components/omnibox/browser/actions/omnibox_pedal_provider.h

// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_OMNIBOX_BROWSER_ACTIONS_OMNIBOX_PEDAL_PROVIDER_H_
#define COMPONENTS_OMNIBOX_BROWSER_ACTIONS_OMNIBOX_PEDAL_PROVIDER_H_

#include <unordered_map>

#include "base/gtest_prod_util.h"
#include "base/memory/scoped_refptr.h"
#include "base/strings/utf_offset_string_conversions.h"
#include "base/values.h"
#include "components/omnibox/browser/actions/omnibox_pedal.h"
#include "components/omnibox/browser/autocomplete_provider.h"

class OmniboxPedal;
class AutocompleteInput;
class AutocompleteProviderClient;

// Note: This is not an autocomplete provider; it doesn't produce suggestions
// but rather "annotates" suggestions by attaching pedals to matches from other
// providers (search in particular).
class OmniboxPedalProvider {
 public:
  OmniboxPedalProvider(
      AutocompleteProviderClient& client,
      std::unordered_map<OmniboxPedalId, scoped_refptr<OmniboxPedal>> pedals);
  ~OmniboxPedalProvider();
  OmniboxPedalProvider(const OmniboxPedalProvider&) = delete;
  OmniboxPedalProvider& operator=(const OmniboxPedalProvider&) = delete;

  // Returns the Pedal found to match given |match_text| or else nullptr if
  // none match. Triggering readiness is irrelevant.
  OmniboxPedal* FindPedalMatch(const std::u16string& match_text);

  // Returns the Pedal triggered by given |match_text| or nullptr if none
  // trigger. The |input| is used to determine suitability for current context.
  OmniboxPedal* FindReadyPedalMatch(const AutocompleteInput& input,
                                    const std::u16string& match_text);

  // "Fake" implementation of AutocompleteProvider AddProviderInfo, though this
  // class is not a true subclass of AutocompleteProvider. This is used
  // for logging and reporting for our field trial.
  void AddProviderInfo(ProvidersInfo* provider_info) const;

  // "Fake" implementation of AutocompleteProvider::ResetSession. Resets the
  // field trial flags.
  void ResetSession();

  void set_field_trial_triggered(bool triggered) {
    field_trial_triggered_ = triggered;
  }

  // Estimates memory usage for this and all contained Pedals.
  size_t EstimateMemoryUsage() const;

 protected:
  // Befriending this test base class prevents duplication of a long exhaustive
  // unit test (specifically the TestLiteralConceptExpressions method).
  friend class OmniboxPedalImplementationsTest;
  FRIEND_TEST_ALL_PREFIXES(OmniboxPedalImplementationsTest,
                           ProviderFiltersPedalUpdateChrome);
  FRIEND_TEST_ALL_PREFIXES(
      OmniboxPedalImplementationsWithoutTranslationConsoleTest,
      ProviderFiltersPedalUpdateChrome);
  FRIEND_TEST_ALL_PREFIXES(OmniboxPedalImplementationsTest,
                           UnorderedSynonymExpressionsAreConceptMatches);
  FRIEND_TEST_ALL_PREFIXES(
      OmniboxPedalImplementationsWithoutTranslationConsoleTest,
      UnorderedSynonymExpressionsAreConceptMatches);

  // Generate a token sequence for text using internal dictionary & delimiters.
  // Outputs empty sequence if any delimited part of text is not in dictionary.
  // Note, the ignore_group is applied to eliminate stop words from output.
  void Tokenize(OmniboxPedal::TokenSequence& out_tokens,
                const std::u16string& text) const;

  // An open variant of Tokenize that expands the token dictionary as needed.
  void TokenizeAndExpandDictionary(OmniboxPedal::TokenSequence& out_tokens,
                                   const std::u16string& token_sequence_string);

  void LoadPedalConcepts();

  // Load a synonym group from a JSON sourced Value.
  OmniboxPedal::SynonymGroup LoadSynonymGroupValue(
      const base::Value& group_value) const;

  // Load a synonym group from a localization sourced string with comma
  // separated synonyms.
  OmniboxPedal::SynonymGroup LoadSynonymGroupString(
      bool required,
      bool match_once,
      std::u16string synonyms_csv);

  AutocompleteProviderClient& client_;

  // Contains mapping from well-known identifier to Pedal implementation.
  // Note: since the set is small, we use one map here for simplicity; but if
  // someday there are lots of Pedals, it may make sense to switch this to a
  // vector and index by id separately.  The lookup is needed rarely but
  // iterating over the whole collection happens very frequently, so we should
  // really optimize for iteration (vector), not lookup (map).
  std::unordered_map<OmniboxPedalId, scoped_refptr<OmniboxPedal>> pedals_;

  // Common words that may be used when typing to trigger Pedals.  All instances
  // of these words are removed from match text when looking for triggers.
  // Therefore no Pedal should have a trigger or synonym group that includes
  // any of these words (as a whole word; substrings are fine).
  OmniboxPedal::SynonymGroup ignore_group_;

  // Map from string token to unique int token identifier.
  std::unordered_map<std::u16string, int> dictionary_;

  // This contains all token delimiter characters.  It may be empty, in which
  // case no delimiting takes place (input is treated as raw token sequence).
  std::u16string tokenize_characters_;

  // This holds the tokens currently being matched against.
  OmniboxPedal::TokenSequence match_tokens_;

  // This serves as an upper bound on the number of tokens we will accept from
  // text before giving up and treating it as non-match for all Pedals.
  size_t max_tokens_ = 0;

  // Whether a field trial has triggered for this query and this session
  bool field_trial_triggered_ = false;
  bool field_trial_triggered_in_session_ = false;
};

#endif  // COMPONENTS_OMNIBOX_BROWSER_ACTIONS_OMNIBOX_PEDAL_PROVIDER_H_