Command line Javascript REPL using QtScript. If given a filename argument, runs the file and exits.

javascript.py

#!/usr/bin/env python3 

import sys

from PyQt4 import QtCore
from PyQt4.QtScript import QScriptEngine, QScriptValue

def my_exit(context, eng):
    exit(0)

def my_print(context, eng):
    if context.argumentCount() == 0:
        print("")
    else:
        na = context.argumentCount()
        args = list()
        for i in range(na):
            args.append( str(context.argument(i).toVariant()))
        pval = ' '.join(args)
        global show_val
        print(pval)
    return QScriptValue("Okay")

def do_repl(qse):
    curScript = ''
    
    while(True):
        if len(curScript)>0:
            prompt = '... '
        else:
            prompt = '>>> '
        print(prompt, end='')
        curScript += input()
        if QScriptEngine.checkSyntax(curScript).state() != 1:
            res = qse.evaluate(curScript)
            if res.isError():
                if res.property("expressionBeginOffset").toVariant() is not None:
                    off1 = int(res.property("expressionBeginOffset").toVariant())
                else:
                    off1 = 0
                if res.property("expressionEndOffset").toVariant() is not None:
                    off2 = int(res.property("expressionEndOffset").toVariant())
                else:
                    off2 = len(curScript)
                print("Syntax error at:")
                print('    ' + curScript)
                print('    ', end='')
                for i in range(off1):
                    print(' ', end='')
                for i in range(off2-off1):
                    print('^', end='')
                print('')
            curScript = ''

def main(args):
    app = QtCore.QCoreApplication(args)
    qse = QScriptEngine()
    mef = qse.newFunction(my_exit)
    qse.globalObject().setProperty('exit', mef)
    pf = qse.newFunction(my_print)
    qse.globalObject().setProperty('print', pf)

    if len(args)==0:
        do_repl(qse)
    script = ''
    with open(args[0]) as inf:
        script = inf.read()
        
    rv = qse.evaluate(script)

if __name__=='__main__':
    main(sys.argv[1:])