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// Trie table for Romaji (or Kana) conversion

#ifndef MOZC_COMPOSER_TABLE_H_
#define MOZC_COMPOSER_TABLE_H_

#include <cstddef>
#include <cstdint>
#include <istream>
#include <memory>
#include <string>
#include <vector>

#include "absl/base/nullability.h"
#include "absl/container/flat_hash_map.h"
#include "absl/container/flat_hash_set.h"
#include "absl/strings/string_view.h"
#include "base/container/trie.h"
#include "composer/special_key.h"
#include "protocol/commands.pb.h"
#include "protocol/config.pb.h"

namespace mozc {
namespace composer {

// This is a bitmap representing Entry's additional attributes.
enum TableAttribute {
  NO_TABLE_ATTRIBUTE = 0,
  // When the typing is beginning, the rule with this attribute is
  // executed even if the previous characters can be a part of other
  // rules.
  NEW_CHUNK = 1,
  // This flag suppresses any transliteration performed in CharChunk
  // and treated as an as-is key event.
  NO_TRANSLITERATION = 2,
  // This flag indicates that the composition should be ended and committed.
  DIRECT_INPUT = 4,

  // This flag treats the next typing as a new input.  This flag is
  // used with the NEW_CHUNK flag.
  END_CHUNK = 8,
};
typedef uint32_t TableAttributes;

class Entry final {
 public:
  Entry(absl::string_view input, absl::string_view result,
        absl::string_view pending, TableAttributes attributes);
  constexpr const std::string& input() const { return input_; }
  constexpr const std::string& result() const { return result_; }
  constexpr const std::string& pending() const { return pending_; }
  constexpr TableAttributes attributes() const { return attributes_; }

 private:
  const std::string input_;
  const std::string result_;
  const std::string pending_;
  TableAttributes attributes_;
};

class Table final {
 public:
  Table();
  Table(const Table&) = delete;
  Table& operator=(const Table&) = delete;

  bool InitializeWithRequestAndConfig(const commands::Request& request,
                                      const config::Config& config);

  // Return true if adding the input-pending pair makes a loop of
  // conversion rules.
  bool IsLoopingEntry(absl::string_view input, absl::string_view pending) const;
  const Entry* absl_nullable AddRule(absl::string_view input,
                                     absl::string_view output,
                                     absl::string_view pending);

  const Entry* absl_nullable AddRuleWithAttributes(absl::string_view input,
                                                   absl::string_view output,
                                                   absl::string_view pending,
                                                   TableAttributes attributes);

  void DeleteRule(absl::string_view input);

  bool LoadFromString(const std::string& str);
  bool LoadFromFile(const char* filepath);

  const Entry* LookUp(absl::string_view input) const;
  const Entry* LookUpPrefix(absl::string_view input, size_t* key_length,
                            bool* fixed) const;
  void LookUpPredictiveAll(absl::string_view input,
                           std::vector<const Entry*>* results) const;
  // TODO(komatsu): Delete this function.
  bool HasSubRules(absl::string_view input) const;

  bool HasNewChunkEntry(absl::string_view input) const;

  bool case_sensitive() const;
  void set_case_sensitive(bool case_sensitive);

  // Parses special key strings escaped with the pair of "{" and "}"
  // and returns the parsed string.
  std::string ParseSpecialKey(const absl::string_view input) const {
    return special_key_map_.Parse(input);
  }

  // Return the default table.
  static const Table& GetDefaultTable();

  // Return the default shared table.
  static std::shared_ptr<const Table> GetSharedDefaultTable();

 private:
  friend class TypingCorrectorTest;
  friend class TypingCorrectionTest;

  bool LoadFromStream(std::istream* is);
  void DeleteEntry(const Entry* entry);

  using EntryTrie = Trie<const Entry*>;
  EntryTrie entries_;
  using EntrySet = absl::flat_hash_set<std::unique_ptr<Entry>>;
  EntrySet entry_set_;

  internal::SpecialKeyMap special_key_map_;

  // If false, input alphabet characters are normalized to lower
  // characters.  The default value is false.
  bool case_sensitive_ = false;
};

class TableManager {
 public:
  TableManager();
  ~TableManager() = default;
  // Return Table for the request and the config
  // Return nullptr when no Table is available.
  std::shared_ptr<const Table> GetTable(const commands::Request& request,
                                        const config::Config& config);

  void ClearCaches();

 private:
  // Table caches.
  // Key uint32_t is calculated hash and unique for
  //  commands::Request::SpecialRomanjiTable
  //  config::Config::PreeditMethod
  //  config::Config::PunctuationMethod
  //  config::Config::SymbolMethod
  absl::flat_hash_map<size_t, std::shared_ptr<const Table>> table_map_;
  // Fingerprint for Config::custom_roman_table;
  uint64_t custom_roman_table_fingerprint_;
};

}  // namespace composer
}  // namespace mozc

#endif  // MOZC_COMPOSER_TABLE_H_
