ui/views/controls/textfield/textfield

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This source file includes following definitions.
Undo
Redo
Merge
Commit
new_text_start_
type
mergeable
merge_with_previous
old_text_end
new_text_end
MergeReplace
DoMerge
DoMerge
DoMerge
GetFirstEmphasizedRange
current_edit_
SetText
Append
Delete
Backspace
GetCursorPosition
MoveCursor
MoveCursorTo
MoveCursorTo
GetSelectedText
SelectRange
SelectSelectionModel
SelectAll
SelectWord
ClearSelection
CanUndo
CanRedo
Undo
Redo
Cut
Copy
Paste
HasSelection
DeleteSelection
DeleteSelectionAndInsertTextAt
GetTextFromRange
GetTextRange
SetCompositionText
ConfirmCompositionText
CancelCompositionText
ClearComposition
GetCompositionTextRange
HasCompositionText
ClearEditHistory
InsertTextInternal
ReplaceTextInternal
ClearRedoHistory
ExecuteAndRecordDelete
ExecuteAndRecordReplaceSelection
ExecuteAndRecordReplace
ExecuteAndRecordInsert
AddOrMergeEditHistory
ModifyText
// Copyright 2014 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.

#include "ui/views/controls/textfield/textfield_model.h"

#include <algorithm>

#include "base/i18n/break_iterator.h"
#include "base/logging.h"
#include "base/stl_util.h"
#include "base/strings/utf_string_conversions.h"
#include "ui/base/clipboard/clipboard.h"
#include "ui/base/clipboard/scoped_clipboard_writer.h"
#include "ui/gfx/canvas.h"
#include "ui/gfx/font.h"
#include "ui/gfx/range/range.h"
#include "ui/gfx/render_text.h"
#include "ui/gfx/text_constants.h"
#include "ui/gfx/utf16_indexing.h"
#include "ui/views/controls/textfield/textfield.h"

namespace views {

namespace internal {

// An edit object holds enough information/state to undo/redo the
// change. Two edits are merged when possible, for example, when
// you type new characters in sequence.  |Commit()| can be used to
// mark an edit as an independent edit and it shouldn't be merged.
// (For example, when you did undo/redo, or a text is appended via
// API)
class Edit {
 public:
  enum Type {
    INSERT_EDIT,
    DELETE_EDIT,
    REPLACE_EDIT
  };

  virtual ~Edit() {
  }

  // Revert the change made by this edit in |model|.
  void Undo(TextfieldModel* model) {
    model->ModifyText(new_text_start_, new_text_end(),
                      old_text_, old_text_start_,
                      old_cursor_pos_);
  }

  // Apply the change of this edit to the |model|.
  void Redo(TextfieldModel* model) {
    model->ModifyText(old_text_start_, old_text_end(),
                      new_text_, new_text_start_,
                      new_cursor_pos_);
  }

  // Try to merge the |edit| into this edit. Returns true if merge was
  // successful, or false otherwise. Merged edit will be deleted after
  // redo and should not be reused.
  bool Merge(const Edit* edit) {
    // Don't merge if previous edit is DELETE. This happens when a
    // user deletes characters then hits return. In this case, the
    // delete should be treated as separate edit that can be undone
    // and should not be merged with the replace edit.
    if (type_ != DELETE_EDIT && edit->merge_with_previous()) {
      MergeReplace(edit);
      return true;
    }
    return mergeable() && edit->mergeable() && DoMerge(edit);
  }

  // Commits the edit and marks as un-mergeable.
  void Commit() { merge_type_ = DO_NOT_MERGE; }

 private:
  friend class InsertEdit;
  friend class ReplaceEdit;
  friend class DeleteEdit;

  Edit(Type type,
       MergeType merge_type,
       size_t old_cursor_pos,
       const base::string16& old_text,
       size_t old_text_start,
       bool delete_backward,
       size_t new_cursor_pos,
       const base::string16& new_text,
       size_t new_text_start)
      : type_(type),
        merge_type_(merge_type),
        old_cursor_pos_(old_cursor_pos),
        old_text_(old_text),
        old_text_start_(old_text_start),
        delete_backward_(delete_backward),
        new_cursor_pos_(new_cursor_pos),
        new_text_(new_text),
        new_text_start_(new_text_start) {
  }

  // A template method pattern that provides specific merge
  // implementation for each type of edit.
  virtual bool DoMerge(const Edit* edit) = 0;

  Type type() const { return type_; }

  // Can this edit be merged?
  bool mergeable() const { return merge_type_ == MERGEABLE; }

  // Should this edit be forcibly merged with the previous edit?
  bool merge_with_previous() const {
    return merge_type_ == MERGE_WITH_PREVIOUS;
  }

  // Returns the end index of the |old_text_|.
  size_t old_text_end() const { return old_text_start_ + old_text_.length(); }

  // Returns the end index of the |new_text_|.
  size_t new_text_end() const { return new_text_start_ + new_text_.length(); }

  // Merge the replace edit into the current edit. This is a special case to
  // handle an omnibox setting autocomplete string after new character is
  // typed in.
  void MergeReplace(const Edit* edit) {
    CHECK_EQ(REPLACE_EDIT, edit->type_);
    CHECK_EQ(0U, edit->old_text_start_);
    CHECK_EQ(0U, edit->new_text_start_);
    base::string16 old_text = edit->old_text_;
    old_text.erase(new_text_start_, new_text_.length());
    old_text.insert(old_text_start_, old_text_);
    // SetText() replaces entire text. Set |old_text_| to the entire
    // replaced text with |this| edit undone.
    old_text_ = old_text;
    old_text_start_ = edit->old_text_start_;
    delete_backward_ = false;

    new_text_ = edit->new_text_;
    new_text_start_ = edit->new_text_start_;
    merge_type_ = DO_NOT_MERGE;
  }

  Type type_;

  // True if the edit can be marged.
  MergeType merge_type_;
  // Old cursor position.
  size_t old_cursor_pos_;
  // Deleted text by this edit.
  base::string16 old_text_;
  // The index of |old_text_|.
  size_t old_text_start_;
  // True if the deletion is made backward.
  bool delete_backward_;
  // New cursor position.
  size_t new_cursor_pos_;
  // Added text.
  base::string16 new_text_;
  // The index of |new_text_|
  size_t new_text_start_;

  DISALLOW_COPY_AND_ASSIGN(Edit);
};

class InsertEdit : public Edit {
 public:
  InsertEdit(bool mergeable, const base::string16& new_text, size_t at)
      : Edit(INSERT_EDIT,
             mergeable ? MERGEABLE : DO_NOT_MERGE,
             at  /* old cursor */,
             base::string16(),
             at,
             false  /* N/A */,
             at + new_text.length()  /* new cursor */,
             new_text,
             at) {
  }

  // Edit implementation.
  virtual bool DoMerge(const Edit* edit) OVERRIDE {
    if (edit->type() != INSERT_EDIT || new_text_end() != edit->new_text_start_)
      return false;
    // If continuous edit, merge it.
    // TODO(oshima): gtk splits edits between whitespace. Find out what
    // we want to here and implement if necessary.
    new_text_ += edit->new_text_;
    new_cursor_pos_ = edit->new_cursor_pos_;
    return true;
  }
};

class ReplaceEdit : public Edit {
 public:
  ReplaceEdit(MergeType merge_type,
              const base::string16& old_text,
              size_t old_cursor_pos,
              size_t old_text_start,
              bool backward,
              size_t new_cursor_pos,
              const base::string16& new_text,
              size_t new_text_start)
      : Edit(REPLACE_EDIT, merge_type,
             old_cursor_pos,
             old_text,
             old_text_start,
             backward,
             new_cursor_pos,
             new_text,
             new_text_start) {
  }

  // Edit implementation.
  virtual bool DoMerge(const Edit* edit) OVERRIDE {
    if (edit->type() == DELETE_EDIT ||
        new_text_end() != edit->old_text_start_ ||
        edit->old_text_start_ != edit->new_text_start_)
      return false;
    old_text_ += edit->old_text_;
    new_text_ += edit->new_text_;
    new_cursor_pos_ = edit->new_cursor_pos_;
    return true;
  }
};

class DeleteEdit : public Edit {
 public:
  DeleteEdit(bool mergeable,
             const base::string16& text,
             size_t text_start,
             bool backward)
      : Edit(DELETE_EDIT,
             mergeable ? MERGEABLE : DO_NOT_MERGE,
             (backward ? text_start + text.length() : text_start),
             text,
             text_start,
             backward,
             text_start,
             base::string16(),
             text_start) {
  }

  // Edit implementation.
  virtual bool DoMerge(const Edit* edit) OVERRIDE {
    if (edit->type() != DELETE_EDIT)
      return false;

    if (delete_backward_) {
      // backspace can be merged only with backspace at the
      // same position.
      if (!edit->delete_backward_ || old_text_start_ != edit->old_text_end())
        return false;
      old_text_start_ = edit->old_text_start_;
      old_text_ = edit->old_text_ + old_text_;
      new_cursor_pos_ = edit->new_cursor_pos_;
    } else {
      // delete can be merged only with delete at the same
      // position.
      if (edit->delete_backward_ || old_text_start_ != edit->old_text_start_)
        return false;
      old_text_ += edit->old_text_;
    }
    return true;
  }
};

}  // namespace internal

namespace {

// Returns the first segment that is visually emphasized. Usually it's used for
// representing the target clause (on Windows). Returns an invalid range if
// there is no such a range.
gfx::Range GetFirstEmphasizedRange(const ui::CompositionText& composition) {
  for (size_t i = 0; i < composition.underlines.size(); ++i) {
    const ui::CompositionUnderline& underline = composition.underlines[i];
    if (underline.thick)
      return gfx::Range(underline.start_offset, underline.end_offset);
  }
  return gfx::Range::InvalidRange();
}

}  // namespace

using internal::Edit;
using internal::DeleteEdit;
using internal::InsertEdit;
using internal::ReplaceEdit;
using internal::MergeType;
using internal::DO_NOT_MERGE;
using internal::MERGE_WITH_PREVIOUS;
using internal::MERGEABLE;

/////////////////////////////////////////////////////////////////
// TextfieldModel: public

TextfieldModel::Delegate::~Delegate() {
}

TextfieldModel::TextfieldModel(Delegate* delegate)
    : delegate_(delegate),
      render_text_(gfx::RenderText::CreateInstance()),
      current_edit_(edit_history_.end()) {
}

TextfieldModel::~TextfieldModel() {
  ClearEditHistory();
  ClearComposition();
}

bool TextfieldModel::SetText(const base::string16& new_text) {
  bool changed = false;
  if (HasCompositionText()) {
    ConfirmCompositionText();
    changed = true;
  }
  if (text() != new_text) {
    if (changed)  // No need to remember composition.
      Undo();
    size_t old_cursor = GetCursorPosition();
    // SetText moves the cursor to the end.
    size_t new_cursor = new_text.length();
    SelectAll(false);
    // If there is a composition text, don't merge with previous edit.
    // Otherwise, force merge the edits.
    ExecuteAndRecordReplace(
        changed ? DO_NOT_MERGE : MERGE_WITH_PREVIOUS,
        old_cursor,
        new_cursor,
        new_text,
        0U);
    render_text_->SetCursorPosition(new_cursor);
  }
  ClearSelection();
  return changed;
}

void TextfieldModel::Append(const base::string16& new_text) {
  if (HasCompositionText())
    ConfirmCompositionText();
  size_t save = GetCursorPosition();
  MoveCursor(gfx::LINE_BREAK,
             render_text_->GetVisualDirectionOfLogicalEnd(),
             false);
  InsertText(new_text);
  render_text_->SetCursorPosition(save);
  ClearSelection();
}

bool TextfieldModel::Delete() {
  if (HasCompositionText()) {
    // No undo/redo for composition text.
    CancelCompositionText();
    return true;
  }
  if (HasSelection()) {
    DeleteSelection();
    return true;
  }
  if (text().length() > GetCursorPosition()) {
    size_t cursor_position = GetCursorPosition();
    size_t next_grapheme_index = render_text_->IndexOfAdjacentGrapheme(
        cursor_position, gfx::CURSOR_FORWARD);
    ExecuteAndRecordDelete(gfx::Range(cursor_position, next_grapheme_index),
                           true);
    return true;
  }
  return false;
}

bool TextfieldModel::Backspace() {
  if (HasCompositionText()) {
    // No undo/redo for composition text.
    CancelCompositionText();
    return true;
  }
  if (HasSelection()) {
    DeleteSelection();
    return true;
  }
  size_t cursor_position = GetCursorPosition();
  if (cursor_position > 0) {
    // Delete one code point, which may be two UTF-16 words.
    size_t previous_char = gfx::UTF16OffsetToIndex(text(), cursor_position, -1);
    ExecuteAndRecordDelete(gfx::Range(cursor_position, previous_char), true);
    return true;
  }
  return false;
}

size_t TextfieldModel::GetCursorPosition() const {
  return render_text_->cursor_position();
}

void TextfieldModel::MoveCursor(gfx::BreakType break_type,
                                gfx::VisualCursorDirection direction,
                                bool select) {
  if (HasCompositionText())
    ConfirmCompositionText();
  render_text_->MoveCursor(break_type, direction, select);
}

bool TextfieldModel::MoveCursorTo(const gfx::SelectionModel& model) {
  if (HasCompositionText()) {
    ConfirmCompositionText();
    // ConfirmCompositionText() updates cursor position. Need to reflect it in
    // the SelectionModel parameter of MoveCursorTo().
    gfx::Range range(render_text_->selection().start(), model.caret_pos());
    if (!range.is_empty())
      return render_text_->SelectRange(range);
    return render_text_->MoveCursorTo(
        gfx::SelectionModel(model.caret_pos(), model.caret_affinity()));
  }
  return render_text_->MoveCursorTo(model);
}

bool TextfieldModel::MoveCursorTo(const gfx::Point& point, bool select) {
  if (HasCompositionText())
    ConfirmCompositionText();
  return render_text_->MoveCursorTo(point, select);
}

base::string16 TextfieldModel::GetSelectedText() const {
  return text().substr(render_text_->selection().GetMin(),
                       render_text_->selection().length());
}

void TextfieldModel::SelectRange(const gfx::Range& range) {
  if (HasCompositionText())
    ConfirmCompositionText();
  render_text_->SelectRange(range);
}

void TextfieldModel::SelectSelectionModel(const gfx::SelectionModel& sel) {
  if (HasCompositionText())
    ConfirmCompositionText();
  render_text_->MoveCursorTo(sel);
}

void TextfieldModel::SelectAll(bool reversed) {
  if (HasCompositionText())
    ConfirmCompositionText();
  render_text_->SelectAll(reversed);
}

void TextfieldModel::SelectWord() {
  if (HasCompositionText())
    ConfirmCompositionText();
  render_text_->SelectWord();
}

void TextfieldModel::ClearSelection() {
  if (HasCompositionText())
    ConfirmCompositionText();
  render_text_->ClearSelection();
}

bool TextfieldModel::CanUndo() {
  return edit_history_.size() && current_edit_ != edit_history_.end();
}

bool TextfieldModel::CanRedo() {
  if (!edit_history_.size())
    return false;
  // There is no redo iff the current edit is the last element
  // in the history.
  EditHistory::iterator iter = current_edit_;
  return iter == edit_history_.end() || // at the top.
      ++iter != edit_history_.end();
}

bool TextfieldModel::Undo() {
  if (!CanUndo())
    return false;
  DCHECK(!HasCompositionText());
  if (HasCompositionText())  // safe guard for release build.
    CancelCompositionText();

  base::string16 old = text();
  size_t old_cursor = GetCursorPosition();
  (*current_edit_)->Commit();
  (*current_edit_)->Undo(this);

  if (current_edit_ == edit_history_.begin())
    current_edit_ = edit_history_.end();
  else
    current_edit_--;
  return old != text() || old_cursor != GetCursorPosition();
}

bool TextfieldModel::Redo() {
  if (!CanRedo())
    return false;
  DCHECK(!HasCompositionText());
  if (HasCompositionText()) // safe guard for release build.
    CancelCompositionText();

  if (current_edit_ == edit_history_.end())
    current_edit_ = edit_history_.begin();
  else
    current_edit_ ++;
  base::string16 old = text();
  size_t old_cursor = GetCursorPosition();
  (*current_edit_)->Redo(this);
  return old != text() || old_cursor != GetCursorPosition();
}

bool TextfieldModel::Cut() {
  if (!HasCompositionText() && HasSelection() && !render_text_->obscured()) {
    ui::ScopedClipboardWriter(
        ui::Clipboard::GetForCurrentThread(),
        ui::CLIPBOARD_TYPE_COPY_PASTE).WriteText(GetSelectedText());
    // A trick to let undo/redo handle cursor correctly.
    // Undoing CUT moves the cursor to the end of the change rather
    // than beginning, unlike Delete/Backspace.
    // TODO(oshima): Change Delete/Backspace to use DeleteSelection,
    // update DeleteEdit and remove this trick.
    const gfx::Range& selection = render_text_->selection();
    render_text_->SelectRange(gfx::Range(selection.end(), selection.start()));
    DeleteSelection();
    return true;
  }
  return false;
}

bool TextfieldModel::Copy() {
  if (!HasCompositionText() && HasSelection() && !render_text_->obscured()) {
    ui::ScopedClipboardWriter(
        ui::Clipboard::GetForCurrentThread(),
        ui::CLIPBOARD_TYPE_COPY_PASTE).WriteText(GetSelectedText());
    return true;
  }
  return false;
}

bool TextfieldModel::Paste() {
  base::string16 result;
  ui::Clipboard::GetForCurrentThread()->ReadText(ui::CLIPBOARD_TYPE_COPY_PASTE,
                                                 &result);
  if (!result.empty()) {
    InsertTextInternal(result, false);
    return true;
  }
  return false;
}

bool TextfieldModel::HasSelection() const {
  return !render_text_->selection().is_empty();
}

void TextfieldModel::DeleteSelection() {
  DCHECK(!HasCompositionText());
  DCHECK(HasSelection());
  ExecuteAndRecordDelete(render_text_->selection(), false);
}

void TextfieldModel::DeleteSelectionAndInsertTextAt(
    const base::string16& new_text,
    size_t position) {
  if (HasCompositionText())
    CancelCompositionText();
  ExecuteAndRecordReplace(DO_NOT_MERGE,
                          GetCursorPosition(),
                          position + new_text.length(),
                          new_text,
                          position);
}

base::string16 TextfieldModel::GetTextFromRange(const gfx::Range& range) const {
  if (range.IsValid() && range.GetMin() < text().length())
    return text().substr(range.GetMin(), range.length());
  return base::string16();
}

void TextfieldModel::GetTextRange(gfx::Range* range) const {
  *range = gfx::Range(0, text().length());
}

void TextfieldModel::SetCompositionText(
    const ui::CompositionText& composition) {
  if (HasCompositionText())
    CancelCompositionText();
  else if (HasSelection())
    DeleteSelection();

  if (composition.text.empty())
    return;

  size_t cursor = GetCursorPosition();
  base::string16 new_text = text();
  render_text_->SetText(new_text.insert(cursor, composition.text));
  gfx::Range range(cursor, cursor + composition.text.length());
  render_text_->SetCompositionRange(range);
  gfx::Range emphasized_range = GetFirstEmphasizedRange(composition);
  if (emphasized_range.IsValid()) {
    // This is a workaround due to the lack of support in RenderText to draw
    // a thick underline. In a composition returned from an IME, the segment
    // emphasized by a thick underline usually represents the target clause.
    // Because the target clause is more important than the actual selection
    // range (or caret position) in the composition here we use a selection-like
    // marker instead to show this range.
    // TODO(yukawa, msw): Support thick underline in RenderText and remove
    // this workaround.
    render_text_->SelectRange(gfx::Range(
        cursor + emphasized_range.GetMin(),
        cursor + emphasized_range.GetMax()));
  } else if (!composition.selection.is_empty()) {
    render_text_->SelectRange(gfx::Range(
        cursor + composition.selection.GetMin(),
        cursor + composition.selection.GetMax()));
  } else {
    render_text_->SetCursorPosition(cursor + composition.selection.end());
  }
}

void TextfieldModel::ConfirmCompositionText() {
  DCHECK(HasCompositionText());
  gfx::Range range = render_text_->GetCompositionRange();
  base::string16 composition = text().substr(range.start(), range.length());
  // TODO(oshima): current behavior on ChromeOS is a bit weird and not
  // sure exactly how this should work. Find out and fix if necessary.
  AddOrMergeEditHistory(new InsertEdit(false, composition, range.start()));
  render_text_->SetCursorPosition(range.end());
  ClearComposition();
  if (delegate_)
    delegate_->OnCompositionTextConfirmedOrCleared();
}

void TextfieldModel::CancelCompositionText() {
  DCHECK(HasCompositionText());
  gfx::Range range = render_text_->GetCompositionRange();
  ClearComposition();
  base::string16 new_text = text();
  render_text_->SetText(new_text.erase(range.start(), range.length()));
  render_text_->SetCursorPosition(range.start());
  if (delegate_)
    delegate_->OnCompositionTextConfirmedOrCleared();
}

void TextfieldModel::ClearComposition() {
  render_text_->SetCompositionRange(gfx::Range::InvalidRange());
}

void TextfieldModel::GetCompositionTextRange(gfx::Range* range) const {
  *range = gfx::Range(render_text_->GetCompositionRange());
}

bool TextfieldModel::HasCompositionText() const {
  return !render_text_->GetCompositionRange().is_empty();
}

void TextfieldModel::ClearEditHistory() {
  STLDeleteElements(&edit_history_);
  current_edit_ = edit_history_.end();
}

/////////////////////////////////////////////////////////////////
// TextfieldModel: private

void TextfieldModel::InsertTextInternal(const base::string16& new_text,
                                        bool mergeable) {
  if (HasCompositionText()) {
    CancelCompositionText();
    ExecuteAndRecordInsert(new_text, mergeable);
  } else if (HasSelection()) {
    ExecuteAndRecordReplaceSelection(mergeable ? MERGEABLE : DO_NOT_MERGE,
                                     new_text);
  } else {
    ExecuteAndRecordInsert(new_text, mergeable);
  }
}

void TextfieldModel::ReplaceTextInternal(const base::string16& new_text,
                                         bool mergeable) {
  if (HasCompositionText()) {
    CancelCompositionText();
  } else if (!HasSelection()) {
    size_t cursor = GetCursorPosition();
    const gfx::SelectionModel& model = render_text_->selection_model();
    // When there is no selection, the default is to replace the next grapheme
    // with |new_text|. So, need to find the index of next grapheme first.
    size_t next =
        render_text_->IndexOfAdjacentGrapheme(cursor, gfx::CURSOR_FORWARD);
    if (next == model.caret_pos())
      render_text_->MoveCursorTo(model);
    else
      render_text_->SelectRange(gfx::Range(next, model.caret_pos()));
  }
  // Edit history is recorded in InsertText.
  InsertTextInternal(new_text, mergeable);
}

void TextfieldModel::ClearRedoHistory() {
  if (edit_history_.begin() == edit_history_.end())
    return;
  if (current_edit_ == edit_history_.end()) {
    ClearEditHistory();
    return;
  }
  EditHistory::iterator delete_start = current_edit_;
  delete_start++;
  STLDeleteContainerPointers(delete_start, edit_history_.end());
  edit_history_.erase(delete_start, edit_history_.end());
}

void TextfieldModel::ExecuteAndRecordDelete(gfx::Range range, bool mergeable) {
  size_t old_text_start = range.GetMin();
  const base::string16 old_text = text().substr(old_text_start, range.length());
  bool backward = range.is_reversed();
  Edit* edit = new DeleteEdit(mergeable, old_text, old_text_start, backward);
  bool delete_edit = AddOrMergeEditHistory(edit);
  edit->Redo(this);
  if (delete_edit)
    delete edit;
}

void TextfieldModel::ExecuteAndRecordReplaceSelection(
    MergeType merge_type,
    const base::string16& new_text) {
  size_t new_text_start = render_text_->selection().GetMin();
  size_t new_cursor_pos = new_text_start + new_text.length();
  ExecuteAndRecordReplace(merge_type,
                          GetCursorPosition(),
                          new_cursor_pos,
                          new_text,
                          new_text_start);
}

void TextfieldModel::ExecuteAndRecordReplace(MergeType merge_type,
                                             size_t old_cursor_pos,
                                             size_t new_cursor_pos,
                                             const base::string16& new_text,
                                             size_t new_text_start) {
  size_t old_text_start = render_text_->selection().GetMin();
  bool backward = render_text_->selection().is_reversed();
  Edit* edit = new ReplaceEdit(merge_type,
                               GetSelectedText(),
                               old_cursor_pos,
                               old_text_start,
                               backward,
                               new_cursor_pos,
                               new_text,
                               new_text_start);
  bool delete_edit = AddOrMergeEditHistory(edit);
  edit->Redo(this);
  if (delete_edit)
    delete edit;
}

void TextfieldModel::ExecuteAndRecordInsert(const base::string16& new_text,
                                            bool mergeable) {
  Edit* edit = new InsertEdit(mergeable, new_text, GetCursorPosition());
  bool delete_edit = AddOrMergeEditHistory(edit);
  edit->Redo(this);
  if (delete_edit)
    delete edit;
}

bool TextfieldModel::AddOrMergeEditHistory(Edit* edit) {
  ClearRedoHistory();

  if (current_edit_ != edit_history_.end() && (*current_edit_)->Merge(edit)) {
    // If a current edit exists and has been merged with a new edit,
    // don't add to the history, and return true to delete |edit| after
    // redo.
    return true;
  }
  edit_history_.push_back(edit);
  if (current_edit_ == edit_history_.end()) {
    // If there is no redoable edit, this is the 1st edit because
    // RedoHistory has been already deleted.
    DCHECK_EQ(1u, edit_history_.size());
    current_edit_ = edit_history_.begin();
  } else {
    current_edit_++;
  }
  return false;
}

void TextfieldModel::ModifyText(size_t delete_from,
                                size_t delete_to,
                                const base::string16& new_text,
                                size_t new_text_insert_at,
                                size_t new_cursor_pos) {
  DCHECK_LE(delete_from, delete_to);
  base::string16 old_text = text();
  ClearComposition();
  if (delete_from != delete_to)
    render_text_->SetText(old_text.erase(delete_from, delete_to - delete_from));
  if (!new_text.empty())
    render_text_->SetText(old_text.insert(new_text_insert_at, new_text));
  render_text_->SetCursorPosition(new_cursor_pos);
  // TODO(oshima): mac selects the text that is just undone (but gtk doesn't).
  // This looks fine feature and we may want to do the same.
}

}  // namespace views
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root/ui/views/controls/textfield/textfield_model.cc

DEFINITIONS
