@Override
public void requestSuggestions(final Request request, final Callback callback) {
if (current != null) {
pending_req = request;
pending_cb = callback;
return;
}
current = callback;
{
final String this_query = request.getQuery();
// Check if we can serve this from our local cache, without even talking
// to the server. This is possible if either of those is true:
// 1. We've already seen this query recently.
// 2. This new query precedes another one and the user basically just
// typed another letter, so if the new query is "less than" the last
// result we got from the server, we know we already cached the full
// range of results covering the new request.
if ((last_query != null
&& last_query.compareTo(this_query) <= 0
&& this_query.compareTo(last_suggestion) < 0)
|| queries_seen.check(this_query)) {
current = null;
cache.requestSuggestions(request, callback);
return;
}
last_query = this_query;
}
final RequestBuilder builder =
new RequestBuilder(RequestBuilder.GET, SUGGEST_URL + type + "&q=" + last_query);
try {
builder.sendRequest(
null,
new RequestCallback() {
public void onError(final com.google.gwt.http.client.Request r, final Throwable e) {
current = null; // Something bad happened, drop the current request.
if (pending_req != null) { // But if we have another waiting...
requestSuggestions(pending_req, pending_cb); // ... try it now.
}
}
// Need to use fully-qualified names as this class inherits already
// from a pair of inner classes called Request / Response :-/
public void onResponseReceived(
final com.google.gwt.http.client.Request r,
final com.google.gwt.http.client.Response response) {
if (response.getStatusCode() == com.google.gwt.http.client.Response.SC_OK) {
final JSONValue json = JSONParser.parse(response.getText());
// In case this request returned nothing, we pretend the last
// suggestion ended with the largest character possible, so we
// won't send more requests to the server if the user keeps
// adding extra characters.
last_suggestion = last_query + "\377";
if (json != null && json.isArray() != null) {
final JSONArray results = json.isArray();
final int n = Math.min(request.getLimit(), results.size());
for (int i = 0; i < n; i++) {
final JSONValue suggestion = results.get(i);
if (suggestion == null || suggestion.isString() == null) {
continue;
}
final String suggestionstr = suggestion.isString().stringValue();
last_suggestion = suggestionstr;
cache.add(suggestionstr);
}
// Is this response still relevant to what the requester wants?
if (requester.getText().startsWith(last_query)) {
cache.requestSuggestions(request, callback);
pending_req = null;
pending_cb = null;
}
}
}
current = null; // Regardless of what happened above, this is done.
if (pending_req != null) {
final Request req = pending_req;
final Callback cb = pending_cb;
pending_req = null;
pending_cb = null;
requestSuggestions(req, cb);
}
}
});
} catch (RequestException ignore) {
}
}
