p.py

def charorquoted(strn):
    c = anychar(strn)
    if c[0] == '"':
        return None
    elif c[0] == '\\':
        c2 = anychar(c[1])
        if c2[0] in ('\\', '"'):
            return (c[0] + c2[0], c2[1])
    else:
        return c

def wsed(p):
    def _(strn):
        w = repeat0(whitespace)(strn)
        if w:
            pres = p(w[1])
            if pres:
                w2 = repeat0(whitespace)(pres[1])
                if w2:
                    return (pres[0], w2[1])
        return None
    return _


class Forward(object):
    def __init__(self):
        self.p = None
    def __call__(self, *args, **kwargs):
        return self.p(*args, **kwargs)

anint = sequence(optional(matchchr("-")), repeat(digit))
astring = betweenchrs(repeat0(charorquoted), left='"', right='"')
acolon = matchchr(':')
acomma = matchchr(',')

akey = wsed(alt(anint, astring))
avalue = Forward() #wsed(alt(anint, astring))
akeyvaluepair = sequence(akey, acolon, avalue)

def commaseparated(p):
    def _(strn):
        r = repeat0(sequence(p, acomma))(strn)
        if r:
            r2 = repeat0(p)(r[1])
            if r2:
                return (r[0] + r2[0], r2[1])
        return None
    return _


adict = betweencurlies(commaseparated(akeyvaluepair))
alist = betweenbrackets(commaseparated(avalue))

avalue.p = alt(wsed(adict), wsed(alist), wsed(anint), wsed(astring))

json = alt(adict, alist)