New encoding layer

encoding.go

@@ -0,0 +1,226 @@
+package viper
+
+import (
+	"errors"
+	"strings"
+	"sync"
+
+	"github.com/spf13/viper/internal/encoding/dotenv"
+	"github.com/spf13/viper/internal/encoding/hcl"
+	"github.com/spf13/viper/internal/encoding/ini"
+	"github.com/spf13/viper/internal/encoding/javaproperties"
+	"github.com/spf13/viper/internal/encoding/json"
+	"github.com/spf13/viper/internal/encoding/toml"
+	"github.com/spf13/viper/internal/encoding/yaml"
+)
+
+// Encoder encodes Viper's internal data structures into a byte representation.
+// It's primarily used for encoding a map[string]any into a file format.
+type Encoder interface {
+	Encode(v map[string]any) ([]byte, error)
+}
+
+// Decoder decodes the contents of a byte slice into Viper's internal data structures.
+// It's primarily used for decoding contents of a file into a map[string]any.
+type Decoder interface {
+	Decode(b []byte, v map[string]any) error
+}
+
+// Codec combines [Encoder] and [Decoder] interfaces.
+type Codec interface {
+	Encoder
+	Decoder
+}
+
+// TODO: consider adding specific errors for not found scenarios
+
+// EncoderRegistry returns an [Encoder] for a given format.
+//
+// Format is case-insensitive.
+//
+// [EncoderRegistry] returns an error if no [Encoder] is registered for the format.
+type EncoderRegistry interface {
+	Encoder(format string) (Encoder, error)
+}
+
+// DecoderRegistry returns an [Decoder] for a given format.
+//
+// Format is case-insensitive.
+//
+// [DecoderRegistry] returns an error if no [Decoder] is registered for the format.
+type DecoderRegistry interface {
+	Decoder(format string) (Decoder, error)
+}
+
+// [CodecRegistry] combines [EncoderRegistry] and [DecoderRegistry] interfaces.
+type CodecRegistry interface {
+	EncoderRegistry
+	DecoderRegistry
+}
+
+// WithEncoderRegistry sets a custom [EncoderRegistry].
+func WithEncoderRegistry(r EncoderRegistry) Option {
+	return optionFunc(func(v *Viper) {
+		v.encoderRegistry = r
+	})
+}
+
+// WithDecoderRegistry sets a custom [DecoderRegistry].
+func WithDecoderRegistry(r DecoderRegistry) Option {
+	return optionFunc(func(v *Viper) {
+		v.decoderRegistry = r
+	})
+}
+
+// WithCodecRegistry sets a custom [EncoderRegistry] and [DecoderRegistry].
+func WithCodecRegistry(r CodecRegistry) Option {
+	return optionFunc(func(v *Viper) {
+		v.encoderRegistry = r
+		v.decoderRegistry = r
+	})
+}
+
+type codecRegistry struct {
+	v *Viper
+}
+
+func (r codecRegistry) Encoder(format string) (Encoder, error) {
+	encoder, ok := r.codec(format)
+	if !ok {
+		return nil, errors.New("encoder not found for this format")
+	}
+
+	return encoder, nil
+}
+
+func (r codecRegistry) Decoder(format string) (Decoder, error) {
+	decoder, ok := r.codec(format)
+	if !ok {
+		return nil, errors.New("decoder not found for this format")
+	}
+
+	return decoder, nil
+}
+
+func (r codecRegistry) codec(format string) (Codec, bool) {
+	switch strings.ToLower(format) {
+	case "yaml", "yml":
+		return yaml.Codec{}, true
+
+	case "json":
+		return json.Codec{}, true
+
+	case "toml":
+		return toml.Codec{}, true
+
+	case "hcl", "tfvars":
+		return hcl.Codec{}, true
+
+	case "ini":
+		return ini.Codec{
+			KeyDelimiter: r.v.keyDelim,
+			LoadOptions:  r.v.iniLoadOptions,
+		}, true
+
+	case "properties", "props", "prop": // Note: This breaks writing a properties file.
+		return &javaproperties.Codec{
+			KeyDelimiter: v.keyDelim,
+		}, true
+
+	case "dotenv", "env":
+		return &dotenv.Codec{}, true
+	}
+
+	return nil, false
+}
+
+// DefaultCodecRegistry is a simple implementation of [CodecRegistry] that allows registering custom [Codec]s.
+type DefaultCodecRegistry struct {
+	codecs map[string]Codec
+
+	mu   sync.RWMutex
+	once sync.Once
+}
+
+// NewCodecRegistry returns a new [CodecRegistry], ready to accept custom [Codec]s.
+func NewCodecRegistry() *DefaultCodecRegistry {
+	r := &DefaultCodecRegistry{}
+
+	r.init()
+
+	return r
+}
+
+func (r *DefaultCodecRegistry) init() {
+	r.once.Do(func() {
+		r.codecs = map[string]Codec{}
+	})
+}
+
+// RegisterCodec registers a custom [Codec].
+//
+// Format is case-insensitive.
+func (r *DefaultCodecRegistry) RegisterCodec(format string, codec Codec) error {
+	r.init()
+
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	r.codecs[strings.ToLower(format)] = codec
+
+	return nil
+}
+
+// Encoder implements the [EncoderRegistry] interface.
+//
+// Format is case-insensitive.
+func (r *DefaultCodecRegistry) Encoder(format string) (Encoder, error) {
+	encoder, ok := r.codec(format)
+	if !ok {
+		return nil, errors.New("encoder not found for this format")
+	}
+
+	return encoder, nil
+}
+
+// Decoder implements the [DecoderRegistry] interface.
+//
+// Format is case-insensitive.
+func (r *DefaultCodecRegistry) Decoder(format string) (Decoder, error) {
+	decoder, ok := r.codec(format)
+	if !ok {
+		return nil, errors.New("decoder not found for this format")
+	}
+
+	return decoder, nil
+}
+
+func (r *DefaultCodecRegistry) codec(format string) (Codec, bool) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	format = strings.ToLower(format)
+
+	if r.codecs != nil {
+		codec, ok := r.codecs[format]
+		if ok {
+			return codec, true
+		}
+	}
+
+	switch format {
+	case "yaml", "yml":
+		return yaml.Codec{}, true
+
+	case "json":
+		return json.Codec{}, true
+
+	case "toml":
+		return toml.Codec{}, true
+
+	case "dotenv", "env":
+		return &dotenv.Codec{}, true
+	}
+
+	return nil, false
+}

encoding_test.go

@@ -0,0 +1,105 @@
+package viper
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type codec struct{}
+
+func (codec) Encode(_ map[string]any) ([]byte, error) {
+	return nil, nil
+}
+
+func (codec) Decode(_ []byte, _ map[string]any) error {
+	return nil
+}
+
+func TestDefaultCodecRegistry(t *testing.T) {
+	t.Run("OK", func(t *testing.T) {
+		registry := NewCodecRegistry()
+
+		c := codec{}
+
+		err := registry.RegisterCodec("myformat", c)
+		require.NoError(t, err)
+
+		encoder, err := registry.Encoder("myformat")
+		require.NoError(t, err)
+
+		assert.Equal(t, c, encoder)
+
+		decoder, err := registry.Decoder("myformat")
+		require.NoError(t, err)
+
+		assert.Equal(t, c, decoder)
+	})
+
+	t.Run("CodecNotFound", func(t *testing.T) {
+		registry := NewCodecRegistry()
+
+		_, err := registry.Encoder("myformat")
+		require.Error(t, err)
+
+		_, err = registry.Decoder("myformat")
+		require.Error(t, err)
+	})
+
+	t.Run("FormatIsCaseInsensitive", func(t *testing.T) {
+		registry := NewCodecRegistry()
+
+		c := codec{}
+
+		err := registry.RegisterCodec("MYFORMAT", c)
+		require.NoError(t, err)
+
+		{
+			encoder, err := registry.Encoder("myformat")
+			require.NoError(t, err)
+
+			assert.Equal(t, c, encoder)
+		}
+
+		{
+			encoder, err := registry.Encoder("MYFORMAT")
+			require.NoError(t, err)
+
+			assert.Equal(t, c, encoder)
+		}
+
+		{
+			decoder, err := registry.Decoder("myformat")
+			require.NoError(t, err)
+
+			assert.Equal(t, c, decoder)
+		}
+
+		{
+			decoder, err := registry.Decoder("MYFORMAT")
+			require.NoError(t, err)
+
+			assert.Equal(t, c, decoder)
+		}
+	})
+
+	t.Run("OverrideDefault", func(t *testing.T) {
+		registry := NewCodecRegistry()
+
+		c := codec{}
+
+		err := registry.RegisterCodec("yaml", c)
+		require.NoError(t, err)
+
+		encoder, err := registry.Encoder("yaml")
+		require.NoError(t, err)
+
+		assert.Equal(t, c, encoder)
+
+		decoder, err := registry.Decoder("yaml")
+		require.NoError(t, err)
+
+		assert.Equal(t, c, decoder)
+	})
+}