Model, View and Controller for a Gap Buffer based one line text field in view...

views/controls/textfield/textfield_model.h

Index: views/controls/textfield/textfield_model.h
diff --git a/views/controls/textfield/textfield_model.h b/views/controls/textfield/textfield_model.h
new file mode 100644
index 0000000000000000000000000000000000000000..98a02376c9c82f8d61b9d3b40c3904bb0489e779
--- /dev/null
+++ b/views/controls/textfield/textfield_model.h
@@ -0,0 +1,78 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_MODEL_H_
+#define VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_MODEL_H_
+#pragma once
+
+#include <string>
+#include <vector>

[tfarina, 2010/11/18 11:55:31]

It seems you don't need this include also.

+
+#include "base/gap_buffer.h"
+#include "views/event.h"

[tfarina, 2010/11/18 11:55:31]

It seems you don't need this include here.

+
+namespace views {
+
+// Model for a single line textfield. It uses a gap buffer under the hood to
+// store data and perform cursor movement.
+class TextfieldModel {
+ public:
+  TextfieldModel();
+  explicit TextfieldModel(const std::wstring& text);
+
+  // Inserts a character at the current cursor position.
+  void Insert(wchar_t c);
+
+  // Deletes the first character after the current cursor position (as if, the
+  // the user has pressed delete key in the textfield).
+  wchar_t InsertDelete();
+
+  // Deletes the first character before the current cursor position (as if, the
+  // the user has pressed backspace key in the textfield).
+  wchar_t InsertBackspace();
+
+  // Returns the current cursor position.
+  int GetCurrentCursorPos();
+
+  // Moves the cursor left by one position (as if, the user has pressed the left
+  // arrow key).
+  void MoveCursorLeft();
+
+  // Moves the cursor right by one position (as if, the user has pressed the
+  // right arrow key).
+  void MoveCursorRight();
+
+  // Moves the cursor left by one word (word boundry is defined by space).
+  void MoveCursorToPreviousWord();
+
+  // Moves the cursor right by one word (word boundry is defined by space).
+  void MoveCursorToNextWord();
+
+  // Moves the cursor to start of the textfield contents.
+  void MoveCursorToStart();
+
+  // Moves the cursor to end of the textfield contents.
+  void MoveCursorToEnd();
+
+  // Returns the current contents of the textfield model.
+  std::wstring text();

[tfarina, 2010/11/18 11:55:31]

Since this is not a trivial getter, can you name this as GetText? Also, since
you are returning |text_| can you write this as:
const std::wstring& GetText() const;

+
+ private:
+  // Synchronizes this model's member field "text_" with the contents of the
+  // underlying gap buffer. The need for synchronization is determined by the
+  // "dirty_" flag.
+  void SyncText();
+
+  scoped_ptr<base::GapBuffer<wchar_t> > buffer_;
+  std::wstring text_;
+  bool dirty_;
+};

[tfarina, 2010/11/18 11:55:31]

DISALLOW_COPY_AND_ASSIGN?

+
+class TextfieldController {

[tfarina, 2010/11/18 11:55:31]

Can you name this TextfieldDelegate or even TextfieldListener? So this match
with other examples in views.

[tfarina, 2010/11/18 11:55:31]

I'd also move this above, before the TextfieldModel class, or move inside it.
Your call.

[Ben Goodger (Google), 2010/11/18 15:52:45]

TextfieldDelegate doesn't make sense... it's not doing work on behalf of the
Textfield. Listener perhaps, but I am not sure what other responsibilities this
interface will take on as this code evolves.

+ public:
+  virtual ~TextfieldController();

[tfarina, 2010/11/18 11:55:31]

add a {} here?

+  virtual void TextChanged(const std::wstring new_text);

[tfarina, 2010/11/18 11:55:31]

It looks like this class is an interface. I think this virtual method needs to
be a pure virtual method instead, so please add = 0; here.

+};
+};

[tfarina, 2010/11/18 11:55:31]

// namespace views

Also don't need the ; here

+#endif  // VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_MODEL_H_