Add singleton support for ease of use

README.md

@@ -74,6 +74,46 @@ localizer.Localize(&i18n.LocalizeConfig{
 }) // Nick has 2 cats.
 ```
 
+
+Use the singleton to ease usage.
+
+```go
+bundle := i18n.NewBundle(language.English)
+bundle.RegisterUnmarshalFunc("toml", toml.Unmarshal)
+bundle.MustParseMessageFileBytes([]byte(`
+HelloCookie = "Hello Cookie!"
+
+[Cookies]
+one = "I have {{.PluralCount}} cookie!"
+other = "I have {{.PluralCount}} cookies!"
+
+[CookiesX]
+other = "I have {{.X}} cookies!"
+
+[CookiesX2]
+one = "I have {{.PluralCount}} {{.X}} cookie!"
+other = "I have {{.PluralCount}} {{.X}} cookies!"
+
+[CookiesABC]
+other = "I have {{.A}} cookies in my {{.B}} back at {{.C}}!"
+
+[CookiesABC2]
+other = "I have {{.PluralCount}} {{.A}} cookies in my {{.B}} back at {{.C}}!"
+`), "en.toml")
+
+localizer := i18n.NewLocalizer(bundle, "en-US")
+i18n.SetLocalizerInstance(localizer)
+i18n.SetABCParams([]string{"A", "B", "C"})
+
+i18n.Localize("HelloCookie") // "Hello Cookie!"
+i18n.LocalizePlural("Cookies", 4) // "I have 4 cookies!"
+i18n.LocalizeTemplateSingle("CookiesX", "X", "chocolate") // "I have chocolate cookies!"
+i18n.LocalizeTemplateSingleWithPlural("CookiesX2", 4, "X", "chocolate") // "I have 4 chocolate cookies!"
+i18n.LocalizeTemplateX("CookiesABC", "chocolate", "basket", "home") // "I have chocolate cookies in my basket back at home!"
+i18n.LocalizeTemplateXPlural("CookiesABC2", 400, "chocolate", "basket", "home") // "I have 400 chocolate cookies in my basket back at home!"
+```
+
+
 ## Command goi18n
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/nicksnyder/go-i18n/v2/goi18n.svg)](https://pkg.go.dev/github.com/nicksnyder/go-i18n/v2/goi18n)

i18n/singleton.go

@@ -0,0 +1,196 @@
+package i18n
+
+import (
+	"sync"
+)
+
+var (
+	localizerSingletonOnce sync.Once
+	localizerInstance      *Localizer
+	localizerMutex         = &sync.Mutex{}
+
+	notLocalized string
+
+	abcParams []string
+)
+
+func GetLocalizerInstance() *Localizer {
+	localizerSingletonOnce.Do(func() {
+		if localizerInstance == nil {
+			localizerInstance = new(Localizer)
+		}
+	})
+	return localizerInstance
+}
+
+// SetLocalizerInstance must be run before using `GetLocalizerInstance()` in a multi-threading manner.
+func SetLocalizerInstance(l *Localizer) {
+	if localizerMutex != nil {
+		localizerMutex.Lock()
+		defer localizerMutex.Unlock()
+	}
+
+	localizerInstance = l
+}
+
+// SetUseNotLocalizedInfo is optional.
+func SetUseNotLocalizedInfo(use bool) {
+	if use {
+		notLocalized = Localize("NotLocalized")
+	} else {
+		notLocalized = ""
+	}
+}
+
+func ResetSingletonContext() {
+	SetUseNotLocalizedInfo(false)
+	SetABCParams(nil)
+}
+
+// Localize loads localization for static text.
+//
+// Use only if you called SetLocalizerInstance().
+func Localize(id string) string {
+	localizerMutex.Lock()
+	defer localizerMutex.Unlock()
+
+	localization, err := GetLocalizerInstance().Localize(&LocalizeConfig{MessageID: id})
+	if err != nil {
+		return notLocalized
+	}
+	return localization
+}
+
+// LocalizePlural loads localization for text with plural count.
+//
+// Use only if you called SetLocalizerInstance().
+func LocalizePlural(id string, count int) string {
+	localizerMutex.Lock()
+	defer localizerMutex.Unlock()
+
+	localization, err := GetLocalizerInstance().Localize(&LocalizeConfig{
+		MessageID:   id,
+		PluralCount: count,
+	})
+	if err != nil {
+		return notLocalized
+	}
+	return localization
+}
+
+// LocalizeTemplate loads localization using template.
+//
+// Use only if you called SetLocalizerInstance().
+func LocalizeTemplate(id string, templateData map[string]any) string {
+	localizerMutex.Lock()
+	defer localizerMutex.Unlock()
+
+	localization, err := GetLocalizerInstance().Localize(&LocalizeConfig{
+		MessageID:    id,
+		TemplateData: templateData,
+	})
+	if err != nil {
+		return notLocalized
+	}
+	return localization
+}
+
+// LocalizeTemplateSingle loads localization using template which has only one key-value pair.
+//
+// Use only if you called SetLocalizerInstance().
+func LocalizeTemplateSingle(id, singleKey string, singleValue any) string {
+	localizerMutex.Lock()
+	defer localizerMutex.Unlock()
+
+	localization, err := GetLocalizerInstance().Localize(&LocalizeConfig{
+		MessageID:    id,
+		TemplateData: map[string]any{singleKey: singleValue},
+	})
+	if err != nil {
+		return notLocalized
+	}
+	return localization
+}
+
+// LocalizeTemplateSingleWithPlural loads localization using template
+// which has only one key-value pair for text with plural count.
+//
+// Use only if you called SetLocalizerInstance().
+func LocalizeTemplateSingleWithPlural(id string, count int, key string, value any) string {
+	localizerMutex.Lock()
+	defer localizerMutex.Unlock()
+
+	localization, err := GetLocalizerInstance().Localize(&LocalizeConfig{
+		MessageID: id,
+		TemplateData: map[string]any{
+			key:           value,
+			"PluralCount": count,
+		},
+		PluralCount: count,
+	})
+	if err != nil {
+		return notLocalized
+	}
+	return localization
+}
+
+// SetABCParams defines the default keys for TemplateData when using an x-func.
+// Defining a non-empty slice unlocks the following funcs:
+//   - LocalizeTemplateX()
+//   - LocalizeTemplateXPlural()
+//
+// Use only if you called SetLocalizerInstance().
+func SetABCParams(abc []string) {
+	abcParams = abc
+}
+
+func buildABCTemplateData(values []any) map[string]any {
+	if len(values) > len(abcParams) {
+		return nil
+	}
+
+	data := map[string]any{}
+	for i, val := range values {
+		data[abcParams[i]] = val
+	}
+	return data
+}
+
+// LocalizeTemplateX assigns the given values to the TemplateData keys
+// as per the key definitions you set by calling SetABCParams().
+//
+// Use only if you called SetLocalizerInstance().
+func LocalizeTemplateX(id string, values ...any) string {
+	localizerMutex.Lock()
+	defer localizerMutex.Unlock()
+
+	localization, err := GetLocalizerInstance().Localize(&LocalizeConfig{
+		MessageID:    id,
+		TemplateData: buildABCTemplateData(values),
+	})
+	if err != nil {
+		return notLocalized
+	}
+	return localization
+}
+
+// LocalizeTemplateXPlural assigns the given values to the TemplateData keys
+// as per the key definitions you set by calling SetABCParams() with plural count.
+//
+// Use only if you called SetLocalizerInstance().
+func LocalizeTemplateXPlural(id string, count int, values ...any) string {
+	localizerMutex.Lock()
+	defer localizerMutex.Unlock()
+
+	data := buildABCTemplateData(values)
+	data["PluralCount"] = count
+
+	localization, err := GetLocalizerInstance().Localize(&LocalizeConfig{
+		MessageID:    id,
+		TemplateData: data,
+	})
+	if err != nil {
+		return notLocalized
+	}
+	return localization
+}