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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "util/i18n/locale.h"
     18 
     19 #include "util/strings/split.h"
     20 
     21 namespace libtextclassifier2 {
     22 
     23 namespace {
     24 
     25 bool CheckLanguage(StringPiece language) {
     26   if (language.size() != 2 && language.size() != 3) {
     27     return false;
     28   }
     29 
     30   // Needs to be all lowercase.
     31   for (int i = 0; i < language.size(); ++i) {
     32     if (!std::islower(language[i])) {
     33       return false;
     34     }
     35   }
     36 
     37   return true;
     38 }
     39 
     40 bool CheckScript(StringPiece script) {
     41   if (script.size() != 4) {
     42     return false;
     43   }
     44 
     45   if (!std::isupper(script[0])) {
     46     return false;
     47   }
     48 
     49   // Needs to be all lowercase.
     50   for (int i = 1; i < script.size(); ++i) {
     51     if (!std::islower(script[i])) {
     52       return false;
     53     }
     54   }
     55 
     56   return true;
     57 }
     58 
     59 bool CheckRegion(StringPiece region) {
     60   if (region.size() == 2) {
     61     return std::isupper(region[0]) && std::isupper(region[1]);
     62   } else if (region.size() == 3) {
     63     return std::isdigit(region[0]) && std::isdigit(region[1]) &&
     64            std::isdigit(region[2]);
     65   } else {
     66     return false;
     67   }
     68 }
     69 
     70 }  // namespace
     71 
     72 Locale Locale::FromBCP47(const std::string& locale_tag) {
     73   std::vector<StringPiece> parts = strings::Split(locale_tag, '-');
     74   if (parts.empty()) {
     75     return Locale::Invalid();
     76   }
     77 
     78   auto parts_it = parts.begin();
     79   StringPiece language = *parts_it;
     80   if (!CheckLanguage(language)) {
     81     return Locale::Invalid();
     82   }
     83   ++parts_it;
     84 
     85   StringPiece script;
     86   if (parts_it != parts.end()) {
     87     script = *parts_it;
     88     if (!CheckScript(script)) {
     89       script = "";
     90     } else {
     91       ++parts_it;
     92     }
     93   }
     94 
     95   StringPiece region;
     96   if (parts_it != parts.end()) {
     97     region = *parts_it;
     98     if (!CheckRegion(region)) {
     99       region = "";
    100     } else {
    101       ++parts_it;
    102     }
    103   }
    104 
    105   // NOTE: We don't parse the rest of the BCP47 tag here even if specified.
    106 
    107   return Locale(language.ToString(), script.ToString(), region.ToString());
    108 }
    109 
    110 }  // namespace libtextclassifier2
    111