zero_suggest_provider.h revision 5821806d5e7f356e8fa4b058a389a808ea183019 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4//
5// This file contains the zero-suggest autocomplete provider. This experimental
6// provider is invoked when the user focuses in the omnibox prior to editing,
7// and generates search query suggestions based on the current URL. To enable
8// this provider, point --experimental-zero-suggest-url-prefix at an
9// appropriate suggestion service.
10//
11// HUGE DISCLAIMER: This is just here for experimenting and will probably be
12// deleted entirely as we revise how suggestions work with the omnibox.
13
14#ifndef CHROME_BROWSER_AUTOCOMPLETE_ZERO_SUGGEST_PROVIDER_H_
15#define CHROME_BROWSER_AUTOCOMPLETE_ZERO_SUGGEST_PROVIDER_H_
16
17#include <string>
18#include <vector>
19
20#include "base/basictypes.h"
21#include "base/compiler_specific.h"
22#include "base/memory/scoped_ptr.h"
23#include "base/string16.h"
24#include "chrome/browser/autocomplete/autocomplete_provider.h"
25#include "net/url_request/url_fetcher_delegate.h"
26
27class AutocompleteInput;
28class GURL;
29class TemplateURLService;
30
31namespace base {
32class Value;
33}
34
35namespace net {
36class URLFetcher;
37}
38
39// Autocomplete provider for searches based on the current URL.
40//
41// The controller will call StartZeroSuggest when the user focuses in the
42// omnibox. After construction, the autocomplete controller repeatedly calls
43// Start() with some user input, each time expecting to receive an updated
44// set of matches.
45//
46// TODO(jered): Consider deleting this class and building this functionality
47// into SearchProvider after dogfood and after we break the association between
48// omnibox text and suggestions.
49class ZeroSuggestProvider : public AutocompleteProvider,
50                            public net::URLFetcherDelegate {
51 public:
52  // Creates and returns an instance of this provider if the feature is enabled.
53  // Returns NULL if not enabled.
54  static ZeroSuggestProvider* Create(AutocompleteProviderListener* listener,
55                                     Profile* profile);
56
57  // AutocompleteProvider:
58  virtual void Start(const AutocompleteInput& input,
59                     bool /*minimal_changes*/) OVERRIDE;
60  virtual void Stop(bool clear_cached_results) OVERRIDE;
61
62  // net::URLFetcherDelegate
63  virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
64
65  // Initiates a new fetch for the given |url|, limiting suggestions to those
66  // matching |user_text|. |user_text| may be non-empty if the user previously
67  // interacted with zero-suggest suggestions and then unfocused the omnibox.
68  // TODO(jered): Rip out |user_text| once the first match is decoupled from
69  // the current typing in the omnibox.
70  void StartZeroSuggest(const GURL& url, const string16& user_text);
71
72 private:
73  ZeroSuggestProvider(AutocompleteProviderListener* listener,
74                      Profile* profile,
75                      const std::string& url_prefix);
76
77  virtual ~ZeroSuggestProvider();
78
79  // Update matches given the user has typed |user_text|.
80  void UpdateMatches(const string16& user_text);
81
82  // Fetches zero-suggest suggestions for |current_query_|.
83  void Run();
84
85  // Parses results from the zero-suggest server and updates results.
86  // Returns true if results were updated.
87  bool ParseSuggestResults(base::Value* root_val);
88
89  // Converts the parsed results to a set of AutocompleteMatches and adds them
90  // to |matches_|.
91  void ConvertResultsToAutocompleteMatches();
92
93  // Adds a URL suggestion for the current URL. This should be in the top
94  // position so that pressing enter has the effect of reloading the page.
95  void AddMatchForCurrentURL();
96
97  // Adds a query suggestion from response position |result_index| with text
98  // |result| to |matches_|. Uses |search_provider| to build a search URL for
99  // this match.
100  void AddMatchForResult(const TemplateURL* search_provider,
101                         size_t result_index,
102                         const string16& result);
103
104  // Prefix of the URL from which to fetch zero-suggest suggestions.
105  const std::string url_prefix_;
106
107  // Used to build default search engine URLs for suggested queries.
108  TemplateURLService* template_url_service_;
109
110  // The URL for which a suggestion fetch is pending.
111  std::string current_query_;
112
113  // What the user has typed.
114  string16 user_text_;
115
116  // Fetcher used to retrieve results.
117  scoped_ptr<net::URLFetcher> fetcher_;
118
119  // Suggestions for the most recent query.
120  std::vector<string16> results_;
121
122  DISALLOW_COPY_AND_ASSIGN(ZeroSuggestProvider);
123};
124
125#endif  // CHROME_BROWSER_AUTOCOMPLETE_ZERO_SUGGEST_PROVIDER_H_
126