#001
// Autocomplete provider for searches and suggestions from a search engine.
#002
//
#003
// After construction, the autocomplete controller repeatedly calls Start()
#004
// with some user input, each time expecting to receive a small set of the best
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// matches (either synchronously or asynchronously).
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//
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// Initially the provider creates a match that searches for the current input
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// text.
It also starts a task to query the Suggest servers.
When that data
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// comes back, the provider creates and returns matches for the best
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// suggestions.
SearchProvider
类是继承
AutocompleteProvider
和
URLFetcher
类，
AutocompleteProvider
提供一个自动完成的结果，
URLFetcher
主要提供从
URL
获取数据和状态。
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class SearchProvider : public AutocompleteProvider,
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public URLFetcher::Delegate {
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public:
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SearchProvider(ACProviderListener* listener, Profile* profile)
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: AutocompleteProvider(listener, profile, "Search"),
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last_default_provider_(NULL),
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fetcher_(NULL),
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history_request_pending_(false),
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have_history_results_(false),
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suggest_results_pending_(false),
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have_suggest_results_(false) {
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}
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开始获取。
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// AutocompleteProvider
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virtual void Start(const AutocompleteInput& input,
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bool minimal_changes,
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bool synchronous_only);
停止查找。
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virtual void Stop();
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当获取到数据回来时响应。
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// URLFetcher::Delegate
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virtual void OnURLFetchComplete(const URLFetcher* source,
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const GURL& url,
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const URLRequestStatus& status,
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int response_code,
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const ResponseCookies& cookies,
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const std::string& data);
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private:
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struct NavigationResult {
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NavigationResult(const std::wstring& url, const std::wstring& site_name)
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: url(url),
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site_name(site_name) {
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}
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// The URL.
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std::wstring url;
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// Name for the site.
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std::wstring site_name;
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};
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保存返回的结果。
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typedef std::vector<std::wstring> SuggestResults;
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typedef std::vector<NavigationResult> NavigationResults;
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typedef std::vector<history::KeywordSearchTermVisit> HistoryResults;
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typedef std::map<std::wstring, AutocompleteMatch> MatchMap;
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运行获取搜索引擎数据。
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// Called when timer_ expires.
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void Run();
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// Determines whether an asynchronous subcomponent query should run for the
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// current input.
If so, starts it if necessary; otherwise stops it.
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// NOTE: These functions do not update |done_|.
Callers must do so.
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void StartOrStopHistoryQuery(bool minimal_changes, bool synchronous_only);
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void StartOrStopSuggestQuery(bool minimal_changes, bool synchronous_only);
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// Functions to stop the separate asynchronous subcomponents.
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// NOTE: These functions do not update |done_|.
Callers must do so.
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void StopHistory();
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void StopSuggest();
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// Called back by the history system to return searches that begin with the
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// input text.
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void OnGotMostRecentKeywordSearchTerms(
#074
CancelableRequestProvider::Handle handle,
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HistoryResults* results);
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// Parses the results from the Suggest server and stores up to kMaxMatches of
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// them in server_results_.
Returns whether parsing succeeded.
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bool ParseSuggestResults(Value* root_val);
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// Converts the parsed server results in server_results_ to a set of
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// AutocompleteMatches and adds them to |matches_|.
This also sets |done_|
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// correctly.
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void ConvertResultsToAutocompleteMatches();
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// Determines the relevance for a particular match.
We use different scoring
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// algorithms for the different types of matches.
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int CalculateRelevanceForWhatYouTyped() const;
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// |time| is the time at which this query was last seen.
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int CalculateRelevanceForHistory(const Time& time) const;
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// |suggestion_value| is which suggestion this is in the list returned from
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// the server; the best suggestion is suggestion number 0.
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int CalculateRelevanceForSuggestion(size_t suggestion_value) const;
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// |suggestion_value| is same as above.
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int CalculateRelevanceForNavigation(size_t suggestion_value) const;
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// Creates an AutocompleteMatch for "Search <engine> for |query_string|" with
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// the supplied relevance.
Adds this match to |map|; if such a match already
#099
// exists, whichever one has lower relevance is eliminated.
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void AddMatchToMap(const std::wstring& query_string,
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int relevance,
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int accepted_suggestion,
#103
MatchMap* map);
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// Returns an AutocompleteMatch for a navigational suggestion.
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AutocompleteMatch NavigationToMatch(const NavigationResult& query_string,
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int relevance);
#107
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// Trims "http:" and up to two subsequent slashes from |url|.
Returns the
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// number of characters that were trimmed.
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// TODO(
#111
static size_t TrimHttpPrefix(std::wstring* url);
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// Don't send any queries to the server until some time has elapsed after
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// the last keypress, to avoid flooding the server with requests we are
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// likely to end up throwing away anyway.
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static const int kQueryDelayMs;
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// The user's input.
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AutocompleteInput input_;
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TemplateURL default_provider_;
// Cached across the life of a query so we
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// behave consistently even if the user
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// changes their default while the query is
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// running.
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const TemplateURL* last_default_provider_;
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// TODO(pkasting): http://b/1162970
We
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// shouldn't need this.
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// An object we can use to cancel history requests.
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CancelableRequestConsumer history_request_consumer_;
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// Searches in the user's history that begin with the input text.
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HistoryResults history_results_;
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// Whether history_results_ is valid (so we can tell invalid apart from
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// empty).
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bool have_history_results_;
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// Whether we are waiting for a history request to finish.
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bool history_request_pending_;
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// True if we're expecting suggest results that haven't yet arrived.
This
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// could be because either |timer_| or |fetcher| is still running (see below).
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bool suggest_results_pending_;
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// A timer to start a query to the suggest server after the user has stopped
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// typing for long enough.
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base::OneShotTimer<SearchProvider> timer_;
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// The fetcher that retrieves suggest results from the server.
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scoped_ptr<URLFetcher> fetcher_;
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// Suggestions returned by the Suggest server for the input text.
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SuggestResults suggest_results_;
#155
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// Navigational suggestions returned by the server.
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NavigationResults navigation_results_;
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// Whether suggest_results_ is valid.
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bool have_suggest_results_;
#161
#162
DISALLOW_EVIL_CONSTRUCTORS(SearchProvider);
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};
#164
在这个类里先调用函数
SearchProvider::Start
来获取缺省的搜索引擎，然后停止以前的搜索，接着
SearchProvider::Run()
函数里使用
URLFetcher
获取数据回来，它的代码如下：
#001
void SearchProvider::Run() {
#002
// Start a new request with the current input.
#003
DCHECK(!done_);
获取搜索的
URL
。
#004
const TemplateURLRef* const suggestions_url =
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default_provider_.suggestions_url();
建议代替的字符。
#006
DCHECK(suggestions_url->SupportsReplacement());
开始新的搜索。
#007
fetcher_.reset(new URLFetcher(GURL(suggestions_url->ReplaceSearchTerms(
#008
default_provider_, input_.text(),
#009
TemplateURLRef::NO_SUGGESTIONS_AVAILABLE, std::wstring())),
#010
URLFetcher::GET, this));
#011
fetcher_->set_request_context(profile_->GetRequestContext());
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fetcher_->Start();
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}
当前上面的搜索完成时，就会通知
SearchProvider::OnURLFetchComplete
函数来分析返回的结果，最后调用
SearchProvider::ConvertResultsToAutocompleteMatches()
函数来把结果转换自动完成的列表项。
通过上面的分析，就了解通过
GOOGLE
搜索引擎自动完成功能的实现。
