libshell|AbstractLineEditor: Adjusted behavior of autocompletion

The first press of Tab only sends the autocompletion notification if
there is no unambiguous completion available. Further presses send
the notification and then on subsequent presses start cycling through
the possible completions.

The objective here is to avoid showing the autocompletion popup
unnecessarily/too early.

doomsday/client/include/ui/widgets/consolecommandwidget.h

@@ -43,7 +43,7 @@ class ConsoleCommandWidget : public LineEditWidget
     bool handleEvent(de::Event const &event);
 
 protected:
-    void autoCompletionBegan();
+    void autoCompletionBegan(de::String const &prefix);
     void autoCompletionEnded(bool accepted);
 
 signals:

doomsday/client/src/ui/widgets/consolecommandwidget.cpp

@@ -162,7 +162,7 @@ bool ConsoleCommandWidget::handleEvent(Event const &event)
     return false;
 }
 
-void ConsoleCommandWidget::autoCompletionBegan()
+void ConsoleCommandWidget::autoCompletionBegan(String const &)
 {
     // Prepare a list of annotated completions to show in the popup.
     QStringList const compls = suggestedCompletions();

doomsday/libshell/include/de/shell/abstractlineeditor.h

@@ -127,7 +127,7 @@ class LIBSHELL_PUBLIC AbstractLineEditor : public ITextEditor
     virtual void numberOfLinesChanged(int lineCount) = 0;
     virtual void cursorMoved() = 0;
     virtual void contentChanged() = 0;
-    virtual void autoCompletionBegan();
+    virtual void autoCompletionBegan(String const &wordBase);
     virtual void autoCompletionEnded(bool accepted);
 
     enum LineWrapUpdateBehavior {

doomsday/libshell/src/abstractlineeditor.cpp

@@ -50,12 +50,16 @@ DENG2_PIMPL(AbstractLineEditor)
     };
     Completion completion;
     QStringList suggestions;
+    bool suggesting;
+    bool completionNotified;
 
     Instance(Public *i, ILineWrapping *lineWraps)
         : Base(i),
           cursor(0),
           echoMode(NormalEchoMode),
-          wraps(lineWraps)
+          wraps(lineWraps),
+          suggesting(false),
+          completionNotified(false)
     {
         // Initialize line wrapping.
         completion.reset();
@@ -158,11 +162,8 @@ DENG2_PIMPL(AbstractLineEditor)
 
     void doBackspace()
     {
-        if(suggestingCompletion())
-        {
-            rejectCompletion();
+        if(rejectCompletion())
             return;
-        }
 
         if(!text.isEmpty() && cursor > 0)
         {
@@ -264,17 +265,23 @@ DENG2_PIMPL(AbstractLineEditor)
 
     bool suggestingCompletion() const
     {
-        return completion.size > 0;
+        return suggesting;
+        //return completion.size > 0;
     }
 
-    String wordBehindCursor() const
+    String wordBehindPos(int pos) const
     {
         String word;
-        int i = cursor - 1;
+        int i = pos - 1;
         while(i >= 0 && lexicon.isWordChar(text[i])) word.prepend(text[i--]);
         return word;
     }
 
+    String wordBehindCursor() const
+    {
+        return wordBehindPos(cursor);
+    }
+
     QStringList completionsForBase(String base, String &commonPrefix) const
     {
         bool first = true;
@@ -306,6 +313,7 @@ DENG2_PIMPL(AbstractLineEditor)
     {
         if(!suggestingCompletion())
         {
+            completionNotified = false;
             String const base = wordBehindCursor();
             if(!base.isEmpty())
             {
@@ -322,26 +330,37 @@ DENG2_PIMPL(AbstractLineEditor)
                     text.insert(cursor, commonPrefix);
                     cursor += completion.size;
                     rewrapNow();
-                    self.autoCompletionBegan();
+                    suggesting = true;
                     return true;
                 }
                 if(!suggestions.isEmpty())
                 {
-                    completion.ordinal = (forwardCycle? 0 : suggestions.size() - 1);
-                    String comp = suggestions[completion.ordinal];
-                    comp.remove(0, base.size());
+                    completion.ordinal = -1; //(forwardCycle? 0 : suggestions.size() - 1);
+                    /*String comp = suggestions[completion.ordinal];
+                    comp.remove(0, base.size());*/
                     completion.pos = cursor;
-                    completion.size = comp.size();
-                    text.insert(cursor, comp);
-                    cursor += completion.size;
-                    rewrapNow();
-                    self.autoCompletionBegan();
+                    completion.size = 0; //comp.size();
+                    //text.insert(cursor, comp);
+                    //cursor += completion.size;
+                    //rewrapNow();
+                    suggesting = true;
+                    // Notify immediately.
+                    self.autoCompletionBegan(base);
+                    completionNotified = true;
                     return true;
                 }
             }
         }
         else
         {
+            if(!completionNotified)
+            {
+                // Time to notify now.
+                self.autoCompletionBegan(wordBehindPos(completion.pos));
+                completionNotified = true;
+                return true;
+            }
+
             // Replace the current completion with another suggestion.
             cursor = completion.pos;
             String const base = wordBehindCursor();
@@ -371,6 +390,7 @@ DENG2_PIMPL(AbstractLineEditor)
             completion.size = comp.size();
             cursor = completion.pos + completion.size;
             rewrapNow();
+
             return true;
         }
         return false;
@@ -386,6 +406,8 @@ DENG2_PIMPL(AbstractLineEditor)
     {
         completion.reset();
         suggestions.clear();
+        suggesting = false;
+        completionNotified = false;
     }
 
     void acceptCompletion()
@@ -397,14 +419,20 @@ DENG2_PIMPL(AbstractLineEditor)
         self.autoCompletionEnded(true);
     }
 
-    void rejectCompletion()
+    bool rejectCompletion()
     {
+        if(!suggestingCompletion()) return false;
+
+        int oldCursor = cursor;
+
         text.remove(completion.pos, completion.size);
         cursor = completion.pos;
         resetCompletion();
         rewrapNow();
 
         self.autoCompletionEnded(false);
+
+        return cursor != oldCursor; // cursor was moved as part of the rejection
     }
 };
 
@@ -609,7 +637,7 @@ ILineWrapping &AbstractLineEditor::lineWraps()
     return *d->wraps;
 }
 
-void AbstractLineEditor::autoCompletionBegan()
+void AbstractLineEditor::autoCompletionBegan(String const &)
 {}
 
 void AbstractLineEditor::autoCompletionEnded(bool /*accepted*/)