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// Copyright (c) 2012 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 CHROME_BROWSER_HISTORY_TOP_SITES_CACHE_H_
#define CHROME_BROWSER_HISTORY_TOP_SITES_CACHE_H_
#include <map>
#include <utility>
#include "base/memory/ref_counted.h"
#include "chrome/browser/history/history_types.h"
#include "chrome/browser/history/url_utils.h"
namespace history {
// TopSiteCache caches thumbnails for visited pages. Retrieving thumbnails from
// a given input URL is a two-stage process:
//
// input URL --(map 1)--> canonical URL --(map 2)--> image.
//
// (map 1) searches input URL in |canonical_urls_|. canonical URL is
// assigned to the resulting value if found; else input URL.
//
// (map 2) simply looks up canonical URL in |images_|.
//
// TopSiteCache also provides GetCanonicalURLsIteratorForPrefix(), which is an
// alternative implementation of (map 1) that does the following:
// - if canonical URL is a key in |canonical_urls_|, return the value.
// - else if canonical URL is a "URL prefix" (see comment in url_utils.h) of
// some key in |canonical_urls_|, return the value corresponding to the key.
// - else return input URL.
// TopSitesCache caches the top sites and thumbnails for TopSites.
class TopSitesCache {
public:
TopSitesCache();
~TopSitesCache();
// The top sites.
void SetTopSites(const MostVisitedURLList& top_sites);
const MostVisitedURLList& top_sites() const { return top_sites_; }
// The thumbnails.
void SetThumbnails(const URLToImagesMap& images);
const URLToImagesMap& images() const { return images_; }
// Returns the thumbnail as an Image for the specified url. This adds an entry
// for |url| if one has not yet been added.
Images* GetImage(const GURL& url);
// Fetches the thumbnail for the specified url. Returns true if there is a
// thumbnail for the specified url. It is possible for a URL to be in TopSites
// but not have an thumbnail.
bool GetPageThumbnail(const GURL& url,
scoped_refptr<base::RefCountedMemory>* bytes);
// Fetches the thumbnail score for the specified url. Returns true if
// there is a thumbnail score for the specified url.
bool GetPageThumbnailScore(const GURL& url, ThumbnailScore* score);
// Returns the canonical URL for |url|.
const GURL& GetCanonicalURL(const GURL& url);
// Returns the canonical URL for |url_prefix| that matches by prefix.
// Multiple matches exst, returns the canonical URL for the first
// matching entry under lexicographical order.
const GURL& GetCanonicalURLForPrefix(const GURL& url_prefix);
// Returns true if |url| is known.
bool IsKnownURL(const GURL& url);
// Returns the index into |top_sites_| for |url|.
size_t GetURLIndex(const GURL& url);
private:
// The entries in CanonicalURLs, see CanonicalURLs for details. The second
// argument gives the index of the URL into MostVisitedURLs redirects.
typedef std::pair<MostVisitedURL*, size_t> CanonicalURLEntry;
// Comparator used for CanonicalURLs.
class CanonicalURLComparator {
public:
bool operator()(const CanonicalURLEntry& e1,
const CanonicalURLEntry& e2) const {
return CanonicalURLStringCompare(e1.first->redirects[e1.second].spec(),
e2.first->redirects[e2.second].spec());
}
};
// This is used to map from redirect url to the MostVisitedURL the redirect is
// from. Ideally this would be map<GURL, size_t> (second param indexing into
// top_sites_), but this results in duplicating all redirect urls. As some
// sites have a lot of redirects, we instead use the MostVisitedURL* and the
// index of the redirect as the key, and the index into top_sites_ as the
// value. This way we aren't duplicating GURLs. CanonicalURLComparator
// enforces the ordering as if we were using GURLs.
typedef std::map<CanonicalURLEntry, size_t,
CanonicalURLComparator> CanonicalURLs;
// Generates the set of canonical urls from |top_sites_|.
void GenerateCanonicalURLs();
// Stores a set of redirects. This is used by GenerateCanonicalURLs.
void StoreRedirectChain(const RedirectList& redirects, size_t destination);
// Returns the iterator into |canonical_urls_| for the |url|.
CanonicalURLs::iterator GetCanonicalURLsIterator(const GURL& url);
// Returns the first iterator into |canonical_urls_| for which |prefix_url|
// is a URL prefix. Returns |canonical_urls_.end()| if no match is found.
CanonicalURLs::iterator GetCanonicalURLsIteratorForPrefix(
const GURL& prefix_url);
// The top sites.
MostVisitedURLList top_sites_;
// The images. These map from canonical url to image.
URLToImagesMap images_;
// Generated from the redirects to and from the most visited pages. See
// description above typedef for details.
CanonicalURLs canonical_urls_;
DISALLOW_COPY_AND_ASSIGN(TopSitesCache);
};
} // namespace history
#endif // CHROME_BROWSER_HISTORY_TOP_SITES_CACHE_H_
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