278 lines
4.1 KiB
C
278 lines
4.1 KiB
C
#include <sys/ioctl.h>
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#include <ctype.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <termios.h>
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#include <unistd.h>
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#define ESCSEQ "\x1b["
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#define CTRL_KEY(key) ((key)&0x1f)
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/*
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* define the keyboard input modes
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* normal: no special mode
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* kcommand: ^k commands
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*/
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#define MODE_NORMAL 0
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#define MODE_KCOMMAND 1
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struct {
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struct termios entry_term;
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int rows, cols;
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} editor;
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/* append buffer */
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struct abuf {
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char *b;
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int len;
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};
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#define ABUF_INIT {NULL, 0}
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void
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ab_append(struct abuf *buf, const char *s, int len)
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{
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char *nc = realloc(buf->b, buf->len + len);
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if (nc == NULL) {
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return;
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}
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memcpy(&nc[buf->len], s, len);
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buf->b = nc;
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buf->len += len; /* DANGER: overflow */
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}
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void
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ab_free(struct abuf *buf)
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{
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free(buf->b);
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}
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void
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die(const char *s)
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{
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/*
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* NOTE(kyle): this is a duplication of the code in display.c
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* but I would like to be able to import these files from there.
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*/
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write(STDOUT_FILENO, "\x1b[2J", 4);
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write(STDOUT_FILENO, "\x1b[H", 3);
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perror(s);
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exit(1);
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}
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/*
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* get_winsz uses the TIOCGWINSZ to get the window size.
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*
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* there's a fallback way to do this, too, that involves moving the
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* cursor down and to the left \x1b[999C\x1b[999B. I'm going to skip
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* on this for now because it's bloaty and this works on OpenBSD and
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* Linux, at least.
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*/
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int
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get_winsz(int *rows, int *cols)
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{
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struct winsize ws;
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if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == -1 ||
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ws.ws_col == 0) {
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return -1;
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}
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*cols = ws.ws_col;
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*rows = ws.ws_row;
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return 0;
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}
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static char
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get_keypress()
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{
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char c = 0;
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if (read(STDIN_FILENO, &c, 1) == -1) {
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die("get_keypress:read");
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}
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return c;
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}
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void
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process_keypress()
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{
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static int m = MODE_NORMAL;
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char c = get_keypress();
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if (c == 0x0) {
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return;
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}
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switch (m) {
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case MODE_KCOMMAND:
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switch (c) {
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case 'q':
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case CTRL_KEY('q'):
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exit(0);
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}
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m = MODE_NORMAL;
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return;
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}
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if (c == CTRL_KEY('k')) {
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m = MODE_KCOMMAND;
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return;
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}
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}
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/*
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* A text editor needs the terminal to be in raw mode; but the default
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* is to be in canonical (cooked) mode, which is a buffered input mode.
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*/
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static void
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enable_termraw()
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{
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struct termios raw;
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/* Read the current terminal parameters for standard input. */
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if (tcgetattr(STDIN_FILENO, &raw) == -1) {
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die("tcgetattr while enabling raw mode");
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}
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/*
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* Put the terminal into raw mode.
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*/
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cfmakeraw(&raw);
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/*
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* Set timeout for read(2).
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*
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* VMIN: what is the minimum number of bytes required for read
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* to return?
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*
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* VTIME: max time before read(2) returns in hundreds of milli-
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* seconds.
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*/
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raw.c_cc[VMIN] = 0;
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raw.c_cc[VTIME] = 1;
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/*
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* Now write the terminal parameters to the current terminal,
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* after flushing any waiting input out.
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*/
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if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1) {
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die("tcsetattr while enabling raw mode");
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}
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}
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static void
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disable_termraw()
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{
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display_clear(NULL);
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if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &editor.entry_term) == -1) {
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die("couldn't disable terminal raw mode");
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}
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}
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void
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setup_terminal()
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{
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if (tcgetattr(STDIN_FILENO, &editor.entry_term) == -1) {
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die("can't snapshot terminal settings");
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}
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atexit(disable_termraw);
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enable_termraw();
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}
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void
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display_clear(struct abuf *ab)
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{
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if (ab == NULL) {
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write(STDOUT_FILENO, ESCSEQ "2J", 4);
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write(STDOUT_FILENO, ESCSEQ "H", 3);
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} else {
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ab_append(ab, ESCSEQ "2J", 4);
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ab_append(ab, ESCSEQ "H", 3);
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}
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}
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void
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draw_rows(struct abuf *ab)
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{
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int y;
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for (y = 0; y < editor.rows-1; y++) {
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ab_append(ab, "|\r\n", 3);
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}
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ab_append(ab, "|", 1);
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}
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void
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display_refresh()
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{
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struct abuf ab = ABUF_INIT;
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ab_append(&ab, ESCSEQ "?25l", 6);
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display_clear(&ab);
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draw_rows(&ab);
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ab_append(&ab, ESCSEQ "1;2H", 7);
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ab_append(&ab, ESCSEQ "?25h", 6);
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write(STDOUT_FILENO, ab.b, ab.len);
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ab_free(&ab);
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}
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void
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loop()
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{
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while (1) {
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display_refresh();
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process_keypress();
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}
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}
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/*
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* init_editor should set up the global editor struct.
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*/
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void
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init_editor()
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{
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if (get_winsz(&editor.rows, &editor.cols) == -1) {
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die("can't get window size");
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}
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}
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int
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main()
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{
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setup_terminal();
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init_editor();
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display_clear(NULL);
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loop();
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return 0;
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}
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