Allow locale to be a list

This allows an arbitrary-length of fallback chain for the user-requested
locale.

Author: benjaminwinger

README.md

@@ -105,6 +105,8 @@ When a value is not found, the lib has several fallback mechanisms:
 
 The parents of a locale are found by splitting the locale by its hyphens. Other separation characters (spaces, underscores, etc) are not supported.
 
+You can also pass a list of locales to `setLocale` to provide multiple options before the fallback locale is used.
+
 Using language files
 ====================
 

i18n/init.lua

@@ -64,7 +64,11 @@ local function assertFunctionOrNil(functionName, paramName, value)
 end
 
 local function defaultPluralizeFunction(count)
-  return plural.get(variants.root(i18n.getLocale()), count)
+  local locale = i18n.getLocale()
+  if type(locale) == "table" then
+      locale = locale[1]
+  end
+  return plural.get(variants.root(locale), count)
 end
 
 local function pluralize(t, data)
@@ -110,6 +114,13 @@ local function localizedTranslate(key, loc, data)
   return treatNode(node, data)
 end
 
+local function concat(arr1, arr2)
+  for i = 1, #arr2 do
+    arr1[#arr1 + i] = arr2[i]
+  end
+  return arr1
+end
+
 -- public interface
 
 function i18n.set(key, value)
@@ -133,9 +144,19 @@ function i18n.translate(key, data)
   assertPresent('translate', 'key', key)
 
   data = data or {}
-  local usedLocale = data.locale or locale
+  local usedLocales
+  local locales = locale
+  if type(locale) == 'string' then
+    locales = {locale}
+  end
+  if isPresent(data.locale) then
+    usedLocales = concat({data.locale}, locales)
+  else
+    usedLocales = concat({}, locales)
+  end
 
-  local fallbacks = variants.fallbacks(usedLocale, fallbackLocale)
+  table.insert(usedLocales, fallbackLocale)
+  local fallbacks = variants.fallbacks(usedLocales)
   for i=1, #fallbacks do
     local value = localizedTranslate(key, fallbacks[i], data)
     if value then return value end
@@ -145,7 +166,7 @@ function i18n.translate(key, data)
 end
 
 function i18n.setLocale(newLocale, newPluralizeFunction)
-  assertPresent('setLocale', 'newLocale', newLocale)
+  assertPresentOrTable('setLocale', 'newLocale', newLocale)
   assertFunctionOrNil('setLocale', 'newPluralizeFunction', newPluralizeFunction)
   locale = newLocale
   pluralizeFunction = newPluralizeFunction or defaultPluralizeFunction

i18n/variants.lua

@@ -31,19 +31,18 @@ function variants.root(locale)
   return locale:match("[^%-]+")
 end
 
-function variants.fallbacks(locale, fallbackLocale)
-  if locale == fallbackLocale or
-     variants.isParent(fallbackLocale, locale) then
-     return variants.ancestry(locale)
+function variants.fallbacks(locales)
+  local seen = {}
+  local ancestry, length = {}, 0
+  for index, value in ipairs(locales) do
+      if not seen[value] then
+          seen[value] = true
+          local ancestry1, length1 = variants.ancestry(value)
+          ancestry, length = concat(ancestry, length, ancestry1, length1)
+      end
   end
-  if variants.isParent(locale, fallbackLocale) then
-    return variants.ancestry(fallbackLocale)
-  end
-
-  local ancestry1, length1 = variants.ancestry(locale)
-  local ancestry2, length2 = variants.ancestry(fallbackLocale)
 
-  return concat(ancestry1, length1, ancestry2, length2)
+  return ancestry, length
 end
 
 return variants