Home | History | Annotate | Download | only in Modules
      1 
      2 #include "Python.h"
      3 
      4 PyDoc_STRVAR(operator_doc,
      5 "Operator interface.\n\
      6 \n\
      7 This module exports a set of functions implemented in C corresponding\n\
      8 to the intrinsic operators of Python.  For example, operator.add(x, y)\n\
      9 is equivalent to the expression x+y.  The function names are those\n\
     10 used for special methods; variants without leading and trailing\n\
     11 '__' are also provided for convenience.");
     12 
     13 #define spam1(OP,AOP) static PyObject *OP(PyObject *s, PyObject *a1) { \
     14   return AOP(a1); }
     15 
     16 #define spam2(OP,AOP) static PyObject *OP(PyObject *s, PyObject *a) { \
     17   PyObject *a1, *a2; \
     18   if(! PyArg_UnpackTuple(a,#OP,2,2,&a1,&a2)) return NULL; \
     19   return AOP(a1,a2); }
     20 
     21 #define spamoi(OP,AOP) static PyObject *OP(PyObject *s, PyObject *a) { \
     22   PyObject *a1; int a2; \
     23   if(! PyArg_ParseTuple(a,"Oi:" #OP,&a1,&a2)) return NULL; \
     24   return AOP(a1,a2); }
     25 
     26 #define spam2n(OP,AOP) static PyObject *OP(PyObject *s, PyObject *a) { \
     27   PyObject *a1, *a2; \
     28   if(! PyArg_UnpackTuple(a,#OP,2,2,&a1,&a2)) return NULL; \
     29   if(-1 == AOP(a1,a2)) return NULL; \
     30   Py_INCREF(Py_None); \
     31   return Py_None; }
     32 
     33 #define spam3n(OP,AOP) static PyObject *OP(PyObject *s, PyObject *a) { \
     34   PyObject *a1, *a2, *a3; \
     35   if(! PyArg_UnpackTuple(a,#OP,3,3,&a1,&a2,&a3)) return NULL; \
     36   if(-1 == AOP(a1,a2,a3)) return NULL; \
     37   Py_INCREF(Py_None); \
     38   return Py_None; }
     39 
     40 #define spami(OP,AOP) static PyObject *OP(PyObject *s, PyObject *a1) { \
     41   long r; \
     42   if(-1 == (r=AOP(a1))) return NULL; \
     43   return PyBool_FromLong(r); }
     44 
     45 #define spami2(OP,AOP) static PyObject *OP(PyObject *s, PyObject *a) { \
     46   PyObject *a1, *a2; long r; \
     47   if(! PyArg_UnpackTuple(a,#OP,2,2,&a1,&a2)) return NULL; \
     48   if(-1 == (r=AOP(a1,a2))) return NULL; \
     49   return PyInt_FromLong(r); }
     50 
     51 #define spamn2(OP,AOP) static PyObject *OP(PyObject *s, PyObject *a) { \
     52   PyObject *a1, *a2; Py_ssize_t r; \
     53   if(! PyArg_UnpackTuple(a,#OP,2,2,&a1,&a2)) return NULL; \
     54   if(-1 == (r=AOP(a1,a2))) return NULL; \
     55   return PyInt_FromSsize_t(r); }
     56 
     57 #define spami2b(OP,AOP) static PyObject *OP(PyObject *s, PyObject *a) { \
     58   PyObject *a1, *a2; long r; \
     59   if(! PyArg_UnpackTuple(a,#OP,2,2,&a1,&a2)) return NULL; \
     60   if(-1 == (r=AOP(a1,a2))) return NULL; \
     61   return PyBool_FromLong(r); }
     62 
     63 #define spamrc(OP,A) static PyObject *OP(PyObject *s, PyObject *a) { \
     64   PyObject *a1, *a2; \
     65   if(! PyArg_UnpackTuple(a,#OP,2,2,&a1,&a2)) return NULL; \
     66   return PyObject_RichCompare(a1,a2,A); }
     67 
     68 /* Deprecated operators that need warnings. */
     69 static int
     70 op_isCallable(PyObject *x)
     71 {
     72     if (PyErr_WarnPy3k("operator.isCallable() is not supported in 3.x. "
     73                        "Use hasattr(obj, '__call__').", 1) < 0)
     74         return -1;
     75     return PyCallable_Check(x);
     76 }
     77 
     78 static int
     79 op_sequenceIncludes(PyObject *seq, PyObject* ob)
     80 {
     81     if (PyErr_WarnPy3k("operator.sequenceIncludes() is not supported "
     82                        "in 3.x. Use operator.contains().", 1) < 0)
     83         return -1;
     84     return PySequence_Contains(seq, ob);
     85 }
     86 
     87 spami(isCallable       , op_isCallable)
     88 spami(isNumberType     , PyNumber_Check)
     89 spami(truth            , PyObject_IsTrue)
     90 spam2(op_add           , PyNumber_Add)
     91 spam2(op_sub           , PyNumber_Subtract)
     92 spam2(op_mul           , PyNumber_Multiply)
     93 spam2(op_div           , PyNumber_Divide)
     94 spam2(op_floordiv      , PyNumber_FloorDivide)
     95 spam2(op_truediv       , PyNumber_TrueDivide)
     96 spam2(op_mod           , PyNumber_Remainder)
     97 spam1(op_neg           , PyNumber_Negative)
     98 spam1(op_pos           , PyNumber_Positive)
     99 spam1(op_abs           , PyNumber_Absolute)
    100 spam1(op_inv           , PyNumber_Invert)
    101 spam1(op_invert        , PyNumber_Invert)
    102 spam2(op_lshift        , PyNumber_Lshift)
    103 spam2(op_rshift        , PyNumber_Rshift)
    104 spami(op_not_          , PyObject_Not)
    105 spam2(op_and_          , PyNumber_And)
    106 spam2(op_xor           , PyNumber_Xor)
    107 spam2(op_or_           , PyNumber_Or)
    108 spam2(op_iadd          , PyNumber_InPlaceAdd)
    109 spam2(op_isub          , PyNumber_InPlaceSubtract)
    110 spam2(op_imul          , PyNumber_InPlaceMultiply)
    111 spam2(op_idiv          , PyNumber_InPlaceDivide)
    112 spam2(op_ifloordiv     , PyNumber_InPlaceFloorDivide)
    113 spam2(op_itruediv      , PyNumber_InPlaceTrueDivide)
    114 spam2(op_imod          , PyNumber_InPlaceRemainder)
    115 spam2(op_ilshift       , PyNumber_InPlaceLshift)
    116 spam2(op_irshift       , PyNumber_InPlaceRshift)
    117 spam2(op_iand          , PyNumber_InPlaceAnd)
    118 spam2(op_ixor          , PyNumber_InPlaceXor)
    119 spam2(op_ior           , PyNumber_InPlaceOr)
    120 spami(isSequenceType   , PySequence_Check)
    121 spam2(op_concat        , PySequence_Concat)
    122 spamoi(op_repeat       , PySequence_Repeat)
    123 spam2(op_iconcat       , PySequence_InPlaceConcat)
    124 spamoi(op_irepeat      , PySequence_InPlaceRepeat)
    125 spami2b(op_contains     , PySequence_Contains)
    126 spami2b(sequenceIncludes, op_sequenceIncludes)
    127 spamn2(indexOf         , PySequence_Index)
    128 spamn2(countOf         , PySequence_Count)
    129 spami(isMappingType    , PyMapping_Check)
    130 spam2(op_getitem       , PyObject_GetItem)
    131 spam2n(op_delitem       , PyObject_DelItem)
    132 spam3n(op_setitem      , PyObject_SetItem)
    133 spamrc(op_lt           , Py_LT)
    134 spamrc(op_le           , Py_LE)
    135 spamrc(op_eq           , Py_EQ)
    136 spamrc(op_ne           , Py_NE)
    137 spamrc(op_gt           , Py_GT)
    138 spamrc(op_ge           , Py_GE)
    139 
    140 static PyObject*
    141 op_pow(PyObject *s, PyObject *a)
    142 {
    143     PyObject *a1, *a2;
    144     if (PyArg_UnpackTuple(a,"pow", 2, 2, &a1, &a2))
    145         return PyNumber_Power(a1, a2, Py_None);
    146     return NULL;
    147 }
    148 
    149 static PyObject*
    150 op_ipow(PyObject *s, PyObject *a)
    151 {
    152     PyObject *a1, *a2;
    153     if (PyArg_UnpackTuple(a,"ipow", 2, 2, &a1, &a2))
    154         return PyNumber_InPlacePower(a1, a2, Py_None);
    155     return NULL;
    156 }
    157 
    158 static PyObject *
    159 op_index(PyObject *s, PyObject *a)
    160 {
    161     return PyNumber_Index(a);
    162 }
    163 
    164 static PyObject*
    165 is_(PyObject *s, PyObject *a)
    166 {
    167     PyObject *a1, *a2, *result = NULL;
    168     if (PyArg_UnpackTuple(a,"is_", 2, 2, &a1, &a2)) {
    169         result = (a1 == a2) ? Py_True : Py_False;
    170         Py_INCREF(result);
    171     }
    172     return result;
    173 }
    174 
    175 static PyObject*
    176 is_not(PyObject *s, PyObject *a)
    177 {
    178     PyObject *a1, *a2, *result = NULL;
    179     if (PyArg_UnpackTuple(a,"is_not", 2, 2, &a1, &a2)) {
    180         result = (a1 != a2) ? Py_True : Py_False;
    181         Py_INCREF(result);
    182     }
    183     return result;
    184 }
    185 
    186 static PyObject*
    187 op_getslice(PyObject *s, PyObject *a)
    188 {
    189     PyObject *a1;
    190     Py_ssize_t a2, a3;
    191 
    192     if (!PyArg_ParseTuple(a, "Onn:getslice", &a1, &a2, &a3))
    193         return NULL;
    194     return PySequence_GetSlice(a1, a2, a3);
    195 }
    196 
    197 static PyObject*
    198 op_setslice(PyObject *s, PyObject *a)
    199 {
    200     PyObject *a1, *a4;
    201     Py_ssize_t a2, a3;
    202 
    203     if (!PyArg_ParseTuple(a, "OnnO:setslice", &a1, &a2, &a3, &a4))
    204         return NULL;
    205 
    206     if (-1 == PySequence_SetSlice(a1, a2, a3, a4))
    207         return NULL;
    208 
    209     Py_RETURN_NONE;
    210 }
    211 
    212 static PyObject*
    213 op_delslice(PyObject *s, PyObject *a)
    214 {
    215     PyObject *a1;
    216     Py_ssize_t a2, a3;
    217 
    218     if (!PyArg_ParseTuple(a, "Onn:delslice", &a1, &a2, &a3))
    219         return NULL;
    220 
    221     if (-1 == PySequence_DelSlice(a1, a2, a3))
    222         return NULL;
    223 
    224     Py_RETURN_NONE;
    225 }
    226 
    227 #undef spam1
    228 #undef spam2
    229 #undef spam1o
    230 #undef spam1o
    231 #define spam1(OP,DOC) {#OP, OP, METH_VARARGS, PyDoc_STR(DOC)},
    232 #define spam2(OP,ALTOP,DOC) {#OP, op_##OP, METH_VARARGS, PyDoc_STR(DOC)}, \
    233                            {#ALTOP, op_##OP, METH_VARARGS, PyDoc_STR(DOC)},
    234 #define spam1o(OP,DOC) {#OP, OP, METH_O, PyDoc_STR(DOC)},
    235 #define spam2o(OP,ALTOP,DOC) {#OP, op_##OP, METH_O, PyDoc_STR(DOC)}, \
    236                            {#ALTOP, op_##OP, METH_O, PyDoc_STR(DOC)},
    237 
    238 
    239 
    240 /* compare_digest **********************************************************/
    241 
    242 /*
    243  * timing safe compare
    244  *
    245  * Returns 1 of the strings are equal.
    246  * In case of len(a) != len(b) the function tries to keep the timing
    247  * dependent on the length of b. CPU cache locally may still alter timing
    248  * a bit.
    249  */
    250 static int
    251 _tscmp(const unsigned char *a, const unsigned char *b,
    252         Py_ssize_t len_a, Py_ssize_t len_b)
    253 {
    254     /* The volatile type declarations make sure that the compiler has no
    255      * chance to optimize and fold the code in any way that may change
    256      * the timing.
    257      */
    258     volatile Py_ssize_t length;
    259     volatile const unsigned char *left;
    260     volatile const unsigned char *right;
    261     Py_ssize_t i;
    262     unsigned char result;
    263 
    264     /* loop count depends on length of b */
    265     length = len_b;
    266     left = NULL;
    267     right = b;
    268 
    269     /* don't use else here to keep the amount of CPU instructions constant,
    270      * volatile forces re-evaluation
    271      *  */
    272     if (len_a == length) {
    273         left = *((volatile const unsigned char**)&a);
    274         result = 0;
    275     }
    276     if (len_a != length) {
    277         left = b;
    278         result = 1;
    279     }
    280 
    281     for (i=0; i < length; i++) {
    282         result |= *left++ ^ *right++;
    283     }
    284 
    285     return (result == 0);
    286 }
    287 
    288 PyDoc_STRVAR(compare_digest__doc__,
    289 "compare_digest(a, b) -> bool\n"
    290 "\n"
    291 "Return 'a == b'.  This function uses an approach designed to prevent\n"
    292 "timing analysis, making it appropriate for cryptography.\n"
    293 "a and b must both be of the same type: either str (ASCII only),\n"
    294 "or any type that supports the buffer protocol (e.g. bytes).\n"
    295 "\n"
    296 "Note: If a and b are of different lengths, or if an error occurs,\n"
    297 "a timing attack could theoretically reveal information about the\n"
    298 "types and lengths of a and b--but not their values.\n");
    299 
    300 static PyObject*
    301 compare_digest(PyObject *self, PyObject *args)
    302 {
    303     PyObject *a, *b;
    304     int rc;
    305 
    306     if (!PyArg_ParseTuple(args, "OO:compare_digest", &a, &b)) {
    307         return NULL;
    308     }
    309 
    310     /* Unicode string */
    311     if (PyUnicode_Check(a) && PyUnicode_Check(b)) {
    312         rc = _tscmp((const unsigned char *)PyUnicode_AS_DATA(a),
    313                     (const unsigned char *)PyUnicode_AS_DATA(b),
    314                     PyUnicode_GET_DATA_SIZE(a),
    315                     PyUnicode_GET_DATA_SIZE(b));
    316     }
    317     /* fallback to buffer interface for bytes, bytesarray and other */
    318     else {
    319         Py_buffer view_a;
    320         Py_buffer view_b;
    321 
    322         if (PyObject_CheckBuffer(a) == 0 && PyObject_CheckBuffer(b) == 0) {
    323             PyErr_Format(PyExc_TypeError,
    324                          "unsupported operand types(s) or combination of types: "
    325                          "'%.100s' and '%.100s'",
    326                          Py_TYPE(a)->tp_name, Py_TYPE(b)->tp_name);
    327             return NULL;
    328         }
    329 
    330         if (PyObject_GetBuffer(a, &view_a, PyBUF_SIMPLE) == -1) {
    331             return NULL;
    332         }
    333         if (view_a.ndim > 1) {
    334             PyErr_SetString(PyExc_BufferError,
    335                             "Buffer must be single dimension");
    336             PyBuffer_Release(&view_a);
    337             return NULL;
    338         }
    339 
    340         if (PyObject_GetBuffer(b, &view_b, PyBUF_SIMPLE) == -1) {
    341             PyBuffer_Release(&view_a);
    342             return NULL;
    343         }
    344         if (view_b.ndim > 1) {
    345             PyErr_SetString(PyExc_BufferError,
    346                             "Buffer must be single dimension");
    347             PyBuffer_Release(&view_a);
    348             PyBuffer_Release(&view_b);
    349             return NULL;
    350         }
    351 
    352         rc = _tscmp((const unsigned char*)view_a.buf,
    353                     (const unsigned char*)view_b.buf,
    354                     view_a.len,
    355                     view_b.len);
    356 
    357         PyBuffer_Release(&view_a);
    358         PyBuffer_Release(&view_b);
    359     }
    360 
    361     return PyBool_FromLong(rc);
    362 }
    363 
    364 static struct PyMethodDef operator_methods[] = {
    365 
    366 spam1o(isCallable,
    367  "isCallable(a) -- Same as callable(a).")
    368 spam1o(isNumberType,
    369  "isNumberType(a) -- Return True if a has a numeric type, False otherwise.")
    370 spam1o(isSequenceType,
    371  "isSequenceType(a) -- Return True if a has a sequence type, False otherwise.")
    372 spam1o(truth,
    373  "truth(a) -- Return True if a is true, False otherwise.")
    374 spam2(contains,__contains__,
    375  "contains(a, b) -- Same as b in a (note reversed operands).")
    376 spam1(sequenceIncludes,
    377  "sequenceIncludes(a, b) -- Same as b in a (note reversed operands; deprecated).")
    378 spam1(indexOf,
    379  "indexOf(a, b) -- Return the first index of b in a.")
    380 spam1(countOf,
    381  "countOf(a, b) -- Return the number of times b occurs in a.")
    382 spam1o(isMappingType,
    383  "isMappingType(a) -- Return True if a has a mapping type, False otherwise.")
    384 
    385 spam1(is_, "is_(a, b) -- Same as a is b.")
    386 spam1(is_not, "is_not(a, b) -- Same as a is not b.")
    387 spam2o(index, __index__, "index(a) -- Same as a.__index__()")
    388 spam2(add,__add__, "add(a, b) -- Same as a + b.")
    389 spam2(sub,__sub__, "sub(a, b) -- Same as a - b.")
    390 spam2(mul,__mul__, "mul(a, b) -- Same as a * b.")
    391 spam2(div,__div__, "div(a, b) -- Same as a / b when __future__.division is not in effect.")
    392 spam2(floordiv,__floordiv__, "floordiv(a, b) -- Same as a // b.")
    393 spam2(truediv,__truediv__, "truediv(a, b) -- Same as a / b when __future__.division is in effect.")
    394 spam2(mod,__mod__, "mod(a, b) -- Same as a % b.")
    395 spam2o(neg,__neg__, "neg(a) -- Same as -a.")
    396 spam2o(pos,__pos__, "pos(a) -- Same as +a.")
    397 spam2o(abs,__abs__, "abs(a) -- Same as abs(a).")
    398 spam2o(inv,__inv__, "inv(a) -- Same as ~a.")
    399 spam2o(invert,__invert__, "invert(a) -- Same as ~a.")
    400 spam2(lshift,__lshift__, "lshift(a, b) -- Same as a << b.")
    401 spam2(rshift,__rshift__, "rshift(a, b) -- Same as a >> b.")
    402 spam2o(not_,__not__, "not_(a) -- Same as not a.")
    403 spam2(and_,__and__, "and_(a, b) -- Same as a & b.")
    404 spam2(xor,__xor__, "xor(a, b) -- Same as a ^ b.")
    405 spam2(or_,__or__, "or_(a, b) -- Same as a | b.")
    406 spam2(iadd,__iadd__, "a = iadd(a, b) -- Same as a += b.")
    407 spam2(isub,__isub__, "a = isub(a, b) -- Same as a -= b.")
    408 spam2(imul,__imul__, "a = imul(a, b) -- Same as a *= b.")
    409 spam2(idiv,__idiv__, "a = idiv(a, b) -- Same as a /= b when __future__.division is not in effect.")
    410 spam2(ifloordiv,__ifloordiv__, "a = ifloordiv(a, b) -- Same as a //= b.")
    411 spam2(itruediv,__itruediv__, "a = itruediv(a, b) -- Same as a /= b when __future__.division is in effect.")
    412 spam2(imod,__imod__, "a = imod(a, b) -- Same as a %= b.")
    413 spam2(ilshift,__ilshift__, "a = ilshift(a, b) -- Same as a <<= b.")
    414 spam2(irshift,__irshift__, "a = irshift(a, b) -- Same as a >>= b.")
    415 spam2(iand,__iand__, "a = iand(a, b) -- Same as a &= b.")
    416 spam2(ixor,__ixor__, "a = ixor(a, b) -- Same as a ^= b.")
    417 spam2(ior,__ior__, "a = ior(a, b) -- Same as a |= b.")
    418 spam2(concat,__concat__,
    419  "concat(a, b) -- Same as a + b, for a and b sequences.")
    420 spam2(repeat,__repeat__,
    421  "repeat(a, b) -- Return a * b, where a is a sequence, and b is an integer.")
    422 spam2(iconcat,__iconcat__,
    423  "a = iconcat(a, b) -- Same as a += b, for a and b sequences.")
    424 spam2(irepeat,__irepeat__,
    425  "a = irepeat(a, b) -- Same as a *= b, where a is a sequence, and b is an integer.")
    426 spam2(getitem,__getitem__,
    427  "getitem(a, b) -- Same as a[b].")
    428 spam2(setitem,__setitem__,
    429  "setitem(a, b, c) -- Same as a[b] = c.")
    430 spam2(delitem,__delitem__,
    431  "delitem(a, b) -- Same as del a[b].")
    432 spam2(pow,__pow__, "pow(a, b) -- Same as a ** b.")
    433 spam2(ipow,__ipow__, "a = ipow(a, b) -- Same as a **= b.")
    434 spam2(getslice,__getslice__,
    435  "getslice(a, b, c) -- Same as a[b:c].")
    436 spam2(setslice,__setslice__,
    437 "setslice(a, b, c, d) -- Same as a[b:c] = d.")
    438 spam2(delslice,__delslice__,
    439 "delslice(a, b, c) -- Same as del a[b:c].")
    440 spam2(lt,__lt__, "lt(a, b) -- Same as a<b.")
    441 spam2(le,__le__, "le(a, b) -- Same as a<=b.")
    442 spam2(eq,__eq__, "eq(a, b) -- Same as a==b.")
    443 spam2(ne,__ne__, "ne(a, b) -- Same as a!=b.")
    444 spam2(gt,__gt__, "gt(a, b) -- Same as a>b.")
    445 spam2(ge,__ge__, "ge(a, b) -- Same as a>=b.")
    446 
    447     {"_compare_digest", (PyCFunction)compare_digest, METH_VARARGS,
    448      compare_digest__doc__},
    449     {NULL,              NULL}           /* sentinel */
    450 
    451 };
    452 
    453 /* itemgetter object **********************************************************/
    454 
    455 typedef struct {
    456     PyObject_HEAD
    457     Py_ssize_t nitems;
    458     PyObject *item;
    459 } itemgetterobject;
    460 
    461 static PyTypeObject itemgetter_type;
    462 
    463 static PyObject *
    464 itemgetter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
    465 {
    466     itemgetterobject *ig;
    467     PyObject *item;
    468     Py_ssize_t nitems;
    469 
    470     if (!_PyArg_NoKeywords("itemgetter()", kwds))
    471         return NULL;
    472 
    473     nitems = PyTuple_GET_SIZE(args);
    474     if (nitems <= 1) {
    475         if (!PyArg_UnpackTuple(args, "itemgetter", 1, 1, &item))
    476             return NULL;
    477     } else
    478         item = args;
    479 
    480     /* create itemgetterobject structure */
    481     ig = PyObject_GC_New(itemgetterobject, &itemgetter_type);
    482     if (ig == NULL)
    483         return NULL;
    484 
    485     Py_INCREF(item);
    486     ig->item = item;
    487     ig->nitems = nitems;
    488 
    489     PyObject_GC_Track(ig);
    490     return (PyObject *)ig;
    491 }
    492 
    493 static void
    494 itemgetter_dealloc(itemgetterobject *ig)
    495 {
    496     PyObject_GC_UnTrack(ig);
    497     Py_XDECREF(ig->item);
    498     PyObject_GC_Del(ig);
    499 }
    500 
    501 static int
    502 itemgetter_traverse(itemgetterobject *ig, visitproc visit, void *arg)
    503 {
    504     Py_VISIT(ig->item);
    505     return 0;
    506 }
    507 
    508 static PyObject *
    509 itemgetter_call(itemgetterobject *ig, PyObject *args, PyObject *kw)
    510 {
    511     PyObject *obj, *result;
    512     Py_ssize_t i, nitems=ig->nitems;
    513 
    514     if (kw != NULL && !_PyArg_NoKeywords("itemgetter", kw))
    515         return NULL;
    516     if (!PyArg_UnpackTuple(args, "itemgetter", 1, 1, &obj))
    517         return NULL;
    518     if (nitems == 1)
    519         return PyObject_GetItem(obj, ig->item);
    520 
    521     assert(PyTuple_Check(ig->item));
    522     assert(PyTuple_GET_SIZE(ig->item) == nitems);
    523 
    524     result = PyTuple_New(nitems);
    525     if (result == NULL)
    526         return NULL;
    527 
    528     for (i=0 ; i < nitems ; i++) {
    529         PyObject *item, *val;
    530         item = PyTuple_GET_ITEM(ig->item, i);
    531         val = PyObject_GetItem(obj, item);
    532         if (val == NULL) {
    533             Py_DECREF(result);
    534             return NULL;
    535         }
    536         PyTuple_SET_ITEM(result, i, val);
    537     }
    538     return result;
    539 }
    540 
    541 PyDoc_STRVAR(itemgetter_doc,
    542 "itemgetter(item, ...) --> itemgetter object\n\
    543 \n\
    544 Return a callable object that fetches the given item(s) from its operand.\n\
    545 After f = itemgetter(2), the call f(r) returns r[2].\n\
    546 After g = itemgetter(2, 5, 3), the call g(r) returns (r[2], r[5], r[3])");
    547 
    548 static PyTypeObject itemgetter_type = {
    549     PyVarObject_HEAD_INIT(NULL, 0)
    550     "operator.itemgetter",              /* tp_name */
    551     sizeof(itemgetterobject),           /* tp_basicsize */
    552     0,                                  /* tp_itemsize */
    553     /* methods */
    554     (destructor)itemgetter_dealloc,     /* tp_dealloc */
    555     0,                                  /* tp_print */
    556     0,                                  /* tp_getattr */
    557     0,                                  /* tp_setattr */
    558     0,                                  /* tp_compare */
    559     0,                                  /* tp_repr */
    560     0,                                  /* tp_as_number */
    561     0,                                  /* tp_as_sequence */
    562     0,                                  /* tp_as_mapping */
    563     0,                                  /* tp_hash */
    564     (ternaryfunc)itemgetter_call,       /* tp_call */
    565     0,                                  /* tp_str */
    566     PyObject_GenericGetAttr,            /* tp_getattro */
    567     0,                                  /* tp_setattro */
    568     0,                                  /* tp_as_buffer */
    569     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,            /* tp_flags */
    570     itemgetter_doc,                     /* tp_doc */
    571     (traverseproc)itemgetter_traverse,          /* tp_traverse */
    572     0,                                  /* tp_clear */
    573     0,                                  /* tp_richcompare */
    574     0,                                  /* tp_weaklistoffset */
    575     0,                                  /* tp_iter */
    576     0,                                  /* tp_iternext */
    577     0,                                  /* tp_methods */
    578     0,                                  /* tp_members */
    579     0,                                  /* tp_getset */
    580     0,                                  /* tp_base */
    581     0,                                  /* tp_dict */
    582     0,                                  /* tp_descr_get */
    583     0,                                  /* tp_descr_set */
    584     0,                                  /* tp_dictoffset */
    585     0,                                  /* tp_init */
    586     0,                                  /* tp_alloc */
    587     itemgetter_new,                     /* tp_new */
    588     0,                                  /* tp_free */
    589 };
    590 
    591 
    592 /* attrgetter object **********************************************************/
    593 
    594 typedef struct {
    595     PyObject_HEAD
    596     Py_ssize_t nattrs;
    597     PyObject *attr;
    598 } attrgetterobject;
    599 
    600 static PyTypeObject attrgetter_type;
    601 
    602 static PyObject *
    603 attrgetter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
    604 {
    605     attrgetterobject *ag;
    606     PyObject *attr;
    607     Py_ssize_t nattrs;
    608 
    609     if (!_PyArg_NoKeywords("attrgetter()", kwds))
    610         return NULL;
    611 
    612     nattrs = PyTuple_GET_SIZE(args);
    613     if (nattrs <= 1) {
    614         if (!PyArg_UnpackTuple(args, "attrgetter", 1, 1, &attr))
    615             return NULL;
    616     } else
    617         attr = args;
    618 
    619     /* create attrgetterobject structure */
    620     ag = PyObject_GC_New(attrgetterobject, &attrgetter_type);
    621     if (ag == NULL)
    622         return NULL;
    623 
    624     Py_INCREF(attr);
    625     ag->attr = attr;
    626     ag->nattrs = nattrs;
    627 
    628     PyObject_GC_Track(ag);
    629     return (PyObject *)ag;
    630 }
    631 
    632 static void
    633 attrgetter_dealloc(attrgetterobject *ag)
    634 {
    635     PyObject_GC_UnTrack(ag);
    636     Py_XDECREF(ag->attr);
    637     PyObject_GC_Del(ag);
    638 }
    639 
    640 static int
    641 attrgetter_traverse(attrgetterobject *ag, visitproc visit, void *arg)
    642 {
    643     Py_VISIT(ag->attr);
    644     return 0;
    645 }
    646 
    647 static PyObject *
    648 dotted_getattr(PyObject *obj, PyObject *attr)
    649 {
    650     char *s, *p;
    651 
    652 #ifdef Py_USING_UNICODE
    653     if (PyUnicode_Check(attr)) {
    654         attr = _PyUnicode_AsDefaultEncodedString(attr, NULL);
    655         if (attr == NULL)
    656             return NULL;
    657     }
    658 #endif
    659 
    660     if (!PyString_Check(attr)) {
    661         PyErr_SetString(PyExc_TypeError,
    662                         "attribute name must be a string");
    663         return NULL;
    664     }
    665 
    666     s = PyString_AS_STRING(attr);
    667     Py_INCREF(obj);
    668     for (;;) {
    669         PyObject *newobj, *str;
    670         p = strchr(s, '.');
    671         str = p ? PyString_FromStringAndSize(s, (p-s)) :
    672               PyString_FromString(s);
    673         if (str == NULL) {
    674             Py_DECREF(obj);
    675             return NULL;
    676         }
    677         newobj = PyObject_GetAttr(obj, str);
    678         Py_DECREF(str);
    679         Py_DECREF(obj);
    680         if (newobj == NULL)
    681             return NULL;
    682         obj = newobj;
    683         if (p == NULL) break;
    684         s = p+1;
    685     }
    686 
    687     return obj;
    688 }
    689 
    690 static PyObject *
    691 attrgetter_call(attrgetterobject *ag, PyObject *args, PyObject *kw)
    692 {
    693     PyObject *obj, *result;
    694     Py_ssize_t i, nattrs=ag->nattrs;
    695 
    696     if (kw != NULL && !_PyArg_NoKeywords("attrgetter", kw))
    697         return NULL;
    698     if (!PyArg_UnpackTuple(args, "attrgetter", 1, 1, &obj))
    699         return NULL;
    700     if (ag->nattrs == 1)
    701         return dotted_getattr(obj, ag->attr);
    702 
    703     assert(PyTuple_Check(ag->attr));
    704     assert(PyTuple_GET_SIZE(ag->attr) == nattrs);
    705 
    706     result = PyTuple_New(nattrs);
    707     if (result == NULL)
    708         return NULL;
    709 
    710     for (i=0 ; i < nattrs ; i++) {
    711         PyObject *attr, *val;
    712         attr = PyTuple_GET_ITEM(ag->attr, i);
    713         val = dotted_getattr(obj, attr);
    714         if (val == NULL) {
    715             Py_DECREF(result);
    716             return NULL;
    717         }
    718         PyTuple_SET_ITEM(result, i, val);
    719     }
    720     return result;
    721 }
    722 
    723 PyDoc_STRVAR(attrgetter_doc,
    724 "attrgetter(attr, ...) --> attrgetter object\n\
    725 \n\
    726 Return a callable object that fetches the given attribute(s) from its operand.\n\
    727 After f = attrgetter('name'), the call f(r) returns r.name.\n\
    728 After g = attrgetter('name', 'date'), the call g(r) returns (r.name, r.date).\n\
    729 After h = attrgetter('name.first', 'name.last'), the call h(r) returns\n\
    730 (r.name.first, r.name.last).");
    731 
    732 static PyTypeObject attrgetter_type = {
    733     PyVarObject_HEAD_INIT(NULL, 0)
    734     "operator.attrgetter",              /* tp_name */
    735     sizeof(attrgetterobject),           /* tp_basicsize */
    736     0,                                  /* tp_itemsize */
    737     /* methods */
    738     (destructor)attrgetter_dealloc,     /* tp_dealloc */
    739     0,                                  /* tp_print */
    740     0,                                  /* tp_getattr */
    741     0,                                  /* tp_setattr */
    742     0,                                  /* tp_compare */
    743     0,                                  /* tp_repr */
    744     0,                                  /* tp_as_number */
    745     0,                                  /* tp_as_sequence */
    746     0,                                  /* tp_as_mapping */
    747     0,                                  /* tp_hash */
    748     (ternaryfunc)attrgetter_call,       /* tp_call */
    749     0,                                  /* tp_str */
    750     PyObject_GenericGetAttr,            /* tp_getattro */
    751     0,                                  /* tp_setattro */
    752     0,                                  /* tp_as_buffer */
    753     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,            /* tp_flags */
    754     attrgetter_doc,                     /* tp_doc */
    755     (traverseproc)attrgetter_traverse,          /* tp_traverse */
    756     0,                                  /* tp_clear */
    757     0,                                  /* tp_richcompare */
    758     0,                                  /* tp_weaklistoffset */
    759     0,                                  /* tp_iter */
    760     0,                                  /* tp_iternext */
    761     0,                                  /* tp_methods */
    762     0,                                  /* tp_members */
    763     0,                                  /* tp_getset */
    764     0,                                  /* tp_base */
    765     0,                                  /* tp_dict */
    766     0,                                  /* tp_descr_get */
    767     0,                                  /* tp_descr_set */
    768     0,                                  /* tp_dictoffset */
    769     0,                                  /* tp_init */
    770     0,                                  /* tp_alloc */
    771     attrgetter_new,                     /* tp_new */
    772     0,                                  /* tp_free */
    773 };
    774 
    775 
    776 /* methodcaller object **********************************************************/
    777 
    778 typedef struct {
    779     PyObject_HEAD
    780     PyObject *name;
    781     PyObject *args;
    782     PyObject *kwds;
    783 } methodcallerobject;
    784 
    785 static PyTypeObject methodcaller_type;
    786 
    787 static PyObject *
    788 methodcaller_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
    789 {
    790     methodcallerobject *mc;
    791     PyObject *name;
    792 
    793     if (PyTuple_GET_SIZE(args) < 1) {
    794         PyErr_SetString(PyExc_TypeError, "methodcaller needs at least "
    795                         "one argument, the method name");
    796         return NULL;
    797     }
    798 
    799     /* create methodcallerobject structure */
    800     mc = PyObject_GC_New(methodcallerobject, &methodcaller_type);
    801     if (mc == NULL)
    802         return NULL;
    803 
    804     name = PyTuple_GET_ITEM(args, 0);
    805     Py_INCREF(name);
    806     mc->name = name;
    807 
    808     Py_XINCREF(kwds);
    809     mc->kwds = kwds;
    810 
    811     mc->args = PyTuple_GetSlice(args, 1, PyTuple_GET_SIZE(args));
    812     if (mc->args == NULL) {
    813         Py_DECREF(mc);
    814         return NULL;
    815     }
    816 
    817     PyObject_GC_Track(mc);
    818     return (PyObject *)mc;
    819 }
    820 
    821 static void
    822 methodcaller_dealloc(methodcallerobject *mc)
    823 {
    824     PyObject_GC_UnTrack(mc);
    825     Py_XDECREF(mc->name);
    826     Py_XDECREF(mc->args);
    827     Py_XDECREF(mc->kwds);
    828     PyObject_GC_Del(mc);
    829 }
    830 
    831 static int
    832 methodcaller_traverse(methodcallerobject *mc, visitproc visit, void *arg)
    833 {
    834     Py_VISIT(mc->args);
    835     Py_VISIT(mc->kwds);
    836     return 0;
    837 }
    838 
    839 static PyObject *
    840 methodcaller_call(methodcallerobject *mc, PyObject *args, PyObject *kw)
    841 {
    842     PyObject *method, *obj, *result;
    843 
    844     if (kw != NULL && !_PyArg_NoKeywords("methodcaller", kw))
    845         return NULL;
    846     if (!PyArg_UnpackTuple(args, "methodcaller", 1, 1, &obj))
    847         return NULL;
    848     method = PyObject_GetAttr(obj, mc->name);
    849     if (method == NULL)
    850         return NULL;
    851     result = PyObject_Call(method, mc->args, mc->kwds);
    852     Py_DECREF(method);
    853     return result;
    854 }
    855 
    856 PyDoc_STRVAR(methodcaller_doc,
    857 "methodcaller(name, ...) --> methodcaller object\n\
    858 \n\
    859 Return a callable object that calls the given method on its operand.\n\
    860 After f = methodcaller('name'), the call f(r) returns r.name().\n\
    861 After g = methodcaller('name', 'date', foo=1), the call g(r) returns\n\
    862 r.name('date', foo=1).");
    863 
    864 static PyTypeObject methodcaller_type = {
    865     PyVarObject_HEAD_INIT(NULL, 0)
    866     "operator.methodcaller",            /* tp_name */
    867     sizeof(methodcallerobject),         /* tp_basicsize */
    868     0,                                  /* tp_itemsize */
    869     /* methods */
    870     (destructor)methodcaller_dealloc, /* tp_dealloc */
    871     0,                                  /* tp_print */
    872     0,                                  /* tp_getattr */
    873     0,                                  /* tp_setattr */
    874     0,                                  /* tp_compare */
    875     0,                                  /* tp_repr */
    876     0,                                  /* tp_as_number */
    877     0,                                  /* tp_as_sequence */
    878     0,                                  /* tp_as_mapping */
    879     0,                                  /* tp_hash */
    880     (ternaryfunc)methodcaller_call,     /* tp_call */
    881     0,                                  /* tp_str */
    882     PyObject_GenericGetAttr,            /* tp_getattro */
    883     0,                                  /* tp_setattro */
    884     0,                                  /* tp_as_buffer */
    885     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
    886     methodcaller_doc,                           /* tp_doc */
    887     (traverseproc)methodcaller_traverse,        /* tp_traverse */
    888     0,                                  /* tp_clear */
    889     0,                                  /* tp_richcompare */
    890     0,                                  /* tp_weaklistoffset */
    891     0,                                  /* tp_iter */
    892     0,                                  /* tp_iternext */
    893     0,                                  /* tp_methods */
    894     0,                                  /* tp_members */
    895     0,                                  /* tp_getset */
    896     0,                                  /* tp_base */
    897     0,                                  /* tp_dict */
    898     0,                                  /* tp_descr_get */
    899     0,                                  /* tp_descr_set */
    900     0,                                  /* tp_dictoffset */
    901     0,                                  /* tp_init */
    902     0,                                  /* tp_alloc */
    903     methodcaller_new,                   /* tp_new */
    904     0,                                  /* tp_free */
    905 };
    906 
    907 
    908 /* Initialization function for the module (*must* be called initoperator) */
    909 
    910 PyMODINIT_FUNC
    911 initoperator(void)
    912 {
    913     PyObject *m;
    914 
    915     /* Create the module and add the functions */
    916     m = Py_InitModule4("operator", operator_methods, operator_doc,
    917                    (PyObject*)NULL, PYTHON_API_VERSION);
    918     if (m == NULL)
    919         return;
    920 
    921     if (PyType_Ready(&itemgetter_type) < 0)
    922         return;
    923     Py_INCREF(&itemgetter_type);
    924     PyModule_AddObject(m, "itemgetter", (PyObject *)&itemgetter_type);
    925 
    926     if (PyType_Ready(&attrgetter_type) < 0)
    927         return;
    928     Py_INCREF(&attrgetter_type);
    929     PyModule_AddObject(m, "attrgetter", (PyObject *)&attrgetter_type);
    930 
    931     if (PyType_Ready(&methodcaller_type) < 0)
    932         return;
    933     Py_INCREF(&methodcaller_type);
    934     PyModule_AddObject(m, "methodcaller", (PyObject *)&methodcaller_type);
    935 }
    936