C_Editor/kilo.c

/*** includes ***/

#define _DEFAULT_SOURCE
#define _BSD_SOURCE
#define _GNU_SOURCE

#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <unistd.h>
#include <termios.h>

/*** defines ***/

#define KILO_VERSION "0.0.1"

#define CTRL_KEY(k) ((k) & 0x1f)

enum editorKey
{
  ARROW_LEFT = 1000,
  ARROW_RIGHT,
  ARROW_UP,
  ARROW_DOWN,
  DEL_KEY,
  HOME_KEY,
  END_KEY,
  PAGE_UP,
  PAGE_DOWN
};

/*** data ***/

typedef struct erow {
  int size;
  char *chars;
} erow;

struct editorConfig
{
  int cx, cy;
  int rowoff; // Row offset
  int coloff; // Col offset
  int screenrows;
  int screencols;
  int numrows;
  erow *row;
  struct termios orig_termios;
};

struct editorConfig E;

/*** terminal ***/

void die(const char *s)
{
  write(STDOUT_FILENO, "\x1b[2J", 4);
  write(STDOUT_FILENO, "\x1b[H", 3);

  perror(s);
  exit(1);
}

void disableRawMode()
{
  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &E.orig_termios) == 1)
    die("tcsetattr");
}

void enableRawMode()
{
  if (tcgetattr(STDIN_FILENO, &E.orig_termios) == -1)
    die("tcgetattr");
  atexit(disableRawMode);

  struct termios raw = E.orig_termios;

  raw.c_iflag &= ~(IXON | ICRNL | INPCK | ISTRIP | BRKINT);
  raw.c_oflag &= ~(OPOST);
  raw.c_cflag |= (CS8);
  raw.c_lflag &= ~(ECHO | ICANON | ISIG | IEXTEN);
  raw.c_cc[VMIN] = 0;
  raw.c_cc[VTIME] = 1;

  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1)
    die("tcsetattr");
}

int editorReadKey()
{
  int nread;
  char c;
  while ((nread = read(STDIN_FILENO, &c, 1)) != 1)
  {
    if (nread == -1 && errno != EAGAIN)
      die("read");
  }

  if (c == '\x1b')
  {
    char seq[3];
    if (read(STDIN_FILENO, &seq[0], 1) != 1)
      return '\x1b';
    if (read(STDIN_FILENO, &seq[1], 1) != 1)
      return '\x1b';

    if (seq[0] == '[')
    {
      if (seq[1] >= '0' && seq[1] <= '9')
      {
        if (read(STDIN_FILENO, &seq[2], 1) != 1)
          return '\x1b';
        if (seq[2] == '~')
        {
          switch (seq[1])
          {
          case '1': return HOME_KEY;
          case '3': return DEL_KEY;
          case '4': return END_KEY;
          case '5':
            return PAGE_UP;
          case '6':
            return PAGE_DOWN;
          case '7': return HOME_KEY;
          case '8': return END_KEY;
          }
        }
      }
      else
      {
        switch (seq[1])
        {
        case 'A':
          return ARROW_UP;
        case 'B':
          return ARROW_DOWN;
        case 'C':
          return ARROW_RIGHT;
        case 'D':
          return ARROW_LEFT;
        case 'H': return HOME_KEY;
        case 'F': return END_KEY;
        }
      }
    } else if (seq[0] == 'O') {
      switch (seq[1]) {
        case 'H': return HOME_KEY;
        case 'F': return END_KEY;
      }
    }
    return '\x1b';
  }
  else
  {
    return c;
  }
}

int getCursorPosition(int *rows, int *cols)
{
  char buf[32];
  unsigned int i = 0;

  if (write(STDOUT_FILENO, "\x1b[6n", 4) != 4)
    return -1;

  while (i < sizeof(buf) - 1)
  {
    if (read(STDIN_FILENO, &buf[i], 1) != 1)
      break;
    if (buf[i] == 'R')
      break;
    i++;
  }
  buf[i] = '\0';

  if (buf[0] != '\x1b' || buf[1] != '[')
    return -1;
  if (sscanf(&buf[2], "%d;%d", rows, cols) != 2)
    return -1;

  return 0;
}

int getWindowSize(int *rows, int *cols)
{
  struct winsize ws;

  if (1 || ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == -1 || ws.ws_col == 0)
  {
    if (write(STDOUT_FILENO, "\x1b[999C\x1b[999B", 12) != 12)
      return -1;
    //    editorReadKey();
    return getCursorPosition(rows, cols);
  }
  else
  {
    *cols = ws.ws_col;
    *rows = ws.ws_row;
    return 0;
  }
}

/*** row operations ***/

void editorAppendRow(char *s, size_t len) {
  E.row = realloc(E.row, sizeof(erow) * (E.numrows + 1));

  int at = E.numrows;
  E.row[at].size = len;
  E.row[at].chars = malloc(len + 1);
  memcpy(E.row[at].chars, s, len);
  E.row[at].chars[len] = '\0';
  E.numrows++;
}

/*** file i/o ***/

void editorOpen(char *filename) {
  FILE *fp = fopen(filename, "r");
  if (!fp) die("fopen");

  char *line = NULL;
  size_t linecap = 0;
  ssize_t linelen;
  while ((linelen = getline(&line, &linecap, fp)) != -1) {
    while (linelen > 0 && (line[linelen - 1] == '\n' || line[linelen - 1] == '\r'))
      linelen--;
    editorAppendRow(line, linelen);
  }
  free(line);
  fclose(fp);
}

/*** append buffer ***/

struct abuf
{
  char *b;
  int len;
};

#define ABUF_INIT \
  {               \
    NULL, 0       \
  }

void abAppend(struct abuf *ab, const char *s, int len)
{
  char *new = realloc(ab->b, ab->len + len);

  if (new == NULL)
    return;
  memcpy(&new[ab->len], s, len);
  ab->b = new;
  ab->len += len;
}

void abFree(struct abuf *ab)
{
  free(ab->b);
}

/*** output ***/

void editorScroll() {
  if (E.cy < E.rowoff) {
    E.rowoff = E.cy;
  }
  if (E.cy >= E.rowoff + E.screenrows) {
    E.rowoff = E.cy - E.screenrows + 1;
  }
  if (E.cx < E.coloff) {
    E.coloff = E.cx;
  }
  if (E.cx >= E.coloff + E.screencols) {
    E.coloff = E.cx - E.screencols + 1;
  }
}

void editorDrawRows(struct abuf *ab)
{
  int y;
  for (y = 0; y < E.screenrows; y++)
  {
    int filerow = y + E.rowoff;
    if (filerow >= E.numrows) {
      if (E.numrows == 0 && y == E.screenrows / 3)
      {
        char welcome[80];
        int welcomelen = snprintf(welcome, sizeof(welcome),
                                  "Kilo editor -- version %s", KILO_VERSION);
        if (welcomelen > E.screencols)
          welcomelen = E.screencols;
        int padding = (E.screencols - welcomelen) / 2;
        if (padding)
        {
          abAppend(ab, "~", 1);
          padding--;
        }
        while (padding--)
          abAppend(ab, " ", 1);
        abAppend(ab, welcome, welcomelen);
      }
      else
      {
        abAppend(ab, "~", 1);
      }

    } else {
      int len = E.row[filerow].size - E.coloff;
      if (len < 0) len = 0;
      if (len > E.screencols) len = E.screencols;
      abAppend(ab, &E.row[filerow].chars[E.coloff], len);
    }
    abAppend(ab, "\x1b[K", 3);
    if (y < E.screenrows - 1)
    {
      abAppend(ab, "\r\n", 2);
    }
  }
}

void editorRefreshScreen()
{
  editorScroll();
  struct abuf ab = ABUF_INIT;

  abAppend(&ab, "\x1b[?25l", 6);
  abAppend(&ab, "\x1b[H", 3);

  editorDrawRows(&ab);

  char buf[32];
  snprintf(buf, sizeof(buf), "\x1b[%d;%dH", (E.cy - E.rowoff) + 1, (E.cx - E.coloff) + 1);
  abAppend(&ab, buf, strlen(buf));

  abAppend(&ab, "\x1b[?25h", 6);
  write(STDOUT_FILENO, ab.b, ab.len);
  abFree(&ab);
}

/*** input ***/

void editorMoveCursor(int key)
{
  erow *row = (E.cy >=E.numrows) ? NULL : &E.row[E.cy];
  switch (key)
  {
  case ARROW_LEFT:
    if (E.cx != 0)
    {
      E.cx--;
    } else if (E.cy > 0) {
        E.cy--;
        E.cx = E.row[E.cy].size;
      }
    break;
  case ARROW_RIGHT:
      if (row && E.cx < row->size) {
        E.cx++;
      } else if (row && E.cx == row->size) {
        E.cy++;
        E.cx = 0;
      }
    break;

  case ARROW_UP:
    if (E.cy != 0)
    {
      E.cy--;
    }
    break;
  case ARROW_DOWN:
    if (E.cy < E.numrows)
    {
      E.cy++;
    }
    break;
  default:
    break;
  }

  row = (E.cy > E.numrows) ? NULL : &E.row[E.cy];
  int rowlen = row ? row->size : 0;
  if (E.cx > rowlen) {
    E.cx = rowlen;
  }
}

void editorProcessKeypress()
{
  int c = editorReadKey();

  switch (c)
  {
  case CTRL_KEY('q'):
    write(STDOUT_FILENO, "\x1b[2J", 4);
    write(STDOUT_FILENO, "\x1b[H", 3);

    exit(0);
    break;
  case HOME_KEY:
    E.cx = 0;
    break;
  case END_KEY:
    E.cx = E.screencols - 1;
    break;
  case PAGE_UP:
  case PAGE_DOWN:
  {
    int times = E.screenrows;
    while (times--)
      editorMoveCursor(c == PAGE_UP ? ARROW_UP : ARROW_DOWN);
  }
  break;

  case ARROW_UP:
  case ARROW_DOWN:
  case ARROW_LEFT:
  case ARROW_RIGHT:
    editorMoveCursor(c);
    break;
  }
}

/*** init ***/

void initEditor()
{
  E.cx = 0;
  E.cy = 0;
  E.rowoff = 0;
  E.coloff = 0;
  E.numrows = 0;
  E.row = NULL;

  if (getWindowSize(&E.screenrows, &E.screencols) == -1)
    die("getWindowSize");
}

int main(int argc, char *argv[])
{
  enableRawMode();
  initEditor();
  if (argc >= 2) {
    editorOpen(argv[1]);
  }

  while (1)
  {
    editorRefreshScreen();
    editorProcessKeypress();
  }

  return 0;
}