# Implement (a subset of) Sun XDR -- RFC1014.

try:

    import struct

except ImportError:

    struct = None

Long = type(0L)

class Packer:

    def __init__(self):

        self.reset()

    def reset(self):

        self.buf = ''

    def get_buf(self):

        return self.buf

    def pack_uint(self, x):

        self.buf = self.buf + \

                (chr(int(x>>24 & 0xff)) + chr(int(x>>16 & 0xff)) + \

                 chr(int(x>>8 & 0xff)) + chr(int(x & 0xff)))

    if struct and struct.pack('l', 1) == '\0\0\0\1':

        def pack_uint(self, x):

            if type(x) == Long:

                x = int((x + 0x80000000L) % 0x100000000L \

                           - 0x80000000L)

            self.buf = self.buf + struct.pack('l', x)

    pack_int = pack_uint

    pack_enum = pack_int

    def pack_bool(self, x):

        if x: self.buf = self.buf + '\0\0\0\1'

        else: self.buf = self.buf + '\0\0\0\0'

    def pack_uhyper(self, x):

        self.pack_uint(int(x>>32 & 0xffffffff))

        self.pack_uint(int(x & 0xffffffff))

    pack_hyper = pack_uhyper

    def pack_float(self, x):

        # XXX

        self.buf = self.buf + struct.pack('f', x)

    def pack_double(self, x):

        # XXX

        self.buf = self.buf + struct.pack('d', x)

    def pack_fstring(self, n, s):

        if n < 0:

            raise ValueError, 'fstring size must be nonnegative'

        n = ((n + 3)//4)*4

        data = s[:n]

        data = data + (n - len(data)) * '\0'

        self.buf = self.buf + data

    pack_fopaque = pack_fstring

    def pack_string(self, s):

        n = len(s)

        self.pack_uint(n)

        self.pack_fstring(n, s)

    pack_opaque = pack_string

    def pack_list(self, list, pack_item):

        for item in list:

            self.pack_uint(1)

            pack_item(item)

        self.pack_uint(0)

    def pack_farray(self, n, list, pack_item):

        if len(list) <> n:

            raise ValueError, 'wrong array size'

        for item in list:

            pack_item(item)

    def pack_array(self, list, pack_item):

        n = len(list)

        self.pack_uint(n)

        self.pack_farray(n, list, pack_item)

class Unpacker:

    def __init__(self, data):

        self.reset(data)

    def reset(self, data):

        self.buf = data

        self.pos = 0

    def done(self):

        if self.pos < len(self.buf):

            raise RuntimeError, 'unextracted data remains'

    def unpack_uint(self):

        i = self.pos

        self.pos = j = i+4

        data = self.buf[i:j]

        if len(data) < 4:

            raise EOFError

        x = long(ord(data[0]))<<24 | ord(data[1])<<16 | \

                ord(data[2])<<8 | ord(data[3])

        # Return a Python long only if the value is not representable

        # as a nonnegative Python int

        if x < 0x80000000L: x = int(x)

        return x

    if struct and struct.unpack('l', '\0\0\0\1') == 1:

        def unpack_uint(self):

            i = self.pos

            self.pos = j = i+4

            data = self.buf[i:j]

            if len(data) < 4:

                raise EOFError

            return struct.unpack('l', data)

    def unpack_int(self):

        x = self.unpack_uint()

        if x >= 0x80000000L: x = x - 0x100000000L

        return int(x)

    unpack_enum = unpack_int

    unpack_bool = unpack_int

    def unpack_uhyper(self):

        hi = self.unpack_uint()

        lo = self.unpack_uint()

        return long(hi)<<32 | lo

    def unpack_hyper(self):

        x = self.unpack_uhyper()

        if x >= 0x8000000000000000L: x = x - 0x10000000000000000L

        return x

    def unpack_float(self):

        # XXX

        i = self.pos

        self.pos = j = i+4

        data = self.buf[i:j]

        if len(data) < 4:

            raise EOFError

        return struct.unpack('f', data)[0]

    def unpack_double(self):

        # XXX

        i = self.pos

        self.pos = j = i+8

        data = self.buf[i:j]

        if len(data) < 8:

            raise EOFError

        return struct.unpack('d', data)[0]

    def unpack_fstring(self, n):

        if n < 0:

            raise ValueError, 'fstring size must be nonnegative'

        i = self.pos

        j = i + (n+3)//4*4

        if j > len(self.buf):

            raise EOFError

        self.pos = j

        return self.buf[i:i+n]

    unpack_fopaque = unpack_fstring

    def unpack_string(self):

        n = self.unpack_uint()

        return self.unpack_fstring(n)

    unpack_opaque = unpack_string

    def unpack_list(self, unpack_item):

        list = []

        while 1:

            x = self.unpack_uint()

            if x == 0: break

            if x <> 1:

                raise RuntimeError, '0 or 1 expected, got %r' % (x, )

            item = unpack_item()

            list.append(item)

        return list

    def unpack_farray(self, n, unpack_item):

        list = []

        for i in range(n):

            list.append(unpack_item())

        return list

    def unpack_array(self, unpack_item):

        n = self.unpack_uint()

        return self.unpack_farray(n, unpack_item)