Issue #9213: Add index and count methods to range objects, needed to

meet the API of the collections.Sequence ABC.

1 files changed, 132 insertions, 49 deletions

diff --git a/Objects/rangeobject.c b/Objects/rangeobject.c
index e36469c..9650386 100644
--- a/Objects/rangeobject.c
+++ b/Objects/rangeobject.c
@@ -273,58 +273,133 @@ range_reduce(rangeobject *r, PyObject *args)
                          r->start, r->stop, r->step);
 }
 
+/* Assumes (PyLong_CheckExact(ob) || PyBool_Check(ob)) */
+static int
+range_contains_long(rangeobject *r, PyObject *ob)
+{
+    int cmp1, cmp2, cmp3;
+    PyObject *tmp1 = NULL;
+    PyObject *tmp2 = NULL;
+    PyObject *zero = NULL;
+    int result = -1;
+
+    zero = PyLong_FromLong(0);
+    if (zero == NULL) /* MemoryError in int(0) */
+        goto end;
+
+    /* Check if the value can possibly be in the range. */
+
+    cmp1 = PyObject_RichCompareBool(r->step, zero, Py_GT);
+    if (cmp1 == -1)
+        goto end;
+    if (cmp1 == 1) { /* positive steps: start <= ob < stop */
+        cmp2 = PyObject_RichCompareBool(r->start, ob, Py_LE);
+        cmp3 = PyObject_RichCompareBool(ob, r->stop, Py_LT);
+    }
+    else { /* negative steps: stop < ob <= start */
+        cmp2 = PyObject_RichCompareBool(ob, r->start, Py_LE);
+        cmp3 = PyObject_RichCompareBool(r->stop, ob, Py_LT);
+    }
+
+    if (cmp2 == -1 || cmp3 == -1) /* TypeError */
+        goto end;
+    if (cmp2 == 0 || cmp3 == 0) { /* ob outside of range */
+        result = 0;
+        goto end;
+    }
+
+    /* Check that the stride does not invalidate ob's membership. */
+    tmp1 = PyNumber_Subtract(ob, r->start);
+    if (tmp1 == NULL)
+        goto end;
+    tmp2 = PyNumber_Remainder(tmp1, r->step);
+    if (tmp2 == NULL)
+        goto end;
+    /* result = (int(ob) - start % step) == 0 */
+    result = PyObject_RichCompareBool(tmp2, zero, Py_EQ);
+  end:
+    Py_XDECREF(tmp1);
+    Py_XDECREF(tmp2);
+    Py_XDECREF(zero);
+    return result;
+}
+
 static int
 range_contains(rangeobject *r, PyObject *ob) {
+    if (PyLong_CheckExact(ob) || PyBool_Check(ob))
+        return range_contains_long(r, ob);
+
+    return (int)_PySequence_IterSearch((PyObject*)r, ob,
+                                       PY_ITERSEARCH_CONTAINS);
+}
+
+static PyObject *
+range_count(rangeobject *r, PyObject *ob)
+{
     if (PyLong_CheckExact(ob) || PyBool_Check(ob)) {
-        int cmp1, cmp2, cmp3;
-        PyObject *tmp1 = NULL;
-        PyObject *tmp2 = NULL;
-        PyObject *zero = NULL;
-        int result = -1;
-
-        zero = PyLong_FromLong(0);
-        if (zero == NULL) /* MemoryError in int(0) */
-            goto end;
-
-        /* Check if the value can possibly be in the range. */
-
-        cmp1 = PyObject_RichCompareBool(r->step, zero, Py_GT);
-        if (cmp1 == -1)
-            goto end;
-        if (cmp1 == 1) { /* positive steps: start <= ob < stop */
-            cmp2 = PyObject_RichCompareBool(r->start, ob, Py_LE);
-            cmp3 = PyObject_RichCompareBool(ob, r->stop, Py_LT);
-        }
-        else { /* negative steps: stop < ob <= start */
-            cmp2 = PyObject_RichCompareBool(ob, r->start, Py_LE);
-            cmp3 = PyObject_RichCompareBool(r->stop, ob, Py_LT);
-        }
+        if (range_contains_long(r, ob))
+            Py_RETURN_TRUE;
+        else
+            Py_RETURN_FALSE;
+    } else {
+        Py_ssize_t count;
+        count = _PySequence_IterSearch((PyObject*)r, ob, PY_ITERSEARCH_COUNT);
+        if (count == -1)
+            return NULL;
+        return PyLong_FromSsize_t(count);
+    }
+}
 
-        if (cmp2 == -1 || cmp3 == -1) /* TypeError */
-            goto end;
-        if (cmp2 == 0 || cmp3 == 0) { /* ob outside of range */
-            result = 0;
-            goto end;
-        }
+static PyObject *
+range_index(rangeobject *r, PyObject *ob)
+{
+    PyObject *idx, *tmp;
+    int contains;
+    PyObject *format_tuple, *err_string;
+    static PyObject *err_format = NULL;
+
+    if (!PyLong_CheckExact(ob) && !PyBool_Check(ob)) {
+        Py_ssize_t index;
+        index = _PySequence_IterSearch((PyObject*)r, ob, PY_ITERSEARCH_INDEX);
+        if (index == -1)
+            return NULL;
+        return PyLong_FromSsize_t(index);
+    }
+
+    contains = range_contains_long(r, ob);
+    if (contains == -1)
+        return NULL;
+
+    if (!contains)
+        goto value_error;
+
+    tmp = PyNumber_Subtract(ob, r->start);
+    if (tmp == NULL)
+        return NULL;
+
+    /* idx = (ob - r.start) // r.step */
+    idx = PyNumber_FloorDivide(tmp, r->step);
+    Py_DECREF(tmp);
+    return idx;
+
+value_error:
 
-        /* Check that the stride does not invalidate ob's membership. */
-        tmp1 = PyNumber_Subtract(ob, r->start);
-        if (tmp1 == NULL)
-            goto end;
-        tmp2 = PyNumber_Remainder(tmp1, r->step);
-        if (tmp2 == NULL)
-            goto end;
-        /* result = (int(ob) - start % step) == 0 */
-        result = PyObject_RichCompareBool(tmp2, zero, Py_EQ);
-      end:
-        Py_XDECREF(tmp1);
-        Py_XDECREF(tmp2);
-        Py_XDECREF(zero);
-        return result;
+    /* object is not in the range */
+    if (err_format == NULL) {
+        err_format = PyUnicode_FromString("%r is not in range");
+        if (err_format == NULL)
+            return NULL;
     }
-    /* Fall back to iterative search. */
-    return (int)_PySequence_IterSearch((PyObject*)r, ob,
-                                       PY_ITERSEARCH_CONTAINS);
+    format_tuple = PyTuple_Pack(1, ob);
+    if (format_tuple == NULL)
+        return NULL;
+    err_string = PyUnicode_Format(err_format, format_tuple);
+    Py_DECREF(format_tuple);
+    if (err_string == NULL)
+        return NULL;
+    PyErr_SetObject(PyExc_ValueError, err_string);
+    Py_DECREF(err_string);
+    return NULL;
 }
 
 static PySequenceMethods range_as_sequence = {
@@ -344,10 +419,18 @@ static PyObject * range_reverse(PyObject *seq);
 PyDoc_STRVAR(reverse_doc,
 "Returns a reverse iterator.");
 
+PyDoc_STRVAR(count_doc,
+"rangeobject.count(value) -> integer -- return number of occurrences of value");
+
+PyDoc_STRVAR(index_doc,
+"rangeobject.index(value, [start, [stop]]) -> integer -- return index of value.\n"
+"Raises ValueError if the value is not present.");
+
 static PyMethodDef range_methods[] = {
-    {"__reversed__",    (PyCFunction)range_reverse, METH_NOARGS,
-        reverse_doc},
-    {"__reduce__",      (PyCFunction)range_reduce, METH_VARARGS},
+    {"__reversed__",    (PyCFunction)range_reverse, METH_NOARGS, reverse_doc},
+    {"__reduce__",      (PyCFunction)range_reduce,  METH_VARARGS},
+    {"count",           (PyCFunction)range_count,   METH_O,      count_doc},
+    {"index",           (PyCFunction)range_index,   METH_O,      index_doc},
     {NULL,              NULL}           /* sentinel */
 };