Libtalaris is a C library that makes adding interactive command line interfaces easy. An example program is included in example.c
Clone this repository using git clone https://www.github.com/bowdens/libtalaris
Run make to compile the example, then ./example to test it out.
You can also run make libtalaris.a to create the .a file, which you can copy across to your project to easily use the library for your project; just remember to add the include at the top of your .c file(s) #include "libtalaris.h".
Note: Since this library uses readline.h, you will need to include the -lreadline flag when compiling your project if you use libtaralis.
Make sure to add the line `#include "libtaralis.h" in your .c file after copying libtalaris.a into your folder. Also don't forget to use the -lreadline flag when compiling in gcc.
Each program needs to have at least one LT_parser object. Create this with the line
LT_Parser *parser = lt_create_parser();You can add commands to each particular LT_Parser object with the lt_add_commands function. First create an array of LT_commands like this:
LT_Command commands[] = {
{"Command Name", "Command Description" "Extra Command Description", LT_UNIV, callback_function, NULL},
{"Command Name2", "Command Description2" "Extra Command Description2", LT_UNIV, callback_function2, NULL},
{0}
}
lt_add_commands(parser, commands);Each parser has 2 default commands: exit, which will call exit(0), and help, which will print all shown commands (see the state flags section for more).
The default commands can be removed with `
lt_remove_command(LT_Parser *parser, char *command), or the callback can be changed by using lt_get_command(LT_Parser *parser, char *command); like this:
lt_get_command(parser, "exit")->callback = different_function;See below for more information on the STATE_FLAGS (such as LT_UNIV) and the callback functions.
Executing commands is easy. After adding commands, simply call lt_input(LT_Parser *parser, char *matches).
Libtalaris will accept input from stdin and execute the appropriate command based on what the user entered.
For example, to continuously accept user input, this code fragment can be used:
while(lt_input(commander, NULL) != LT_CALL_FAILED);If an unknown command was entered, libtalaris will execute whatever callback function is given at parser->unfound. By default this prints a message advising the user to type help, but it can be changed by changing the function pointer associated with parser->unfound.
lt_input will return LT_CALL_FAILED if the LT_Parser is NULL, or if the end of input was reached (ie Control-D was pressed)
It will also return LT_COMMAND_UNFOUND if there was no command associated with what the user entered.
lt_input will otherwise return whatever the callback function returns otherwise. So it is a good idea to avoid returning LT_COMMAND_UNFOUND and LT_CALL_FAILED (#defined to -99 and -98) in your callbacks.
You can also you lt_call(LT_Parser, string) to execute a command in the same way as if the user typed in the string.
Each command should have a callback function associated with it (if it is set to NULL, nothing will be executed when the user enters that command.
Callbacks must have the following prototype:
int callback(int argc, char **argv, LT_Parser *parser);When the command is executed by lt_input or lt_call, it will pass the number of arguments in argc, and the arguments themselves in argv in the exact same was as it works in main(int argc, char **argv);.
A pointer to the parser that executed the callback is also passed in, for flexibility if you are using multiple parsers and need to change the functionality of the callback depending on which parser called it.
Whatever is returned by the callback will be returned by lt_call or lt_input. This can be used for error catching. You should avoid returning -98 and -99 because that is what LT_COMMAND_UNFOUND and LT_CALL_FAILED is #defined to
Examples of callback functions are provided in the example.c file
There are three bits in the help flag. It determines what the default help function will show, and whether lt_call will execute the command when entered.
The left most bit determines whether the default help function will show the command in the list, ie when then user types help.
The next bit determines whether the default help function will show the extended help when the user types help command. If this is set to zero, help command will print "command not found"
The final bit determines whether lt_call will execute the command when it is entered by the user. If a command which has this bit set to zero is entered, it will act as if the command was unknown.
For most commands you'll probably want all bits set, so it will show help and extended help, and allow for execution. For this reason, this is #defined as LT_UNIV, with all three bits set.
To access each bit, you can use LT_HELP, LT_SPEC, and LT_EXEC for help, extended help, and execution respectively. You can also use LT_HIDE for a state flag with all bits set to zero
For instance, if you wanted a command that would show extended help and can be executed, you bitwise OR the bits like this:
{"command", "Cannot be seen in help", "But will show this extended help if 'help command' is run", LT_SPEC | LT_EXEC, callback, NULL}This is a revamped version of input-handler, created by @bowdens