Query API: Introduces an OfflinePageModelQuery object.

components/offline_pages/offline_page_model_query.h

Index: components/offline_pages/offline_page_model_query.h
diff --git a/components/offline_pages/offline_page_model_query.h b/components/offline_pages/offline_page_model_query.h
new file mode 100644
index 0000000000000000000000000000000000000000..5ce877ebcd24e3cc2f9b0ca67e95237cd9a0ed11
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+++ b/components/offline_pages/offline_page_model_query.h
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+// Copyright 2016 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_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_QUERY_H_
+#define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_QUERY_H_
+
+#include <set>
+#include <vector>
+
+#include "base/memory/ptr_util.h"
+#include "components/offline_pages/client_policy_controller.h"
+#include "components/offline_pages/offline_page_item.h"
+#include "components/offline_pages/offline_page_types.h"
+
+namespace offline_pages {
+
+// Can be used by OfflinePageModel instances to direct a query of the model.
+class OfflinePageModelQuery {
+ public:
+  enum class Requirement {
+    UNSET,
+    MATCH,

[Dmitry Titov, 2016/10/24 18:28:34]

INCLUDE_MATCHING/EXCLUDE_MATCHING ?

[dewittj, 2016/10/24 22:20:12]

Done.

+    EXCLUDE,
+  };
+
+  OfflinePageModelQuery();
+  virtual ~OfflinePageModelQuery();
+
+  bool GetRestrictedToNamespaces(std::set<std::string>* namespaces_out);
+
+  Requirement GetRestrictedToOfflineIds(std::set<int64_t>* ids_out);
+  Requirement GetRestrictedToClientIds(std::set<ClientId>* ids_out);
+  Requirement GetRestrictedToUrls(std::set<GURL>* ids_out);
+  bool GetAllowExpired();
+
+  // This is the workhorse function that is used by the in-memory offline page
+  // model, given a page it will find out whether that page matches the query.
+  bool Matches(const OfflinePageItem& page);
+
+ private:
+  friend class OfflinePageModelQueryBuilder;
+
+  bool allow_expired_ = false;
+
+  std::unique_ptr<std::set<std::string>> restricted_to_namespaces_;
+
+  std::pair<Requirement, std::set<int64_t>> offline_ids_;
+  std::pair<Requirement, std::set<ClientId>> client_ids_;
+  std::pair<Requirement, std::set<GURL>> urls_;
+
+  DISALLOW_COPY_AND_ASSIGN(OfflinePageModelQuery);
+};
+
+// Used to create an offline page model query.  Set policy bits to limit by

[Dmitry Titov, 2016/10/24 18:28:34]

"Set policy bits to limit by namespaces" is unclear.

Also, it looks like an empty query includes everything except expired pages, and
the additional calls are all reducing the set, filtering it, correct? If that is
how you want it, it makes sense to document this way, it's a clear model - query
starts as all-inclusive, you specify a filter on it.

[dewittj, 2016/10/24 22:20:12]

Done.

+// namespaces.  If the number of IDs or the number of namespaces are reduced to
+// zero, the builder will DCHECK. Call |Build| to generate an actual query.

[Dmitry Titov, 2016/10/24 18:28:34]

Not sure why would Builder DCHECK... This seems like a possible code flow to
restrict query to the point it returns nothing.

[dewittj, 2016/10/24 22:20:12]

This was outdated anyway.  The whole comment is now rewritten.

+class OfflinePageModelQueryBuilder {
+ public:
+  using Requirement = OfflinePageModelQuery::Requirement;
+
+  OfflinePageModelQueryBuilder();
+  ~OfflinePageModelQueryBuilder();
+
+  // Sets the offline page IDs that are valid for this request.  If called
+  // multiple times, overwrites previous offline page ID restrictions.
+  OfflinePageModelQueryBuilder& SetOfflinePageIds(
+      Requirement requirement,
+      const std::vector<int64_t>& ids);
+
+  // Sets the client IDs that are valid for this request.  If called // multiple
+  // times, overwrites previous client ID restrictions.
+  OfflinePageModelQueryBuilder& SetClientIds(Requirement requirement,
+                                             const std::vector<ClientId>& ids);
+
+  // Sets the URLs that are valid for this request.  If called multiple times,
+  // overwrites previous URL restrictions.
+  OfflinePageModelQueryBuilder& SetUrls(Requirement requirement,
+                                        const std::vector<GURL>& urls);
+
+  // Only include namespaces whose namespaces satisfy
+  // ClientPolicyController::IsSupportedByDownload(|namespace|) ==
+  //     |supported_by_download|
+  // Multiple calls overwrite previous ones.
+  OfflinePageModelQueryBuilder& RequireSupportedByDownload(
+      Requirement supported_by_download);
+
+  // Only include namespaces whose namespaces satisfy
+  // ClientPolicyController::IsShownAsRecentlyVisitedSite(|namespace|) ==
+  //     |recently_visited|
+  // Multiple calls overwrite previous ones.
+  OfflinePageModelQueryBuilder& RequireShownAsRecentlyVisitedSite(
+      Requirement recently_visited);
+
+  // Only include namespaces whose namespaces satisfy
+  // ClientPolicyController::IsRestrictedToOriginalTab(|namespace|) ==
+  //     |original_tab|
+  // Multiple calls overwrite previous ones.
+  OfflinePageModelQueryBuilder& RequireRestrictedToOriginalTab(
+      Requirement original_tab);
+
+  // Resets whether we return expired pages.  If called multiple times the bit
+  // is overwritten and |allow_expired| from the last call is saved.
+  OfflinePageModelQueryBuilder& AllowExpiredPages(bool allow_expired);
+
+  // Returns the built-up query based on the above APIs.  This resets the
+  // internal state.
+  std::unique_ptr<OfflinePageModelQuery> Build(
+      ClientPolicyController* controller);
+
+ private:
+  // Intersects the allowed namespaces in query_ with |namespaces|.  If
+  // |inverted| is true, intersects the allowed namespaces with all namespaces
+  // except those provided in |namespaces|.
+  void IntersectWithNamespaces(ClientPolicyController* controller,
+                               const std::vector<std::string>& namespaces,
+                               Requirement match_requirement);
+
+  std::pair<Requirement, std::vector<int64_t>> offline_ids_;
+  std::pair<Requirement, std::vector<ClientId>> client_ids_;
+  std::pair<Requirement, std::vector<GURL>> urls_;
+
+  Requirement supported_by_download_ = Requirement::UNSET;
+  Requirement shown_as_recently_visited_site_ = Requirement::UNSET;
+  Requirement restricted_to_original_tab_ = Requirement::UNSET;
+
+  bool allow_expired_ = false;
+
+  DISALLOW_COPY_AND_ASSIGN(OfflinePageModelQueryBuilder);
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_QUERY_H_