Is there a nice way of handling multi-line input with GNU readline?

Question

My application has a command line interface, and I\'m thinking about using the GNU Readline library to provide history, an editable command line, etc.

The hitch is that

Answer 1

You sure can.

You can define options for the '\r' and '\n' values with

rl_bind_key('\r', return_func);

Your return_func can now decide what to do with those keys.

int return_func(int cnt, int key) { ... }

If you're doing this inside a UNIX terminal, you will need to learn about ANSI terminal codes if you want to move your cursor around. There's a starting reference on wikipedia.

Here's some sample code that uses readline to read multi-line and will stop editing when you enter in a semi-colon (I've set that as the EOQ or end-or-query). Readline is extremely powerful, there's plenty of stuff to learn.

#include <stdio.h>
#include <unistd.h>
#include <readline/readline.h>
#include <readline/history.h>

int my_startup(void);
int my_bind_cr(int, int);
int my_bind_eoq(int, int);
char *my_readline(void);

int my_eoq; 

int
main(int argc, char *argv[])
{

  if (isatty(STDIN_FILENO)) {
    rl_readline_name = "my";
    rl_startup_hook = my_startup;
    my_readline();
  }
}

int
my_startup(void) 
{
  my_eoq = 0;
  rl_bind_key('\n', my_bind_cr);
  rl_bind_key('\r', my_bind_cr);
  rl_bind_key(';', my_bind_eoq);
}

int
my_bind_cr(int count, int key) {
  if (my_eoq == 1) {
    rl_done = 1;
  }
  printf("\n");
}

int
my_bind_eoq(int count, int key) {
  my_eoq = 1;

  printf(";");
}

char * 
my_readline(void)
{
  char *line;

  if ((line = readline("")) == NULL) {
    return NULL;
  }

  printf("LINE : %s\n", line);
}