feat(encoding): Encoder/Decoder registry implementations

internal/encoding/decoder.go

@@ -0,0 +1,61 @@
+package encoding
+
+import (
+	"sync"
+)
+
+// Decoder decodes the contents of b into a v representation.
+// It's primarily used for decoding contents of a file into a map[string]interface{}.
+type Decoder interface {
+	Decode(b []byte, v interface{}) error
+}
+
+const (
+	// ErrDecoderNotFound is returned when there is no decoder registered for a format.
+	ErrDecoderNotFound = encodingError("decoder not found for this format")
+
+	// ErrDecoderFormatAlreadyRegistered is returned when an decoder is already registered for a format.
+	ErrDecoderFormatAlreadyRegistered = encodingError("decoder already registered for this format")
+)
+
+// DecoderRegistry can choose an appropriate Decoder based on the provided format.
+type DecoderRegistry struct {
+	decoders map[string]Decoder
+
+	mu sync.RWMutex
+}
+
+// NewDecoderRegistry returns a new, initialized DecoderRegistry.
+func NewDecoderRegistry() *DecoderRegistry {
+	return &DecoderRegistry{
+		decoders: make(map[string]Decoder),
+	}
+}
+
+// RegisterDecoder registers a Decoder for a format.
+// Registering a Decoder for an already existing format is not supported.
+func (e *DecoderRegistry) RegisterDecoder(format string, enc Decoder) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	if _, ok := e.decoders[format]; ok {
+		return ErrDecoderFormatAlreadyRegistered
+	}
+
+	e.decoders[format] = enc
+
+	return nil
+}
+
+// Decode calls the underlying Decoder based on the format.
+func (e *DecoderRegistry) Decode(format string, b []byte, v interface{}) error {
+	e.mu.RLock()
+	decoder, ok := e.decoders[format]
+	e.mu.RUnlock()
+
+	if !ok {
+		return ErrDecoderNotFound
+	}
+
+	return decoder.Decode(b, v)
+}

internal/encoding/decoder_test.go

@@ -0,0 +1,77 @@
+package encoding
+
+import (
+	"testing"
+)
+
+type decoder struct {
+	v interface{}
+}
+
+func (d decoder) Decode(_ []byte, v interface{}) error {
+	rv := v.(*string)
+	*rv = d.v.(string)
+
+	return nil
+}
+
+func TestDecoderRegistry_RegisterDecoder(t *testing.T) {
+	t.Run("OK", func(t *testing.T) {
+		registry := NewDecoderRegistry()
+
+		err := registry.RegisterDecoder("myformat", decoder{})
+		if err != nil {
+			t.Fatal(err)
+		}
+	})
+
+	t.Run("AlreadyRegistered", func(t *testing.T) {
+		registry := NewDecoderRegistry()
+
+		err := registry.RegisterDecoder("myformat", decoder{})
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		err = registry.RegisterDecoder("myformat", decoder{})
+		if err != ErrDecoderFormatAlreadyRegistered {
+			t.Fatalf("expected ErrDecoderFormatAlreadyRegistered, got: %v", err)
+		}
+	})
+}
+
+func TestDecoderRegistry_Decode(t *testing.T) {
+	t.Run("OK", func(t *testing.T) {
+		registry := NewDecoderRegistry()
+		decoder := decoder{
+			v: "decoded value",
+		}
+
+		err := registry.RegisterDecoder("myformat", decoder)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		var v string
+
+		err = registry.Decode("myformat", []byte("some value"), &v)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if v != "decoded value" {
+			t.Fatalf("expected 'decoded value', got: %#v", v)
+		}
+	})
+
+	t.Run("DecoderNotFound", func(t *testing.T) {
+		registry := NewDecoderRegistry()
+
+		var v string
+
+		err := registry.Decode("myformat", []byte("some value"), &v)
+		if err != ErrDecoderNotFound {
+			t.Fatalf("expected ErrDecoderNotFound, got: %v", err)
+		}
+	})
+}

internal/encoding/encoder.go

@@ -0,0 +1,60 @@
+package encoding
+
+import (
+	"sync"
+)
+
+// Encoder encodes the contents of v into a byte representation.
+// It's primarily used for encoding a map[string]interface{} into a file format.
+type Encoder interface {
+	Encode(v interface{}) ([]byte, error)
+}
+
+const (
+	// ErrEncoderNotFound is returned when there is no encoder registered for a format.
+	ErrEncoderNotFound = encodingError("encoder not found for this format")
+
+	// ErrEncoderFormatAlreadyRegistered is returned when an encoder is already registered for a format.
+	ErrEncoderFormatAlreadyRegistered = encodingError("encoder already registered for this format")
+)
+
+// EncoderRegistry can choose an appropriate Encoder based on the provided format.
+type EncoderRegistry struct {
+	encoders map[string]Encoder
+
+	mu sync.RWMutex
+}
+
+// NewEncoderRegistry returns a new, initialized EncoderRegistry.
+func NewEncoderRegistry() *EncoderRegistry {
+	return &EncoderRegistry{
+		encoders: make(map[string]Encoder),
+	}
+}
+
+// RegisterEncoder registers an Encoder for a format.
+// Registering a Encoder for an already existing format is not supported.
+func (e *EncoderRegistry) RegisterEncoder(format string, enc Encoder) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	if _, ok := e.encoders[format]; ok {
+		return ErrEncoderFormatAlreadyRegistered
+	}
+
+	e.encoders[format] = enc
+
+	return nil
+}
+
+func (e *EncoderRegistry) Encode(format string, v interface{}) ([]byte, error) {
+	e.mu.RLock()
+	encoder, ok := e.encoders[format]
+	e.mu.RUnlock()
+
+	if !ok {
+		return nil, ErrEncoderNotFound
+	}
+
+	return encoder.Encode(v)
+}

internal/encoding/encoder_test.go

@@ -0,0 +1,70 @@
+package encoding
+
+import (
+	"testing"
+)
+
+type encoder struct {
+	b []byte
+}
+
+func (e encoder) Encode(_ interface{}) ([]byte, error) {
+	return e.b, nil
+}
+
+func TestEncoderRegistry_RegisterEncoder(t *testing.T) {
+	t.Run("OK", func(t *testing.T) {
+		registry := NewEncoderRegistry()
+
+		err := registry.RegisterEncoder("myformat", encoder{})
+		if err != nil {
+			t.Fatal(err)
+		}
+	})
+
+	t.Run("AlreadyRegistered", func(t *testing.T) {
+		registry := NewEncoderRegistry()
+
+		err := registry.RegisterEncoder("myformat", encoder{})
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		err = registry.RegisterEncoder("myformat", encoder{})
+		if err != ErrEncoderFormatAlreadyRegistered {
+			t.Fatalf("expected ErrEncoderFormatAlreadyRegistered, got: %v", err)
+		}
+	})
+}
+
+func TestEncoderRegistry_Decode(t *testing.T) {
+	t.Run("OK", func(t *testing.T) {
+		registry := NewEncoderRegistry()
+		encoder := encoder{
+			b: []byte("encoded value"),
+		}
+
+		err := registry.RegisterEncoder("myformat", encoder)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		b, err := registry.Encode("myformat", "some value")
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if string(b) != "encoded value" {
+			t.Fatalf("expected 'encoded value', got: %#v", string(b))
+		}
+	})
+
+	t.Run("EncoderNotFound", func(t *testing.T) {
+		registry := NewEncoderRegistry()
+
+		_, err := registry.Encode("myformat", "some value")
+		if err != ErrEncoderNotFound {
+			t.Fatalf("expected ErrEncoderNotFound, got: %v", err)
+		}
+	})
+}

internal/encoding/error.go

@@ -0,0 +1,7 @@
+package encoding
+
+type encodingError string
+
+func (e encodingError) Error() string {
+	return string(e)
+}