/* List object implementation */ #include "Python.h" #include "internal/pystate.h" #include "accu.h" #ifdef STDC_HEADERS #include #else #include /* For size_t */ #endif /*[clinic input] class list "PyListObject *" "&PyList_Type" [clinic start generated code]*/ /*[clinic end generated code: output=da39a3ee5e6b4b0d input=f9b222678f9f71e0]*/ #include "clinic/listobject.c.h" /* Ensure ob_item has room for at least newsize elements, and set * ob_size to newsize. If newsize > ob_size on entry, the content * of the new slots at exit is undefined heap trash; it's the caller's * responsibility to overwrite them with sane values. * The number of allocated elements may grow, shrink, or stay the same. * Failure is impossible if newsize <= self.allocated on entry, although * that partly relies on an assumption that the system realloc() never * fails when passed a number of bytes <= the number of bytes last * allocated (the C standard doesn't guarantee this, but it's hard to * imagine a realloc implementation where it wouldn't be true). * Note that self->ob_item may change, and even if newsize is less * than ob_size on entry. */ static int list_resize(PyListObject *self, Py_ssize_t newsize) { PyObject **items; size_t new_allocated, num_allocated_bytes; Py_ssize_t allocated = self->allocated; /* Bypass realloc() when a previous overallocation is large enough to accommodate the newsize. If the newsize falls lower than half the allocated size, then proceed with the realloc() to shrink the list. */ if (allocated >= newsize && newsize >= (allocated >> 1)) { assert(self->ob_item != NULL || newsize == 0); Py_SIZE(self) = newsize; return 0; } /* This over-allocates proportional to the list size, making room * for additional growth. The over-allocation is mild, but is * enough to give linear-time amortized behavior over a long * sequence of appends() in the presence of a poorly-performing * system realloc(). * The growth pattern is: 0, 4, 8, 16, 25, 35, 46, 58, 72, 88, ... * Note: new_allocated won't overflow because the largest possible value * is PY_SSIZE_T_MAX * (9 / 8) + 6 which always fits in a size_t. */ new_allocated = (size_t)newsize + (newsize >> 3) + (newsize < 9 ? 3 : 6); if (new_allocated > (size_t)PY_SSIZE_T_MAX / sizeof(PyObject *)) { PyErr_NoMemory(); return -1; } if (newsize == 0) new_allocated = 0; num_allocated_bytes = new_allocated * sizeof(PyObject *); items = (PyObject **)PyMem_Realloc(self->ob_item, num_allocated_bytes); if (items == NULL) { PyErr_NoMemory(); return -1; } self->ob_item = items; Py_SIZE(self) = newsize; self->allocated = new_allocated; return 0; } /* Debug statistic to compare allocations with reuse through the free list */ #undef SHOW_ALLOC_COUNT #ifdef SHOW_ALLOC_COUNT static size_t count_alloc = 0; static size_t count_reuse = 0; static void show_alloc(void) { PyInterpreterState *interp = PyThreadState_GET()->interp; if (!inter->core_config.show_alloc_count) { return; } fprintf(stderr, "List allocations: %" PY_FORMAT_SIZE_T "d\n", count_alloc); fprintf(stderr, "List reuse through freelist: %" PY_FORMAT_SIZE_T "d\n", count_reuse); fprintf(stderr, "%.2f%% reuse rate\n\n", (100.0*count_reuse/(count_alloc+count_reuse))); } #endif /* Empty list reuse scheme to save calls to malloc and free */ #ifndef PyList_MAXFREELIST #define PyList_MAXFREELIST 80 #endif static PyListObject *free_list[PyList_MAXFREELIST]; static int numfree = 0; int PyList_ClearFreeList(void) { PyListObject *op; int ret = numfree; while (numfree) { op = free_list[--numfree]; assert(PyList_CheckExact(op)); PyObject_GC_Del(op); } return ret; } void PyList_Fini(void) { PyList_ClearFreeList(); } /* Print summary info about the state of the optimized allocator */ void _PyList_DebugMallocStats(FILE *out) { _PyDebugAllocatorStats(out, "free PyListObject", numfree, sizeof(PyListObject)); } PyObject * PyList_New(Py_ssize_t size) { PyListObject *op; #ifdef SHOW_ALLOC_COUNT static int initialized = 0; if (!initialized) { Py_AtExit(show_alloc); initialized = 1; } #endif if (size < 0) { PyErr_BadInternalCall(); return NULL; } if (numfree) { numfree--; op = free_list[numfree]; _Py_NewReference((PyObject *)op); #ifdef SHOW_ALLOC_COUNT count_reuse++; #endif } else { op = PyObject_GC_New(PyListObject, &PyList_Type); if (op == NULL) return NULL; #ifdef SHOW_ALLOC_COUNT count_alloc++; #endif } if (size <= 0) op->ob_item = NULL; else { op->ob_item = (PyObject **) PyMem_Calloc(size, sizeof(PyObject *)); if (op->ob_item == NULL) { Py_DECREF(op); return PyErr_NoMemory(); } } Py_SIZE(op) = size; op->allocated = size; _PyObject_GC_TRACK(op); return (PyObject *) op; } Py_ssize_t PyList_Size(PyObject *op) { if (!PyList_Check(op)) { PyErr_BadInternalCall(); return -1; } else return Py_SIZE(op); } static PyObject *indexerr = NULL; PyObject * PyList_GetItem(PyObject *op, Py_ssize_t i) { if (!PyList_Check(op)) { PyErr_BadInternalCall(); return NULL; } if (i < 0 || i >= Py_SIZE(op)) { if (indexerr == NULL) { indexerr = PyUnicode_FromString( "list index out of range"); if (indexerr == NULL) return NULL; } PyErr_SetObject(PyExc_IndexError, indexerr); return NULL; } return ((PyListObject *)op) -> ob_item[i]; } int PyList_SetItem(PyObject *op, Py_ssize_t i, PyObject *newitem) { PyObject **p; if (!PyList_Check(op)) { Py_XDECREF(newitem); PyErr_BadInternalCall(); return -1; } if (i < 0 || i >= Py_SIZE(op)) { Py_XDECREF(newitem); PyErr_SetString(PyExc_IndexError, "list assignment index out of range"); return -1; } p = ((PyListObject *)op) -> ob_item + i; Py_XSETREF(*p, newitem); return 0; } static int ins1(PyListObject *self, Py_ssize_t where, PyObject *v) { Py_ssize_t i, n = Py_SIZE(self); PyObject **items; if (v == NULL) { PyErr_BadInternalCall(); return -1; } if (n == PY_SSIZE_T_MAX) { PyErr_SetString(PyExc_OverflowError, "cannot add more objects to list"); return -1; } if (list_resize(self, n+1) < 0) return -1; if (where < 0) { where += n; if (where < 0) where = 0; } if (where > n) where = n; items = self->ob_item; for (i = n; --i >= where; ) items[i+1] = items[i]; Py_INCREF(v); items[where] = v; return 0; } int PyList_Insert(PyObject *op, Py_ssize_t where, PyObject *newitem) { if (!PyList_Check(op)) { PyErr_BadInternalCall(); return -1; } return ins1((PyListObject *)op, where, newitem); } static int app1(PyListObject *self, PyObject *v) { Py_ssize_t n = PyList_GET_SIZE(self); assert (v != NULL); if (n == PY_SSIZE_T_MAX) { PyErr_SetString(PyExc_OverflowError, "cannot add more objects to list"); return -1; } if (list_resize(self, n+1) < 0) return -1; Py_INCREF(v); PyList_SET_ITEM(self, n, v); return 0; } int PyList_Append(PyObject *op, PyObject *newitem) { if (PyList_Check(op) && (newitem != NULL)) return app1((PyListObject *)op, newitem); PyErr_BadInternalCall(); return -1; } /* Methods */ static void list_dealloc(PyListObject *op) { Py_ssize_t i; PyObject_GC_UnTrack(op); Py_TRASHCAN_SAFE_BEGIN(op) if (op->ob_item != NULL) { /* Do it backwards, for Christian Tismer. There's a simple test case where somehow this reduces thrashing when a *very* large list is created and immediately deleted. */ i = Py_SIZE(op); while (--i >= 0) { Py_XDECREF(op->ob_item[i]); } PyMem_FREE(op->ob_item); } if (numfree < PyList_MAXFREELIST && PyList_CheckExact(op)) free_list[numfree++] = op; else Py_TYPE(op)->tp_free((PyObject *)op); Py_TRASHCAN_SAFE_END(op) } static PyObject * list_repr(PyListObject *v) { Py_ssize_t i; PyObject *s; _PyUnicodeWriter writer; if (Py_SIZE(v) == 0) { return PyUnicode_FromString("[]"); } i = Py_ReprEnter((PyObject*)v); if (i != 0) { return i > 0 ? PyUnicode_FromString("[...]") : NULL; } _PyUnicodeWriter_Init(&writer); writer.overallocate = 1; /* "[" + "1" + ", 2" * (len - 1) + "]" */ writer.min_length = 1 + 1 + (2 + 1) * (Py_SIZE(v) - 1) + 1; if (_PyUnicodeWriter_WriteChar(&writer, '[') < 0) goto error; /* Do repr() on each element. Note that this may mutate the list, so must refetch the list size on each iteration. */ for (i = 0; i < Py_SIZE(v); ++i) { if (i > 0) { if (_PyUnicodeWriter_WriteASCIIString(&writer, ", ", 2) < 0) goto error; } s = PyObject_Repr(v->ob_item[i]); if (s == NULL) goto error; if (_PyUnicodeWriter_WriteStr(&writer, s) < 0) { Py_DECREF(s); goto error; } Py_DECREF(s); } writer.overallocate = 0; if (_PyUnicodeWriter_WriteChar(&writer, ']') < 0) goto error; Py_ReprLeave((PyObject *)v); return _PyUnicodeWriter_Finish(&writer); error: _PyUnicodeWriter_Dealloc(&writer); Py_ReprLeave((PyObject *)v); return NULL; } static Py_ssize_t list_length(PyListObject *a) { return Py_SIZE(a); } static int list_contains(PyListObject *a, PyObject *el) { Py_ssize_t i; int cmp; for (i = 0, cmp = 0 ; cmp == 0 && i < Py_SIZE(a); ++i) cmp = PyObject_RichCompareBool(el, PyList_GET_ITEM(a, i), Py_EQ); return cmp; } static PyObject * list_item(PyListObject *a, Py_ssize_t i) { if (i < 0 || i >= Py_SIZE(a)) { if (indexerr == NULL) { indexerr = PyUnicode_FromString( "list index out of range"); if (indexerr == NULL) return NULL; } PyErr_SetObject(PyExc_IndexError, indexerr); return NULL; } Py_INCREF(a->ob_item[i]); return a->ob_item[i]; } static PyObject * list_slice(PyListObject *a, Py_ssize_t ilow, Py_ssize_t ihigh) { PyListObject *np; PyObject **src, **dest; Py_ssize_t i, len; if (ilow < 0) ilow = 0; else if (ilow > Py_SIZE(a)) ilow = Py_SIZE(a); if (ihigh < ilow) ihigh = ilow; else if (ihigh > Py_SIZE(a)) ihigh = Py_SIZE(a); len = ihigh - ilow; np = (PyListObject *) PyList_New(len); if (np == NULL) return NULL; src = a->ob_item + ilow; dest = np->ob_item; for (i = 0; i < len; i++) { PyObject *v = src[i]; Py_INCREF(v); dest[i] = v; } return (PyObject *)np; } PyObject * PyList_GetSlice(PyObject *a, Py_ssize_t ilow, Py_ssize_t ihigh) { if (!PyList_Check(a)) { PyErr_BadInternalCall(); return NULL; } return list_slice((PyListObject *)a, ilow, ihigh); } static PyObject * list_concat(PyListObject *a, PyObject *bb) { Py_ssize_t size; Py_ssize_t i; PyObject **src, **dest; PyListObject *np; if (!PyList_Check(bb)) { PyErr_Format(PyExc_TypeError, "can only concatenate list (not \"%.200s\") to list", bb->ob_type->tp_name); return NULL; } #define b ((PyListObject *)bb) if (Py_SIZE(a) > PY_SSIZE_T_MAX - Py_SIZE(b)) return PyErr_NoMemory(); size = Py_SIZE(a) + Py_SIZE(b); np = (PyListObject *) PyList_New(size); if (np == NULL) { return NULL; } src = a->ob_item; dest = np->ob_item; for (i = 0; i < Py_SIZE(a); i++) { PyObject *v = src[i]; Py_INCREF(v); dest[i] = v; } src = b->ob_item; dest = np->ob_item + Py_SIZE(a); for (i = 0; i < Py_SIZE(b); i++) { PyObject *v = src[i]; Py_INCREF(v); dest[i] = v; } return (PyObject *)np; #undef b } static PyObject * list_repeat(PyListObject *a, Py_ssize_t n) { Py_ssize_t i, j; Py_ssize_t size; PyListObject *np; PyObject **p, **items; PyObject *elem; if (n < 0) n = 0; if (n > 0 && Py_SIZE(a) > PY_SSIZE_T_MAX / n) return PyErr_NoMemory(); size = Py_SIZE(a) * n; if (size == 0) return PyList_New(0); np = (PyListObject *) PyList_New(size); if (np == NULL) return NULL; items = np->ob_item; if (Py_SIZE(a) == 1) { elem = a->ob_item[0]; for (i = 0; i < n; i++) { items[i] = elem; Py_INCREF(elem); } return (PyObject *) np; } p = np->ob_item; items = a->ob_item; for (i = 0; i < n; i++) { for (j = 0; j < Py_SIZE(a); j++) { *p = items[j]; Py_INCREF(*p); p++; } } return (PyObject *) np; } static int _list_clear(PyListObject *a) { Py_ssize_t i; PyObject **item = a->ob_item; if (item != NULL) { /* Because XDECREF can recursively invoke operations on this list, we make it empty first. */ i = Py_SIZE(a); Py_SIZE(a) = 0; a->ob_item = NULL; a->allocated = 0; while (--i >= 0) { Py_XDECREF(item[i]); } PyMem_FREE(item); } /* Never fails; the return value can be ignored. Note that there is no guarantee that the list is actually empty at this point, because XDECREF may have populated it again! */ return 0; } /* a[ilow:ihigh] = v if v != NULL. * del a[ilow:ihigh] if v == NULL. * * Special speed gimmick: when v is NULL and ihigh - ilow <= 8, it's * guaranteed the call cannot fail. */ static int list_ass_slice(PyListObject *a, Py_ssize_t ilow, Py_ssize_t ihigh, PyObject *v) { /* Because [X]DECREF can recursively invoke list operations on this list, we must postpone all [X]DECREF activity until after the list is back in its canonical shape. Therefore we must allocate an additional array, 'recycle', into which we temporarily copy the items that are deleted from the list. :-( */ PyObject *recycle_on_stack[8]; PyObject **recycle = recycle_on_stack; /* will allocate more if needed */ PyObject **item; PyObject **vitem = NULL; PyObject *v_as_SF = NULL; /* PySequence_Fast(v) */ Py_ssize_t n; /* # of elements in replacement list */ Py_ssize_t norig; /* # of elements in list getting replaced */ Py_ssize_t d; /* Change in size */ Py_ssize_t k; size_t s; int result = -1; /* guilty until proved innocent */ #define b ((PyListObject *)v) if (v == NULL) n = 0; else { if (a == b) { /* Special case "a[i:j] = a" -- copy b first */ v = list_slice(b, 0, Py_SIZE(b)); if (v == NULL) return result; result = list_ass_slice(a, ilow, ihigh, v); Py_DECREF(v); return result; } v_as_SF = PySequence_Fast(v, "can only assign an iterable"); if(v_as_SF == NULL) goto Error; n = PySequence_Fast_GET_SIZE(v_as_SF); vitem = PySequence_Fast_ITEMS(v_as_SF); } if (ilow < 0) ilow = 0; else if (ilow > Py_SIZE(a)) ilow = Py_SIZE(a); if (ihigh < ilow) ihigh = ilow; else if (ihigh > Py_SIZE(a)) ihigh = Py_SIZE(a); norig = ihigh - ilow; assert(norig >= 0); d = n - norig; if (Py_SIZE(a) + d == 0) { Py_XDECREF(v_as_SF); return _list_clear(a); } item = a->ob_item; /* recycle the items that we are about to remove */ s = norig * sizeof(PyObject *); /* If norig == 0, item might be NULL, in which case we may not memcpy from it. */ if (s) { if (s > sizeof(recycle_on_stack)) { recycle = (PyObject **)PyMem_MALLOC(s); if (recycle == NULL) { PyErr_NoMemory(); goto Error; } } memcpy(recycle, &item[ilow], s); } if (d < 0) { /* Delete -d items */ Py_ssize_t tail; tail = (Py_SIZE(a) - ihigh) * sizeof(PyObject *); memmove(&item[ihigh+d], &item[ihigh], tail); if (list_resize(a, Py_SIZE(a) + d) < 0) { memmove(&item[ihigh], &item[ihigh+d], tail); memcpy(&item[ilow], recycle, s); goto Error; } item = a->ob_item; } else if (d > 0) { /* Insert d items */ k = Py_SIZE(a); if (list_resize(a, k+d) < 0) goto Error; item = a->ob_item; memmove(&item[ihigh+d], &item[ihigh], (k - ihigh)*sizeof(PyObject *)); } for (k = 0; k < n; k++, ilow++) { PyObject *w = vitem[k]; Py_XINCREF(w); item[ilow] = w; } for (k = norig - 1; k >= 0; --k) Py_XDECREF(recycle[k]); result = 0; Error: if (recycle != recycle_on_stack) PyMem_FREE(recycle); Py_XDECREF(v_as_SF); return result; #undef b } int PyList_SetSlice(PyObject *a, Py_ssize_t ilow, Py_ssize_t ihigh, PyObject *v) { if (!PyList_Check(a)) { PyErr_BadInternalCall(); return -1; } return list_ass_slice((PyListObject *)a, ilow, ihigh, v); } static PyObject * list_inplace_repeat(PyListObject *self, Py_ssize_t n) { PyObject **items; Py_ssize_t size, i, j, p; size = PyList_GET_SIZE(self); if (size == 0 || n == 1) { Py_INCREF(self); return (PyObject *)self; } if (n < 1) { (void)_list_clear(self); Py_INCREF(self); return (PyObject *)self; } if (size > PY_SSIZE_T_MAX / n) { return PyErr_NoMemory(); } if (list_resize(self, size*n) < 0) return NULL; p = size; items = self->ob_item; for (i = 1; i < n; i++) { /* Start counting at 1, not 0 */ for (j = 0; j < size; j++) { PyObject *o = items[j]; Py_INCREF(o); items[p++] = o; } } Py_INCREF(self); return (PyObject *)self; } static int list_ass_item(PyListObject *a, Py_ssize_t i, PyObject *v) { if (i < 0 || i >= Py_SIZE(a)) { PyErr_SetString(PyExc_IndexError, "list assignment index out of range"); return -1; } if (v == NULL) return list_ass_slice(a, i, i+1, v); Py_INCREF(v); Py_SETREF(a->ob_item[i], v); return 0; } /*[clinic input] list.insert index: Py_ssize_t object: object / Insert object before index. [clinic start generated code]*/ static PyObject * list_insert_impl(PyListObject *self, Py_ssize_t index, PyObject *object) /*[clinic end generated code: output=7f35e32f60c8cb78 input=858514cf894c7eab]*/ { if (ins1(self, index, object) == 0) Py_RETURN_NONE; return NULL; } /*[clinic input] list.clear Remove all items from list. [clinic start generated code]*/ static PyObject * list_clear_impl(PyListObject *self) /*[clinic end generated code: output=67a1896c01f74362 input=ca3c1646856742f6]*/ { _list_clear(self); Py_RETURN_NONE; } /*[clinic input] list.copy Return a shallow copy of the list. [clinic start generated code]*/ static PyObject * list_copy_impl(PyListObject *self) /*[clinic end generated code: output=ec6b72d6209d418e input=6453ab159e84771f]*/ { return list_slice(self, 0, Py_SIZE(self)); } /*[clinic input] list.append object: object / Append object to the end of the list. [clinic start generated code]*/ static PyObject * list_append(PyListObject *self, PyObject *object) /*[clinic end generated code: output=7c096003a29c0eae input=43a3fe48a7066e91]*/ { if (app1(self, object) == 0) Py_RETURN_NONE; return NULL; } /*[clinic input] list.extend iterable: object / Extend list by appending elements from the iterable. [clinic start generated code]*/ static PyObject * list_extend(PyListObject *self, PyObject *iterable) /*[clinic end generated code: output=630fb3bca0c8e789 input=9ec5ba3a81be3a4d]*/ { PyObject *it; /* iter(v) */ Py_ssize_t m; /* size of self */ Py_ssize_t n; /* guess for size of iterable */ Py_ssize_t mn; /* m + n */ Py_ssize_t i; PyObject *(*iternext)(PyObject *); /* Special cases: 1) lists and tuples which can use PySequence_Fast ops 2) extending self to self requires making a copy first */ if (PyList_CheckExact(iterable) || PyTuple_CheckExact(iterable) || (PyObject *)self == iterable) { PyObject **src, **dest; iterable = PySequence_Fast(iterable, "argument must be iterable"); if (!iterable) return NULL; n = PySequence_Fast_GET_SIZE(iterable); if (n == 0) { /* short circuit when iterable is empty */ Py_DECREF(iterable); Py_RETURN_NONE; } m = Py_SIZE(self); /* It should not be possible to allocate a list large enough to cause an overflow on any relevant platform */ assert(m < PY_SSIZE_T_MAX - n); if (list_resize(self, m + n) < 0) { Py_DECREF(iterable); return NULL; } /* note that we may still have self == iterable here for the * situation a.extend(a), but the following code works * in that case too. Just make sure to resize self * before calling PySequence_Fast_ITEMS. */ /* populate the end of self with iterable's items */ src = PySequence_Fast_ITEMS(iterable); dest = self->ob_item + m; for (i = 0; i < n; i++) { PyObject *o = src[i]; Py_INCREF(o); dest[i] = o; } Py_DECREF(iterable); Py_RETURN_NONE; } it = PyObject_GetIter(iterable); if (it == NULL) return NULL; iternext = *it->ob_type->tp_iternext; /* Guess a result list size. */ n = PyObject_LengthHint(iterable, 8); if (n < 0) { Py_DECREF(it); return NULL; } m = Py_SIZE(self); if (m > PY_SSIZE_T_MAX - n) { /* m + n overflowed; on the chance that n lied, and there really * is enough room, ignore it. If n was telling the truth, we'll * eventually run out of memory during the loop. */ } else { mn = m + n; /* Make room. */ if (list_resize(self, mn) < 0) goto error; /* Make the list sane again. */ Py_SIZE(self) = m; } /* Run iterator to exhaustion. */ for (;;) { PyObject *item = iternext(it); if (item == NULL) { if (PyErr_Occurred()) { if (PyErr_ExceptionMatches(PyExc_StopIteration)) PyErr_Clear(); else goto error; } break; } if (Py_SIZE(self) < self->allocated) { /* steals ref */ PyList_SET_ITEM(self, Py_SIZE(self), item); ++Py_SIZE(self); } else { int status = app1(self, item); Py_DECREF(item); /* append creates a new ref */ if (status < 0) goto error; } } /* Cut back result list if initial guess was too large. */ if (Py_SIZE(self) < self->allocated) { if (list_resize(self, Py_SIZE(self)) < 0) goto error; } Py_DECREF(it); Py_RETURN_NONE; error: Py_DECREF(it); return NULL; } PyObject * _PyList_Extend(PyListObject *self, PyObject *iterable) { return list_extend(self, iterable); } static PyObject * list_inplace_concat(PyListObject *self, PyObject *other) { PyObject *result; result = list_extend(self, other); if (result == NULL) return result; Py_DECREF(result); Py_INCREF(self); return (PyObject *)self; } /*[clinic input] list.pop index: Py_ssize_t = -1 / Remove and return item at index (default last). Raises IndexError if list is empty or index is out of range. [clinic start generated code]*/ static PyObject * list_pop_impl(PyListObject *self, Py_ssize_t index) /*[clinic end generated code: output=6bd69dcb3f17eca8 input=b83675976f329e6f]*/ { PyObject *v; int status; if (Py_SIZE(self) == 0) { /* Special-case most common failure cause */ PyErr_SetString(PyExc_IndexError, "pop from empty list"); return NULL; } if (index < 0) index += Py_SIZE(self); if (index < 0 || index >= Py_SIZE(self)) { PyErr_SetString(PyExc_IndexError, "pop index out of range"); return NULL; } v = self->ob_item[index]; if (index == Py_SIZE(self) - 1) { status = list_resize(self, Py_SIZE(self) - 1); if (status >= 0) return v; /* and v now owns the reference the list had */ else return NULL; } Py_INCREF(v); status = list_ass_slice(self, index, index+1, (PyObject *)NULL); if (status < 0) { Py_DECREF(v); return NULL; } return v; } /* Reverse a slice of a list in place, from lo up to (exclusive) hi. */ static void reverse_slice(PyObject **lo, PyObject **hi) { assert(lo && hi); --hi; while (lo < hi) { PyObject *t = *lo; *lo = *hi; *hi = t; ++lo; --hi; } } /* Lots of code for an adaptive, stable, natural mergesort. There are many * pieces to this algorithm; read listsort.txt for overviews and details. */ /* A sortslice contains a pointer to an array of keys and a pointer to * an array of corresponding values. In other words, keys[i] * corresponds with values[i]. If values == NULL, then the keys are * also the values. * * Several convenience routines are provided here, so that keys and * values are always moved in sync. */ typedef struct { PyObject **keys; PyObject **values; } sortslice; Py_LOCAL_INLINE(void) sortslice_copy(sortslice *s1, Py_ssize_t i, sortslice *s2, Py_ssize_t j) { s1->keys[i] = s2->keys[j]; if (s1->values != NULL) s1->values[i] = s2->values[j]; } Py_LOCAL_INLINE(void) sortslice_copy_incr(sortslice *dst, sortslice *src) { *dst->keys++ = *src->keys++; if (dst->values != NULL) *dst->values++ = *src->values++; } Py_LOCAL_INLINE(void) sortslice_copy_decr(sortslice *dst, sortslice *src) { *dst->keys-- = *src->keys--; if (dst->values != NULL) *dst->values-- = *src->values--; } Py_LOCAL_INLINE(void) sortslice_memcpy(sortslice *s1, Py_ssize_t i, sortslice *s2, Py_ssize_t j, Py_ssize_t n) { memcpy(&s1->keys[i], &s2->keys[j], sizeof(PyObject *) * n); if (s1->values != NULL) memcpy(&s1->values[i], &s2->values[j], sizeof(PyObject *) * n); } Py_LOCAL_INLINE(void) sortslice_memmove(sortslice *s1, Py_ssize_t i, sortslice *s2, Py_ssize_t j, Py_ssize_t n) { memmove(&s1->keys[i], &s2->keys[j], sizeof(PyObject *) * n); if (s1->values != NULL) memmove(&s1->values[i], &s2->values[j], sizeof(PyObject *) * n); } Py_LOCAL_INLINE(void) sortslice_advance(sortslice *slice, Py_ssize_t n) { slice->keys += n; if (slice->values != NULL) slice->values += n; } /* Comparison function: PyObject_RichCompareBool with Py_LT. * Returns -1 on error, 1 if x < y, 0 if x >= y. */ #define ISLT(X, Y) (PyObject_RichCompareBool(X, Y, Py_LT)) /* Compare X to Y via "<". Goto "fail" if the comparison raises an error. Else "k" is set to true iff X. X and Y are PyObject*s. */ #define IFLT(X, Y) if ((k = ISLT(X, Y)) < 0) goto fail; \ if (k) /* binarysort is the best method for sorting small arrays: it does few compares, but can do data movement quadratic in the number of elements. [lo, hi) is a contiguous slice of a list, and is sorted via binary insertion. This sort is stable. On entry, must have lo <= start <= hi, and that [lo, start) is already sorted (pass start == lo if you don't know!). If islt() complains return -1, else 0. Even in case of error, the output slice will be some permutation of the input (nothing is lost or duplicated). */ static int binarysort(sortslice lo, PyObject **hi, PyObject **start) { Py_ssize_t k; PyObject **l, **p, **r; PyObject *pivot; assert(lo.keys <= start && start <= hi); /* assert [lo, start) is sorted */ if (lo.keys == start) ++start; for (; start < hi; ++start) { /* set l to where *start belongs */ l = lo.keys; r = start; pivot = *r; /* Invariants: * pivot >= all in [lo, l). * pivot < all in [r, start). * The second is vacuously true at the start. */ assert(l < r); do { p = l + ((r - l) >> 1); IFLT(pivot, *p) r = p; else l = p+1; } while (l < r); assert(l == r); /* The invariants still hold, so pivot >= all in [lo, l) and pivot < all in [l, start), so pivot belongs at l. Note that if there are elements equal to pivot, l points to the first slot after them -- that's why this sort is stable. Slide over to make room. Caution: using memmove is much slower under MSVC 5; we're not usually moving many slots. */ for (p = start; p > l; --p) *p = *(p-1); *l = pivot; if (lo.values != NULL) { Py_ssize_t offset = lo.values - lo.keys; p = start + offset; pivot = *p; l += offset; for (p = start + offset; p > l; --p) *p = *(p-1); *l = pivot; } } return 0; fail: return -1; } /* Return the length of the run beginning at lo, in the slice [lo, hi). lo < hi is required on entry. "A run" is the longest ascending sequence, with lo[0] <= lo[1] <= lo[2] <= ... or the longest descending sequence, with lo[0] > lo[1] > lo[2] > ... Boolean *descending is set to 0 in the former case, or to 1 in the latter. For its intended use in a stable mergesort, the strictness of the defn of "descending" is needed so that the caller can safely reverse a descending sequence without violating stability (strict > ensures there are no equal elements to get out of order). Returns -1 in case of error. */ static Py_ssize_t count_run(PyObject **lo, PyObject **hi, int *descending) { Py_ssize_t k; Py_ssize_t n; assert(lo < hi); *descending = 0; ++lo; if (lo == hi) return 1; n = 2; IFLT(*lo, *(lo-1)) { *descending = 1; for (lo = lo+1; lo < hi; ++lo, ++n) { IFLT(*lo, *(lo-1)) ; else break; } } else { for (lo = lo+1; lo < hi; ++lo, ++n) { IFLT(*lo, *(lo-1)) break; } } return n; fail: return -1; } /* Locate the proper position of key in a sorted vector; if the vector contains an element equal to key, return the position immediately to the left of the leftmost equal element. [gallop_right() does the same except returns the position to the right of the rightmost equal element (if any).] "a" is a sorted vector with n elements, starting at a[0]. n must be > 0. "hint" is an index at which to begin the search, 0 <= hint < n. The closer hint is to the final result, the faster this runs. The return value is the int k in 0..n such that a[k-1] < key <= a[k] pretending that *(a-1) is minus infinity and a[n] is plus infinity. IOW, key belongs at index k; or, IOW, the first k elements of a should precede key, and the last n-k should follow key. Returns -1 on error. See listsort.txt for info on the method. */ static Py_ssize_t gallop_left(PyObject *key, PyObject **a, Py_ssize_t n, Py_ssize_t hint) { Py_ssize_t ofs; Py_ssize_t lastofs; Py_ssize_t k; assert(key && a && n > 0 && hint >= 0 && hint < n); a += hint; lastofs = 0; ofs = 1; IFLT(*a, key) { /* a[hint] < key -- gallop right, until * a[hint + lastofs] < key <= a[hint + ofs] */ const Py_ssize_t maxofs = n - hint; /* &a[n-1] is highest */ while (ofs < maxofs) { IFLT(a[ofs], key) { lastofs = ofs; ofs = (ofs << 1) + 1; if (ofs <= 0) /* int overflow */ ofs = maxofs; } else /* key <= a[hint + ofs] */ break; } if (ofs > maxofs) ofs = maxofs; /* Translate back to offsets relative to &a[0]. */ lastofs += hint; ofs += hint; } else { /* key <= a[hint] -- gallop left, until * a[hint - ofs] < key <= a[hint - lastofs] */ const Py_ssize_t maxofs = hint + 1; /* &a[0] is lowest */ while (ofs < maxofs) { IFLT(*(a-ofs), key) break; /* key <= a[hint - ofs] */ lastofs = ofs; ofs = (ofs << 1) + 1; if (ofs <= 0) /* int overflow */ ofs = maxofs; } if (ofs > maxofs) ofs = maxofs; /* Translate back to positive offsets relative to &a[0]. */ k = lastofs; lastofs = hint - ofs; ofs = hint - k; } a -= hint; assert(-1 <= lastofs && lastofs < ofs && ofs <= n); /* Now a[lastofs] < key <= a[ofs], so key belongs somewhere to the * right of lastofs but no farther right than ofs. Do a binary * search, with invariant a[lastofs-1] < key <= a[ofs]. */ ++lastofs; while (lastofs < ofs) { Py_ssize_t m = lastofs + ((ofs - lastofs) >> 1); IFLT(a[m], key) lastofs = m+1; /* a[m] < key */ else ofs = m; /* key <= a[m] */ } assert(lastofs == ofs); /* so a[ofs-1] < key <= a[ofs] */ return ofs; fail: return -1; } /* Exactly like gallop_left(), except that if key already exists in a[0:n], finds the position immediately to the right of the rightmost equal value. The return value is the int k in 0..n such that a[k-1] <= key < a[k] or -1 if error. The code duplication is massive, but this is enough different given that we're sticking to "<" comparisons that it's much harder to follow if written as one routine with yet another "left or right?" flag. */ static Py_ssize_t gallop_right(PyObject *key, PyObject **a, Py_ssize_t n, Py_ssize_t hint) { Py_ssize_t ofs; Py_ssize_t lastofs; Py_ssize_t k; assert(key && a && n > 0 && hint >= 0 && hint < n); a += hint; lastofs = 0; ofs = 1; IFLT(key, *a) { /* key < a[hint] -- gallop left, until * a[hint - ofs] <= key < a[hint - lastofs] */ const Py_ssize_t maxofs = hint + 1; /* &a[0] is lowest */ while (ofs < maxofs) { IFLT(key, *(a-ofs)) { lastofs = ofs; ofs = (ofs << 1) + 1; if (ofs <= 0) /* int overflow */ ofs = maxofs; } else /* a[hint - ofs] <= key */ break; } if (ofs > maxofs) ofs = maxofs; /* Translate back to positive offsets relative to &a[0]. */ k = lastofs; lastofs = hint - ofs; ofs = hint - k; } else { /* a[hint] <= key -- gallop right, until * a[hint + lastofs] <= key < a[hint + ofs] */ const Py_ssize_t maxofs = n - hint; /* &a[n-1] is highest */ while (ofs < maxofs) { IFLT(key, a[ofs]) break; /* a[hint + ofs] <= key */ lastofs = ofs; ofs = (ofs << 1) + 1; if (ofs <= 0) /* int overflow */ ofs = maxofs; } if (ofs > maxofs) ofs = maxofs; /* Translate back to offsets relative to &a[0]. */ lastofs += hint; ofs += hint; } a -= hint; assert(-1 <= lastofs && lastofs < ofs && ofs <= n); /* Now a[lastofs] <= key < a[ofs], so key belongs somewhere to the * right of lastofs but no farther right than ofs. Do a binary * search, with invariant a[lastofs-1] <= key < a[ofs]. */ ++lastofs; while (lastofs < ofs) { Py_ssize_t m = lastofs + ((ofs - lastofs) >> 1); IFLT(key, a[m]) ofs = m; /* key < a[m] */ else lastofs = m+1; /* a[m] <= key */ } assert(lastofs == ofs); /* so a[ofs-1] <= key < a[ofs] */ return ofs; fail: return -1; } /* The maximum number of entries in a MergeState's pending-runs stack. * This is enough to sort arrays of size up to about * 32 * phi ** MAX_MERGE_PENDING * where phi ~= 1.618. 85 is ridiculouslylarge enough, good for an array * with 2**64 elements. */ #define MAX_MERGE_PENDING 85 /* When we get into galloping mode, we stay there until both runs win less * often than MIN_GALLOP consecutive times. See listsort.txt for more info. */ #define MIN_GALLOP 7 /* Avoid malloc for small temp arrays. */ #define MERGESTATE_TEMP_SIZE 256 /* One MergeState exists on the stack per invocation of mergesort. It's just * a convenient way to pass state around among the helper functions. */ struct s_slice { sortslice base; Py_ssize_t len; }; typedef struct s_MergeState { /* This controls when we get *into* galloping mode. It's initialized * to MIN_GALLOP. merge_lo and merge_hi tend to nudge it higher for * random data, and lower for highly structured data. */ Py_ssize_t min_gallop; /* 'a' is temp storage to help with merges. It contains room for * alloced entries. */ sortslice a; /* may point to temparray below */ Py_ssize_t alloced; /* A stack of n pending runs yet to be merged. Run #i starts at * address base[i] and extends for len[i] elements. It's always * true (so long as the indices are in bounds) that * * pending[i].base + pending[i].len == pending[i+1].base * * so we could cut the storage for this, but it's a minor amount, * and keeping all the info explicit simplifies the code. */ int n; struct s_slice pending[MAX_MERGE_PENDING]; /* 'a' points to this when possible, rather than muck with malloc. */ PyObject *temparray[MERGESTATE_TEMP_SIZE]; } MergeState; /* Conceptually a MergeState's constructor. */ static void merge_init(MergeState *ms, Py_ssize_t list_size, int has_keyfunc) { assert(ms != NULL); if (has_keyfunc) { /* The temporary space for merging will need at most half the list * size rounded up. Use the minimum possible space so we can use the * rest of temparray for other things. In particular, if there is * enough extra space, listsort() will use it to store the keys. */ ms->alloced = (list_size + 1) / 2; /* ms->alloced describes how many keys will be stored at ms->temparray, but we also need to store the values. Hence, ms->alloced is capped at half of MERGESTATE_TEMP_SIZE. */ if (MERGESTATE_TEMP_SIZE / 2 < ms->alloced) ms->alloced = MERGESTATE_TEMP_SIZE / 2; ms->a.values = &ms->temparray[ms->alloced]; } else { ms->alloced = MERGESTATE_TEMP_SIZE; ms->a.values = NULL; } ms->a.keys = ms->temparray; ms->n = 0; ms->min_gallop = MIN_GALLOP; } /* Free all the temp memory owned by the MergeState. This must be called * when you're done with a MergeState, and may be called before then if * you want to free the temp memory early. */ static void merge_freemem(MergeState *ms) { assert(ms != NULL); if (ms->a.keys != ms->temparray) PyMem_Free(ms->a.keys); } /* Ensure enough temp memory for 'need' array slots is available. * Returns 0 on success and -1 if the memory can't be gotten. */ static int merge_getmem(MergeState *ms, Py_ssize_t need) { int multiplier; assert(ms != NULL); if (need <= ms->alloced) return 0; multiplier = ms->a.values != NULL ? 2 : 1; /* Don't realloc! That can cost cycles to copy the old data, but * we don't care what's in the block. */ merge_freemem(ms); if ((size_t)need > PY_SSIZE_T_MAX / sizeof(PyObject*) / multiplier) { PyErr_NoMemory(); return -1; } ms->a.keys = (PyObject**)PyMem_Malloc(multiplier * need * sizeof(PyObject *)); if (ms->a.keys != NULL) { ms->alloced = need; if (ms->a.values != NULL) ms->a.values = &ms->a.keys[need]; return 0; } PyErr_NoMemory(); return -1; } #define MERGE_GETMEM(MS, NEED) ((NEED) <= (MS)->alloced ? 0 : \ merge_getmem(MS, NEED)) /* Merge the na elements starting at ssa with the nb elements starting at * ssb.keys = ssa.keys + na in a stable way, in-place. na and nb must be > 0. * Must also have that ssa.keys[na-1] belongs at the end of the merge, and * should have na <= nb. See listsort.txt for more info. Return 0 if * successful, -1 if error. */ static Py_ssize_t merge_lo(MergeState *ms, sortslice ssa, Py_ssize_t na, sortslice ssb, Py_ssize_t nb) { Py_ssize_t k; sortslice dest; int result = -1; /* guilty until proved innocent */ Py_ssize_t min_gallop; assert(ms && ssa.keys && ssb.keys && na > 0 && nb > 0); assert(ssa.keys + na == ssb.keys); if (MERGE_GETMEM(ms, na) < 0) return -1; sortslice_memcpy(&ms->a, 0, &ssa, 0, na); dest = ssa; ssa = ms->a; sortslice_copy_incr(&dest, &ssb); --nb; if (nb == 0) goto Succeed; if (na == 1) goto CopyB; min_gallop = ms->min_gallop; for (;;) { Py_ssize_t acount = 0; /* # of times A won in a row */ Py_ssize_t bcount = 0; /* # of times B won in a row */ /* Do the straightforward thing until (if ever) one run * appears to win consistently. */ for (;;) { assert(na > 1 && nb > 0); k = ISLT(ssb.keys[0], ssa.keys[0]); if (k) { if (k < 0) goto Fail; sortslice_copy_incr(&dest, &ssb); ++bcount; acount = 0; --nb; if (nb == 0) goto Succeed; if (bcount >= min_gallop) break; } else { sortslice_copy_incr(&dest, &ssa); ++acount; bcount = 0; --na; if (na == 1) goto CopyB; if (acount >= min_gallop) break; } } /* One run is winning so consistently that galloping may * be a huge win. So try that, and continue galloping until * (if ever) neither run appears to be winning consistently * anymore. */ ++min_gallop; do { assert(na > 1 && nb > 0); min_gallop -= min_gallop > 1; ms->min_gallop = min_gallop; k = gallop_right(ssb.keys[0], ssa.keys, na, 0); acount = k; if (k) { if (k < 0) goto Fail; sortslice_memcpy(&dest, 0, &ssa, 0, k); sortslice_advance(&dest, k); sortslice_advance(&ssa, k); na -= k; if (na == 1) goto CopyB; /* na==0 is impossible now if the comparison * function is consistent, but we can't assume * that it is. */ if (na == 0) goto Succeed; } sortslice_copy_incr(&dest, &ssb); --nb; if (nb == 0) goto Succeed; k = gallop_left(ssa.keys[0], ssb.keys, nb, 0); bcount = k; if (k) { if (k < 0) goto Fail; sortslice_memmove(&dest, 0, &ssb, 0, k); sortslice_advance(&dest, k); sortslice_advance(&ssb, k); nb -= k; if (nb == 0) goto Succeed; } sortslice_copy_incr(&dest, &ssa); --na; if (na == 1) goto CopyB; } while (acount >= MIN_GALLOP || bcount >= MIN_GALLOP); ++min_gallop; /* penalize it for leaving galloping mode */ ms->min_gallop = min_gallop; } Succeed: result = 0; Fail: if (na) sortslice_memcpy(&dest, 0, &ssa, 0, na); return result; CopyB: assert(na == 1 && nb > 0); /* The last element of ssa belongs at the end of the merge. */ sortslice_memmove(&dest, 0, &ssb, 0, nb); sortslice_copy(&dest, nb, &ssa, 0); return 0; } /* Merge the na elements starting at pa with the nb elements starting at * ssb.keys = ssa.keys + na in a stable way, in-place. na and nb must be > 0. * Must also have that ssa.keys[na-1] belongs at the end of the merge, and * should have na >= nb. See listsort.txt for more info. Return 0 if * successful, -1 if error. */ static Py_ssize_t merge_hi(MergeState *ms, sortslice ssa, Py_ssize_t na, sortslice ssb, Py_ssize_t nb) { Py_ssize_t k; sortslice dest, basea, baseb; int result = -1; /* guilty until proved innocent */ Py_ssize_t min_gallop; assert(ms && ssa.keys && ssb.keys && na > 0 && nb > 0); assert(ssa.keys + na == ssb.keys); if (MERGE_GETMEM(ms, nb) < 0) return -1; dest = ssb; sortslice_advance(&dest, nb-1); sortslice_memcpy(&ms->a, 0, &ssb, 0, nb); basea = ssa; baseb = ms->a; ssb.keys = ms->a.keys + nb - 1; if (ssb.values != NULL) ssb.values = ms->a.values + nb - 1; sortslice_advance(&ssa, na - 1); sortslice_copy_decr(&dest, &ssa); --na; if (na == 0) goto Succeed; if (nb == 1) goto CopyA; min_gallop = ms->min_gallop; for (;;) { Py_ssize_t acount = 0; /* # of times A won in a row */ Py_ssize_t bcount = 0; /* # of times B won in a row */ /* Do the straightforward thing until (if ever) one run * appears to win consistently. */ for (;;) { assert(na > 0 && nb > 1); k = ISLT(ssb.keys[0], ssa.keys[0]); if (k) { if (k < 0) goto Fail; sortslice_copy_decr(&dest, &ssa); ++acount; bcount = 0; --na; if (na == 0) goto Succeed; if (acount >= min_gallop) break; } else { sortslice_copy_decr(&dest, &ssb); ++bcount; acount = 0; --nb; if (nb == 1) goto CopyA; if (bcount >= min_gallop) break; } } /* One run is winning so consistently that galloping may * be a huge win. So try that, and continue galloping until * (if ever) neither run appears to be winning consistently * anymore. */ ++min_gallop; do { assert(na > 0 && nb > 1); min_gallop -= min_gallop > 1; ms->min_gallop = min_gallop; k = gallop_right(ssb.keys[0], basea.keys, na, na-1); if (k < 0) goto Fail; k = na - k; acount = k; if (k) { sortslice_advance(&dest, -k); sortslice_advance(&ssa, -k); sortslice_memmove(&dest, 1, &ssa, 1, k); na -= k; if (na == 0) goto Succeed; } sortslice_copy_decr(&dest, &ssb); --nb; if (nb == 1) goto CopyA; k = gallop_left(ssa.keys[0], baseb.keys, nb, nb-1); if (k < 0) goto Fail; k = nb - k; bcount = k; if (k) { sortslice_advance(&dest, -k); sortslice_advance(&ssb, -k); sortslice_memcpy(&dest, 1, &ssb, 1, k); nb -= k; if (nb == 1) goto CopyA; /* nb==0 is impossible now if the comparison * function is consistent, but we can't assume * that it is. */ if (nb == 0) goto Succeed; } sortslice_copy_decr(&dest, &ssa); --na; if (na == 0) goto Succeed; } while (acount >= MIN_GALLOP || bcount >= MIN_GALLOP); ++min_gallop; /* penalize it for leaving galloping mode */ ms->min_gallop = min_gallop; } Succeed: result = 0; Fail: if (nb) sortslice_memcpy(&dest, -(nb-1), &baseb, 0, nb); return result; CopyA: assert(nb == 1 && na > 0); /* The first element of ssb belongs at the front of the merge. */ sortslice_memmove(&dest, 1-na, &ssa, 1-na, na); sortslice_advance(&dest, -na); sortslice_advance(&ssa, -na); sortslice_copy(&dest, 0, &ssb, 0); return 0; } /* Merge the two runs at stack indices i and i+1. * Returns 0 on success, -1 on error. */ static Py_ssize_t merge_at(MergeState *ms, Py_ssize_t i) { sortslice ssa, ssb; Py_ssize_t na, nb; Py_ssize_t k; assert(ms != NULL); assert(ms->n >= 2); assert(i >= 0); assert(i == ms->n - 2 || i == ms->n - 3); ssa = ms->pending[i].base; na = ms->pending[i].len; ssb = ms->pending[i+1].base; nb = ms->pending[i+1].len; assert(na > 0 && nb > 0); assert(ssa.keys + na == ssb.keys); /* Record the length of the combined runs; if i is the 3rd-last * run now, also slide over the last run (which isn't involved * in this merge). The current run i+1 goes away in any case. */ ms->pending[i].len = na + nb; if (i == ms->n - 3) ms->pending[i+1] = ms->pending[i+2]; --ms->n; /* Where does b start in a? Elements in a before that can be * ignored (already in place). */ k = gallop_right(*ssb.keys, ssa.keys, na, 0); if (k < 0) return -1; sortslice_advance(&ssa, k); na -= k; if (na == 0) return 0; /* Where does a end in b? Elements in b after that can be * ignored (already in place). */ nb = gallop_left(ssa.keys[na-1], ssb.keys, nb, nb-1); if (nb <= 0) return nb; /* Merge what remains of the runs, using a temp array with * min(na, nb) elements. */ if (na <= nb) return merge_lo(ms, ssa, na, ssb, nb); else return merge_hi(ms, ssa, na, ssb, nb); } /* Examine the stack of runs waiting to be merged, merging adjacent runs * until the stack invariants are re-established: * * 1. len[-3] > len[-2] + len[-1] * 2. len[-2] > len[-1] * * See listsort.txt for more info. * * Returns 0 on success, -1 on error. */ static int merge_collapse(MergeState *ms) { struct s_slice *p = ms->pending; assert(ms); while (ms->n > 1) { Py_ssize_t n = ms->n - 2; if ((n > 0 && p[n-1].len <= p[n].len + p[n+1].len) || (n > 1 && p[n-2].len <= p[n-1].len + p[n].len)) { if (p[n-1].len < p[n+1].len) --n; if (merge_at(ms, n) < 0) return -1; } else if (p[n].len <= p[n+1].len) { if (merge_at(ms, n) < 0) return -1; } else break; } return 0; } /* Regardless of invariants, merge all runs on the stack until only one * remains. This is used at the end of the mergesort. * * Returns 0 on success, -1 on error. */ static int merge_force_collapse(MergeState *ms) { struct s_slice *p = ms->pending; assert(ms); while (ms->n > 1) { Py_ssize_t n = ms->n - 2; if (n > 0 && p[n-1].len < p[n+1].len) --n; if (merge_at(ms, n) < 0) return -1; } return 0; } /* Compute a good value for the minimum run length; natural runs shorter * than this are boosted artificially via binary insertion. * * If n < 64, return n (it's too small to bother with fancy stuff). * Else if n is an exact power of 2, return 32. * Else return an int k, 32 <= k <= 64, such that n/k is close to, but * strictly less than, an exact power of 2. * * See listsort.txt for more info. */ static Py_ssize_t merge_compute_minrun(Py_ssize_t n) { Py_ssize_t r = 0; /* becomes 1 if any 1 bits are shifted off */ assert(n >= 0); while (n >= 64) { r |= n & 1; n >>= 1; } return n + r; } static void reverse_sortslice(sortslice *s, Py_ssize_t n) { reverse_slice(s->keys, &s->keys[n]); if (s->values != NULL) reverse_slice(s->values, &s->values[n]); } /* An adaptive, stable, natural mergesort. See listsort.txt. * Returns Py_None on success, NULL on error. Even in case of error, the * list will be some permutation of its input state (nothing is lost or * duplicated). */ /*[clinic input] list.sort * key as keyfunc: object = None reverse: bool(accept={int}) = False Stable sort *IN PLACE*. [clinic start generated code]*/ static PyObject * list_sort_impl(PyListObject *self, PyObject *keyfunc, int reverse) /*[clinic end generated code: output=57b9f9c5e23fbe42 input=b0fcf743982c5b90]*/ { MergeState ms; Py_ssize_t nremaining; Py_ssize_t minrun; sortslice lo; Py_ssize_t saved_ob_size, saved_allocated; PyObject **saved_ob_item; PyObject **final_ob_item; PyObject *result = NULL; /* guilty until proved innocent */ Py_ssize_t i; PyObject **keys; assert(self != NULL); assert(PyList_Check(self)); if (keyfunc == Py_None) keyfunc = NULL; /* The list is temporarily made empty, so that mutations performed * by comparison functions can't affect the slice of memory we're * sorting (allowing mutations during sorting is a core-dump * factory, since ob_item may change). */ saved_ob_size = Py_SIZE(self); saved_ob_item = self->ob_item; saved_allocated = self->allocated; Py_SIZE(self) = 0; self->ob_item = NULL; self->allocated = -1; /* any operation will reset it to >= 0 */ if (keyfunc == NULL) { keys = NULL; lo.keys = saved_ob_item; lo.values = NULL; } else { if (saved_ob_size < MERGESTATE_TEMP_SIZE/2) /* Leverage stack space we allocated but won't otherwise use */ keys = &ms.temparray[saved_ob_size+1]; else { keys = PyMem_MALLOC(sizeof(PyObject *) * saved_ob_size); if (keys == NULL) { PyErr_NoMemory(); goto keyfunc_fail; } } for (i = 0; i < saved_ob_size ; i++) { keys[i] = PyObject_CallFunctionObjArgs(keyfunc, saved_ob_item[i], NULL); if (keys[i] == NULL) { for (i=i-1 ; i>=0 ; i--) Py_DECREF(keys[i]); if (saved_ob_size >= MERGESTATE_TEMP_SIZE/2) PyMem_FREE(keys); goto keyfunc_fail; } } lo.keys = keys; lo.values = saved_ob_item; } merge_init(&ms, saved_ob_size, keys != NULL); nremaining = saved_ob_size; if (nremaining < 2) goto succeed; /* Reverse sort stability achieved by initially reversing the list, applying a stable forward sort, then reversing the final result. */ if (reverse) { if (keys != NULL) reverse_slice(&keys[0], &keys[saved_ob_size]); reverse_slice(&saved_ob_item[0], &saved_ob_item[saved_ob_size]); } /* March over the array once, left to right, finding natural runs, * and extending short natural runs to minrun elements. */ minrun = merge_compute_minrun(nremaining); do { int descending; Py_ssize_t n; /* Identify next run. */ n = count_run(lo.keys, lo.keys + nremaining, &descending); if (n < 0) goto fail; if (descending) reverse_sortslice(&lo, n); /* If short, extend to min(minrun, nremaining). */ if (n < minrun) { const Py_ssize_t force = nremaining <= minrun ? nremaining : minrun; if (binarysort(lo, lo.keys + force, lo.keys + n) < 0) goto fail; n = force; } /* Push run onto pending-runs stack, and maybe merge. */ assert(ms.n < MAX_MERGE_PENDING); ms.pending[ms.n].base = lo; ms.pending[ms.n].len = n; ++ms.n; if (merge_collapse(&ms) < 0) goto fail; /* Advance to find next run. */ sortslice_advance(&lo, n); nremaining -= n; } while (nremaining); if (merge_force_collapse(&ms) < 0) goto fail; assert(ms.n == 1); assert(keys == NULL ? ms.pending[0].base.keys == saved_ob_item : ms.pending[0].base.keys == &keys[0]); assert(ms.pending[0].len == saved_ob_size); lo = ms.pending[0].base; succeed: result = Py_None; fail: if (keys != NULL) { for (i = 0; i < saved_ob_size; i++) Py_DECREF(keys[i]); if (saved_ob_size >= MERGESTATE_TEMP_SIZE/2) PyMem_FREE(keys); } if (self->allocated != -1 && result != NULL) { /* The user mucked with the list during the sort, * and we don't already have another error to report. */ PyErr_SetString(PyExc_ValueError, "list modified during sort"); result = NULL; } if (reverse && saved_ob_size > 1) reverse_slice(saved_ob_item, saved_ob_item + saved_ob_size); merge_freemem(&ms); keyfunc_fail: final_ob_item = self->ob_item; i = Py_SIZE(self); Py_SIZE(self) = saved_ob_size; self->ob_item = saved_ob_item; self->allocated = saved_allocated; if (final_ob_item != NULL) { /* we cannot use _list_clear() for this because it does not guarantee that the list is really empty when it returns */ while (--i >= 0) { Py_XDECREF(final_ob_item[i]); } PyMem_FREE(final_ob_item); } Py_XINCREF(result); return result; } #undef IFLT #undef ISLT int PyList_Sort(PyObject *v) { if (v == NULL || !PyList_Check(v)) { PyErr_BadInternalCall(); return -1; } v = list_sort_impl((PyListObject *)v, NULL, 0); if (v == NULL) return -1; Py_DECREF(v); return 0; } /*[clinic input] list.reverse Reverse *IN PLACE*. [clinic start generated code]*/ static PyObject * list_reverse_impl(PyListObject *self) /*[clinic end generated code: output=482544fc451abea9 input=eefd4c3ae1bc9887]*/ { if (Py_SIZE(self) > 1) reverse_slice(self->ob_item, self->ob_item + Py_SIZE(self)); Py_RETURN_NONE; } int PyList_Reverse(PyObject *v) { PyListObject *self = (PyListObject *)v; if (v == NULL || !PyList_Check(v)) { PyErr_BadInternalCall(); return -1; } if (Py_SIZE(self) > 1) reverse_slice(self->ob_item, self->ob_item + Py_SIZE(self)); return 0; } PyObject * PyList_AsTuple(PyObject *v) { PyObject *w; PyObject **p, **q; Py_ssize_t n; if (v == NULL || !PyList_Check(v)) { PyErr_BadInternalCall(); return NULL; } n = Py_SIZE(v); w = PyTuple_New(n); if (w == NULL) return NULL; p = ((PyTupleObject *)w)->ob_item; q = ((PyListObject *)v)->ob_item; while (--n >= 0) { Py_INCREF(*q); *p = *q; p++; q++; } return w; } /*[clinic input] list.index value: object start: slice_index(accept={int}) = 0 stop: slice_index(accept={int}, c_default="PY_SSIZE_T_MAX") = sys.maxsize / Return first index of value. Raises ValueError if the value is not present. [clinic start generated code]*/ static PyObject * list_index_impl(PyListObject *self, PyObject *value, Py_ssize_t start, Py_ssize_t stop) /*[clinic end generated code: output=ec51b88787e4e481 input=40ec5826303a0eb1]*/ { Py_ssize_t i; if (start < 0) { start += Py_SIZE(self); if (start < 0) start = 0; } if (stop < 0) { stop += Py_SIZE(self); if (stop < 0) stop = 0; } for (i = start; i < stop && i < Py_SIZE(self); i++) { int cmp = PyObject_RichCompareBool(self->ob_item[i], value, Py_EQ); if (cmp > 0) return PyLong_FromSsize_t(i); else if (cmp < 0) return NULL; } PyErr_Format(PyExc_ValueError, "%R is not in list", value); return NULL; } /*[clinic input] list.count value: object / Return number of occurrences of value. [clinic start generated code]*/ static PyObject * list_count(PyListObject *self, PyObject *value) /*[clinic end generated code: output=b1f5d284205ae714 input=3bdc3a5e6f749565]*/ { Py_ssize_t count = 0; Py_ssize_t i; for (i = 0; i < Py_SIZE(self); i++) { int cmp = PyObject_RichCompareBool(self->ob_item[i], value, Py_EQ); if (cmp > 0) count++; else if (cmp < 0) return NULL; } return PyLong_FromSsize_t(count); } /*[clinic input] list.remove value: object / Remove first occurrence of value. Raises ValueError if the value is not present. [clinic start generated code]*/ static PyObject * list_remove(PyListObject *self, PyObject *value) /*[clinic end generated code: output=f087e1951a5e30d1 input=2dc2ba5bb2fb1f82]*/ { Py_ssize_t i; for (i = 0; i < Py_SIZE(self); i++) { int cmp = PyObject_RichCompareBool(self->ob_item[i], value, Py_EQ); if (cmp > 0) { if (list_ass_slice(self, i, i+1, (PyObject *)NULL) == 0) Py_RETURN_NONE; return NULL; } else if (cmp < 0) return NULL; } PyErr_SetString(PyExc_ValueError, "list.remove(x): x not in list"); return NULL; } static int list_traverse(PyListObject *o, visitproc visit, void *arg) { Py_ssize_t i; for (i = Py_SIZE(o); --i >= 0; ) Py_VISIT(o->ob_item[i]); return 0; } static PyObject * list_richcompare(PyObject *v, PyObject *w, int op) { PyListObject *vl, *wl; Py_ssize_t i; if (!PyList_Check(v) || !PyList_Check(w)) Py_RETURN_NOTIMPLEMENTED; vl = (PyListObject *)v; wl = (PyListObject *)w; if (Py_SIZE(vl) != Py_SIZE(wl) && (op == Py_EQ || op == Py_NE)) { /* Shortcut: if the lengths differ, the lists differ */ if (op == Py_EQ) Py_RETURN_FALSE; else Py_RETURN_TRUE; } /* Search for the first index where items are different */ for (i = 0; i < Py_SIZE(vl) && i < Py_SIZE(wl); i++) { int k = PyObject_RichCompareBool(vl->ob_item[i], wl->ob_item[i], Py_EQ); if (k < 0) return NULL; if (!k) break; } if (i >= Py_SIZE(vl) || i >= Py_SIZE(wl)) { /* No more items to compare -- compare sizes */ Py_RETURN_RICHCOMPARE(Py_SIZE(vl), Py_SIZE(wl), op); } /* We have an item that differs -- shortcuts for EQ/NE */ if (op == Py_EQ) { Py_RETURN_FALSE; } if (op == Py_NE) { Py_RETURN_TRUE; } /* Compare the final item again using the proper operator */ return PyObject_RichCompare(vl->ob_item[i], wl->ob_item[i], op); } /*[clinic input] list.__init__ iterable: object(c_default="NULL") = () / Built-in mutable sequence. If no argument is given, the constructor creates a new empty list. The argument must be an iterable if specified. [clinic start generated code]*/ static int list___init___impl(PyListObject *self, PyObject *iterable) /*[clinic end generated code: output=0f3c21379d01de48 input=b3f3fe7206af8f6b]*/ { /* Verify list invariants established by PyType_GenericAlloc() */ assert(0 <= Py_SIZE(self)); assert(Py_SIZE(self) <= self->allocated || self->allocated == -1); assert(self->ob_item != NULL || self->allocated == 0 || self->allocated == -1); /* Empty previous contents */ if (self->ob_item != NULL) { (void)_list_clear(self); } if (iterable != NULL) { PyObject *rv = list_extend(self, iterable); if (rv == NULL) return -1; Py_DECREF(rv); } return 0; } /*[clinic input] list.__sizeof__ Return the size of the list in memory, in bytes. [clinic start generated code]*/ static PyObject * list___sizeof___impl(PyListObject *self) /*[clinic end generated code: output=3417541f95f9a53e input=b8030a5d5ce8a187]*/ { Py_ssize_t res; res = _PyObject_SIZE(Py_TYPE(self)) + self->allocated * sizeof(void*); return PyLong_FromSsize_t(res); } static PyObject *list_iter(PyObject *seq); static PyObject *list_subscript(PyListObject*, PyObject*); static PyMethodDef list_methods[] = { {"__getitem__", (PyCFunction)list_subscript, METH_O|METH_COEXIST, "x.__getitem__(y) <==> x[y]"}, LIST___REVERSED___METHODDEF LIST___SIZEOF___METHODDEF LIST_CLEAR_METHODDEF LIST_COPY_METHODDEF LIST_APPEND_METHODDEF LIST_INSERT_METHODDEF LIST_EXTEND_METHODDEF LIST_POP_METHODDEF LIST_REMOVE_METHODDEF LIST_INDEX_METHODDEF LIST_COUNT_METHODDEF LIST_REVERSE_METHODDEF LIST_SORT_METHODDEF {NULL, NULL} /* sentinel */ }; static PySequenceMethods list_as_sequence = { (lenfunc)list_length, /* sq_length */ (binaryfunc)list_concat, /* sq_concat */ (ssizeargfunc)list_repeat, /* sq_repeat */ (ssizeargfunc)list_item, /* sq_item */ 0, /* sq_slice */ (ssizeobjargproc)list_ass_item, /* sq_ass_item */ 0, /* sq_ass_slice */ (objobjproc)list_contains, /* sq_contains */ (binaryfunc)list_inplace_concat, /* sq_inplace_concat */ (ssizeargfunc)list_inplace_repeat, /* sq_inplace_repeat */ }; static PyObject * list_subscript(PyListObject* self, PyObject* item) { if (PyIndex_Check(item)) { Py_ssize_t i; i = PyNumber_AsSsize_t(item, PyExc_IndexError); if (i == -1 && PyErr_Occurred()) return NULL; if (i < 0) i += PyList_GET_SIZE(self); return list_item(self, i); } else if (PySlice_Check(item)) { Py_ssize_t start, stop, step, slicelength, cur, i; PyObject* result; PyObject* it; PyObject **src, **dest; if (PySlice_Unpack(item, &start, &stop, &step) < 0) { return NULL; } slicelength = PySlice_AdjustIndices(Py_SIZE(self), &start, &stop, step); if (slicelength <= 0) { return PyList_New(0); } else if (step == 1) { return list_slice(self, start, stop); } else { result = PyList_New(slicelength); if (!result) return NULL; src = self->ob_item; dest = ((PyListObject *)result)->ob_item; for (cur = start, i = 0; i < slicelength; cur += (size_t)step, i++) { it = src[cur]; Py_INCREF(it); dest[i] = it; } return result; } } else { PyErr_Format(PyExc_TypeError, "list indices must be integers or slices, not %.200s", item->ob_type->tp_name); return NULL; } } static int list_ass_subscript(PyListObject* self, PyObject* item, PyObject* value) { if (PyIndex_Check(item)) { Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError); if (i == -1 && PyErr_Occurred()) return -1; if (i < 0) i += PyList_GET_SIZE(self); return list_ass_item(self, i, value); } else if (PySlice_Check(item)) { Py_ssize_t start, stop, step, slicelength; if (PySlice_Unpack(item, &start, &stop, &step) < 0) { return -1; } slicelength = PySlice_AdjustIndices(Py_SIZE(self), &start, &stop, step); if (step == 1) return list_ass_slice(self, start, stop, value); /* Make sure s[5:2] = [..] inserts at the right place: before 5, not before 2. */ if ((step < 0 && start < stop) || (step > 0 && start > stop)) stop = start; if (value == NULL) { /* delete slice */ PyObject **garbage; size_t cur; Py_ssize_t i; int res; if (slicelength <= 0) return 0; if (step < 0) { stop = start + 1; start = stop + step*(slicelength - 1) - 1; step = -step; } garbage = (PyObject**) PyMem_MALLOC(slicelength*sizeof(PyObject*)); if (!garbage) { PyErr_NoMemory(); return -1; } /* drawing pictures might help understand these for loops. Basically, we memmove the parts of the list that are *not* part of the slice: step-1 items for each item that is part of the slice, and then tail end of the list that was not covered by the slice */ for (cur = start, i = 0; cur < (size_t)stop; cur += step, i++) { Py_ssize_t lim = step - 1; garbage[i] = PyList_GET_ITEM(self, cur); if (cur + step >= (size_t)Py_SIZE(self)) { lim = Py_SIZE(self) - cur - 1; } memmove(self->ob_item + cur - i, self->ob_item + cur + 1, lim * sizeof(PyObject *)); } cur = start + (size_t)slicelength * step; if (cur < (size_t)Py_SIZE(self)) { memmove(self->ob_item + cur - slicelength, self->ob_item + cur, (Py_SIZE(self) - cur) * sizeof(PyObject *)); } Py_SIZE(self) -= slicelength; res = list_resize(self, Py_SIZE(self)); for (i = 0; i < slicelength; i++) { Py_DECREF(garbage[i]); } PyMem_FREE(garbage); return res; } else { /* assign slice */ PyObject *ins, *seq; PyObject **garbage, **seqitems, **selfitems; Py_ssize_t cur, i; /* protect against a[::-1] = a */ if (self == (PyListObject*)value) { seq = list_slice((PyListObject*)value, 0, PyList_GET_SIZE(value)); } else { seq = PySequence_Fast(value, "must assign iterable " "to extended slice"); } if (!seq) return -1; if (PySequence_Fast_GET_SIZE(seq) != slicelength) { PyErr_Format(PyExc_ValueError, "attempt to assign sequence of " "size %zd to extended slice of " "size %zd", PySequence_Fast_GET_SIZE(seq), slicelength); Py_DECREF(seq); return -1; } if (!slicelength) { Py_DECREF(seq); return 0; } garbage = (PyObject**) PyMem_MALLOC(slicelength*sizeof(PyObject*)); if (!garbage) { Py_DECREF(seq); PyErr_NoMemory(); return -1; } selfitems = self->ob_item; seqitems = PySequence_Fast_ITEMS(seq); for (cur = start, i = 0; i < slicelength; cur += (size_t)step, i++) { garbage[i] = selfitems[cur]; ins = seqitems[i]; Py_INCREF(ins); selfitems[cur] = ins; } for (i = 0; i < slicelength; i++) { Py_DECREF(garbage[i]); } PyMem_FREE(garbage); Py_DECREF(seq); return 0; } } else { PyErr_Format(PyExc_TypeError, "list indices must be integers or slices, not %.200s", item->ob_type->tp_name); return -1; } } static PyMappingMethods list_as_mapping = { (lenfunc)list_length, (binaryfunc)list_subscript, (objobjargproc)list_ass_subscript }; PyTypeObject PyList_Type = { PyVarObject_HEAD_INIT(&PyType_Type, 0) "list", sizeof(PyListObject), 0, (destructor)list_dealloc, /* tp_dealloc */ 0, /* tp_print */ 0, /* tp_getattr */ 0, /* tp_setattr */ 0, /* tp_reserved */ (reprfunc)list_repr, /* tp_repr */ 0, /* tp_as_number */ &list_as_sequence, /* tp_as_sequence */ &list_as_mapping, /* tp_as_mapping */ PyObject_HashNotImplemented, /* tp_hash */ 0, /* tp_call */ 0, /* tp_str */ PyObject_GenericGetAttr, /* tp_getattro */ 0, /* tp_setattro */ 0, /* tp_as_buffer */ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_LIST_SUBCLASS, /* tp_flags */ list___init____doc__, /* tp_doc */ (traverseproc)list_traverse, /* tp_traverse */ (inquiry)_list_clear, /* tp_clear */ list_richcompare, /* tp_richcompare */ 0, /* tp_weaklistoffset */ list_iter, /* tp_iter */ 0, /* tp_iternext */ list_methods, /* tp_methods */ 0, /* tp_members */ 0, /* tp_getset */ 0, /* tp_base */ 0, /* tp_dict */ 0, /* tp_descr_get */ 0, /* tp_descr_set */ 0, /* tp_dictoffset */ (initproc)list___init__, /* tp_init */ PyType_GenericAlloc, /* tp_alloc */ PyType_GenericNew, /* tp_new */ PyObject_GC_Del, /* tp_free */ }; /*********************** List Iterator **************************/ typedef struct { PyObject_HEAD Py_ssize_t it_index; PyListObject *it_seq; /* Set to NULL when iterator is exhausted */ } listiterobject; static void listiter_dealloc(listiterobject *); static int listiter_traverse(listiterobject *, visitproc, void *); static PyObject *listiter_next(listiterobject *); static PyObject *listiter_len(listiterobject *); static PyObject *listiter_reduce_general(void *_it, int forward); static PyObject *listiter_reduce(listiterobject *); static PyObject *listiter_setstate(listiterobject *, PyObject *state); PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it))."); PyDoc_STRVAR(reduce_doc, "Return state information for pickling."); PyDoc_STRVAR(setstate_doc, "Set state information for unpickling."); static PyMethodDef listiter_methods[] = { {"__length_hint__", (PyCFunction)listiter_len, METH_NOARGS, length_hint_doc}, {"__reduce__", (PyCFunction)listiter_reduce, METH_NOARGS, reduce_doc}, {"__setstate__", (PyCFunction)listiter_setstate, METH_O, setstate_doc}, {NULL, NULL} /* sentinel */ }; PyTypeObject PyListIter_Type = { PyVarObject_HEAD_INIT(&PyType_Type, 0) "list_iterator", /* tp_name */ sizeof(listiterobject), /* tp_basicsize */ 0, /* tp_itemsize */ /* methods */ (destructor)listiter_dealloc, /* tp_dealloc */ 0, /* tp_print */ 0, /* tp_getattr */ 0, /* tp_setattr */ 0, /* tp_reserved */ 0, /* tp_repr */ 0, /* tp_as_number */ 0, /* tp_as_sequence */ 0, /* tp_as_mapping */ 0, /* tp_hash */ 0, /* tp_call */ 0, /* tp_str */ PyObject_GenericGetAttr, /* tp_getattro */ 0, /* tp_setattro */ 0, /* tp_as_buffer */ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */ 0, /* tp_doc */ (traverseproc)listiter_traverse, /* tp_traverse */ 0, /* tp_clear */ 0, /* tp_richcompare */ 0, /* tp_weaklistoffset */ PyObject_SelfIter, /* tp_iter */ (iternextfunc)listiter_next, /* tp_iternext */ listiter_methods, /* tp_methods */ 0, /* tp_members */ }; static PyObject * list_iter(PyObject *seq) { listiterobject *it; if (!PyList_Check(seq)) { PyErr_BadInternalCall(); return NULL; } it = PyObject_GC_New(listiterobject, &PyListIter_Type); if (it == NULL) return NULL; it->it_index = 0; Py_INCREF(seq); it->it_seq = (PyListObject *)seq; _PyObject_GC_TRACK(it); return (PyObject *)it; } static void listiter_dealloc(listiterobject *it) { _PyObject_GC_UNTRACK(it); Py_XDECREF(it->it_seq); PyObject_GC_Del(it); } static int listiter_traverse(listiterobject *it, visitproc visit, void *arg) { Py_VISIT(it->it_seq); return 0; } static PyObject * listiter_next(listiterobject *it) { PyListObject *seq; PyObject *item; assert(it != NULL); seq = it->it_seq; if (seq == NULL) return NULL; assert(PyList_Check(seq)); if (it->it_index < PyList_GET_SIZE(seq)) { item = PyList_GET_ITEM(seq, it->it_index); ++it->it_index; Py_INCREF(item); return item; } it->it_seq = NULL; Py_DECREF(seq); return NULL; } static PyObject * listiter_len(listiterobject *it) { Py_ssize_t len; if (it->it_seq) { len = PyList_GET_SIZE(it->it_seq) - it->it_index; if (len >= 0) return PyLong_FromSsize_t(len); } return PyLong_FromLong(0); } static PyObject * listiter_reduce(listiterobject *it) { return listiter_reduce_general(it, 1); } static PyObject * listiter_setstate(listiterobject *it, PyObject *state) { Py_ssize_t index = PyLong_AsSsize_t(state); if (index == -1 && PyErr_Occurred()) return NULL; if (it->it_seq != NULL) { if (index < 0) index = 0; else if (index > PyList_GET_SIZE(it->it_seq)) index = PyList_GET_SIZE(it->it_seq); /* iterator exhausted */ it->it_index = index; } Py_RETURN_NONE; } /*********************** List Reverse Iterator **************************/ typedef struct { PyObject_HEAD Py_ssize_t it_index; PyListObject *it_seq; /* Set to NULL when iterator is exhausted */ } listreviterobject; static void listreviter_dealloc(listreviterobject *); static int listreviter_traverse(listreviterobject *, visitproc, void *); static PyObject *listreviter_next(listreviterobject *); static PyObject *listreviter_len(listreviterobject *); static PyObject *listreviter_reduce(listreviterobject *); static PyObject *listreviter_setstate(listreviterobject *, PyObject *); static PyMethodDef listreviter_methods[] = { {"__length_hint__", (PyCFunction)listreviter_len, METH_NOARGS, length_hint_doc}, {"__reduce__", (PyCFunction)listreviter_reduce, METH_NOARGS, reduce_doc}, {"__setstate__", (PyCFunction)listreviter_setstate, METH_O, setstate_doc}, {NULL, NULL} /* sentinel */ }; PyTypeObject PyListRevIter_Type = { PyVarObject_HEAD_INIT(&PyType_Type, 0) "list_reverseiterator", /* tp_name */ sizeof(listreviterobject), /* tp_basicsize */ 0, /* tp_itemsize */ /* methods */ (destructor)listreviter_dealloc, /* tp_dealloc */ 0, /* tp_print */ 0, /* tp_getattr */ 0, /* tp_setattr */ 0, /* tp_reserved */ 0, /* tp_repr */ 0, /* tp_as_number */ 0, /* tp_as_sequence */ 0, /* tp_as_mapping */ 0, /* tp_hash */ 0, /* tp_call */ 0, /* tp_str */ PyObject_GenericGetAttr, /* tp_getattro */ 0, /* tp_setattro */ 0, /* tp_as_buffer */ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */ 0, /* tp_doc */ (traverseproc)listreviter_traverse, /* tp_traverse */ 0, /* tp_clear */ 0, /* tp_richcompare */ 0, /* tp_weaklistoffset */ PyObject_SelfIter, /* tp_iter */ (iternextfunc)listreviter_next, /* tp_iternext */ listreviter_methods, /* tp_methods */ 0, }; /*[clinic input] list.__reversed__ Return a reverse iterator over the list. [clinic start generated code]*/ static PyObject * list___reversed___impl(PyListObject *self) /*[clinic end generated code: output=b166f073208c888c input=eadb6e17f8a6a280]*/ { listreviterobject *it; it = PyObject_GC_New(listreviterobject, &PyListRevIter_Type); if (it == NULL) return NULL; assert(PyList_Check(self)); it->it_index = PyList_GET_SIZE(self) - 1; Py_INCREF(self); it->it_seq = self; PyObject_GC_Track(it); return (PyObject *)it; } static void listreviter_dealloc(listreviterobject *it) { PyObject_GC_UnTrack(it); Py_XDECREF(it->it_seq); PyObject_GC_Del(it); } static int listreviter_traverse(listreviterobject *it, visitproc visit, void *arg) { Py_VISIT(it->it_seq); return 0; } static PyObject * listreviter_next(listreviterobject *it) { PyObject *item; Py_ssize_t index; PyListObject *seq; assert(it != NULL); seq = it->it_seq; if (seq == NULL) { return NULL; } assert(PyList_Check(seq)); index = it->it_index; if (index>=0 && index < PyList_GET_SIZE(seq)) { item = PyList_GET_ITEM(seq, index); it->it_index--; Py_INCREF(item); return item; } it->it_index = -1; it->it_seq = NULL; Py_DECREF(seq); return NULL; } static PyObject * listreviter_len(listreviterobject *it) { Py_ssize_t len = it->it_index + 1; if (it->it_seq == NULL || PyList_GET_SIZE(it->it_seq) < len) len = 0; return PyLong_FromSsize_t(len); } static PyObject * listreviter_reduce(listreviterobject *it) { return listiter_reduce_general(it, 0); } static PyObject * listreviter_setstate(listreviterobject *it, PyObject *state) { Py_ssize_t index = PyLong_AsSsize_t(state); if (index == -1 && PyErr_Occurred()) return NULL; if (it->it_seq != NULL) { if (index < -1) index = -1; else if (index > PyList_GET_SIZE(it->it_seq) - 1) index = PyList_GET_SIZE(it->it_seq) - 1; it->it_index = index; } Py_RETURN_NONE; } /* common pickling support */ static PyObject * listiter_reduce_general(void *_it, int forward) { PyObject *list; /* the objects are not the same, index is of different types! */ if (forward) { listiterobject *it = (listiterobject *)_it; if (it->it_seq) return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("iter"), it->it_seq, it->it_index); } else { listreviterobject *it = (listreviterobject *)_it; if (it->it_seq) return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("reversed"), it->it_seq, it->it_index); } /* empty iterator, create an empty list */ list = PyList_New(0); if (list == NULL) return NULL; return Py_BuildValue("N(N)", _PyObject_GetBuiltin("iter"), list); }