chromium/components/history/core/browser/url_database.h

// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_HISTORY_CORE_BROWSER_URL_DATABASE_H_
#define COMPONENTS_HISTORY_CORE_BROWSER_URL_DATABASE_H_

#include <stddef.h>

#include <string>
#include <vector>

#include "base/time/time.h"
#include "components/history/core/browser/history_types.h"
#include "components/history/core/browser/keyword_id.h"
#include "components/history/core/browser/url_row.h"
#include "components/query_parser/query_parser.h"
#include "sql/statement.h"

class GURL;

namespace base {
class Time;
}

namespace sql {
class Database;
}

namespace history {

class KeywordSearchTermVisitEnumerator;
struct KeywordSearchTermRow;

class VisitDatabase;  // For friend statement.

// Encapsulates an SQL database that holds URL info.  This is a subset of the
// full history data.  We split this class' functionality out from the larger
// HistoryDatabase class to support maintaining separate databases of URLs with
// different capabilities (for example, the in-memory database).
//
// This is refcounted to support calling InvokeLater() with some of its methods
// (necessary to maintain ordering of DB operations).
class URLDatabase { … };

// The fields and order expected by FillURLRow(). ID is guaranteed to be first
// so that DISTINCT can be prepended to get distinct URLs.
//
// This is available BOTH as a macro and a static string (kURLRowFields). Use
// the macro if you want to put this in the middle of an otherwise constant
// string, it will save time doing string appends. If you have to build a SQL
// string dynamically anyway, use the constant, it will save space.
#define HISTORY_URL_ROW_FIELDS …

// Constants which specify, when considered altogether, 'significant'
// history items. These are used to filter out insignificant items
// for consideration as autocomplete candidates.
extern const int kLowQualityMatchTypedLimit;
extern const int kLowQualityMatchVisitLimit;
extern const int kLowQualityMatchAgeLimitInDays;

// Returns the date threshold for considering an history item as significant.
base::Time AutocompleteAgeThreshold();

// Return true if `row` qualifies as an autocomplete candidate. If `threshold`
// is_null() then this function determines a new time threshold each time it is
// called. Since getting system time can be costly (such as for cases where
// this function will be called in a loop over many history items), you can
// provide a non-null `threshold` by simply initializing `threshold` with
// AutocompleteAgeThreshold() (or any other desired time in the past).
bool RowQualifiesAsSignificant(const URLRow& row, const base::Time& threshold);

}  // namespace history

#endif  // COMPONENTS_HISTORY_CORE_BROWSER_URL_DATABASE_H_