diff options
| -rw-r--r-- | Lib/test/test_long_future.py | 38 | ||||
| -rw-r--r-- | Objects/intobject.c | 9 | ||||
| -rw-r--r-- | Objects/longobject.c | 33 |
3 files changed, 78 insertions, 2 deletions
diff --git a/Lib/test/test_long_future.py b/Lib/test/test_long_future.py new file mode 100644 index 0000000..4348bbe --- /dev/null +++ b/Lib/test/test_long_future.py @@ -0,0 +1,38 @@ +from __future__ import division +# When true division is the default, get rid of this and add it to +# test_long.py instead. In the meantime, it's too obscure to try to +# trick just part of test_long into using future division. + +from test_support import TestFailed, verify, verbose + +def test_true_division(): + if verbose: + print "long true division" + huge = 1L << 40000 + mhuge = -huge + verify(huge / huge == 1.0) + verify(mhuge / mhuge == 1.0) + verify(huge / mhuge == -1.0) + verify(mhuge / huge == -1.0) + verify(1 / huge == 0.0) + verify(1L / huge == 0.0) + verify(1 / mhuge == 0.0) + verify(1L / mhuge ==- 0.0) + verify((666 * huge + (huge >> 1)) / huge == 666.5) + verify((666 * mhuge + (mhuge >> 1)) / mhuge == 666.5) + verify((666 * huge + (huge >> 1)) / mhuge == -666.5) + verify((666 * mhuge + (mhuge >> 1)) / huge == -666.5) + verify(huge / (huge << 1) == 0.5) + + namespace = {'huge': huge, 'mhuge': mhuge} + for overflow in ["float(huge)", "float(mhuge)", + "huge / 1", "huge / 2L", "huge / -1", "huge / -2L", + "mhuge / 100", "mhuge / 100L"]: + try: + eval(overflow, namespace) + except OverflowError: + pass + else: + raise TestFailed("expected OverflowError from %r" % overflow) + +test_true_division() diff --git a/Objects/intobject.c b/Objects/intobject.c index 775213c..73d5e77 100644 --- a/Objects/intobject.c +++ b/Objects/intobject.c @@ -535,7 +535,14 @@ int_classic_div(PyIntObject *x, PyIntObject *y) static PyObject * int_true_divide(PyObject *v, PyObject *w) { - return PyFloat_Type.tp_as_number->nb_true_divide(v, w); + /* If they aren't both ints, give someone else a chance. In + particular, this lets int/long get handled by longs, which + underflows to 0 gracefully if the long is too big to convert + to float. */ + if (PyInt_Check(v) && PyInt_Check(w)) + return PyFloat_Type.tp_as_number->nb_true_divide(v, w); + Py_INCREF(Py_NotImplemented); + return Py_NotImplemented; } static PyObject * diff --git a/Objects/longobject.c b/Objects/longobject.c index 7aa6005..5da5113 100644 --- a/Objects/longobject.c +++ b/Objects/longobject.c @@ -1584,7 +1584,38 @@ long_classic_div(PyObject *v, PyObject *w) static PyObject * long_true_divide(PyObject *v, PyObject *w) { - return PyFloat_Type.tp_as_number->nb_divide(v, w); + PyLongObject *a, *b; + double ad, bd; + int aexp, bexp; + + CONVERT_BINOP(v, w, &a, &b); + ad = _PyLong_AsScaledDouble((PyObject *)a, &aexp); + bd = _PyLong_AsScaledDouble((PyObject *)b, &bexp); + if ((ad == -1.0 || bd == -1.0) && PyErr_Occurred()) + return NULL; + + if (bd == 0.0) { + PyErr_SetString(PyExc_ZeroDivisionError, + "long division or modulo by zero"); + return NULL; + } + + /* True value is very close to ad/bd * 2**(SHIFT*(aexp-bexp)) */ + ad /= bd; /* overflow/underflow impossible here */ + aexp -= bexp; + if (aexp > INT_MAX / SHIFT) + goto overflow; + errno = 0; + ad = ldexp(ad, aexp * SHIFT); + if (ad != 0 && errno == ERANGE) /* ignore underflow to 0.0 */ + goto overflow; + return PyFloat_FromDouble(ad); + +overflow: + PyErr_SetString(PyExc_OverflowError, + "long/long too large for a float"); + return NULL; + } static PyObject * |