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..c664d78002230442046d2a18132470df008e864b
--- /dev/null
+++ b/components/offline_pages/offline_page_model_query.h
@@ -0,0 +1,123 @@
+// 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:
+  OfflinePageModelQuery();
+  virtual ~OfflinePageModelQuery();
+
+  bool GetRestrictedToOfflineIds(std::set<int64_t>* ids_out);
+  bool GetRestrictedToNamespaces(std::set<std::string>* namespaces_out);
+  bool GetRestrictedToClientIds(std::set<ClientId>* ids_out);
+  bool 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<int64_t>> offline_ids_;
+  std::unique_ptr<std::set<GURL>> urls_;
+  std::unique_ptr<std::set<std::string>> restricted_to_namespaces_;
+  std::unique_ptr<std::set<ClientId>> client_ids_;
+
+  DISALLOW_COPY_AND_ASSIGN(OfflinePageModelQuery);
+};
+
+// Used to create an offline page model query.  Set policy bits to limit by
+// 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.
+class OfflinePageModelQueryBuilder {
+ public:
+  enum class Requirement {
+    Unset,

[Dmitry Titov, 2016/10/21 20:21:09]

Enum values should be either CAPITALIZED or kNamed:
https://google.github.io/styleguide/cppguide.html#Enumerator_Names

[dewittj, 2016/10/24 18:19:33]

Done.

+    OnlyMatching,
+    OnlyNotMatching,
+  };
+
+  explicit OfflinePageModelQueryBuilder();

[Dmitry Titov, 2016/10/21 20:21:09]

doesn't have to be explicit

[dewittj, 2016/10/24 18:19:33]

Done.

+  ~OfflinePageModelQueryBuilder();
+
+  // Sets the offline page IDs that are valid for this request.  If called
+  // multiple times, overwrites previous offline page ID restrictions.
+  OfflinePageModelQueryBuilder& SetOfflinePageIds(

[Dmitry Titov, 2016/10/21 20:21:09]

I wonder if those "Set" methods can also take Requirement param to specify
inclusion/exclusion/indifferent...

Then all the methods can share common naming pattern, for example
SelectWhereClientIds(ids, Requirement::Matching)
SelectWhereSupportedByDownload(Requirement::Matching)

[dewittj, 2016/10/24 18:19:33]

Done.  What do you think?  If you like the new shape, I'll add tests for the
EXCLUDE side of these new features.

+      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(const std::vector<ClientId>& ids);
+
+  // Sets the URLs that are valid for this request.  If called multiple times,
+  // overwrites previous URL restrictions.
+  OfflinePageModelQueryBuilder& SetUrls(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,

[Dmitry Titov, 2016/10/21 20:21:09]

If I understand correctly, "intersect with inversion" is basically "remove
specified namespaces". Maybe simply add a second method that would be named
"RemoveNamespaces"? It might produce a bit larger but hopefully more readable
code in the impl as well...

[dewittj, 2016/10/24 18:19:33]

Moved to RemoveNamespaces & IntersectNamespaces.  Seems cleaner now, wdyt?

+                               const std::vector<std::string>& namespaces,
+                               bool invert);
+
+  // The in-progress query object.
+  std::unique_ptr<OfflinePageModelQuery> query_;
+
+  Requirement supported_by_download_ = Requirement::Unset;
+  Requirement shown_as_recently_visited_site_ = Requirement::Unset;
+  Requirement restricted_to_original_tab_ = Requirement::Unset;
+
+  DISALLOW_COPY_AND_ASSIGN(OfflinePageModelQueryBuilder);
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_QUERY_H_