Change the way pre-prompt printing works to avoid having to deal with "magic" menu entries.

Add a default 'exit' command to back out of a menu.

git-svn-id: https://arducopter.googlecode.com/svn/trunk@546 f9c3cf11-9bcb-44bc-f272-b75c42450872

libraries/AP_Common/include/menu.h

@@ -20,6 +20,11 @@ public:
 	/// menu command function
 	///
 	typedef int			(*func)(uint8_t argc, const struct arg *argv);
+
+	/// menu pre-prompt function
+	///
+	/// If this function returns false, the menu exits.
+	typedef bool			(*preprompt)(void);
 	
 	/// menu command description
 	///
@@ -28,8 +33,6 @@ public:
 	struct command {
 		/// Name of the command, as typed or received.
 		/// Command names are limited in size to keep this structure compact.
-		/// If the first command in the menu is named '*', it will be called
-		/// each time before printing the prompt.
 		const char	command[MENU_COMMAND_MAX];
 
 		/// The function to call when the command is received.
@@ -37,6 +40,8 @@ public:
 		/// MENU_ARGS_MAX.  The argv array will be populated with
 		/// arguments typed/received up to MENU_ARGS_MAX.  The command
 		/// name will always be in argv[0].
+		/// Commands may return -2 to cause the menu itself to exit.
+		/// The "?", "help" and "exit" commands are always defined.
 		int			(*func)(uint8_t argc, const struct arg *argv);	///< callback function
 	};
 
@@ -46,7 +51,7 @@ public:
 	/// @param commands		An array of ::command structures.
 	/// @param entries		The number of entries in the menu.
 	///
-	Menu(const char *prompt, const struct command *commands, uint8_t entries);
+	Menu(const char *prompt, const struct command *commands, uint8_t entries, preprompt ppfunc = 0);
 
 	/// menu runner
 	void				run(void);
@@ -62,19 +67,27 @@ private:
 	/// @param argc			Number of arguments prepared for the menu item
 	///
 	int					_call(uint8_t n, uint8_t argc);
+
 	const char			*_prompt;						///< prompt to display
 	const command		*_commands;						///< array of commands
 	const uint8_t		_entries;						///< size of the menu
+	const preprompt		_ppfunc;						///< optional pre-prompt action
 
 	static char			_inbuf[MENU_COMMANDLINE_MAX];	///< input buffer
 	static arg			_argv[MENU_ARGS_MAX + 1];		///< arguments
 };
 
-/// Macro used to define a menu.
+/// Macros used to define a menu.
 ///
 /// Use name.run() to run the menu.
 ///
+/// The MENU2 macro supports the optional pre-prompt printing function.
+///
 #define MENU(name, prompt, commands)							\
 	static const char __menu_name__ ##name[] PROGMEM = prompt;	\
 	static Menu name(__menu_name__ ##name, commands, sizeof(commands) / sizeof(commands[0]))
 	
+#define MENU2(name, prompt, commands, preprompt)				\
+	static const char __menu_name__ ##name[] PROGMEM = prompt;	\
+	static Menu name(__menu_name__ ##name, commands, sizeof(commands) / sizeof(commands[0]), preprompt)
+	

libraries/AP_Common/menu.cpp

@@ -17,10 +17,11 @@ char Menu::_inbuf[MENU_COMMANDLINE_MAX];
 Menu::arg Menu::_argv[MENU_ARGS_MAX + 1];
 
 // constructor
-Menu::Menu(const prog_char *prompt, const Menu::command *commands, uint8_t entries) :
+Menu::Menu(const prog_char *prompt, const Menu::command *commands, uint8_t entries, preprompt ppfunc) :
 	_prompt(prompt),
 	_commands(commands),
-	_entries(entries)
+	_entries(entries),
+	_ppfunc(ppfunc)
 {
 }
 
@@ -35,12 +36,10 @@ Menu::run(void)
 	// loop performing commands
 	for (;;) {
 
-		// if the first command is called '*', call it before displaying the menu
-		if ("*", _commands[0].command) {
-			if (-2 == _call(0, 0))
-				return;
-		}
-	
+		// run the pre-prompt function, if one is defined
+		if ((NULL != _ppfunc) && !_ppfunc())
+			return;
+
 		// loop reading characters from the input
 		len = 0;
 		Serial.printf("%S] ", _prompt);
@@ -91,12 +90,18 @@ Menu::run(void)
 				ret = _call(i, argc);
 				if (-2 == ret)
 					return;
+				break;
 			}
 		}
 
-		// if the menu doesn't provide more comprehensive help, print the command list
-		if ((i == _entries) && (!strcmp(_argv[0].str, "?") || (!strcmp_P(_argv[0].str, PSTR("help")))))
-			_help();
+		// implicit commands
+		if (i == _entries) {
+			if (!strcmp(_argv[0].str, "?") || (!strcmp_P(_argv[0].str, PSTR("help")))) {
+				_help();
+			} else if (!strcmp_P(_argv[0].str, PSTR("exit"))) {
+				return;
+			}
+		}
 	}			
 }