1 // Copyright (C) 2024 Google LLC 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #ifndef ICING_EXPAND_EXPANDER_H_ 16 #define ICING_EXPAND_EXPANDER_H_ 17 18 #include <string> 19 #include <string_view> 20 #include <utility> 21 #include <vector> 22 23 namespace icing { 24 namespace lib { 25 26 // Struct to hold the text of a term, and whether it has undergone certain 27 // expansion operations. 28 struct ExpandedTerm { 29 std::string text; 30 bool is_stemmed_term; 31 ExpandedTermExpandedTerm32 explicit ExpandedTerm(std::string text_in, bool is_stemmed_term_in) 33 : text(std::move(text_in)), is_stemmed_term(is_stemmed_term_in) {} 34 35 bool operator==(const ExpandedTerm& other) const { 36 return text == other.text && is_stemmed_term == other.is_stemmed_term; 37 } 38 }; 39 40 class Expander { 41 public: 42 virtual ~Expander() = default; 43 44 // Expands a given term into a vector of expanded terms. The first term in the 45 // output vector is always the original term. 46 // 47 // See implementation classes for specific expansion behaviors. 48 virtual std::vector<ExpandedTerm> Expand(std::string_view term) const = 0; 49 }; 50 51 } // namespace lib 52 } // namespace icing 53 54 #endif // ICING_EXPAND_EXPANDER_H_ 55