Implement chrome.experimental.downloads.search()

content/browser/download/download_query.h

+// Copyright (c) 2011 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 CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_QUERY_H_
+#define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_QUERY_H_
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/values.h"
+#include "content/browser/download/download_item.h"
+
+namespace download_util {
+
+// Filter and sort a vector of DownloadItem*s. See also the macros at the bottom
+// of this file.
+//
+// std::vector<DownloadItem*> results;
+// std::string error_msg;
+// scoped_ptr<base::ListValue> json_results(new base::ListValue());
+// bool FilterOutOddDownloads(DownloadItem* item) {
+//   CHECK(item);
+//   return 0 == (item->id() % 2);
+// }
+// download_manager->Search(DownloadQuery().
+//   filter_func(base::Bind(&FilterOutOddDownloads)).
+//   filenameRegex(".*foo.*").
+//   urlRegex(".*foo.*"),
+//   &results, &error_msg, json_results.get());
+class DownloadQuery {
+ public:
+  typedef base::Callback<bool(const DownloadItem&)> FilterType;
+
+  DownloadQuery();
+
+  ~DownloadQuery() {}
+
+  // Modify items in-place to sort, filter, and limit.
+  // If results is non-NULL, convert the results to json in it.
+  // Return true iff the query is well-formed. Return false and set error_msg if
+  // query is malformed.
+  bool Search(std::vector<DownloadItem*>* items,

[cbentzel, 2011/10/10 14:35:30]

The way this is used - it seems like it would make more sense to have a const
std::vector of input and std::vector of output, so not doing the sort/filter in
place. If there's only a few items which pass the DownloadQuery, you are doing
extraneous copies.

[benjhayden, 2011/10/13 14:07:34]

Done.

+              std::string* error_msg = NULL,
+              base::ListValue* results = NULL) const;
+
+  // Chainable settors set a field to a value and return |this|.
+  DownloadQuery& filter_func(FilterType func);

[cbentzel, 2011/10/10 14:35:30]

I haven't really seen this style in Chromium (the ref return on set to chain
setters). It also doesn't really seem to be all that useful - the case I saw
just called name() in a macro, without chaining.

It will also usually be set_filter_func rather that filter_func.

[benjhayden, 2011/10/13 14:07:34]

Done.

+  DownloadQuery& state_enum(DownloadItem::DownloadState dstate);
+  DownloadQuery& danger_enum(DownloadItem::DangerType danger_type);
+#define Boolean bool
+#define Integer int
+#define String std::string
+#define FIELD(name, type) \
+ protected: bool has_ ## name ## _; \
+ protected: type name ## _; \
+ public: DownloadQuery& name(type value) { \
+    name ## _ = value; \
+    has_ ## name ## _ = true; \
+    return *this; \
+  }
+#include "content/browser/download/download_query_fields.h"
+#undef FIELD
+#undef Boolean
+#undef Integer
+#undef String
+
+ protected:
+  FilterType filter_func_;
+  bool has_state_enum_;
+  DownloadItem::DownloadState state_enum_;
+  bool has_danger_enum_;
+  DownloadItem::DangerType danger_enum_;
+  // Allow copy and assign.
+};
+}  // namespace download_util
+
+
+// The following macros facilitate using anonymous expressions (lambdas) to
+// create a DownloadQuery and set its filter_func. The parameters passed to the
+// second and third forms MUST be variable names and cannot be expressions.
+//
+// dlman->Search(DOWNLOAD_QUERY_FILTER(item.is_temporary()).
+//   orderBy("-endTime"), results);
+// download_manager->Search(DOWNLOAD_QUERY_FILTER1(otr,
+//   item.is_otr() == otr).orderBy("-endTime"), results);
+// download_manager->Search(DOWNLOAD_QUERY_FILTER2(otr, temp,
+//   ((item.is_otr() == otr) && (item.is_temporary() == temp))).
+//   orderBy("-endTime"), results);
+
+#define SYMCAT(X, Y) X##Y
+#define DOWNLOAD_QUERY_FILTER_IMPL(NAME, expr) \
+  ({struct NAME {static bool Filter(const DownloadItem& item) {return expr;}}; \
+    download_util::DownloadQuery().filter_func(base::Bind(&NAME::Filter));})
+#define DOWNLOAD_QUERY_FILTER(expr) DOWNLOAD_QUERY_FILTER_IMPL( \
+  SYMCAT(DownloadQuery, __LINE__), (expr))
+#define DOWNLOAD_QUERY_FILTER1_IMPL(NAME, var0, expr) \
+  ({struct NAME {static bool Filter( \
+      typeof(var0) var0, const DownloadItem& item) {return expr;}}; \
+    download_util::DownloadQuery().filter_func( \
+      base::Bind(&NAME::Filter, var0));})
+#define DOWNLOAD_QUERY_FILTER1(var0, expr) DOWNLOAD_QUERY_FILTER1_IMPL( \
+  SYMCAT(DownloadQuery, __LINE__), var0, (expr))
+#define DOWNLOAD_QUERY_FILTER2_IMPL(NAME, var0, var1, expr) \
+  ({struct NAME {static bool Filter(typeof(var0) var0, typeof(var1) var1, \
+      const DownloadItem& item) {return expr;}}; \
+    download_util::DownloadQuery().filter_func( \
+      base::Bind(&NAME::Filter, var0, var1));})
+#define DOWNLOAD_QUERY_FILTER2(var0, var1, expr) DOWNLOAD_QUERY_FILTER2_IMPL( \
+  SYMCAT(DownloadQuery, __LINE__), var0, var1, (expr))
+
+#endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_QUERY_H_