breeze.c

// INCLUDES
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <sys/types.h>
// DEFINES
#define BREEZE_VERSION "0.0.1"
#define BREEZE_TAB_STOP 8
#define CTRL_KEY(k) ((k) & 0x1f)
#define _DEFAULT_SOURCE
#define _BSD_SOURCE
#define _GNU_SOURCE

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

// DATA
typedef struct erow {
    int size;
    int rsize;
    char *chars;
    char *render;
} erow;

struct editorConfig {
    int cx, cy;
    int rowoff;
    int coloff;
    int screenrows;
    int screencols;
    int numrows;
    erow *row;
    struct termios orig_termios;
} 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");
}

//  to turn off echoing...
void enableRawMode() {
    if (tcgetattr(STDIN_FILENO, &E.orig_termios) == -1) {
        die("tcgetattr");
    }
    atexit(disableRawMode); //  disable raw mode at exit
    struct termios raw = E.orig_termios;

    raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
    raw.c_oflag &= ~(OPOST);
    raw.c_cflag |= (CS8);
    raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);

    //   timeout for read()
    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 (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 editorUpdateRow(erow *row) {
    int j;
    int tabs = 0;
    
    
    for (j = 0; j < row->size; j++) { 
        if (row->chars[j] == '\t')
            tabs++;
    }

    free(row->render);
    row->render = malloc(row->size + tabs*(BREEZE_TAB_STOP - 1) + 1);

    int idx = 0;

    for (j = 0; j < row->size; j++) {
        if (row->chars[j] == '\t') {
            row->render[idx++] = ' ';
            while (idx % BREEZE_TAB_STOP != 0)
                row->render[idx++] = ' ';
        }
        else
            row->render[idx++] = row->chars[j];
    }

    row->render[idx] = '\0';
    row->rsize = idx;
}

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.row[at].rsize = 0;
    E.row[at].render = NULL;
    editorUpdateRow(&E.row[at]);
    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;
    linelen = getline(&line, &linecap, fp);

    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);
}

//  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;
    }

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

//  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),
                    "Breeze editor -- version %s", BREEZE_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, "\x1b[?25h", 6);
    
    abAppend(&ab, "\x1b[H", 3);
    abAppend(&ab, "\x1b[?25h", 6);

    write(STDOUT_FILENO, ab.b, ab.len);
    abFree(&ab);
}

//  INIT
void initEditor() {
    E.cx = 0;
    E.cy = 0;
    E.numrows = 0;
    E.row = NULL;
    E.rowoff = 0;
    E.coloff = 0;
    if (getWindowSize(&E.screenrows, &E.screencols) == -1) 
        die("getWindowSize");
}
int main(int argc, char *argv[]) {
    // printf("Hello! Breeze is a Text Editor written in C\nPress 'q' to quit!\n\n");
    
    enableRawMode();
    initEditor();
    if (argc >= 2)
        editorOpen(argv[1]);
    
    while (1) {
        editorRefreshScreen();
        editorProcessKeypress();
    }

    return 0;
}