experiment with encoder/decoder for data encapsulation

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

internal/formats/formats.go

@@ -15,7 +15,7 @@ import (
 // TODO: eventually this is the source of truth for all formatters
 func All() []format.Format {
 	return []format.Format{
-		syftjson.Format(),
+		syftjson.Format( /*...now there is a requirement for app config here...*/ ),
 		table.Format(),
 		cyclonedx12xml.Format(),
 		spdx22json.Format(),

internal/formats/syftjson/decoder.go

@@ -10,7 +10,10 @@ import (
 	"github.com/anchore/syft/internal/formats/syftjson/model"
 )
 
-func decoder(reader io.Reader) (*sbom.SBOM, error) {
+type decoder struct {
+}
+
+func (d decoder) Decode(reader io.Reader) (*sbom.SBOM, error) {
 	dec := json.NewDecoder(reader)
 
 	var doc model.Document

internal/formats/syftjson/encoder.go

@@ -7,8 +7,12 @@ import (
 	"github.com/anchore/syft/syft/sbom"
 )
 
-func encoder(output io.Writer, s sbom.SBOM, appConfig interface{}) error {
+type encoder struct {
-	doc := ToFormatModel(s, appConfig)
+	appConfig interface{}
+}
+
+func (e encoder) Encode(output io.Writer, s sbom.SBOM) error {
+	doc := ToFormatModel(s, e.appConfig)
 
 	enc := json.NewEncoder(output)
 	// prevent > and < from being escaped in the payload

internal/formats/syftjson/format.go

@@ -2,11 +2,25 @@ package syftjson
 
 import "github.com/anchore/syft/syft/format"
 
-func Format() format.Format {
+func Format(appConfig interface{}) format.Format {
 	return format.NewFormat(
 		format.JSONOption,
-		encoder,
+		Encoder(appConfig),
-		decoder,
+		Decoder(),
-		validator,
+		Validator(),
 	)
 }
+
+func Encoder(appConfig interface{}) format.Encoder {
+	return &encoder{
+		appConfig: appConfig,
+	}
+}
+
+func Decoder() format.Decoder {
+	return &decoder{}
+}
+
+func Validator() format.Validator {
+	return &validator{}
+}

internal/formats/syftjson/validator.go

@@ -9,7 +9,10 @@ import (
 	"github.com/anchore/syft/internal/formats/syftjson/model"
 )
 
-func validator(reader io.Reader) error {
+type validator struct {
+}
+
+func (v validator) Validate(reader io.Reader) error {
 	type Document struct {
 		Schema model.Schema `json:"schema"`
 	}

syft/format/decoder.go

@@ -6,5 +6,7 @@ import (
 	"github.com/anchore/syft/syft/sbom"
 )
 
-// Decoder is a function that can convert an SBOM document of a specific format from a reader into Syft native objects.
+// Decoder is an object that can convert an SBOM document of a specific format from a reader into Syft native objects.
-type Decoder func(reader io.Reader) (*sbom.SBOM, error)
+type Decoder interface {
+	Decode(reader io.Reader) (*sbom.SBOM, error)
+}

syft/format/encoder.go

@@ -6,5 +6,7 @@ import (
 	"github.com/anchore/syft/syft/sbom"
 )
 
-// Encoder is a function that can transform Syft native objects into an SBOM document of a specific format written to the given writer.
+// Encoder is a function that can transform Syft native objects from an SBOM document of a specific format written to the given writer.
-type Encoder func(io.Writer, sbom.SBOM, interface{}) error
+type Encoder interface {
+	Encode(io.Writer, sbom.SBOM) error
+}

syft/format/format.go

@@ -15,45 +15,45 @@ var (
 
 type Format struct {
 	Option Option
-	encoder   Encoder
+	Encoder
-	decoder   Decoder
+	Decoder
-	validator Validator
+	Validator
 }
 
 func NewFormat(option Option, encoder Encoder, decoder Decoder, validator Validator) Format {
 	return Format{
 		Option:    option,
-		encoder:   encoder,
+		Encoder:   encoder,
-		decoder:   decoder,
+		Decoder:   decoder,
-		validator: validator,
+		Validator: validator,
 	}
 }
 
-func (f Format) Encode(output io.Writer, s sbom.SBOM, appConfig interface{}) error {
+func (f Format) Encode(output io.Writer, s sbom.SBOM) error {
-	if f.encoder == nil {
+	if f.Encoder == nil {
 		return ErrEncodingNotSupported
 	}
-	return f.encoder(output, s, appConfig)
+	return f.Encoder.Encode(output, s)
 }
 
 func (f Format) Decode(reader io.Reader) (*sbom.SBOM, error) {
-	if f.decoder == nil {
+	if f.Decoder == nil {
 		return nil, ErrDecodingNotSupported
 	}
-	return f.decoder(reader)
+	return f.Decoder.Decode(reader)
 }
 
 func (f Format) Validate(reader io.Reader) error {
-	if f.validator == nil {
+	if f.Validator == nil {
 		return ErrValidationNotSupported
 	}
 
-	return f.validator(reader)
+	return f.Validator.Validate(reader)
 }
 
-func (f Format) Presenter(s sbom.SBOM, appConfig interface{}) *Presenter {
+func (f Format) Presenter(s sbom.SBOM) *Presenter {
-	if f.encoder == nil {
+	if f.Encoder == nil {
 		return nil
 	}
-	return NewPresenter(f.encoder, s, appConfig)
+	return NewPresenter(f.Encoder, s)
 }

syft/format/presenter.go

@@ -8,18 +8,16 @@ import (
 
 type Presenter struct {
 	sbom    sbom.SBOM
-	appConfig interface{}
 	encoder Encoder
 }
 
-func NewPresenter(encoder Encoder, s sbom.SBOM, appConfig interface{}) *Presenter {
+func NewPresenter(encoder Encoder, s sbom.SBOM) *Presenter {
 	return &Presenter{
 		sbom:    s,
-		appConfig: appConfig,
 		encoder: encoder,
 	}
 }
 
 func (pres *Presenter) Present(output io.Writer) error {
-	return pres.encoder(output, pres.sbom, pres.appConfig)
+	return pres.encoder.Encode(output, pres.sbom)
 }

syft/format/validator.go

@@ -9,4 +9,6 @@ import "io"
 // assertions protect against "simple" format decoding validations that may lead to false positives (e.g. I decoded
 // json successfully therefore this must be the target format, however, all values are their default zero-value and
 // really represent a different format that also uses json)
-type Validator func(reader io.Reader) error
+type Validator interface {
+	Validate(reader io.Reader) error
+}