Detect translations in low-level structs

This patch adds .IsTranslated(), .IsTranslatedN() and related functions
to following objects:
- Translation
- Domain

This makes it possible to detect whether a string is translatable or not
during runtime.

domain.go

@@ -402,7 +402,51 @@ func (do *Domain) GetNC(str, plural string, n int, ctx string, vars ...interface
 	return Printf(plural, vars...)
 }
 
-//GetTranslations returns a copy of every translation in the domain. It does not support contexts.
+// IsTranslated reports whether a string is translated
+func (do *Domain) IsTranslated(str string) bool {
+	return do.IsTranslatedN(str, 0)
+}
+
+// IsTranslatedN reports whether a plural string is translated
+func (do *Domain) IsTranslatedN(str string, n int) bool {
+	do.trMutex.RLock()
+	defer do.trMutex.RUnlock()
+
+	if do.translations == nil {
+		return false
+	}
+	tr, ok := do.translations[str]
+	if !ok {
+		return false
+	}
+	return tr.IsTranslatedN(n)
+}
+
+// IsTranslatedC reports whether a context string is translated
+func (do *Domain) IsTranslatedC(str, ctx string) bool {
+	return do.IsTranslatedNC(str, 0, ctx)
+}
+
+// IsTranslatedNC reports whether a plural context string is translated
+func (do *Domain) IsTranslatedNC(str string, n int, ctx string) bool {
+	do.trMutex.RLock()
+	defer do.trMutex.RUnlock()
+
+	if do.contextTranslations == nil {
+		return false
+	}
+	translations, ok := do.contextTranslations[ctx]
+	if !ok {
+		return false
+	}
+	tr, ok := translations[str]
+	if !ok {
+		return false
+	}
+	return tr.IsTranslatedN(n)
+}
+
+// GetTranslations returns a copy of every translation in the domain. It does not support contexts.
 func (do *Domain) GetTranslations() map[string]*Translation {
 	all := make(map[string]*Translation, len(do.translations))
 

domain_test.go

@@ -6,6 +6,7 @@ import (
 
 const (
 	enUSFixture = "fixtures/en_US/default.po"
+	arFixture   = "fixtures/ar/categories.po"
 )
 
 //since both Po and Mo just pass-through to Domain for MarshalBinary and UnmarshalBinary, test it here
@@ -72,6 +73,58 @@ func TestDomain_GetTranslations(t *testing.T) {
 	}
 }
 
+func TestDomain_IsTranslated(t *testing.T) {
+	englishPo := NewPo()
+	englishPo.ParseFile(enUSFixture)
+	english := englishPo.GetDomain()
+
+	// singular and plural
+	if english.IsTranslated("My Text") {
+		t.Error("'My text' should be reported as translated.")
+	}
+	if english.IsTranslated("Another string") {
+		t.Error("'Another string' should be reported as not translated.")
+	}
+	if !english.IsTranslatedN("Empty plural form singular", 0) {
+		t.Error("'Empty plural form singular' should be reported as translated for n=0.")
+	}
+	if english.IsTranslatedN("Empty plural form singular", 1) {
+		t.Error("'Empty plural form singular' should be reported as not translated for n=1.")
+	}
+
+	arabicPo := NewPo()
+	arabicPo.ParseFile(arFixture)
+	arabic := arabicPo.GetDomain()
+
+	// multiple plurals
+	if !arabic.IsTranslated("Load %d more document") {
+		t.Error("Arabic singular should be reported as translated.")
+	}
+	if !arabic.IsTranslatedN("Load %d more document", 0) {
+		t.Error("Arabic plural should be reported as translated for n=0.")
+	}
+	if !arabic.IsTranslatedN("Load %d more document", 1) {
+		t.Error("Arabic plural should be reported as translated for n=1.")
+	}
+	if !arabic.IsTranslatedN("Load %d more document", 5) {
+		t.Error("Arabic plural should be reported as translated for n=5.")
+	}
+	if arabic.IsTranslatedN("Load %d more document", 6) {
+		t.Error("Arabic plural should be reported as not translated for n=6.")
+	}
+
+	// context
+	if !english.IsTranslatedC("One with var: %s", "Ctx") {
+		t.Error("Context singular should be reported as translated.")
+	}
+	if !english.IsTranslatedNC("One with var: %s", 0, "Ctx") {
+		t.Error("Context plural should be reported as translated for n=0")
+	}
+	if english.IsTranslatedNC("One with var: %s", 2, "Ctx") {
+		t.Error("Context plural should be reported as translated for n=2")
+	}
+}
+
 func TestDomain_CheckExportFormatting(t *testing.T) {
 	po := NewPo()
 	po.Set("myid", "test string\nwith \"newline\"")

translation.go

@@ -78,3 +78,15 @@ func (t *Translation) GetN(n int) string {
 	// Return untranslated plural by default
 	return t.PluralID
 }
+
+// IsTranslated reports whether a string is translated
+func (t *Translation) IsTranslated() bool {
+	tr, ok := t.Trs[0]
+	return tr != "" && ok
+}
+
+// IsTranslatedN reports whether a plural string is translated
+func (t *Translation) IsTranslatedN(n int) bool {
+	tr, ok := t.Trs[n]
+	return tr != "" && ok
+}