simpler fallback behavior (#189)

5 files changed, 109 insertions, 94 deletions

diff --git a/v2/go.mod b/v2/go.mod
index bd92c7c..e8cb75f 100644
--- a/v2/go.mod
+++ b/v2/go.mod
@@ -3,11 +3,7 @@ module github.com/nicksnyder/go-i18n/v2
 go 1.9
 
 require (
-	github.com/BurntSushi/toml v0.3.0
-	golang.org/x/crypto v0.0.0-20190506204251-e1dfcc566284 // indirect
-	golang.org/x/net v0.0.0-20190503192946-f4e77d36d62c // indirect
-	golang.org/x/sys v0.0.0-20190507160741-ecd444e8653b // indirect
+	github.com/BurntSushi/toml v0.3.1
 	golang.org/x/text v0.3.2
-	golang.org/x/tools v0.0.0-20190506145303-2d16b83fe98c // indirect
 	gopkg.in/yaml.v2 v2.2.1
 )
diff --git a/v2/go.sum b/v2/go.sum
index 96207c2..ce639e9 100644
--- a/v2/go.sum
+++ b/v2/go.sum
@@ -1,21 +1,10 @@
-github.com/BurntSushi/toml v0.3.0 h1:e1/Ivsx3Z0FVTV0NSOv/aVgbUWyQuzj7DDnFblkRvsY=
-github.com/BurntSushi/toml v0.3.0/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20190506204251-e1dfcc566284/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
-golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190503192946-f4e77d36d62c/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190507160741-ecd444e8653b/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/text v0.0.0-20171214130843-f21a4dfb5e38 h1:yr7ItWHARpqySNZjEh5mPMHrw3xPR9tMnomFZVcO1mQ=
-golang.org/x/text v0.0.0-20171214130843-f21a4dfb5e38/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/nicksnyder/go-i18n v1.10.1 h1:isfg77E/aCD7+0lD/D00ebR2MV5vgeQ276WYyDaCRQc=
 golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
-golang.org/x/tools v0.0.0-20190506145303-2d16b83fe98c/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.1 h1:mUhvW9EsL+naU5Q3cakzfE91YhliOondGd6ZrsDBHQE=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/v2/i18n/bundle.go b/v2/i18n/bundle.go
index 6c6f5ce..513c127 100644
--- a/v2/i18n/bundle.go
+++ b/v2/i18n/bundle.go
@@ -134,3 +134,11 @@ func (b *Bundle) addTag(tag language.Tag) {
 func (b *Bundle) LanguageTags() []language.Tag {
 	return b.tags
 }
+
+func (b *Bundle) getMessageTemplate(tag language.Tag, id string) *MessageTemplate {
+	templates := b.messageTemplates[tag]
+	if templates == nil {
+		return nil
+	}
+	return templates[id]
+}
diff --git a/v2/i18n/localizer.go b/v2/i18n/localizer.go
index 5d3b0df..17261e2 100644
--- a/v2/i18n/localizer.go
+++ b/v2/i18n/localizer.go
@@ -2,7 +2,6 @@ package i18n
 
 import (
 	"fmt"
-
 	"text/template"
 
 	"github.com/nicksnyder/go-i18n/v2/internal/plural"
@@ -74,11 +73,12 @@ func (e *invalidPluralCountErr) Error() string {
 
 // MessageNotFoundErr is returned from Localize when a message could not be found.
 type MessageNotFoundErr struct {
+	tag       language.Tag
 	messageID string
 }
 
 func (e *MessageNotFoundErr) Error() string {
-	return fmt.Sprintf("message %q not found", e.messageID)
+	return fmt.Sprintf("message %q not found in language %q", e.messageID, e.tag)
 }
 
 type pluralizeErr struct {
@@ -146,82 +146,62 @@ func (l *Localizer) LocalizeWithTag(lc *LocalizeConfig) (string, language.Tag, e
 		}
 	}
 
-	tag, template := l.getTemplate(messageID, lc.DefaultMessage)
+	tag, template, err := l.getMessageTemplate(messageID, lc.DefaultMessage)
 	if template == nil {
-		return "", language.Und, &MessageNotFoundErr{messageID: messageID}
+		return "", language.Und, err
 	}
 
 	pluralForm := l.pluralForm(tag, operands)
-	if pluralForm == plural.Invalid {
-		return "", language.Und, &pluralizeErr{messageID: messageID, tag: tag}
-	}
+	msg, err2 := template.Execute(pluralForm, templateData, lc.Funcs)
+	if err2 != nil {
+		if err == nil {
+			err = err2
+		}
 
-	msg, err := template.Execute(pluralForm, templateData, lc.Funcs)
-	if err != nil {
 		// Attempt to fallback to "Other" pluralization in case translations are incomplete.
 		if pluralForm != plural.Other {
-			msg2, err2 := template.Execute(plural.Other, templateData, lc.Funcs)
-			if err2 == nil {
-				return msg2, tag, err
+			msg2, err3 := template.Execute(plural.Other, templateData, lc.Funcs)
+			if err3 == nil {
+				msg = msg2
 			}
 		}
-		return "", language.Und, err
 	}
-	return msg, tag, nil
+	return msg, tag, err
 }
 
-func (l *Localizer) getTemplate(id string, defaultMessage *Message) (language.Tag, *MessageTemplate) {
-	// Fast path.
-	// Optimistically assume this message id is defined in each language.
-	fastTag, template := l.matchTemplate(id, defaultMessage, l.bundle.matcher, l.bundle.tags)
-	if template != nil {
-		return fastTag, template
+func (l *Localizer) getMessageTemplate(id string, defaultMessage *Message) (language.Tag, *MessageTemplate, error) {
+	_, i, _ := l.bundle.matcher.Match(l.tags...)
+	tag := l.bundle.tags[i]
+	mt := l.bundle.getMessageTemplate(tag, id)
+	if mt != nil {
+		return tag, mt, nil
 	}
 
-	if len(l.bundle.tags) <= 1 {
-		return l.bundle.defaultLanguage, nil
-	}
-
-	// Slow path.
-	// We didn't find a translation for the tag suggested by the default matcher
-	// so we need to create a new matcher that contains only the tags in the bundle
-	// that have this message.
-	foundTags := make([]language.Tag, 0, len(l.bundle.messageTemplates)+1)
-	foundTags = append(foundTags, l.bundle.defaultLanguage)
-
-	for t, templates := range l.bundle.messageTemplates {
-		template := templates[id]
-		if template == nil || template.Other == "" {
-			continue
+	if tag == l.bundle.defaultLanguage {
+		if defaultMessage == nil {
+			return language.Und, nil, &MessageNotFoundErr{tag: tag, messageID: id}
 		}
-		foundTags = append(foundTags, t)
+		return tag, NewMessageTemplate(defaultMessage), nil
 	}
 
-	return l.matchTemplate(id, defaultMessage, language.NewMatcher(foundTags), foundTags)
-}
-
-func (l *Localizer) matchTemplate(id string, defaultMessage *Message, matcher language.Matcher, tags []language.Tag) (language.Tag, *MessageTemplate) {
-	_, i, _ := matcher.Match(l.tags...)
-	tag := tags[i]
-	templates := l.bundle.messageTemplates[tag]
-	if templates != nil && templates[id] != nil {
-		return tag, templates[id]
+	// Fallback to default language in bundle.
+	mt = l.bundle.getMessageTemplate(l.bundle.defaultLanguage, id)
+	if mt != nil {
+		return l.bundle.defaultLanguage, mt, &MessageNotFoundErr{tag: tag, messageID: id}
 	}
-	if tag == l.bundle.defaultLanguage && defaultMessage != nil {
-		return tag, NewMessageTemplate(defaultMessage)
+
+	// Fallback to default message.
+	if defaultMessage == nil {
+		return language.Und, nil, &MessageNotFoundErr{tag: tag, messageID: id}
 	}
-	return tag, nil
+	return l.bundle.defaultLanguage, NewMessageTemplate(defaultMessage), &MessageNotFoundErr{tag: tag, messageID: id}
 }
 
 func (l *Localizer) pluralForm(tag language.Tag, operands *plural.Operands) plural.Form {
 	if operands == nil {
 		return plural.Other
 	}
-	pluralRule := l.bundle.pluralRules.Rule(tag)
-	if pluralRule == nil {
-		return plural.Invalid
-	}
-	return pluralRule.PluralFormFunc(operands)
+	return l.bundle.pluralRules.Rule(tag).PluralFormFunc(operands)
 }
 
 // MustLocalize is similar to Localize, except it panics if an error happens.
diff --git a/v2/i18n/localizer_test.go b/v2/i18n/localizer_test.go
index 4194914..3dedfb6 100644
--- a/v2/i18n/localizer_test.go
+++ b/v2/i18n/localizer_test.go
@@ -1,6 +1,7 @@
 package i18n
 
 import (
+	"fmt"
 	"reflect"
 	"testing"
 
@@ -52,28 +53,19 @@ func localizerTests() []localizerTest {
 			defaultLanguage:   language.English,
 			acceptLangs:       []string{"en"},
 			conf:              &LocalizeConfig{MessageID: "HelloWorld"},
-			expectedErr:       &MessageNotFoundErr{messageID: "HelloWorld"},
+			expectedErr:       &MessageNotFoundErr{tag: language.English, messageID: "HelloWorld"},
 			expectedLocalized: "",
 		},
 		{
 			name:            "empty translation without fallback",
 			defaultLanguage: language.English,
 			messages: map[language.Tag][]*Message{
-				language.Spanish: {{ID: "HelloWorld"}},
-			},
-			acceptLangs: []string{"es"},
-			conf:        &LocalizeConfig{MessageID: "HelloWorld"},
-			expectedErr: &MessageNotFoundErr{messageID: "HelloWorld"},
-		},
-		{
-			name:            "empty translation with fallback",
-			defaultLanguage: language.English,
-			messages: map[language.Tag][]*Message{
 				language.English: {{ID: "HelloWorld", Other: "Hello World!"}},
 				language.Spanish: {{ID: "HelloWorld"}},
 			},
 			acceptLangs:       []string{"es"},
 			conf:              &LocalizeConfig{MessageID: "HelloWorld"},
+			expectedErr:       &MessageNotFoundErr{tag: language.Spanish, messageID: "HelloWorld"},
 			expectedLocalized: "Hello World!",
 		},
 		{
@@ -84,26 +76,38 @@ func localizerTests() []localizerTest {
 			},
 			acceptLangs:       []string{"en"},
 			conf:              &LocalizeConfig{MessageID: "HelloWorld"},
-			expectedErr:       &MessageNotFoundErr{messageID: "HelloWorld"},
+			expectedErr:       &MessageNotFoundErr{tag: language.English, messageID: "HelloWorld"},
 			expectedLocalized: "",
 		},
 		{
-			name:              "missing translation from not default language",
+			name:              "missing translations from not default language",
 			defaultLanguage:   language.English,
 			acceptLangs:       []string{"es"},
 			conf:              &LocalizeConfig{MessageID: "HelloWorld"},
-			expectedErr:       &MessageNotFoundErr{messageID: "HelloWorld"},
+			expectedErr:       &MessageNotFoundErr{tag: language.English, messageID: "HelloWorld"},
+			expectedLocalized: "",
+		},
+		{
+			name:            "missing translation from not default language",
+			defaultLanguage: language.English,
+			messages: map[language.Tag][]*Message{
+				language.Spanish: {{ID: "SomethingElse", Other: "other"}},
+			},
+			acceptLangs:       []string{"es"},
+			conf:              &LocalizeConfig{MessageID: "HelloWorld"},
+			expectedErr:       &MessageNotFoundErr{tag: language.Spanish, messageID: "HelloWorld"},
 			expectedLocalized: "",
 		},
 		{
 			name:            "missing translation not default language with other translation",
 			defaultLanguage: language.English,
 			messages: map[language.Tag][]*Message{
-				language.French: {{ID: "HelloWorld", Other: "other"}},
+				language.French:  {{ID: "HelloWorld", Other: "other"}},
+				language.Spanish: {{ID: "SomethingElse", Other: "other"}},
 			},
 			acceptLangs:       []string{"es"},
 			conf:              &LocalizeConfig{MessageID: "HelloWorld"},
-			expectedErr:       &MessageNotFoundErr{messageID: "HelloWorld"},
+			expectedErr:       &MessageNotFoundErr{tag: language.Spanish, messageID: "HelloWorld"},
 			expectedLocalized: "",
 		},
 		{
@@ -513,7 +517,7 @@ func localizerTests() []localizerTest {
 			expectedLocalized: "Nick has 2.5 cats",
 		},
 		{
-			name:            "test slow path",
+			name:            "no fallback",
 			defaultLanguage: language.Spanish,
 			messages: map[language.Tag][]*Message{
 				language.English: {{
@@ -529,10 +533,10 @@ func localizerTests() []localizerTest {
 			conf: &LocalizeConfig{
 				MessageID: "Hello",
 			},
-			expectedLocalized: "Hello!",
+			expectedErr: &MessageNotFoundErr{tag: language.AmericanEnglish, messageID: "Hello"},
 		},
 		{
-			name:            "test slow path default message",
+			name:            "fallback default message",
 			defaultLanguage: language.Spanish,
 			messages: map[language.Tag][]*Message{
 				language.English: {{
@@ -552,9 +556,10 @@ func localizerTests() []localizerTest {
 				},
 			},
 			expectedLocalized: "Hola!",
+			expectedErr:       &MessageNotFoundErr{tag: language.AmericanEnglish, messageID: "Hello"},
 		},
 		{
-			name:            "test slow path no message",
+			name:            "no fallback default message",
 			defaultLanguage: language.Spanish,
 			messages: map[language.Tag][]*Message{
 				language.English: {{
@@ -570,7 +575,7 @@ func localizerTests() []localizerTest {
 			conf: &LocalizeConfig{
 				MessageID: "Hello",
 			},
-			expectedErr: &MessageNotFoundErr{messageID: "Hello"},
+			expectedErr: &MessageNotFoundErr{tag: language.AmericanEnglish, messageID: "Hello"},
 		},
 	}
 }
@@ -625,3 +630,40 @@ func BenchmarkLocalizer_Localize(b *testing.B) {
 		})
 	}
 }
+
+func TestMessageNotFoundError(t *testing.T) {
+	actual := (&MessageNotFoundErr{tag: language.AmericanEnglish, messageID: "hello"}).Error()
+	expected := `message "hello" not found in language "en-US"`
+	if actual != expected {
+		t.Fatalf("expected %q; got %q", expected, actual)
+	}
+}
+
+func TestMessageIDMismatchError(t *testing.T) {
+	actual := (&messageIDMismatchErr{messageID: "hello", defaultMessageID: "world"}).Error()
+	expected := `message id "hello" does not match default message id "world"`
+	if actual != expected {
+		t.Fatalf("expected %q; got %q", expected, actual)
+	}
+}
+
+func TestInvalidPluralCountError(t *testing.T) {
+	actual := (&invalidPluralCountErr{messageID: "hello", pluralCount: "blah", err: fmt.Errorf("error")}).Error()
+	expected := `invalid plural count "blah" for message id "hello": error`
+	if actual != expected {
+		t.Fatalf("expected %q; got %q", expected, actual)
+	}
+}
+
+func TestMustLocalize(t *testing.T) {
+	defer func() {
+		if recover() == nil {
+			t.Fatalf("MustLocalize did not panic")
+		}
+	}()
+	bundle := NewBundle(language.English)
+	localizer := NewLocalizer(bundle)
+	localizer.MustLocalize(&LocalizeConfig{
+		MessageID: "hello",
+	})
+}