I’m writing a readline replacement in C++, and I want to process terminal input in raw mode, including special/escaped keys like "up arrow" e[A
. However, I also want to be able to distinguish between a single press of the escape key e
followed by a press of [
and a press of A
vs a press of the up arrow.
I assume that the primary difference between those two situations is that when up arrow is pressed, the input characters come in within less than a millisecond, so I thought I could do something like:
#include <termios.h>
#include <absl/strings/escaping.h>
#include <iostream>
termios enter_raw() {
termios orig;
termios raw;
tcgetattr(STDOUT_FILENO, &orig);
tcgetattr(STDOUT_FILENO, &raw);
raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
raw.c_oflag &= ~OPOST;
raw.c_cflag |= CS8;
raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
raw.c_cc[VMIN] = 1;
raw.c_cc[VTIME] = 0;
tcsetattr(STDOUT_FILENO, TCSAFLUSH, &raw);
return orig;
}
int main() {
termios orig = enter_raw();
while(true) {
char buf[10];
memset(buf, 0, sizeof(buf));
std::cin >> buf[0];
usleep(1000);
int actual = std::cin.readsome(buf + 1, sizeof(buf) - 2);
std::cout << "Got string: "" << absl::CEscape(buf) << ""n";
if(buf[0] == 35) { break; } // received ctrl-c
}
tcsetattr(STDOUT_FILENO, TCSAFLUSH, &orig);
return 0;
}
However, the output of this is not Got string: "3[A"
as I hoped; instead, it does Got string
three times, as it would if it was just a naive loop over characters. Varying the number of microseconds for which it sleeps does not seem to affect anything.
Is there a way to implement this kind of thing easily in C++? Is it portable to most terminals? I don’t care about supporting Windows.
Source: Windows Questions C++