1 /* 2 * Copyright (C) 2018 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 "lang_id/features/relevant-script-feature.h" 18 19 #include <string> 20 21 #include "lang_id/common/fel/feature-types.h" 22 #include "lang_id/common/fel/task-context.h" 23 #include "lang_id/common/fel/workspace.h" 24 #include "lang_id/common/lite_base/logging.h" 25 #include "lang_id/common/utf8.h" 26 #include "lang_id/script/script-detector.h" 27 28 namespace libtextclassifier3 { 29 namespace mobile { 30 namespace lang_id { 31 32 bool RelevantScriptFeature::Setup(TaskContext *context) { 33 string script_detector_name = GetParameter( 34 "script_detector_name", /* default_value = */ "tiny-script-detector"); 35 36 // We don't use absl::WrapUnique, nor the rest of absl, see http://b/71873194 37 script_detector_.reset(ScriptDetector::Create(script_detector_name)); 38 if (script_detector_ == nullptr) { 39 // This means ScriptDetector::Create() could not find the requested 40 // script_detector_name. In that case, Create() already logged an error 41 // message. 42 return false; 43 } 44 45 // We use default value 172 because this is the number of scripts supported by 46 // the first model we trained with this feature. See http://b/70617713. 47 // Newer models may support more scripts. 48 num_supported_scripts_ = GetIntParameter("num_supported_scripts", 172); 49 return true; 50 } 51 52 bool RelevantScriptFeature::Init(TaskContext *context) { 53 set_feature_type(new NumericFeatureType(name(), num_supported_scripts_)); 54 return true; 55 } 56 57 void RelevantScriptFeature::Evaluate( 58 const WorkspaceSet &workspaces, const LightSentence &sentence, 59 FeatureVector *result) const { 60 // counts[s] is the number of characters with script s. 61 std::vector<int> counts(num_supported_scripts_); 62 int total_count = 0; 63 for (const string &word : sentence) { 64 const char *const word_end = word.data() + word.size(); 65 const char *curr = word.data(); 66 67 // Skip over token start '^'. 68 SAFTM_DCHECK_EQ(*curr, '^'); 69 curr += utils::OneCharLen(curr); 70 while (true) { 71 const int num_bytes = utils::OneCharLen(curr); 72 73 int script = script_detector_->GetScript(curr, num_bytes); 74 75 // We do this update and the if (...) break below *before* incrementing 76 // counts[script] in order to skip the token end '$'. 77 curr += num_bytes; 78 if (curr >= word_end) { 79 SAFTM_DCHECK_EQ(*(curr - num_bytes), '$'); 80 break; 81 } 82 SAFTM_DCHECK_GE(script, 0); 83 84 if (script < num_supported_scripts_) { 85 counts[script]++; 86 total_count++; 87 } else { 88 // Unsupported script: this usually indicates a script that is 89 // recognized by newer versions of the code, after the model was 90 // trained. E.g., new code running with old model. 91 } 92 } 93 } 94 95 for (int script_id = 0; script_id < num_supported_scripts_; ++script_id) { 96 int count = counts[script_id]; 97 if (count > 0) { 98 const float weight = static_cast<float>(count) / total_count; 99 FloatFeatureValue value(script_id, weight); 100 result->add(feature_type(), value.discrete_value); 101 } 102 } 103 } 104 105 SAFTM_STATIC_REGISTRATION(RelevantScriptFeature); 106 107 } // namespace lang_id 108 } // namespace mobile 109 } // namespace nlp_saft 110
