Determine language tag and order of UI components.

This patch changes BuildComponents() function to read the UI language
tag and determine the language tag that should be stored with the
address data. The function also chooses between the default and the
Latin order of UI components in the address form.

A language tag is a sequence of one of more subtags separated by
hyphen ("-"). All characters are in ASCII and case-insensitive. The
first subtag is the base language, for example "zh". The first
four-character subtag is the script, for example "Hans".

1 files changed, 60 insertions, 4 deletions

diff --git a/cpp/src/address_ui.cc b/cpp/src/address_ui.cc
index 15f3c61..0eb28fc 100644
--- a/cpp/src/address_ui.cc
+++ b/cpp/src/address_ui.cc
@@ -18,12 +18,15 @@
 #include <libaddressinput/address_ui_component.h>
 #include <libaddressinput/localization.h>
 
+#include <cassert>
+#include <cstddef>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "address_field_util.h"
 #include "grit.h"
+#include "language.h"
 #include "messages.h"
 #include "region_data_constants.h"
 #include "rule.h"
@@ -33,6 +36,41 @@ namespace addressinput {
 
 namespace {
 
+Language ChooseBestAddressLanguage(
+    const std::vector<Language>& available_languages,
+    bool has_latin_format,
+    const Language& ui_language) {
+  if (available_languages.empty()) {
+    return ui_language;
+  }
+
+  if (ui_language.tag.empty()) {
+    return available_languages.front();
+  }
+
+  // The conventionally formatted BCP 47 Latin script with a preceding subtag
+  // separator.
+  static const char kLatinScriptSuffix[] = "-Latn";
+  Language latin_script_language(
+      available_languages.front().base + kLatinScriptSuffix);
+  if (has_latin_format && ui_language.has_latin_script) {
+    return latin_script_language;
+  }
+
+  for (std::vector<Language>::const_iterator
+       available_lang_it = available_languages.begin();
+       available_lang_it != available_languages.end(); ++available_lang_it) {
+    // Base language comparison works because no region supports the same base
+    // language with different scripts, for now. For example, no region supports
+    // "zh-Hant" and "zh-Hans" at the same time.
+    if (ui_language.base == available_lang_it->base) {
+      return *available_lang_it;
+    }
+  }
+
+  return has_latin_format ? latin_script_language : available_languages.front();
+}
+
 int GetMessageIdForField(AddressField field,
                          int admin_area_name_message_id,
                          int postal_code_name_message_id) {
@@ -71,7 +109,9 @@ const std::vector<std::string>& GetRegionCodes() {
 
 std::vector<AddressUiComponent> BuildComponents(
     const std::string& region_code,
-    const Localization& localization) {
+    const Localization& localization,
+    std::string* best_address_language_tag) {
+  assert(best_address_language_tag != NULL);
   std::vector<AddressUiComponent> result;
 
   Rule rule;
@@ -81,15 +121,31 @@ std::vector<AddressUiComponent> BuildComponents(
     return result;
   }
 
+  std::vector<Language> available_languages;
+  for (std::vector<std::string>::const_iterator language_tag_it =
+       rule.GetLanguages().begin();
+       language_tag_it != rule.GetLanguages().end(); ++language_tag_it) {
+    available_languages.push_back(Language(*language_tag_it));
+  }
+
+  const Language& best_address_language = ChooseBestAddressLanguage(
+      available_languages, !rule.GetLatinFormat().empty(),
+      Language(localization.GetLanguage()));
+  *best_address_language_tag = best_address_language.tag;
+
+  const std::vector<AddressField>& format =
+      !rule.GetLatinFormat().empty() &&
+      best_address_language.has_latin_script
+          ? rule.GetLatinFormat() : rule.GetFormat();
+
   // For avoiding showing an input field twice, when the field is displayed
   // twice on an envelope.
   std::set<AddressField> fields;
 
   bool previous_field_is_newline = true;
   bool next_field_is_newline = true;
-  for (std::vector<AddressField>::const_iterator field_it =
-       rule.GetFormat().begin();
-       field_it != rule.GetFormat().end(); ++field_it) {
+  for (std::vector<AddressField>::const_iterator field_it = format.begin();
+       field_it != format.end(); ++field_it) {
     if (IsNewline(*field_it)) {
       previous_field_is_newline = true;
       continue;