	}
 	// apply flags
-	fs.StringVar(&opts.FormatFlag, "format", opts.FormatFlag, buf.String())
+	fs.StringVar(&opts.FormatFlag, "format", defaultTypeName, buf.String())
 	fs.StringVar(&opts.Template, "template", "", "[Experimental] Template string used to format output")
 }
 
@@ -93,7 +108,7 @@ func (opts *Format) Parse(_ *cobra.Command) error {
 		return err
 	}
 
-	if opts.Type == "" {
+	if opts.Type == FormatTypeText.Name {
 		// flag not specified
 		return nil
 	}
@@ -106,7 +121,7 @@ func (opts *Format) Parse(_ *cobra.Command) error {
 	}
 
 	var optionalTypes []string
-	for _, t := range opts.AllowedTypes {
+	for _, t := range opts.allowedTypes {
 		if opts.Type == t.Name {
 			// type validation passed
 			return nil
@@ -129,7 +144,7 @@ func (opts *Format) parseFlag() error {
 		return nil
 	}
 
-	for _, t := range opts.AllowedTypes {
+	for _, t := range opts.allowedTypes {
 		if !t.HasParams {
 			continue
 		}

cmd/oras/root/attach.go

@@ -102,7 +102,7 @@ Example - Attach file to the manifest tagged 'v1' in an OCI image layout folder
 	opts.FlagDescription = "[Preview] attach to an arch-specific subject"
 	_ = cmd.MarkFlagRequired("artifact-type")
 	opts.EnableDistributionSpecFlag()
-	opts.AllowedTypes = []*option.FormatType{option.FormatTypeJSON, option.FormatTypeGoTemplate}
+	opts.SetTypes(option.FormatTypeText, option.FormatTypeJSON, option.FormatTypeGoTemplate)
 	option.ApplyFlags(&opts, cmd.Flags())
 	return oerrors.Command(cmd, &opts.Target)
 }

cmd/oras/root/discover.go

@@ -100,12 +100,12 @@ Example - Discover referrers of the manifest tagged 'v1' in an OCI image layout
 	cmd.Flags().StringVarP(&opts.artifactType, "artifact-type", "", "", "artifact type")
 	cmd.Flags().StringVarP(&opts.Format.FormatFlag, "output", "o", "tree", "[Deprecated] format in which to display referrers (table, json, or tree). tree format will also show indirect referrers")
 	opts.FormatFlag = option.FormatTypeTree.Name
-	opts.AllowedTypes = []*option.FormatType{
+	opts.SetTypes(
 		option.FormatTypeTree,
 		option.FormatTypeTable,
 		option.FormatTypeJSON.WithUsage("Get direct referrers and output in JSON format"),
 		option.FormatTypeGoTemplate.WithUsage("Print direct referrers using the given Go template"),
-	}
+	)
 	opts.EnableDistributionSpecFlag()
 	option.ApplyFlags(&opts, cmd.Flags())
 	return oerrors.Command(cmd, &opts.Target)

cmd/oras/root/manifest/fetch.go

@@ -73,7 +73,7 @@ Example - Fetch raw manifest from an OCI layout archive file 'layout.tar':
 		Args: oerrors.CheckArgs(argument.Exactly(1), "the manifest to fetch"),
 		PreRunE: func(cmd *cobra.Command, args []string) error {
 			switch {
-			case opts.outputPath == "-" && opts.FormatFlag != "":
+			case opts.outputPath == "-" && opts.FormatFlag != option.FormatTypeText.Name:
 				return fmt.Errorf("`--output -` cannot be used with `--format %s` at the same time", opts.Template)
 			case opts.outputPath == "-" && opts.OutputDescriptor:
 				return fmt.Errorf("`--descriptor` cannot be used with `--output -` at the same time")
@@ -98,10 +98,11 @@ Example - Fetch raw manifest from an OCI layout archive file 'layout.tar':
 
 	cmd.Flags().StringSliceVarP(&opts.mediaTypes, "media-type", "", nil, "accepted media types")
 	cmd.Flags().StringVarP(&opts.outputPath, "output", "o", "", "file `path` to write the fetched manifest to, use - for stdout")
-	opts.AllowedTypes = []*option.FormatType{
+	opts.SetTypes(
+		option.FormatTypeText,
 		option.FormatTypeJSON.WithUsage("Print in prettified JSON format"),
 		option.FormatTypeGoTemplate.WithUsage("Print using the given Go template"),
-	}
+	)
 	option.ApplyFlags(&opts, cmd.Flags())
 	return oerrors.Command(cmd, &opts.Target)
 }

cmd/oras/root/pull.go

@@ -104,7 +104,7 @@ Example - Pull artifact files from an OCI layout archive 'layout.tar':
 	cmd.Flags().StringVarP(&opts.Output, "output", "o", ".", "output directory")
 	cmd.Flags().StringVarP(&opts.ManifestConfigRef, "config", "", "", "output manifest config file")
 	cmd.Flags().IntVarP(&opts.concurrency, "concurrency", "", 3, "concurrency level")
-	opts.AllowedTypes = []*option.FormatType{option.FormatTypeJSON, option.FormatTypeGoTemplate}
+	opts.SetTypes(option.FormatTypeText, option.FormatTypeJSON, option.FormatTypeGoTemplate)
 	option.ApplyFlags(&opts, cmd.Flags())
 	return oerrors.Command(cmd, &opts.Target)
 }

cmd/oras/root/push.go

@@ -144,7 +144,7 @@ Example - Push file "hi.txt" into an OCI image layout folder 'layout-dir' with t
 	cmd.Flags().StringVarP(&opts.manifestConfigRef, "config", "", "", "`path` of image config file")
 	cmd.Flags().StringVarP(&opts.artifactType, "artifact-type", "", "", "artifact type")
 	cmd.Flags().IntVarP(&opts.concurrency, "concurrency", "", 5, "concurrency level")
-	opts.AllowedTypes = []*option.FormatType{option.FormatTypeJSON, option.FormatTypeGoTemplate}
+	opts.SetTypes(option.FormatTypeText, option.FormatTypeJSON, option.FormatTypeGoTemplate)
 	option.ApplyFlags(&opts, cmd.Flags())
 	return oerrors.Command(cmd, &opts.Target)
 }