/*
|
/*
|
From: Jeff Solomon <jsolomon@stanford.edu>
|
From: Jeff Solomon <jsolomon@stanford.edu>
|
Date: Fri, 9 Apr 1999 10:13:27 -0700 (PDT)
|
Date: Fri, 9 Apr 1999 10:13:27 -0700 (PDT)
|
To: chet@po.cwru.edu
|
To: chet@po.cwru.edu
|
Subject: new readline example
|
Subject: new readline example
|
Message-ID: <14094.12094.527305.199695@mrclean.Stanford.EDU>
|
Message-ID: <14094.12094.527305.199695@mrclean.Stanford.EDU>
|
|
|
Chet,
|
Chet,
|
|
|
I've been using readline 4.0. Specifically, I've been using the perl
|
I've been using readline 4.0. Specifically, I've been using the perl
|
version Term::ReadLine::Gnu. It works great.
|
version Term::ReadLine::Gnu. It works great.
|
|
|
Anyway, I've been playing around the alternate interface and I wanted
|
Anyway, I've been playing around the alternate interface and I wanted
|
to contribute a little C program, callback.c, to you that you could
|
to contribute a little C program, callback.c, to you that you could
|
use as an example of the alternate interface in the /examples
|
use as an example of the alternate interface in the /examples
|
directory of the readline distribution.
|
directory of the readline distribution.
|
|
|
My example shows how, using the alternate interface, you can
|
My example shows how, using the alternate interface, you can
|
interactively change the prompt (which is very nice imo). Also, I
|
interactively change the prompt (which is very nice imo). Also, I
|
point out that you must roll your own terminal setting when using the
|
point out that you must roll your own terminal setting when using the
|
alternate interface because readline depreps (using your parlance) the
|
alternate interface because readline depreps (using your parlance) the
|
terminal while in the user callback. I try to demostrate what I mean
|
terminal while in the user callback. I try to demostrate what I mean
|
with an example. I've included the program below.
|
with an example. I've included the program below.
|
|
|
To compile, I just put the program in the examples directory and made
|
To compile, I just put the program in the examples directory and made
|
the appropriate changes to the EXECUTABLES and OBJECTS line and added
|
the appropriate changes to the EXECUTABLES and OBJECTS line and added
|
an additional target 'callback'.
|
an additional target 'callback'.
|
|
|
I compiled on my Sun Solaris2.6 box using Sun's cc.
|
I compiled on my Sun Solaris2.6 box using Sun's cc.
|
|
|
Let me know what you think.
|
Let me know what you think.
|
|
|
Jeff
|
Jeff
|
*/
|
*/
|
|
|
#if defined (HAVE_CONFIG_H)
|
#if defined (HAVE_CONFIG_H)
|
#include <config.h>
|
#include <config.h>
|
#endif
|
#endif
|
|
|
#include <stdio.h>
|
#include <stdio.h>
|
#include <sys/types.h>
|
#include <sys/types.h>
|
|
|
#ifdef HAVE_UNISTD_H
|
#ifdef HAVE_UNISTD_H
|
#include <unistd.h>
|
#include <unistd.h>
|
#endif
|
#endif
|
|
|
#include <termios.h> /* xxx - should make this more general */
|
#include <termios.h> /* xxx - should make this more general */
|
|
|
#ifdef READLINE_LIBRARY
|
#ifdef READLINE_LIBRARY
|
# include "readline.h"
|
# include "readline.h"
|
#else
|
#else
|
# include <readline/readline.h>
|
# include <readline/readline.h>
|
#endif
|
#endif
|
|
|
/* This little examples demonstrates the alternate interface to using readline.
|
/* This little examples demonstrates the alternate interface to using readline.
|
* In the alternate interface, the user maintains control over program flow and
|
* In the alternate interface, the user maintains control over program flow and
|
* only calls readline when STDIN is readable. Using the alternate interface,
|
* only calls readline when STDIN is readable. Using the alternate interface,
|
* you can do anything else while still using readline (like talking to a
|
* you can do anything else while still using readline (like talking to a
|
* network or another program) without blocking.
|
* network or another program) without blocking.
|
*
|
*
|
* Specifically, this program highlights two importants features of the
|
* Specifically, this program highlights two importants features of the
|
* alternate interface. The first is the ability to interactively change the
|
* alternate interface. The first is the ability to interactively change the
|
* prompt, which can't be done using the regular interface since rl_prompt is
|
* prompt, which can't be done using the regular interface since rl_prompt is
|
* read-only.
|
* read-only.
|
*
|
*
|
* The second feature really highlights a subtle point when using the alternate
|
* The second feature really highlights a subtle point when using the alternate
|
* interface. That is, readline will not alter the terminal when inside your
|
* interface. That is, readline will not alter the terminal when inside your
|
* callback handler. So let's so, your callback executes a user command that
|
* callback handler. So let's so, your callback executes a user command that
|
* takes a non-trivial amount of time to complete (seconds). While your
|
* takes a non-trivial amount of time to complete (seconds). While your
|
* executing the command, the user continues to type keystrokes and expects them
|
* executing the command, the user continues to type keystrokes and expects them
|
* to be re-echoed on the new prompt when it returns. Unfortunately, the default
|
* to be re-echoed on the new prompt when it returns. Unfortunately, the default
|
* terminal configuration doesn't do this. After the prompt returns, the user
|
* terminal configuration doesn't do this. After the prompt returns, the user
|
* must hit one additional keystroke and then will see all of his previous
|
* must hit one additional keystroke and then will see all of his previous
|
* keystrokes. To illustrate this, compile and run this program. Type "sleep" at
|
* keystrokes. To illustrate this, compile and run this program. Type "sleep" at
|
* the prompt and then type "bar" before the prompt returns (you have 3
|
* the prompt and then type "bar" before the prompt returns (you have 3
|
* seconds). Notice how "bar" is re-echoed on the prompt after the prompt
|
* seconds). Notice how "bar" is re-echoed on the prompt after the prompt
|
* returns? This is what you expect to happen. Now comment out the 4 lines below
|
* returns? This is what you expect to happen. Now comment out the 4 lines below
|
* the line that says COMMENT LINE BELOW. Recompile and rerun the program and do
|
* the line that says COMMENT LINE BELOW. Recompile and rerun the program and do
|
* the same thing. When the prompt returns, you should not see "bar". Now type
|
* the same thing. When the prompt returns, you should not see "bar". Now type
|
* "f", see how "barf" magically appears? This behavior is un-expected and not
|
* "f", see how "barf" magically appears? This behavior is un-expected and not
|
* desired.
|
* desired.
|
*/
|
*/
|
|
|
void process_line(char *line);
|
void process_line(char *line);
|
int change_prompt(void);
|
int change_prompt(void);
|
char *get_prompt(void);
|
char *get_prompt(void);
|
|
|
int prompt = 1;
|
int prompt = 1;
|
char prompt_buf[40], line_buf[256];
|
char prompt_buf[40], line_buf[256];
|
tcflag_t old_lflag;
|
tcflag_t old_lflag;
|
cc_t old_vtime;
|
cc_t old_vtime;
|
struct termios term;
|
struct termios term;
|
|
|
int
|
int
|
main()
|
main()
|
{
|
{
|
fd_set fds;
|
fd_set fds;
|
|
|
/* Adjust the terminal slightly before the handler is installed. Disable
|
/* Adjust the terminal slightly before the handler is installed. Disable
|
* canonical mode processing and set the input character time flag to be
|
* canonical mode processing and set the input character time flag to be
|
* non-blocking.
|
* non-blocking.
|
*/
|
*/
|
if( tcgetattr(STDIN_FILENO, &term) < 0 ) {
|
if( tcgetattr(STDIN_FILENO, &term) < 0 ) {
|
perror("tcgetattr");
|
perror("tcgetattr");
|
exit(1);
|
exit(1);
|
}
|
}
|
old_lflag = term.c_lflag;
|
old_lflag = term.c_lflag;
|
old_vtime = term.c_cc[VTIME];
|
old_vtime = term.c_cc[VTIME];
|
term.c_lflag &= ~ICANON;
|
term.c_lflag &= ~ICANON;
|
term.c_cc[VTIME] = 1;
|
term.c_cc[VTIME] = 1;
|
/* COMMENT LINE BELOW - see above */
|
/* COMMENT LINE BELOW - see above */
|
if( tcsetattr(STDIN_FILENO, TCSANOW, &term) < 0 ) {
|
if( tcsetattr(STDIN_FILENO, TCSANOW, &term) < 0 ) {
|
perror("tcsetattr");
|
perror("tcsetattr");
|
exit(1);
|
exit(1);
|
}
|
}
|
|
|
rl_add_defun("change-prompt", change_prompt, CTRL('t'));
|
rl_add_defun("change-prompt", change_prompt, CTRL('t'));
|
rl_callback_handler_install(get_prompt(), process_line);
|
rl_callback_handler_install(get_prompt(), process_line);
|
|
|
while(1) {
|
while(1) {
|
FD_ZERO(&fds);
|
FD_ZERO(&fds);
|
FD_SET(fileno(stdin), &fds);
|
FD_SET(fileno(stdin), &fds);
|
|
|
if( select(FD_SETSIZE, &fds, NULL, NULL, NULL) < 0) {
|
if( select(FD_SETSIZE, &fds, NULL, NULL, NULL) < 0) {
|
perror("select");
|
perror("select");
|
exit(1);
|
exit(1);
|
}
|
}
|
|
|
if( FD_ISSET(fileno(stdin), &fds) ) {
|
if( FD_ISSET(fileno(stdin), &fds) ) {
|
rl_callback_read_char();
|
rl_callback_read_char();
|
}
|
}
|
}
|
}
|
}
|
}
|
|
|
void
|
void
|
process_line(char *line)
|
process_line(char *line)
|
{
|
{
|
if( line == NULL ) {
|
if( line == NULL ) {
|
fprintf(stderr, "\n", line);
|
fprintf(stderr, "\n", line);
|
|
|
/* reset the old terminal setting before exiting */
|
/* reset the old terminal setting before exiting */
|
term.c_lflag = old_lflag;
|
term.c_lflag = old_lflag;
|
term.c_cc[VTIME] = old_vtime;
|
term.c_cc[VTIME] = old_vtime;
|
if( tcsetattr(STDIN_FILENO, TCSANOW, &term) < 0 ) {
|
if( tcsetattr(STDIN_FILENO, TCSANOW, &term) < 0 ) {
|
perror("tcsetattr");
|
perror("tcsetattr");
|
exit(1);
|
exit(1);
|
}
|
}
|
exit(0);
|
exit(0);
|
}
|
}
|
|
|
if( strcmp(line, "sleep") == 0 ) {
|
if( strcmp(line, "sleep") == 0 ) {
|
sleep(3);
|
sleep(3);
|
} else {
|
} else {
|
fprintf(stderr, "|%s|\n", line);
|
fprintf(stderr, "|%s|\n", line);
|
}
|
}
|
|
|
free (line);
|
free (line);
|
}
|
}
|
|
|
int
|
int
|
change_prompt(void)
|
change_prompt(void)
|
{
|
{
|
/* toggle the prompt variable */
|
/* toggle the prompt variable */
|
prompt = !prompt;
|
prompt = !prompt;
|
|
|
/* save away the current contents of the line */
|
/* save away the current contents of the line */
|
strcpy(line_buf, rl_line_buffer);
|
strcpy(line_buf, rl_line_buffer);
|
|
|
/* install a new handler which will change the prompt and erase the current line */
|
/* install a new handler which will change the prompt and erase the current line */
|
rl_callback_handler_install(get_prompt(), process_line);
|
rl_callback_handler_install(get_prompt(), process_line);
|
|
|
/* insert the old text on the new line */
|
/* insert the old text on the new line */
|
rl_insert_text(line_buf);
|
rl_insert_text(line_buf);
|
|
|
/* redraw the current line - this is an undocumented function. It invokes the
|
/* redraw the current line - this is an undocumented function. It invokes the
|
* redraw-current-line command.
|
* redraw-current-line command.
|
*/
|
*/
|
rl_refresh_line(0, 0);
|
rl_refresh_line(0, 0);
|
}
|
}
|
|
|
char *
|
char *
|
get_prompt(void)
|
get_prompt(void)
|
{
|
{
|
/* The prompts can even be different lengths! */
|
/* The prompts can even be different lengths! */
|
sprintf(prompt_buf, "%s",
|
sprintf(prompt_buf, "%s",
|
prompt ? "Hit ctrl-t to toggle prompt> " : "Pretty cool huh?> ");
|
prompt ? "Hit ctrl-t to toggle prompt> " : "Pretty cool huh?> ");
|
return prompt_buf;
|
return prompt_buf;
|
}
|
}
|
|
|
