text: // Copyright 2017-2019 The Verible Authors.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //      http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  // Generic Lexer interface to be implemented by language-specific lexers.
  
  #ifndef VERIBLE_COMMON_LEXER_LEXER_H_
  #define VERIBLE_COMMON_LEXER_LEXER_H_
  
  #include "absl/strings/string_view.h"
  #include "common/text/token_info.h"
  
  namespace verible {
  
  class Lexer {
   public:
    virtual ~Lexer() {}
  
    Lexer(const Lexer&) = delete;
    Lexer& operator=(const Lexer&) = delete;
  
    // Returns the last token scanned.
    virtual const TokenInfo& GetLastToken() const = 0;
  
    // Scan next token and return it.
    virtual const TokenInfo& DoNextToken() = 0;
  
    // Reset lexer to new input.  Overrides should discard all previous state.
    virtual void Restart(absl::string_view) = 0;
  
    // Return true if token is a lexical error.
    virtual bool TokenIsError(const TokenInfo&) const = 0;
  
   protected:
    Lexer() {}
  };
  
  }  // namespace verible
  
  #endif  // VERIBLE_COMMON_LEXER_LEXER_H_
  