repl.js

/* eslint-disable */

/*
 * QuickJS Read Eval Print Loop
 *
 * Copyright (c) 2017-2019 Fabrice Bellard
 * Copyright (c) 2017-2019 Charlie Gordon
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

function _run(g) {
    /* close global objects */
    var Object = g.Object;
    var String = g.String;
    var Array = g.Array;
    var Date = g.Date;
    var Math = g.Math;
    var isFinite = g.isFinite;

    var colors = {
        none:    '\x1b[0m',
        black:   '\x1b[30m',
        red:     '\x1b[31m',
        green:   '\x1b[32m',
        yellow:  '\x1b[33m',
        blue:    '\x1b[34m',
        magenta: '\x1b[35m',
        cyan:    '\x1b[36m',
        white:   '\x1b[37m',
        gray:    '\x1b[30;1m',
        grey:    '\x1b[30;1m',
        bright_red:     '\x1b[31;1m',
        bright_green:   '\x1b[32;1m',
        bright_yellow:  '\x1b[33;1m',
        bright_blue:    '\x1b[34;1m',
        bright_magenta: '\x1b[35;1m',
        bright_cyan:    '\x1b[36;1m',
        bright_white:   '\x1b[37;1m',
    };

    var styles = {
        'default':    'bright_green',
        'comment':    'grey',
        'string':     'bright_cyan',
        'regex':      'cyan',
        'number':     'green',
        'keyword':    'bright_magenta',
        'function':   'bright_yellow',
        'type':       'grey',
        'identifier': 'bright_green',
        'error':      'red',
        'result':     'grey',
        'error_msg':  'bright_red',
    };

    var history = [];
    var clip_board = '';

    var pstate = '';
    var prompt = '';
    var plen = 0;
    var ps1 = '> ';
    var ps2 = '  ... ';
    var utf8 = true;
    var show_colors = true;

    var mexpr = '';
    var level = 0;
    var cmd = '';
    var cursor_pos = 0;
    var last_cmd = '';
    var last_cursor_pos = 0;
    var history_index;
    var this_fun, last_fun;
    var quote_flag = false;

    var utf8_state = 0;
    var utf8_val = 0;

    var term_width;
    /* current X position of the cursor in the terminal */
    var term_cursor_x = 0;

    var { evalScript } = tjs[Symbol.for('tjs.internal')].core;

    var encoder = new TextEncoder();

    function stdout_write(data) {
        tjs.stdout.write(encoder.encode(data));
    }

    function termInit() {
        if (!tjs.stdin.isTTY) {
            throw new Error('stdin is not a TTY');
        }

        /* get the terminal size */
        term_width = tjs.stdout.width;

        /* set the TTY to raw mode */
        tjs.stdin.setRawMode(true);

        /* install a Ctrl-C signal handler */
        tjs.addSignalListener('SIGINT', sigint_handler);

        /* handler to read stdin */
        term_read_handler();
    }

    function exit(code) {
        tjs.exit(code);
    }

    function sigint_handler() {
        /* send Ctrl-C to readline */
        handle_byte(3);
    }

    async function term_read_handler() {
        var buf = new Uint8Array(4096);
        var nread;

        while (true) {
            try {
                nread = await tjs.stdin.read(buf);

                for (var i = 0; i < nread; i++) {
                    handle_byte(buf[i]);
                }
            } catch (error) {
                dump_error(error);
            }
        }
    }

    function handle_byte(c) {
        if (!utf8) {
            handle_char(c);
        } else if (utf8_state !== 0 && (c >= 0x80 && c < 0xc0)) {
            utf8_val = (utf8_val << 6) | (c & 0x3F);
            utf8_state--;

            if (utf8_state === 0) {
                handle_char(utf8_val);
            }
        } else if (c >= 0xc0 && c < 0xf8) {
            utf8_state = 1 + (c >= 0xe0) + (c >= 0xf0);
            utf8_val = c & ((1 << (6 - utf8_state)) - 1);
        } else {
            utf8_state = 0;
            handle_char(c);
        }
    }

    function is_alpha(c) {
        return typeof c === 'string' &&
            ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'));
    }

    function is_digit(c) {
        return typeof c === 'string' && (c >= '0' && c <= '9');
    }

    function is_word(c) {
        return typeof c === 'string' &&
            (is_alpha(c) || is_digit(c) || c == '_' || c == '$');
    }

    function is_balanced(a, b) {
        switch (a + b) {
            case '()':
            case '[]':
            case '{}':
                return true;
        }

        return false;
    }

    function print_color_text(str, start, style_names) {
        var i, j;

        for (j = start; j < str.length;) {
            var style = style_names[i = j];

            while (++j < str.length && style_names[j] == style) {
                continue;
            }

            stdout_write(colors[styles[style] || 'default']);
            stdout_write(str.substring(i, j));
            stdout_write(colors['none']);
        }
    }

    function print_csi(n, code) {
        stdout_write('\x1b[' + ((n != 1) ? n : '') + code);
    }

    function move_cursor(delta) {
        var i, l;

        if (delta > 0) {
            while (delta != 0) {
                if (term_cursor_x == (term_width - 1)) {
                    stdout_write('\n'); /* translated to CRLF */
                    term_cursor_x = 0;
                    delta--;
                } else {
                    l = Math.min(term_width - 1 - term_cursor_x, delta);
                    print_csi(l, 'C'); /* right */
                    delta -= l;
                    term_cursor_x += l;
                }
            }
        } else {
            delta = -delta;

            while (delta != 0) {
                if (term_cursor_x == 0) {
                    print_csi(1, 'A'); /* up */
                    print_csi(term_width - 1, 'C'); /* right */
                    delta--;
                    term_cursor_x = term_width - 1;
                } else {
                    l = Math.min(delta, term_cursor_x);
                    print_csi(l, 'D'); /* left */
                    delta -= l;
                    term_cursor_x -= l;
                }
            }
        }
    }

    function update() {
        var i;

        if (cmd != last_cmd) {
            if (!show_colors && last_cmd.substring(0, last_cursor_pos) == cmd.substring(0, last_cursor_pos)) {
                /* optimize common case */
                stdout_write(cmd.substring(last_cursor_pos));
            } else {
                /* goto the start of the line */
                move_cursor(-last_cursor_pos);

                if (show_colors) {
                    var str = mexpr ? mexpr + '\n' + cmd : cmd;
                    var start = str.length - cmd.length;
                    var colorstate = colorize_js(str);

                    print_color_text(str, start, colorstate[2]);
                } else {
                    stdout_write(cmd);
                }
            }

            /* Note: assuming no surrogate pairs */
            term_cursor_x = (term_cursor_x + cmd.length) % term_width;

            if (term_cursor_x == 0) {
                /* show the cursor on the next line */
                stdout_write(' \x08');
            }

            /* remove the trailing characters */
            stdout_write('\x1b[J');
            last_cmd = cmd;
            last_cursor_pos = cmd.length;
        }

        move_cursor(cursor_pos - last_cursor_pos);
        last_cursor_pos = cursor_pos;
    }

    /* editing commands */
    function insert(str) {
        if (str) {
            cmd = cmd.substring(0, cursor_pos) + str + cmd.substring(cursor_pos);
            cursor_pos += str.length;
        }
    }

    function quoted_insert() {
        quote_flag = true;
    }

    function abort() {
        cmd = '';
        cursor_pos = 0;

        return -2;
    }

    function alert() {
    }

    function clear_screen() {
        stdout_write('\x1b[H\x1b[J');

        return -2;
    }

    function beginning_of_line() {
        cursor_pos = 0;
    }

    function end_of_line() {
        cursor_pos = cmd.length;
    }

    function forward_char() {
        if (cursor_pos < cmd.length) {
            cursor_pos++;
        }
    }

    function backward_char() {
        if (cursor_pos > 0) {
            cursor_pos--;
        }
    }

    function skip_word_forward(pos) {
        while (pos < cmd.length && !is_word(cmd.charAt(pos))) {
            pos++;
        }

        while (pos < cmd.length && is_word(cmd.charAt(pos))) {
            pos++;
        }

        return pos;
    }

    function skip_word_backward(pos) {
        while (pos > 0 && !is_word(cmd.charAt(pos - 1))) {
            pos--;
        }

        while (pos > 0 && is_word(cmd.charAt(pos - 1))) {
            pos--;
        }

        return pos;
    }

    function forward_word() {
        cursor_pos = skip_word_forward(cursor_pos);
    }

    function backward_word() {
        cursor_pos = skip_word_backward(cursor_pos);
    }

    function accept_line() {
        stdout_write('\n');
        history_add(cmd);

        return -1;
    }

    function history_add(str) {
        if (str) {
            history.push(str);
        }

        history_index = history.length;
    }

    function previous_history() {
        if (history_index > 0) {
            if (history_index == history.length) {
                history.push(cmd);
            }

            history_index--;
            cmd = history[history_index];
            cursor_pos = cmd.length;
        }
    }

    function next_history() {
        if (history_index < history.length - 1) {
            history_index++;
            cmd = history[history_index];
            cursor_pos = cmd.length;
        }
    }

    function history_search(dir) {
        var pos = cursor_pos;

        for (var i = 1; i <= history.length; i++) {
            var index = (history.length + i * dir + history_index) % history.length;

            if (history[index].substring(0, pos) == cmd.substring(0, pos)) {
                history_index = index;
                cmd = history[index];

                return;
            }
        }
    }

    function history_search_backward() {
        return history_search(-1);
    }

    function history_search_forward() {
        return history_search(1);
    }

    function delete_char_dir(dir) {
        var start = cursor_pos - (dir < 0);
        var end = start + 1;

        if (start >= 0 && start < cmd.length) {
            if (last_fun === kill_region) {
                kill_region(start, end, dir);
            } else {
                cmd = cmd.substring(0, start) + cmd.substring(end);
                cursor_pos = start;
            }
        }
    }

    function delete_char() {
        delete_char_dir(1);
    }

    function control_d() {
        if (cmd.length == 0) {
            stdout_write('\n');
            exit(0);
        } else {
            delete_char_dir(1);
        }
    }

    function backward_delete_char() {
        delete_char_dir(-1);
    }

    function transpose_chars() {
        var pos = cursor_pos;

        if (cmd.length > 1 && pos > 0) {
            if (pos == cmd.length) {
                pos--;
            }

            cmd = cmd.substring(0, pos - 1) + cmd.substring(pos, pos + 1) +
                cmd.substring(pos - 1, pos) + cmd.substring(pos + 1);
            cursor_pos = pos + 1;
        }
    }

    function transpose_words() {
        var p1 = skip_word_backward(cursor_pos);
        var p2 = skip_word_forward(p1);
        var p4 = skip_word_forward(cursor_pos);
        var p3 = skip_word_backward(p4);

        if (p1 < p2 && p2 <= cursor_pos && cursor_pos <= p3 && p3 < p4) {
            cmd = cmd.substring(0, p1) + cmd.substring(p3, p4) +
            cmd.substring(p2, p3) + cmd.substring(p1, p2);
            cursor_pos = p4;
        }
    }

    function upcase_word() {
        var end = skip_word_forward(cursor_pos);

        cmd = cmd.substring(0, cursor_pos) +
            cmd.substring(cursor_pos, end).toUpperCase() +
            cmd.substring(end);
    }

    function downcase_word() {
        var end = skip_word_forward(cursor_pos);

        cmd = cmd.substring(0, cursor_pos) +
            cmd.substring(cursor_pos, end).toLowerCase() +
            cmd.substring(end);
    }

    function kill_region(start, end, dir) {
        var s = cmd.substring(start, end);

        if (last_fun !== kill_region) {
            clip_board = s;
        } else if (dir < 0) {
            clip_board = s + clip_board;
        } else {
            clip_board = clip_board + s;
        }

        cmd = cmd.substring(0, start) + cmd.substring(end);

        if (cursor_pos > end) {
            cursor_pos -= end - start;
        } else if (cursor_pos > start) {
            cursor_pos = start;
        }

        this_fun = kill_region;
    }

    function kill_line() {
        kill_region(cursor_pos, cmd.length, 1);
    }

    function backward_kill_line() {
        kill_region(0, cursor_pos, -1);
    }

    function kill_word() {
        kill_region(cursor_pos, skip_word_forward(cursor_pos), 1);
    }

    function backward_kill_word() {
        kill_region(skip_word_backward(cursor_pos), cursor_pos, -1);
    }

    function yank() {
        insert(clip_board);
    }

    function control_c() {
        if (last_fun === control_c) {
            stdout_write('\n');
            exit(0);
        } else {
            stdout_write('\n(Press Ctrl-C again to quit)\n');
            readline_print_prompt();
        }
    }

    function reset() {
        cmd = '';
        cursor_pos = 0;
    }

    function get_context_word(line, pos) {
        var s = '';

        while (pos > 0 && is_word(line[pos - 1])) {
            pos--;
            s = line[pos] + s;
        }

        return s;
    }

    function get_context_object(line, pos) {
        var obj, base, c;

        if (pos <= 0 || ' ~!%^&*(-+={[|:;,<>?/'.indexOf(line[pos - 1]) >= 0) {
            return g;
        }

        if (pos >= 2 && line[pos - 1] === '.') {
            pos--;
            obj = {};

            switch (c = line[pos - 1]) {
                case '\'':
                case '\"':
                    return 'a';
                case ']':
                    return [];
                case '}':
                    return {};
                case '/':
                    return / /;
                default:
                    if (is_word(c)) {
                        base = get_context_word(line, pos);

                        if ([ 'true', 'false', 'null', 'this' ].includes(base) || !isNaN(+base)) {
                            return eval(base);
                        }

                        obj = get_context_object(line, pos - base.length);

                        if (obj === null || obj === void 0) {
                            return obj;
                        }

                        if (obj === g && obj[base] === void 0) {
                            return eval(base);
                        } else {
                            return obj[base];
                        }
                    }

                    return {};
            }
        }

        return void 0;
    }

    function get_completions(line, pos) {
        var s, obj, ctx_obj, r, i, j, paren;

        s = get_context_word(line, pos);
        ctx_obj = get_context_object(line, pos - s.length);
        r = [];

        /* enumerate properties from object and its prototype chain,
           add non-numeric regular properties with s as e prefix
         */
        for (i = 0, obj = ctx_obj; i < 10 && obj !== null && obj !== void 0; i++) {
            var props = Object.getOwnPropertyNames(obj);

            /* add non-numeric regular properties */
            for (j = 0; j < props.length; j++) {
                var prop = props[j];

                if (typeof prop === 'string' && ''+(+prop) != prop && prop.startsWith(s)) {
                    r.push(prop);
                }
            }

            obj = Object.getPrototypeOf(obj);
        }

        if (r.length > 1) {
            /* sort list with internal names last and remove duplicates */
            function symcmp(a, b) {
                if (a[0] != b[0]) {
                    if (a[0] == '_') {
                        return 1;
                    }

                    if (b[0] == '_') {
                        return -1;
                    }
                }

                if (a < b) {
                    return -1;
                }

                if (a > b) {
                    return +1;
                }

                return 0;
            }

            r.sort(symcmp);

            for (i = j = 1; i < r.length; i++) {
                if (r[i] != r[i - 1]) {
                    r[j++] = r[i];
                }
            }

            r.length = j;
        }

        /* 'tab' = list of completions, 'pos' = cursor position inside
           the completions */
        return { tab: r, pos: s.length, ctx: ctx_obj };
    }

    function completion() {
        var tab, res, s, i, j, len, t, max_width, col, n_cols, row, n_rows;

        res = get_completions(cmd, cursor_pos);
        tab = res.tab;

        if (tab.length === 0) {
            return;
        }

        s = tab[0];
        len = s.length;

        /* add the chars which are identical in all the completions */
        for (i = 1; i < tab.length; i++) {
            t = tab[i];

            for (j = 0; j < len; j++) {
                if (t[j] !== s[j]) {
                    len = j;
                    break;
                }
            }
        }

        for (i = res.pos; i < len; i++) {
            insert(s[i]);
        }

        if (last_fun === completion && tab.length == 1) {
            /* append parentheses to function names */
            var m = res.ctx[tab[0]];

            if (typeof m === 'function') {
                insert('(');

                if (m.length == 0) {
                    insert(')');
                }
            } else if (typeof m === 'object') {
                insert('.');
            }
        }

        /* show the possible completions */
        if (last_fun === completion && tab.length >= 2) {
            max_width = 0;

            for (i = 0; i < tab.length; i++) {
                max_width = Math.max(max_width, tab[i].length);
            }

            max_width += 2;
            n_cols = Math.max(1, Math.floor((term_width + 1) / max_width));
            n_rows = Math.ceil(tab.length / n_cols);
            stdout_write('\n');

            /* display the sorted list column-wise */
            for (row = 0; row < n_rows; row++) {
                for (col = 0; col < n_cols; col++) {
                    i = col * n_rows + row;

                    if (i >= tab.length) {
                        break;
                    }

                    s = tab[i];

                    if (col != n_cols - 1) {
                        s = s.padEnd(max_width);
                    }

                    stdout_write(s);
                }

                stdout_write('\n');
            }

            /* show a new prompt */
            readline_print_prompt();
        }
    }

    var commands = {        /* command table */
        '\x01':     beginning_of_line,      /* ^A - bol */
        '\x02':     backward_char,          /* ^B - backward-char */
        '\x03':     control_c,              /* ^C - abort */
        '\x04':     control_d,              /* ^D - delete-char or exit */
        '\x05':     end_of_line,            /* ^E - eol */
        '\x06':     forward_char,           /* ^F - forward-char */
        '\x07':     abort,                  /* ^G - bell */
        '\x08':     backward_delete_char,   /* ^H - backspace */
        '\x09':     completion,             /* ^I - history-search-backward */
        '\x0a':     accept_line,            /* ^J - newline */
        '\x0b':     kill_line,              /* ^K - delete to end of line */
        '\x0c':     clear_screen,           /* ^L - clear screen */
        '\x0d':     accept_line,            /* ^M - enter */
        '\x0e':     next_history,           /* ^N - down */
        '\x10':     previous_history,       /* ^P - up */
        '\x11':     quoted_insert,          /* ^Q - quoted-insert */
        '\x12':     alert,                  /* ^R - reverse-search */
        '\x13':     alert,                  /* ^S - search */
        '\x14':     transpose_chars,        /* ^T - transpose */
        '\x18':     reset,                  /* ^X - cancel */
        '\x19':     yank,                   /* ^Y - yank */
        '\x1bOA':   previous_history,       /* ^[OA - up */
        '\x1bOB':   next_history,           /* ^[OB - down */
        '\x1bOC':   forward_char,           /* ^[OC - right */
        '\x1bOD':   backward_char,          /* ^[OD - left */
        '\x1bOF':   forward_word,           /* ^[OF - ctrl-right */
        '\x1bOH':   backward_word,          /* ^[OH - ctrl-left */
        '\x1b[1;5C': forward_word,          /* ^[[1;5C - ctrl-right */
        '\x1b[1;5D': backward_word,         /* ^[[1;5D - ctrl-left */
        '\x1b[1~':  beginning_of_line,      /* ^[[1~ - bol */
        '\x1b[3~':  delete_char,            /* ^[[3~ - delete */
        '\x1b[4~':  end_of_line,            /* ^[[4~ - eol */
        '\x1b[5~':  history_search_backward,/* ^[[5~ - page up */
        '\x1b[6~':  history_search_forward, /* ^[[5~ - page down */
        '\x1b[A':   previous_history,       /* ^[[A - up */
        '\x1b[B':   next_history,           /* ^[[B - down */
        '\x1b[C':   forward_char,           /* ^[[C - right */
        '\x1b[D':   backward_char,          /* ^[[D - left */
        '\x1b[F':   end_of_line,            /* ^[[F - end */
        '\x1b[H':   beginning_of_line,      /* ^[[H - home */
        '\x1b\x7f': backward_kill_word,     /* M-C-? - backward_kill_word */
        '\x1bb':    backward_word,          /* M-b - backward_word */
        '\x1bd':    kill_word,              /* M-d - kill_word */
        '\x1bf':    forward_word,           /* M-f - backward_word */
        '\x1bk':    backward_kill_line,     /* M-k - backward_kill_line */
        '\x1bl':    downcase_word,          /* M-l - downcase_word */
        '\x1bt':    transpose_words,        /* M-t - transpose_words */
        '\x1bu':    upcase_word,            /* M-u - upcase_word */
        '\x7f':     backward_delete_char,   /* ^? - delete */
    };

    function dupstr(str, count) {
        var res = '';

        while (count-- > 0) {
            res += str;
        }

        return res;
    }

    var readline_keys;
    var readline_state;
    var readline_cb;

    function readline_print_prompt() {
        stdout_write(prompt);
        term_cursor_x = prompt.length % term_width;
        last_cmd = '';
        last_cursor_pos = 0;
    }

    function readline_start(defstr, cb) {
        cmd = defstr || '';
        cursor_pos = cmd.length;
        history_index = history.length;
        readline_cb = cb;

        prompt = pstate;

        if (mexpr) {
            prompt += dupstr(' ', plen - prompt.length);
            prompt += ps2;
        } else {
            plen = prompt.length;
            prompt += ps1;
        }

        readline_print_prompt();
        update();
        readline_state = 0;
    }

    function handle_char(c1) {
        var c;

        c = String.fromCharCode(c1);

        switch (readline_state) {
            case 0:
                if (c == '\x1b') {  /* '^[' - ESC */
                    readline_keys = c;
                    readline_state = 1;
                } else {
                    handle_key(c);
                }

                break;
            case 1: /* '^[ */
                readline_keys += c;

                if (c == '[') {
                    readline_state = 2;
                } else if (c == 'O') {
                    readline_state = 3;
                } else {
                    handle_key(readline_keys);
                    readline_state = 0;
                }

                break;
            case 2: /* '^[[' - CSI */
                readline_keys += c;

                if (!(c == ';' || (c >= '0' && c <= '9'))) {
                    handle_key(readline_keys);
                    readline_state = 0;
                }

                break;
            case 3: /* '^[O' - ESC2 */
                readline_keys += c;
                handle_key(readline_keys);
                readline_state = 0;
                break;
        }
    }

    function handle_key(keys) {
        var fun;

        if (quote_flag) {
            if (keys.length === 1) {
                insert(keys);
            }

            quote_flag = false;
        } else if (fun = commands[keys]) {
            this_fun = fun;

            switch (fun(keys)) {
                case -1:
                    readline_cb(cmd);

                    return;
                case -2:
                    readline_cb(null);

                    return;
            }

            last_fun = this_fun;
        } else if (keys.length === 1 && keys >= ' ') {
            insert(keys);
            last_fun = insert;
        } else {
            alert(); /* beep! */
        }

        cursor_pos = (cursor_pos < 0) ? 0 :
            (cursor_pos > cmd.length) ? cmd.length : cursor_pos;
        update();
    }

    function number_to_string(a, radix) {
        var s;

        if (!isFinite(a)) {
            /* NaN, Infinite */
            return a.toString();
        } else {
            if (a == 0) {
                if (1 / a < 0) {
                    s = '-0';
                } else {
                    s = '0';
                }
            } else {
                if (radix == 16) {
                    var s;

                    if (a < 0) {
                        a = -a;
                        s = '-';
                    } else {
                        s = '';
                    }

                    s += '0x' + a.toString(16);
                } else {
                    s = a.toString();
                }
            }

            return s;
        }
    }

    function bigint_to_string(a, radix) {
        var s;

        if (radix == 16) {
            var s;

            if (a < 0) {
                a = -a;
                s = '-';
            } else {
                s = '';
            }

            s += '0x' + a.toString(16);
        } else {
            s = a.toString();
        }

        s += 'n';

        return s;
    }

    function print(a) {
        var stack = [];

        function print_rec(a) {
            var n, i, keys, key, type;

            type = typeof a;

            if (type === 'object') {
                if (a === null) {
                    stdout_write(String(a));
                } else if (stack.indexOf(a) >= 0) {
                    stdout_write('[circular]');
                } else if (a instanceof Date) {
                    stdout_write(`Date ${JSON.stringify(a.toGMTString())}`);
                } else if (a instanceof RegExp) {
                    stdout_write(a.toString());
                } else {
                    stack.push(a);

                    if (Array.isArray(a)) {
                        n = a.length;
                        stdout_write('[ ');

                        for (i = 0; i < n; i++) {
                            if (i !== 0) {
                                stdout_write(', ');
                            }

                            if (i in a) {
                                print_rec(a[i]);
                            } else {
                                stdout_write('<empty>');
                            }

                            if (i > 20) {
                                stdout_write('...');
                                break;
                            }
                        }

                        stdout_write(' ]');
                    } else {
                        keys = Object.keys(a);
                        n = keys.length;
                        var name = a[Symbol.toStringTag];
                        if (name)
                            stdout_write(name + ' ');
                        stdout_write('{ ');

                        for (i = 0; i < n; i++) {
                            if (i !== 0) {
                                stdout_write(', ');
                            }

                            key = keys[i];
                            stdout_write(key + ': ');
                            print_rec(a[key]);
                        }

                        stdout_write(' }');
                    }

                    stack.pop(a);
                }
            } else if (type === 'string') {
                var s = JSON.stringify(a);
                if (s.length > 79)
                    s = s.substring(0, 75) + "...\"";
                stdout_write(s);
            } else if (type === 'number') {
                stdout_write(number_to_string(a, 10));
            } else if (type === 'bigint') {
                stdout_write(bigint_to_string(a, 10));
            } else if (type === 'symbol') {
                stdout_write(String(a));
            } else if (type === 'function') {
                stdout_write('function ' + a.name + '()');
            } else {
                stdout_write(String(a));
            }
        }

        print_rec(a);
    }

    function extract_directive(a) {
        var pos;

        if (a[0] !== '\\') {
            return '';
        }

        for (pos = 1; pos < a.length; pos++) {
            if (!is_alpha(a[pos])) {
                break;
            }
        }

        return a.substring(1, pos);
    }

    /* return true if the string after cmd can be evaluted as JS */
    function handle_directive(cmd, expr) {
        if (cmd === 'h' || cmd === '?' || cmd == 'help') {
            help();
        } else if (cmd === 'clear') {
            clear_screen();
        } else if (cmd === 'q') {
            exit(0);
        } else {
            stdout_write('Unknown directive: ' + cmd + '\n');

            return false;
        }

        return true;
    }

    function help() {
        stdout_write('\\h      this help\n' +
                     '\\clear  clear the terminal\n' +
                     '\\q      exit\n');
    }

    function preprocessEval(input) {
        const awaitMatcher = /^(?:\s*(?:(?:let|var|const)\s)?\s*([^=]+)=\s*|^\s*)(await\s[\s\S]*)/;
        const asyncWrapper = (code, binder) => {
            let assign = binder ? `global.${binder} = ` : '';
            return `(function(){ async function _wrap() { return ${assign}${code} } return _wrap();})()`;
        };
      
        // match & transform
        const match = input.match(awaitMatcher);
        if (match) {
            input = `${asyncWrapper(match[2], match[1])}`;
        }
        return input;
      }

    function doEval(input) {
        const code = preprocessEval(input);

        return evalScript(code);
    }

    function eval_and_print(expr) {
        var result;

        try {
            /* eval as a script */
            result = doEval(expr);
            stdout_write(colors[styles.result]);
            print(result);
            stdout_write('\n');
            stdout_write(colors.none);
            /* set the last result */
            g._ = result;
        } catch (error) {
            dump_error(error);
        }
    }

    function dump_error(error) {
        stdout_write(colors[styles.error_msg]);

        if (error instanceof Error) {
            stdout_write(error);
            stdout_write('\n');
            stdout_write(error.stack);
        } else {
            stdout_write('Throw: ');
            stdout_write(error);
        }

        stdout_write('\n');
        stdout_write(colors.none);
    }

    function cmd_start() {
        stdout_write('Welcome to txiki.js — The tiny JavaScript runtime\nType "\\h" for help\n');
        cmd_readline_start();
    }

    function cmd_readline_start() {
        readline_start(dupstr('    ', level), readline_handle_cmd);
    }

    function readline_handle_cmd(expr) {
        handle_cmd(expr);
        cmd_readline_start();
    }

    function handle_cmd(expr) {
        var colorstate, cmd;

        if (expr === null) {
            expr = '';

            return;
        }

        if (expr === '?') {
            help();

            return;
        }

        cmd = extract_directive(expr);

        if (cmd.length > 0) {
            if (!handle_directive(cmd, expr)) {
                return;
            }

            expr = expr.substring(cmd.length + 1);
        }

        if (expr === '') {
            return;
        }

        if (mexpr) {
            expr = mexpr + '\n' + expr;
        }

        colorstate = colorize_js(expr);
        pstate = colorstate[0];
        level = colorstate[1];

        if (pstate) {
            mexpr = expr;

            return;
        }

        mexpr = '';

        eval_and_print(expr);

        level = 0;

        /* run the garbage collector after each command */
        tjs.gc();
    }

    function colorize_js(str) {
        var i, c, start, n = str.length;
        var style, state = '', level = 0;
        var primary, can_regex = 1;
        var r = [];

        function push_state(c) {
            state += c;
        }

        function last_state(c) {
            return state.substring(state.length - 1);
        }

        function pop_state(c) {
            var c = last_state();

            state = state.substring(0, state.length - 1);

            return c;
        }

        function parse_block_comment() {
            style = 'comment';
            push_state('/');

            for (i++; i < n - 1; i++) {
                if (str[i] == '*' && str[i + 1] == '/') {
                    i += 2;
                    pop_state('/');
                    break;
                }
            }
        }

        function parse_line_comment() {
            style = 'comment';

            for (i++; i < n; i++) {
                if (str[i] == '\n') {
                    break;
                }
            }
        }

        function parse_string(delim) {
            style = 'string';
            push_state(delim);

            while (i < n) {
                c = str[i++];

                if (c == '\n') {
                    style = 'error';
                    continue;
                }

                if (c == '\\') {
                    if (i >= n) {
                        break;
                    }

                    i++;
                } else
                if (c == delim) {
                    pop_state();
                    break;
                }
            }
        }

        function parse_regex() {
            style = 'regex';
            push_state('/');

            while (i < n) {
                c = str[i++];

                if (c == '\n') {
                    style = 'error';
                    continue;
                }

                if (c == '\\') {
                    if (i < n) {
                        i++;
                    }

                    continue;
                }

                if (last_state() == '[') {
                    if (c == ']') {
                        pop_state();
                    }

                    // ECMA 5: ignore '/' inside char classes
                    continue;
                }

                if (c == '[') {
                    push_state('[');

                    if (str[i] == '[' || str[i] == ']') {
                        i++;
                    }

                    continue;
                }

                if (c == '/') {
                    pop_state();

                    while (i < n && is_word(str[i])) {
                        i++;
                    }

                    break;
                }
            }
        }

        function parse_number() {
            style = 'number';

            while (i < n && (is_word(str[i]) || (str[i] == '.' && (i == n - 1 || str[i + 1] != '.')))) {
                i++;
            }
        }

        var js_keywords = '|' +
            'break|case|catch|continue|debugger|default|delete|do|' +
            'else|finally|for|function|if|in|instanceof|new|' +
            'return|switch|this|throw|try|typeof|while|with|' +
            'class|const|enum|import|export|extends|super|' +
            'implements|interface|let|package|private|protected|' +
            'public|static|yield|' +
            'undefined|null|true|false|Infinity|NaN|' +
            'eval|arguments|' +
            'await|';

        var js_no_regex = '|this|super|undefined|null|true|false|Infinity|NaN|arguments|';
        var js_types = '|void|var|';

        function parse_identifier() {
            can_regex = 1;

            while (i < n && is_word(str[i])) {
                i++;
            }

            var w = '|' + str.substring(start, i) + '|';

            if (js_keywords.indexOf(w) >= 0) {
                style = 'keyword';

                if (js_no_regex.indexOf(w) >= 0) {
                    can_regex = 0;
                }

                return;
            }

            var i1 = i;

            while (i1 < n && str[i1] == ' ') {
                i1++;
            }

            if (i1 < n && str[i1] == '(') {
                style = 'function';

                return;
            }

            if (js_types.indexOf(w) >= 0) {
                style = 'type';

                return;
            }

            style = 'identifier';
            can_regex = 0;
        }

        function set_style(from, to) {
            while (r.length < from) {
                r.push('default');
            }

            while (r.length < to) {
                r.push(style);
            }
        }

        for (i = 0; i < n;) {
            style = null;
            start = i;

            switch (c = str[i++]) {
                case ' ':
                case '\t':
                case '\r':
                case '\n':
                    continue;
                case '+':
                case '-':
                    if (i < n && str[i] == c) {
                        i++;
                        continue;
                    }

                    can_regex = 1;
                    continue;
                case '/':
                    if (i < n && str[i] == '*') { // block comment
                        parse_block_comment();
                        break;
                    }

                    if (i < n && str[i] == '/') { // line comment
                        parse_line_comment();
                        break;
                    }

                    if (can_regex) {
                        parse_regex();
                        can_regex = 0;
                        break;
                    }

                    can_regex = 1;
                    continue;
                case '\'':
                case '\"':
                case '`':
                    parse_string(c);
                    can_regex = 0;
                    break;
                case '(':
                case '[':
                case '{':
                    can_regex = 1;
                    level++;
                    push_state(c);
                    continue;
                case ')':
                case ']':
                case '}':
                    can_regex = 0;

                    if (level > 0 && is_balanced(last_state(), c)) {
                        level--;
                        pop_state();
                        continue;
                    }

                    style = 'error';
                    break;
                default:
                    if (is_digit(c)) {
                        parse_number();
                        can_regex = 0;
                        break;
                    }

                    if (is_word(c) || c == '$') {
                        parse_identifier();
                        break;
                    }

                    can_regex = 1;
                    continue;
            }

            if (style) {
                set_style(start, i);
            }
        }

        set_style(n, n);

        return [ state, level, r ];
    }

    termInit();

    cmd_start();
}

export async function runRepl() {
    /* expose stdlib */
    const r = await Promise.allSettled([
        import('tjs:assert'),
        import('tjs:ffi'),
        import('tjs:getopts'),
        import('tjs:hashing'),
        import('tjs:ipaddr'),
        import('tjs:path'),
        import('tjs:uuid')
    ]);

    globalThis.assert = r[0].value.default;
    globalThis.ffi = r[1].value.default;
    globalThis.getopts = r[2].value.default;
    globalThis.hashing = r[3].value.default;
    globalThis.ipaddr = r[4].value.default;
    globalThis.path = r[5].value.default;
    globalThis.uuid = r[6].value.default;

    window.addEventListener('unhandledrejection', event => {
        // Avoid aborting in unhandled promised on the REPL.
        event.preventDefault();
    });

    _run(globalThis);
}