--- a/gui-main.cpp	Thu May 23 11:26:44 2019 -0400
+++ b/gui-main.cpp	Thu May 23 12:36:26 2019 -0400
@@ -6,383 +6,19 @@
 #include <cstring>
 
 #include <QApplication>
-#include <QKeyEvent>
-#include <QTextDocument>
-#include <QTextEdit>
-#include <QTimer>
 
-#include "gui-main.h"
-#include "main.h"
-
+#include "command-window.h"
 #include "gui-main.h"
-#include "interpreter.h"
-#include "parser.h"
-
-#include <readline/readline.h>
-#include <readline/history.h>
-
-namespace gui
-{
-  static int available_char = 0;
-
-  static command_window *calc_interaction_window = 0;
-
-  static inline int ctrl (int c)
-  {
-    return c & 0x1f;
-  }
-
-  static int getc (FILE *)
-  {
-    int tmp = available_char;
-    available_char = 0;
-    return tmp;
-  }
-
-  static void redisplay (void)
-  {
-    if (calc_interaction_window)
-      emit calc_interaction_window->redisplay_signal ();
-  }
-
-  static void prep_term (int)
-  {
-  }
-
-  static void deprep_term (void)
-  {
-  }
-
-  static void accept_line (char *line)
-  {
-    if (calc_interaction_window)
-      calc_interaction_window->accept_line (line ? line : "");
-  }
-
-  static void display_completion_matches (char **matches, int num_matches,
-                                          int /* max_length */)
-  {
-    if (calc_interaction_window)
-      {
-        std::ostringstream buf;
-
-        if (num_matches > 1)
-          buf << "\n";
-
-        for (int i = 1; i < num_matches; i++)
-          buf << matches[i] << "\n";
-
-        calc_interaction_window->insert_at_end (buf.str ());
-
-        emit calc_interaction_window->redisplay_signal ();
-      }
-  }
-
-  static void readline_init (void)
-  {
-    rl_initialize ();
-
-    rl_getc_function = getc;
-    rl_redisplay_function = redisplay;
-    rl_prep_term_function = prep_term;
-    rl_deprep_term_function = deprep_term;
-    rl_completion_display_matches_hook = display_completion_matches;
-
-    rl_callback_handler_install (">> ", accept_line);
-  }
-
-  static void readline_fini (void)
-  {
-    rl_callback_handler_remove ();
-  }
-
-  command_window::command_window (QWidget *p)
-    : QTextEdit (p),
-      m_buffer (new QTextDocument ()),
-      m_interpreter (new calc::qt_interpreter ()),
-      beg_mark (), prompt_mark ()
-  {
-    setWindowTitle ("Qt::TextEdit example");
-
-    setMinimumSize (QSize (600, 400));
-
-    setDocument (m_buffer);
-
-    connect (m_interpreter, SIGNAL (result_ready (double)),
-             this, SLOT (handle_result (double)));
-
-    connect (m_interpreter, SIGNAL (error_signal (const QString&)),
-             this, SLOT (handle_error (const QString&)));
-
-    connect (this, SIGNAL (input_char_available (int)),
-             this, SLOT (handle_input_char (int)));
-
-    connect (this, SIGNAL (redisplay_signal (void)),
-             this, SLOT (redisplay (void)));
-
-    connect (this, SIGNAL (accept_line_signal (const QString&)),
-             m_interpreter, SLOT (accept_input_line (const QString&)));
-
-    insert_at_end
-      ("Qt Example Calculator.\n"
-       "Available operations: + - * / ^ ()\n"
-       "Semicolon terminates statement.\n"
-       "Up Arrow key moves to previous line in the command history.\n"
-       "Down Arrow key moves to next line in the comand history.\n\n");
-
-    beg_mark = set_mark ();
-
-    // Defer initializing and executing the interpreter until after the main
-    // window and QApplication are running to prevent race conditions
-    QTimer::singleShot (0, m_interpreter, SLOT (execute (void)));
-  }
-
-  // Accept an input line, parse and possibly execute it.
-
-  void command_window::accept_line (const std::string& line)
-  {
-    if (calc::debug_mode)
-      std::cerr << "accept: " << line << std::endl;
-
-    insert_at_end ("\n");
-
-    if (! line.empty ())
-      {
-        add_history (line.c_str ());
-        using_history ();
-
-        emit accept_line_signal (QString::fromStdString (line));
-      }
-  }
-
-  void command_window::insert_at_end (const std::string& text)
-  {
-    scroll_to_bottom ();
-
-    insert_at_cursor (text);
-  }
-
-  void command_window::handle_error (const QString& msg)
-  {
-    insert_at_end ("parse error: " + msg.toStdString () + "\n");
-
-    rl_abort (0, 0);
-  }
-
-  // FIXME: do we really need this extra function?
-  void command_window::handle_result (double value)
-  {
-    insert_result (value);
-  }
-
-  // Redisplay current command line.
-
-  void command_window::redisplay (void)
-  {
-    erase_line ();
-
-    std::string line = rl_line_buffer ? rl_line_buffer : "";
-    std::string prompt = (rl_prompt && parser::beg_of_stmt) ? rl_prompt : "";
-
-    insert_line (prompt, line);
-
-    scroll_to_bottom ();
-
-    QTextCursor cursor = textCursor ();
-
-    cursor.setPosition (prompt_mark + rl_point, QTextCursor::MoveAnchor);
 
-    setTextCursor (cursor);
-  }
-
-  void command_window::keyPressEvent (QKeyEvent *event)
-  {
-    if (! event)
-      return;
-
-    if (event->type () == QEvent::KeyPress)
-      {
-        int key = event->key ();
-
-        switch (key)
-          {
-          case Qt::Key_Return:
-            key = 0x0A;
-            break;
-
-          case Qt::Key_Backspace:
-            key = 0x08;
-            break;
-
-          case Qt::Key_Tab:
-            key = 0x09;
-            break;
-
-          case Qt::Key_Escape:
-            key = 0x1b;
-            break;
-
-          case Qt::Key_Up:
-          case Qt::Key_Down:
-          case Qt::Key_Right:
-          case Qt::Key_Left:
-            key = do_arrow_key (key);
-            break;
-
-          default:
-            {
-              switch (event->modifiers ())
-                {
-                case Qt::ControlModifier:
-                  if (key > 0x3f && key < 0x7b)
-                    key &= 0x1f;
-                  else
-                    key = -1;
-                  break;
-
-                default:
-                  {
-                    // Don't shoot me, this is just a demo...
-                    QString text = event->text ();
-                    QByteArray latin_text = text.toLatin1 ();
-                    key = latin_text[0];
-                  }
-                  break;
-                }
-            }
-            break;
-          }
-
-        if (key >= 0)
-          emit input_char_available (key);
-      }
-  }
-
-  void command_window::handle_input_char (int key)
-  {
-    available_char = key;
-    rl_callback_read_char ();
-  }
-
-  int command_window::do_arrow_key (int arrow_key)
-  {
-    int retval = 0;
-
-    available_char = 0x1b;
-    rl_callback_read_char ();
-
-    available_char = '[';
-    rl_callback_read_char ();
-
-    switch (arrow_key)
-      {
-      case Qt::Key_Up:
-        retval = 'A';
-        break;
-
-      case Qt::Key_Down:
-        retval = 'B';
-        break;
-
-      case Qt::Key_Right:
-        retval = 'C';
-        break;
-
-      case Qt::Key_Left:
-        retval = 'D';
-        break;
-      }
-
-    return retval;
-  }
-
-  // Retrieve a command from the history list and insert it on the
-  // current command.
-
-  void command_window::history (bool up)
-  {
-    HIST_ENTRY *entry = up ? previous_history () : next_history ();
-
-    if (entry)
-      {
-        erase_line ();
-
-        std::string prompt = rl_prompt ? rl_prompt : "";
-
-        insert_line (prompt, entry->line);
-      }
-    else if (! up)
-      erase_line ();
-
-    scroll_to_bottom ();
-  }
-
-  void command_window::erase_line (void)
-  {
-    QTextCursor cursor = textCursor ();
-
-    cursor.movePosition (QTextCursor::End);
-    cursor.select (QTextCursor::LineUnderCursor);
-    cursor.removeSelectedText ();
-
-    setTextCursor (cursor);
-  }
-
-  void command_window::insert_at_cursor (const std::string& text)
-  {
-    QTextCursor cursor = textCursor ();
-
-    cursor.insertText (QString::fromStdString (text));
-
-    setTextCursor (cursor);
-  }
-
-  void command_window::insert_line (const std::string& prompt,
-                                    const std::string& line)
-  {
-    beg_mark = set_mark ();
-
-    insert_at_cursor (prompt);
-
-    prompt_mark = set_mark ();
-
-    insert_at_cursor (line);
-  }
-
-  int command_window::set_mark (void)
-  {
-    return textCursor ().position ();
-  }
-
-  void command_window::insert_result (double value)
-  {
-    std::ostringstream buf;
-
-    buf << "ans = " << value << "\n";
-
-    insert_at_cursor (buf.str ());
-
-    beg_mark = set_mark ();
-
-    scroll_to_bottom ();
-  }
-
-  void command_window::scroll_to_bottom (void)
-  {
-    QTextCursor cursor = textCursor ();
-
-    cursor.movePosition (QTextCursor::End);
-
-    setTextCursor (cursor);
-  }
-
-  int main (int argc, char *argv[])
+namespace calc
+{
+  int gui_main (int argc, char *argv[])
   {
     QApplication app (argc, argv);
 
-    calc_interaction_window = new command_window ();
+    command_window command_window;
 
-    calc_interaction_window->show ();
+    command_window.show ();
 
     readline_init ();
 
@@ -393,69 +29,3 @@
     return status;
   }
 }
-
-// -- Variable: rl_getc_func_t * rl_getc_function
-//     If non-zero, Readline will call indirectly through this pointer to
-//     get a character from the input stream.  By default, it is set to
-//     `rl_getc', the default Readline character input function (*note
-//     Character Input::).
-
-// -- Variable: rl_voidfunc_t * rl_redisplay_function
-//     If non-zero, Readline will call indirectly through this pointer to
-//     update the display with the current contents of the editing buffer.
-//     By default, it is set to `rl_redisplay', the default Readline
-//     redisplay function (*note Redisplay::).
-
-// -- Variable: rl_vintfunc_t * rl_prep_term_function
-//     If non-zero, Readline will call indirectly through this pointer to
-//     initialize the terminal.  The function takes a single argument, an
-//     `int' flag that says whether or not to use eight-bit characters.
-//     By default, this is set to `rl_prep_terminal' (*note Terminal
-//     Management::).
-
-// -- Variable: rl_voidfunc_t * rl_deprep_term_function
-//     If non-zero, Readline will call indirectly through this pointer to
-//     reset the terminal.  This function should undo the effects of
-//     `rl_prep_term_function'.  By default, this is set to
-//     `rl_deprep_terminal' (*note Terminal Management::).
-
-// -- Function: void rl_callback_handler_install (const char *prompt,
-//          rl_vcpfunc_t *lhandler)
-//     Set up the terminal for readline I/O and display the initial
-//     expanded value of PROMPT.  Save the value of LHANDLER to use as a
-//     function to call when a complete line of input has been entered.
-//     The function takes the text of the line as an argument.
-
-// -- Function: void rl_callback_read_char (void)
-//     Whenever an application determines that keyboard input is
-//     available, it should call `rl_callback_read_char()', which will
-//     read the next character from the current input source.  If that
-//     character completes the line, `rl_callback_read_char' will invoke
-//     the LHANDLER function saved by `rl_callback_handler_install' to
-//     process the line.  Before calling the LHANDLER function, the
-//     terminal settings are reset to the values they had before calling
-//     `rl_callback_handler_install'.  If the LHANDLER function returns,
-//     the terminal settings are modified for Readline's use again.
-//     `EOF' is  indicated by calling LHANDLER with a `NULL' line.
-
-// -- Function: void rl_callback_handler_remove (void)
-//     Restore the terminal to its initial state and remove the line
-//     handler.  This may be called from within a callback as well as
-//     independently.  If the LHANDLER installed by
-//     `rl_callback_handler_install' does not exit the program, either
-//     this function or the function referred to by the value of
-//     `rl_deprep_term_function' should be called before the program
-//     exits to reset the terminal settings.
-
-// -- Variable: rl_compdisp_func_t * rl_completion_display_matches_hook
-//     If non-zero, then this is the address of a function to call when
-//     completing a word would normally display the list of possible
-//     matches.  This function is called in lieu of Readline displaying
-//     the list.  It takes three arguments: (`char **'MATCHES, `int'
-//     NUM_MATCHES, `int' MAX_LENGTH) where MATCHES is the array of
-//     matching strings, NUM_MATCHES is the number of strings in that
-//     array, and MAX_LENGTH is the length of the longest string in that
-//     array.  Readline provides a convenience function,
-//     `rl_display_match_list', that takes care of doing the display to
-//     Readline's output stream.  That function may be called from this
-//     hook.