menuconfig: Add a mode that shows invisible items

When show-all mode is enabled, all items in the current menu are shown,
including promptless and invisible items. Promptless items are shown
with their name within <> brackets in place of the prompt.

This will make it possible to jump to invisible items once the jump-to
feature is added. It is also a handy feature on its own.

.config loading from within the interface will make use of it as well,
in case the current menu becomes complete invisible.

Piggyback various code cleanups. Rename _visible* to _shown*, as it now
includes invisible items in show-all mode.

2 files changed, 166 insertions, 63 deletions

diff --git a/README.rst b/README.rst
index d71639c..5351e2d 100644
--- a/README.rst
+++ b/README.rst
@@ -242,6 +242,10 @@ Two configuration interfaces are currently available:
 
   .. image:: https://raw.githubusercontent.com/ulfalizer/Kconfiglib/screenshots/screenshots/ss6.png
 
+  "Show-all" mode, which includes promptless/invisible items:
+
+  .. image:: https://raw.githubusercontent.com/ulfalizer/Kconfiglib/screenshots/screenshots/ss9.png
+
   (Sorry about that yellow color. See the styling code at the top of
   ``menuconfig.py`` if you want to try to make it prettier. :))
 
diff --git a/menuconfig.py b/menuconfig.py
index 3f639fb..9377101 100755
--- a/menuconfig.py
+++ b/menuconfig.py
@@ -100,6 +100,7 @@ _N_SCROLL_ARROWS = 14
 _MAIN_HELP_LINES = """
 [Space/Enter] Toggle/enter   [ESC] Leave menu   [S] Save
 [M] Save minimal config      [?] Symbol info    [Q] Quit (prompts for save)
+[A] Toggle show-all mode
 """[1:-1].split("\n")
 
 # Lines of help text shown at the bottom of the information display
@@ -112,6 +113,8 @@ def _init_styles():
     global _TOP_SEP_STYLE
     global _MENU_LIST_STYLE
     global _MENU_LIST_SEL_STYLE
+    global _MENU_LIST_INVISIBLE_STYLE
+    global _MENU_LIST_INVISIBLE_SEL_STYLE
     global _BOT_SEP_STYLE
     global _HELP_STYLE
 
@@ -141,45 +144,53 @@ def _init_styles():
 
 
     # Top row, with menu path
-    _PATH_STYLE          = _style(curses.COLOR_BLACK, curses.COLOR_WHITE,  BOLD                              )
+    _PATH_STYLE                    = _style(curses.COLOR_BLACK, curses.COLOR_WHITE,  BOLD                              )
 
     # Separator below menu path, with title and arrows pointing up
-    _TOP_SEP_STYLE       = _style(curses.COLOR_BLACK, curses.COLOR_YELLOW, BOLD,            curses.A_STANDOUT)
+    _TOP_SEP_STYLE                 = _style(curses.COLOR_BLACK, curses.COLOR_YELLOW, BOLD,            curses.A_STANDOUT)
 
-    # The "main" menu display with the list of symbols, etc.
-    _MENU_LIST_STYLE     = _style(curses.COLOR_BLACK, curses.COLOR_WHITE,  curses.A_NORMAL                   )
+    # Non-selected visible (see show-all mode below) menu entry in the "main"
+    # menu display, which has the list of symbols, etc.
+    _MENU_LIST_STYLE               = _style(curses.COLOR_BLACK, curses.COLOR_WHITE,  curses.A_NORMAL                   )
 
-    # Selected menu entry
-    _MENU_LIST_SEL_STYLE = _style(curses.COLOR_WHITE, curses.COLOR_BLUE,   curses.A_NORMAL, curses.A_STANDOUT)
+    # Selected visible menu entry
+    _MENU_LIST_SEL_STYLE           = _style(curses.COLOR_WHITE, curses.COLOR_BLUE,   curses.A_NORMAL, curses.A_STANDOUT)
+
+    # Non-selected invisible menu entry in the main menu display, for show-all
+    # mode
+    _MENU_LIST_INVISIBLE_STYLE     = _style(curses.COLOR_RED,   curses.COLOR_WHITE,  curses.A_NORMAL, BOLD             )
+
+    # Selected invisible menu entry, for show-all mode
+    _MENU_LIST_INVISIBLE_SEL_STYLE = _style(curses.COLOR_RED,   curses.COLOR_BLUE,   curses.A_NORMAL, curses.A_STANDOUT)
 
     # Row below menu list, with arrows pointing down
-    _BOT_SEP_STYLE       = _style(curses.COLOR_BLACK, curses.COLOR_YELLOW, BOLD,            curses.A_STANDOUT)
+    _BOT_SEP_STYLE                 = _style(curses.COLOR_BLACK, curses.COLOR_YELLOW, BOLD,            curses.A_STANDOUT)
 
     # Help window with keys at the bottom
-    _HELP_STYLE          = _style(curses.COLOR_BLACK, curses.COLOR_WHITE,  BOLD                              )
+    _HELP_STYLE                    = _style(curses.COLOR_BLACK, curses.COLOR_WHITE,  BOLD                              )
 
 
     # Frame around dialog boxes
-    _DIALOG_FRAME_STYLE  = _style(curses.COLOR_BLACK, curses.COLOR_YELLOW, BOLD,            curses.A_STANDOUT)
+    _DIALOG_FRAME_STYLE            = _style(curses.COLOR_BLACK, curses.COLOR_YELLOW, BOLD,            curses.A_STANDOUT)
 
     # Body of dialog boxes
-    _DIALOG_BODY_STYLE   = _style(curses.COLOR_WHITE, curses.COLOR_BLACK,  curses.A_NORMAL                   )
+    _DIALOG_BODY_STYLE             = _style(curses.COLOR_WHITE, curses.COLOR_BLACK,  curses.A_NORMAL                   )
 
     # Text input field in dialog boxes
-    _INPUT_FIELD_STYLE   = _style(curses.COLOR_WHITE, curses.COLOR_BLUE,   curses.A_NORMAL, curses.A_STANDOUT)
+    _INPUT_FIELD_STYLE             = _style(curses.COLOR_WHITE, curses.COLOR_BLUE,   curses.A_NORMAL, curses.A_STANDOUT)
 
 
     # Top line of information display, with title and arrows pointing up
-    _INFO_TOP_LINE_STYLE = _style(curses.COLOR_BLACK, curses.COLOR_YELLOW, BOLD,            curses.A_STANDOUT)
+    _INFO_TOP_LINE_STYLE           = _style(curses.COLOR_BLACK, curses.COLOR_YELLOW, BOLD,            curses.A_STANDOUT)
 
     # Main information display window
-    _INFO_TEXT_STYLE     = _style(curses.COLOR_BLACK, curses.COLOR_WHITE,  curses.A_NORMAL                   )
+    _INFO_TEXT_STYLE               = _style(curses.COLOR_BLACK, curses.COLOR_WHITE,  curses.A_NORMAL                   )
 
     # Separator below information display, with arrows pointing down
-    _INFO_BOT_SEP_STYLE  = _style(curses.COLOR_BLACK, curses.COLOR_YELLOW, BOLD,            curses.A_STANDOUT)
+    _INFO_BOT_SEP_STYLE            = _style(curses.COLOR_BLACK, curses.COLOR_YELLOW, BOLD,            curses.A_STANDOUT)
 
     # Help window with keys at the bottom of the information display
-    _INFO_HELP_STYLE     = _style(curses.COLOR_BLACK, curses.COLOR_WHITE,  BOLD                              )
+    _INFO_HELP_STYLE               = _style(curses.COLOR_BLACK, curses.COLOR_WHITE,  BOLD                              )
 
 
 #
@@ -277,6 +288,7 @@ def menuconfig(kconf):
 
     globals()["_kconf"] = kconf
     global _config_filename
+    global _show_all
 
 
     _config_filename = os.environ.get("KCONFIG_CONFIG")
@@ -294,12 +306,17 @@ def menuconfig(kconf):
     else:
         print("Using default symbol values as base")
 
-
-    # We rely on having a selected node
-    if not _visible_nodes(_kconf.top_node):
-        print("No visible symbols in the top menu -- nothing to configure.\n"
-              "Check that environment variables are set properly.")
-        return
+    # Any visible items in the top menu?
+    _show_all = False
+    if not _shown_nodes(_kconf.top_node):
+        # Nothing visible. Start in show-all mode and try again.
+        _show_all = True
+        if not _shown_nodes(_kconf.top_node):
+            # Give up. The implementation relies on always having a selected
+            # node.
+            print("Empty configuration -- nothing to configure.\n"
+                  "Check that environment variables are set properly.")
+            return
 
     # Disable warnings. They get mangled in curses mode, and we deal with
     # errors ourselves.
@@ -321,19 +338,28 @@ def menuconfig(kconf):
 #     Menu node of the menu (or menuconfig symbol, or choice) currently being
 #     shown
 #
-#   _visible:
-#     List of visible symbols in _cur_menu
+#   _shown:
+#     List of items in _cur_menu that are shown (ignoring scrolling). In
+#     show-all mode, this list contains all items in _cur_menu. Otherwise, it
+#     contains just the visible items.
 #
 #   _sel_node_i:
-#     Index in _visible of the currently selected node
+#     Index in _shown of the currently selected node
 #
 #   _menu_scroll:
-#     Index in _visible of the top row of the menu display
+#     Index in _shown of the top row of the menu display
 #
 #   _parent_screen_rows:
 #     List/stack of the row numbers that the selections in the parent menus
 #     appeared on. This is used to prevent the scrolling from jumping around
 #     when going in and out of menus.
+#
+#   _show_all:
+#     If True, "show-all" mode is on. Show-all mode shows all symbols and other
+#     items in the current menu, including those that lack a prompt or aren't
+#     currently visible.
+#
+#     Invisible items are drawn in a different style to make them stand out.
 
 def _menuconfig(stdscr):
     # Logic for the "main" display, with the list of symbols, etc.
@@ -378,7 +404,7 @@ def _menuconfig(stdscr):
             # Do appropriate node action. Only Space is treated specially,
             # preferring to toggle nodes rather than enter menus.
 
-            sel_node = _visible[_sel_node_i]
+            sel_node = _shown[_sel_node_i]
 
             if sel_node.is_menuconfig and not \
                (c == " " and _prefer_toggle(sel_node.item)):
@@ -407,7 +433,10 @@ def _menuconfig(stdscr):
                          "minimal configuration")
 
         elif c == "?":
-            _display_info(_visible[_sel_node_i])
+            _display_info(_shown[_sel_node_i])
+
+        elif c in ("a", "A"):
+            _toggle_show_all()
 
         elif c in ("q", "Q"):
             while True:
@@ -446,7 +475,7 @@ def _init():
 
     global _parent_screen_rows
     global _cur_menu
-    global _visible
+    global _shown
     global _sel_node_i
     global _menu_scroll
 
@@ -487,7 +516,7 @@ def _init():
 
     # Initial state
     _cur_menu = _kconf.top_node
-    _visible = _visible_nodes(_cur_menu)
+    _shown = _shown_nodes(_cur_menu)
     _sel_node_i = 0
     _menu_scroll = 0
 
@@ -542,7 +571,7 @@ def _max_menu_scroll():
     # Returns the maximum amount the menu display can be scrolled down. We stop
     # scrolling when the bottom node is visible.
 
-    return max(0, len(_visible) - _menu_win_height())
+    return max(0, len(_shown) - _menu_win_height())
 
 def _prefer_toggle(item):
     # For nodes with menus, determines whether Space should change the value of
@@ -557,20 +586,20 @@ def _enter_menu(menu):
     # Makes 'menu' the currently displayed menu
 
     global _cur_menu
-    global _visible
+    global _shown
     global _sel_node_i
     global _menu_scroll
 
-    visible_sub = _visible_nodes(menu)
+    shown_sub = _shown_nodes(menu)
     # Never enter empty menus. We depend on having a current node.
-    if visible_sub:
+    if shown_sub:
         # Remember where the current node appears on the screen, so we can try
         # to get it to appear in the same place when we leave the menu
         _parent_screen_rows.append(_sel_node_i - _menu_scroll)
 
         # Jump into menu
         _cur_menu = menu
-        _visible = visible_sub
+        _shown = shown_sub
         _sel_node_i = 0
         _menu_scroll = 0
 
@@ -579,7 +608,7 @@ def _leave_menu():
     # the top menu.
 
     global _cur_menu
-    global _visible
+    global _shown
     global _sel_node_i
     global _menu_scroll
 
@@ -588,8 +617,8 @@ def _leave_menu():
 
     # Jump to parent menu
     parent = _parent_menu(_cur_menu)
-    _visible = _visible_nodes(parent)
-    _sel_node_i = _visible.index(_cur_menu)
+    _shown = _shown_nodes(parent)
+    _sel_node_i = _shown.index(_cur_menu)
     _cur_menu = parent
 
     # Try to make the menu entry appear on the same row on the screen as it did
@@ -603,7 +632,7 @@ def _select_next_menu_entry():
     global _sel_node_i
     global _menu_scroll
 
-    if _sel_node_i < len(_visible) - 1:
+    if _sel_node_i < len(_shown) - 1:
         # Jump to the next node
         _sel_node_i += 1
 
@@ -635,7 +664,7 @@ def _select_last_menu_entry():
     global _sel_node_i
     global _menu_scroll
 
-    _sel_node_i = len(_visible) - 1
+    _sel_node_i = len(_shown) - 1
     _menu_scroll = _max_menu_scroll()
 
 def _select_first_menu_entry():
@@ -646,6 +675,53 @@ def _select_first_menu_entry():
 
     _sel_node_i = _menu_scroll = 0
 
+def _toggle_show_all():
+    # Toggles show-all mode on/off
+
+    global _show_all
+    global _shown
+    global _sel_node_i
+    global _menu_scroll
+
+    # Row on the screen the cursor is on. Preferably we want the same row to
+    # stay highlighted.
+    old_row = _sel_node_i - _menu_scroll
+
+    _show_all = not _show_all
+    # List of new nodes to be shown after toggling _show_all
+    new_shown = _shown_nodes(_cur_menu)
+
+    # Find a good node to select. The selected node might disappear if show-all
+    # mode is turned off.
+
+    # If there are visible nodes before the previously selected node, select
+    # the closest one. This will select the previously selected node itself if
+    # it is still visible.
+    for node in reversed(_shown[:_sel_node_i + 1]):
+        if node in new_shown:
+            _sel_node_i = new_shown.index(node)
+            break
+    else:
+        # No visible nodes before the previously selected node. Select the
+        # closest visible node after it instead.
+        for node in _shown[_sel_node_i + 1:]:
+            if node in new_shown:
+                _sel_node_i = new_shown.index(node)
+                break
+        else:
+            # No visible nodes at all, meaning show-all was turned off inside
+            # an invisible menu. Don't allow that, as the implementation relies
+            # on always having a selected node.
+            _show_all = True
+
+            return
+
+    _shown = new_shown
+
+    # Try to make the cursor stay on the same row in the menu window. This
+    # might be impossible if too many nodes have disappeared above the node.
+    _menu_scroll = max(_sel_node_i - old_row, 0)
+
 def _draw_main():
     # Draws the "main" display, with the list of symbols, the header, and the
     # footer.
@@ -703,16 +779,21 @@ def _draw_main():
 
     _menu_win.erase()
 
-    # Draw the _visible nodes starting from index _menu_scroll up to either as
-    # many as fit in the window, or to the end of _visible
+    # Draw the _shown nodes starting from index _menu_scroll up to either as
+    # many as fit in the window, or to the end of _shown
     for i in range(_menu_scroll,
-                   min(_menu_scroll + _menu_win_height(), len(_visible))):
+                   min(_menu_scroll + _menu_win_height(), len(_shown))):
 
-        _safe_addstr(_menu_win, i - _menu_scroll, 0,
-                     _node_str(_visible[i]),
-                     # Highlight the selected entry
-                     _MENU_LIST_SEL_STYLE
-                         if i == _sel_node_i else curses.A_NORMAL)
+        node = _shown[i]
+
+        if node.prompt and expr_value(node.prompt[1]):
+            style = _MENU_LIST_SEL_STYLE if i == _sel_node_i else \
+                    _MENU_LIST_STYLE
+        else:
+            style = _MENU_LIST_INVISIBLE_SEL_STYLE if i == _sel_node_i else \
+                    _MENU_LIST_INVISIBLE_STYLE
+
+        _safe_addstr(_menu_win, i - _menu_scroll, 0, _node_str(node), style)
 
     _menu_win.noutrefresh()
 
@@ -727,6 +808,13 @@ def _draw_main():
     if _menu_scroll < _max_menu_scroll():
         _safe_hline(_bot_sep_win, 0, 4, curses.ACS_DARROW, _N_SCROLL_ARROWS)
 
+    # Indicate when show-all mode is enabled
+    if _show_all:
+        s = "Show-all mode enabled"
+        _safe_addstr(_bot_sep_win,
+                     0, stdscr.getmaxyx()[1] - len(s) - 2,
+                     s)
+
     _bot_sep_win.noutrefresh()
 
 
@@ -751,31 +839,34 @@ def _parent_menu(node):
         menu = menu.parent
     return menu
 
-def _visible_nodes(menu):
+def _shown_nodes(menu):
     # Returns a list of the nodes in 'menu' (see _parent_menu()) that should be
-    # visible in the menu window
+    # shown in the menu window
+
+    res = []
 
     def rec(node):
-        res = []
+        nonlocal res
 
         while node:
             # Show the node if its prompt is visible. For menus, also check
-            # 'visible if'.
-            if node.prompt and expr_value(node.prompt[1]) and not \
-               (node.item == MENU and not expr_value(node.visibility)):
+            # 'visible if'. In show-all mode, show everything.
+            if _show_all or \
+               (node.prompt and expr_value(node.prompt[1]) and not \
+                (node.item == MENU and not expr_value(node.visibility))):
+
                 res.append(node)
 
                 # If a node has children but doesn't have the is_menuconfig
                 # flag set, the children come from a submenu created implicitly
                 # from dependencies. Show those in this menu too.
                 if node.list and not node.is_menuconfig:
-                    res.extend(rec(node.list))
+                    rec(node.list)
 
             node = node.next
 
-        return res
-
-    return rec(menu.list)
+    rec(menu.list)
+    return res
 
 def _change_node(node):
     # Changes the value of the menu node 'node' if it is a symbol. Bools and
@@ -783,13 +874,17 @@ def _change_node(node):
     # dialog.
 
     global _cur_menu
-    global _visible
+    global _shown
     global _sel_node_i
     global _menu_scroll
 
     if not isinstance(node.item, (Symbol, Choice)):
         return
 
+    # This will hit for invisible symbols in show-all mode
+    if not (node.prompt and expr_value(node.prompt[1])):
+        return
+
     # sc = symbol/choice
     sc = node.item
 
@@ -834,13 +929,13 @@ def _change_node(node):
     # Row on the screen the cursor was on
     old_row = _sel_node_i - _menu_scroll
 
-    sel_node = _visible[_sel_node_i]
+    sel_node = _shown[_sel_node_i]
 
     # New visible nodes
-    _visible = _visible_nodes(_cur_menu)
+    _shown = _shown_nodes(_cur_menu)
 
     # New index of selected node
-    _sel_node_i = _visible.index(sel_node)
+    _sel_node_i = _shown.index(sel_node)
 
     # Try to make the cursor stay on the same row in the menu window. This
     # might be impossible if too many nodes have disappeared above the node.
@@ -1528,7 +1623,11 @@ def _node_str(node):
     # This approach gives nice alignment for empty string symbols ("()  Foo")
     s = "{:{}} ".format(_value_str(node), 3 + indent)
 
-    if node.prompt:
+    if not node.prompt:
+        # Show the symbol/choice name in <> brackets if it has no prompt. This
+        # path can only hit in show-all mode.
+        s += "<{}>".format(node.item.name)
+    else:
         if node.item == COMMENT:
             s += "*** {} ***".format(node.prompt[0])
         else:
@@ -1557,7 +1656,7 @@ def _node_str(node):
     # entered. Add "(empty)" if the menu is empty. We don't allow those to be
     # entered.
     if node.is_menuconfig:
-        s += "  --->" if _visible_nodes(node) else "  ---> (empty)"
+        s += "  --->" if _shown_nodes(node) else "  ---> (empty)"
 
     return s