stdin.py

#!/usr/bin/env python2
from __future__ import print_function
from telnetlib import Telnet
import json
import sys
import os
import re

HOST = 'localhost'
PORT = 17428

conn = Telnet(HOST, PORT)

conn.read_until('\nl> ')

code = sys.stdin.read()

stub = ur'''
(function (global, code, url, line, context) {
    function debugEval(sandbox) {
        Components.utils.import('resource://gre/modules/jsdebugger.jsm', {})
                  .addDebuggerToGlobal(sandbox);
        let d = Debugger();
        let res = d.addDebuggee(window)
                   .evalInGlobal(code, { url: url, lineNumber: line });
        d.removeDebuggee(window);
        return res;
    }

    if (context)
        context.split(/\./g).forEach(p => {
            global = global[p];
        });

    if ({}.toString.call(global) == '[object Sandbox]')
        return Components.utils.evalInSandbox(code, global, "1.8", url, line);
    else {
        let sandbox = Components.utils.Sandbox(window);
        sandbox.window = global;
        sandbox.code = code;
        sandbox.url = url;
        sandbox.line = line;
        return Components.utils.evalInSandbox('(' + debugEval + ')(this)',
                                              sandbox, "1.8",
                                              'dactyl-eval.py', 20);
    }

})(window, %s, %s, %s, %s);
'''

stub = stub.replace('\n', '\n\\ ')[1:-1] + '.\n'

conn.write(
    (stub % tuple(map(json.dumps, 
                      (code, sys.argv[1], int(sys.argv[2]),
                       sys.argv[3] if len(sys.argv) > 3 else ''))))
        .encode('utf-8'))

end = re.compile('^l> ', re.M)

print(conn.expect([end])[2][:-3],
      end='')