Experimental AutocompleteProvider for zerosuggest.

chrome/browser/autocomplete/zero_suggest_provider.h

+// 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.
+//
+// This file contains the zero-suggest autocomplete provider. This experimental
+// provider is invoked when the user focuses in the omnibox prior to editing,
+// and generates search query suggestions based on the current URL. To enable
+// this provider, point --experimental-zero-suggest-url-prefix at an
+// appropriate suggestion service.
+//
+// HUGE DISCLAIMER: This is just here for experimenting and will probably be
+// deleted entirely as we revise how suggestions work with the omnibox.
+
+#ifndef CHROME_BROWSER_AUTOCOMPLETE_ZERO_SUGGEST_PROVIDER_H_
+#define CHROME_BROWSER_AUTOCOMPLETE_ZERO_SUGGEST_PROVIDER_H_
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/string16.h"
+#include "chrome/browser/autocomplete/autocomplete_provider.h"
+#include "net/url_request/url_fetcher_delegate.h"
+
+class AutocompleteInput;
+class GURL;
+class TemplateURLService;
+
+namespace base {
+class Value;
+}
+
+namespace net {
+class URLFetcher;
+}
+
+// Autocomplete provider for searches based on the current URL.
+//
+// The controller will call StartZeroSuggest when the user focuses in the
+// omnibox. After construction, the autocomplete controller repeatedly calls
+// Start() with some user input, each time expecting to receive an updated
+// set of matches.
+//
+// TODO(jered): Consider deleting this class and building this functionality
+// into SearchProvider after dogfood and after we break the association between
+// omnibox text and suggestions.
+class ZeroSuggestProvider : public AutocompleteProvider,
+                            public net::URLFetcherDelegate {
+ public:
+  ZeroSuggestProvider(AutocompleteProviderListener* listener,
+                      Profile* profile,
+                      const std::string& url_prefix);
+
+  // AutocompleteProvider:
+  virtual void Start(const AutocompleteInput& input,
+                     bool /*minimal_changes*/) OVERRIDE;
+  virtual void Stop(bool clear_cached_results) OVERRIDE;
+
+  // net::URLFetcherDelegate
+  virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
+
+  // Initiates a new fetch for the given |url|, limiting suggestions to those
+  // matching |user_text|. |user_text| may be non-empty if the user previously
+  // interacted with zero-suggest suggestions and then unfocused the omnibox.
+  // TODO(jered): Rip out |user_text| once the first match is decoupled from
+  // the current typing in the omnibox.
+  void StartZeroSuggest(const GURL& url, const string16& user_text);
+
+ private:
+  virtual ~ZeroSuggestProvider();
+
+  // Update matches given the user has typed |user_text|.
+  void UpdateMatches(const string16& user_text);
+
+  // Fetches zero-suggest suggestions for |current_query_|.
+  void Run();
+
+  // Parses results from the zero-suggest server and updates results.
+  // Returns true if results were updated.
+  bool ParseSuggestResults(base::Value* root_val);
+
+  // Converts the parsed results to a set of AutocompleteMatches and adds them
+  // to |matches_|.
+  void ConvertResultsToAutocompleteMatches();
+
+  // Adds a URL suggestion for the current URL. This should be in the top
+  // position so that pressing enter has the effect of reloading the page.
+  void AddMatchForCurrentURL();
+
+  // Adds a query suggestion from response position |result_index| with text
+  // |result| to |matches_|. Uses |search_provider| to build a search URL for
+  // this match.
+  void AddMatchForResult(const TemplateURL* search_provider,
+                         size_t result_index,
+                         const string16& result);
+
+  // Prefix of the URL from which to fetch zero-suggest suggestions.
+  const std::string url_prefix_;
+
+  // Used to build default search engine URLs for suggested queries.
+  TemplateURLService* template_url_service_;
+
+  // The URL for which a suggestion fetch is pending.
+  std::string current_query_;
+
+  // Current query as UTF-16.

[Peter Kasting, 2012/08/15 21:52:44]

Nit: Don't keep both these members just to reduce the number of string
conversions you do, because those conversions aren't in the inner loop of
anything time-critical.  Pick one -- probably the UTF8 version -- and convert
elsewhere as needed.

[Jered, 2012/08/15 23:13:00]

Done.

+  string16 current_query_text_;
+
+  // What the user has typed.
+  string16 user_text_;
+
+  // Fetcher used to retrieve results.
+  scoped_ptr<net::URLFetcher> fetcher_;
+
+  // Suggestions for the most recent query.
+  std::vector<string16> results_;
+
+  DISALLOW_COPY_AND_ASSIGN(ZeroSuggestProvider);
+};
+
+#endif  // CHROME_BROWSER_AUTOCOMPLETE_ZERO_SUGGEST_PROVIDER_H_