GWT completion: only return request.getLimit() results to the SuggestBox. Re-request completions from the server if there is only one completion.

src/server/gwt/src/se/chalmers/cs/gf/gwt/client/CompletionOracle.java

@@ -9,7 +9,7 @@ import com.google.gwt.user.client.ui.SuggestOracle;
 public class CompletionOracle extends SuggestOracle {
 
 	private static final int LIMIT_SCALE_FACTOR = 10;
-	
+
 	private PGF pgf;
 
 	private ErrorHandler errorHandler;
@@ -17,9 +17,9 @@ public class CompletionOracle extends SuggestOracle {
 	private List<String> inputLangs = null;
 
 	private JSONRequest jsonRequest = null;
-	
+
 	private String oldQuery = null;
-	
+
 	private List<CompletionSuggestion> oldSuggestions = Collections.emptyList();
 
 
@@ -78,7 +78,7 @@ public class CompletionOracle extends SuggestOracle {
 			retrieveSuggestions(request, callback);
 		}
 	}
-	
+
 	/** Filters old suggestions and checks if we still have enough suggestions. */
 	private List<CompletionSuggestion> filterOldSuggestions(SuggestOracle.Request request) {
 		List<CompletionSuggestion> suggestions = new ArrayList<CompletionSuggestion>();
@@ -87,16 +87,14 @@ public class CompletionOracle extends SuggestOracle {
 				if (c.getReplacementString().startsWith(request.getQuery())) {
 					suggestions.add(c);
 				}
-			}			
+			}
-			// Use filtered old suggestions, if there are enough of them,
+			if (suggestions.size() > 1 && (suggestions.size() >= request.getLimit() || oldSuggestions.size() < request.getLimit())) {
-			// or if the old ones were already fewer than the limit.
-			if (suggestions.size() > 0 && (suggestions.size() >= request.getLimit() || oldSuggestions.size() < request.getLimit())) {
 				return suggestions;
 			}
 		}
 		return null;
 	}
-	
+
 	private void retrieveSuggestions(final SuggestOracle.Request request, final SuggestOracle.Callback callback) {
 		// hack: first report no completions, to hide suggestions until we get the new completions
 		callback.onSuggestionsReady(request, new SuggestOracle.Response(Collections.<CompletionSuggestion>emptyList()));
@@ -117,10 +115,11 @@ public class CompletionOracle extends SuggestOracle {
 
 		});
 	}
-	
+
 	private void suggestionsReady(SuggestOracle.Request request, SuggestOracle.Callback callback, List<CompletionSuggestion> suggestions) {
 		this.oldQuery = request.getQuery();
 		this.oldSuggestions = suggestions;
+		suggestions = suggestions.size() <= request.getLimit() ? suggestions : SubList.makeSubList(suggestions, 0, request.getLimit());
 		callback.onSuggestionsReady(request, new SuggestOracle.Response(suggestions));
 	}
 

src/server/gwt/src/se/chalmers/cs/gf/gwt/client/SubList.java

@@ -0,0 +1,37 @@
+package se.chalmers.cs.gf.gwt.client;
+
+import java.util.AbstractList;
+import java.util.List;
+
+/** Work-around for missing List.subList() method in GWT JRE API emulation. */
+public class SubList<T> extends AbstractList<T> {
+
+	private List<T> list;
+
+	private int fromIndex;
+
+	private int toIndex;
+
+	public SubList(List<T> list, int fromIndex, int toIndex) {
+		this.list = list;
+		this.fromIndex = fromIndex;
+		this.toIndex = toIndex;
+		if (fromIndex < 0 || toIndex > list.size())
+			throw new IndexOutOfBoundsException("Endpoint index value out of range");
+		if (fromIndex > toIndex)
+			throw new IllegalArgumentException("Endpoint indices out of order");
+	}
+
+	public T get(int index) {
+		return list.get(fromIndex + index);
+	}
+
+	public int size() {
+		return toIndex - fromIndex;
+	}
+
+	public static <T> SubList<T> makeSubList(List<T> list, int fromIndex, int toIndex) {
+		return new SubList<T>(list, fromIndex, toIndex);
+	}
+
+}