Implement heapq in terms of less-than (to match list.sort()).

diff --git a/Lib/heapq.py b/Lib/heapq.py
index 4af9af17717c79e0d3d8f7c941f6dce606e110b9..0a83b76b464d1db250ea8172fc4ed17ab9ef54e2 100644 (file)
--- a/Lib/heapq.py
+++ b/Lib/heapq.py
@@ -167,7 +167,7 @@ def heapreplace(heap, item):
 
 def heappushpop(heap, item):
     """Fast version of a heappush followed by a heappop."""
-    if heap and item > heap[0]:
+    if heap and heap[0] < item:
         item, heap[0] = heap[0], item
         _siftup(heap, 0)
     return item
@@ -240,10 +240,11 @@ def _siftdown(heap, startpos, pos):
     while pos > startpos:
         parentpos = (pos - 1) >> 1
         parent = heap[parentpos]
-        if parent <= newitem:
-            break
-        heap[pos] = parent
-        pos = parentpos
+        if newitem < parent:
+            heap[pos] = parent
+            pos = parentpos
+            continue
+        break
     heap[pos] = newitem
 
 # The child indices of heap index pos are already heaps, and we want to make
@@ -294,7 +295,7 @@ def _siftup(heap, pos):
     while childpos < endpos:
         # Set childpos to index of smaller child.
         rightpos = childpos + 1
-        if rightpos < endpos and heap[rightpos] <= heap[childpos]:
+        if rightpos < endpos and not heap[childpos] < heap[rightpos]:
             childpos = rightpos
         # Move the smaller child up.
         heap[pos] = heap[childpos]

diff --git a/Misc/NEWS b/Misc/NEWS
index 8ab9ce41758e82b180364edad5e9d5f8bf3fec99..21465f225dfcd935584c66bcb0ef016604fa59d2 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -36,6 +36,9 @@ Core and Builtins
 Extension Modules
 -----------------
 
+- The heapq module does comparisons using LT instead of LE.  This
+  makes its implementation match that used by list.sort().
+
 - Issue #2819: add full-precision summation function to math module,
   based on Hettinger's ASPN Python Cookbook recipe.
 

diff --git a/Modules/_heapqmodule.c b/Modules/_heapqmodule.c
index 1482b5a62ae9d6b28cb47fb188ad96fc255f0146..ad2fd70f53a9640c0356ba343c20b27a81d0dd0a 100644 (file)
--- a/Modules/_heapqmodule.c
+++ b/Modules/_heapqmodule.c
@@ -28,12 +28,12 @@ _siftdown(PyListObject *heap, Py_ssize_t startpos, Py_ssize_t pos)
        while (pos > startpos){
                parentpos = (pos - 1) >> 1;
                parent = PyList_GET_ITEM(heap, parentpos);
-               cmp = PyObject_RichCompareBool(parent, newitem, Py_LE);
+               cmp = PyObject_RichCompareBool(newitem, parent, Py_LT);
                if (cmp == -1) {
                        Py_DECREF(newitem);
                        return -1;
                }
-               if (cmp == 1)
+               if (cmp == 0)
                        break;
                Py_INCREF(parent);
                Py_DECREF(PyList_GET_ITEM(heap, pos));
@@ -69,14 +69,14 @@ _siftup(PyListObject *heap, Py_ssize_t pos)
                rightpos = childpos + 1;
                if (rightpos < endpos) {
                        cmp = PyObject_RichCompareBool(
-                               PyList_GET_ITEM(heap, rightpos),
                                PyList_GET_ITEM(heap, childpos),
-                               Py_LE);
+                               PyList_GET_ITEM(heap, rightpos),
+                               Py_LT);
                        if (cmp == -1) {
                                Py_DECREF(newitem);
                                return -1;
                        }
-                       if (cmp == 1)
+                       if (cmp == 0)
                                childpos = rightpos;
                }
                /* Move the smaller child up. */
@@ -214,10 +214,10 @@ heappushpop(PyObject *self, PyObject *args)
                return item;
        }
 
-       cmp = PyObject_RichCompareBool(item, PyList_GET_ITEM(heap, 0), Py_LE);
+       cmp = PyObject_RichCompareBool(PyList_GET_ITEM(heap, 0), item, Py_LT);
        if (cmp == -1)
                return NULL;
-       if (cmp == 1) {
+       if (cmp == 0) {
                Py_INCREF(item);
                return item;
        }
@@ -270,6 +270,7 @@ nlargest(PyObject *self, PyObject *args)
 {
        PyObject *heap=NULL, *elem, *iterable, *sol, *it, *oldelem;
        Py_ssize_t i, n;
+       int cmp;
 
        if (!PyArg_ParseTuple(args, "nO:nlargest", &n, &iterable))
                return NULL;
@@ -312,7 +313,12 @@ nlargest(PyObject *self, PyObject *args)
                        else
                                goto sortit;
                }
-               if (PyObject_RichCompareBool(elem, sol, Py_LE)) {
+               cmp = PyObject_RichCompareBool(sol, elem, Py_LT);
+               if (cmp == -1) {
+                       Py_DECREF(elem);
+                       goto fail;
+               }
+               if (cmp == 0) {
                        Py_DECREF(elem);
                        continue;
                }
@@ -362,12 +368,12 @@ _siftdownmax(PyListObject *heap, Py_ssize_t startpos, Py_ssize_t pos)
        while (pos > startpos){
                parentpos = (pos - 1) >> 1;
                parent = PyList_GET_ITEM(heap, parentpos);
-               cmp = PyObject_RichCompareBool(newitem, parent, Py_LE);
+               cmp = PyObject_RichCompareBool(parent, newitem, Py_LT);
                if (cmp == -1) {
                        Py_DECREF(newitem);
                        return -1;
                }
-               if (cmp == 1)
+               if (cmp == 0)
                        break;
                Py_INCREF(parent);
                Py_DECREF(PyList_GET_ITEM(heap, pos));
@@ -403,14 +409,14 @@ _siftupmax(PyListObject *heap, Py_ssize_t pos)
                rightpos = childpos + 1;
                if (rightpos < endpos) {
                        cmp = PyObject_RichCompareBool(
-                               PyList_GET_ITEM(heap, childpos),
                                PyList_GET_ITEM(heap, rightpos),
-                               Py_LE);
+                               PyList_GET_ITEM(heap, childpos),
+                               Py_LT);
                        if (cmp == -1) {
                                Py_DECREF(newitem);
                                return -1;
                        }
-                       if (cmp == 1)
+                       if (cmp == 0)
                                childpos = rightpos;
                }
                /* Move the smaller child up. */
@@ -434,6 +440,7 @@ nsmallest(PyObject *self, PyObject *args)
 {
        PyObject *heap=NULL, *elem, *iterable, *los, *it, *oldelem;
        Py_ssize_t i, n;
+       int cmp;
 
        if (!PyArg_ParseTuple(args, "nO:nsmallest", &n, &iterable))
                return NULL;
@@ -477,7 +484,12 @@ nsmallest(PyObject *self, PyObject *args)
                        else
                                goto sortit;
                }
-               if (PyObject_RichCompareBool(los, elem, Py_LE)) {
+               cmp = PyObject_RichCompareBool(elem, los, Py_LT);
+               if (cmp == -1) {
+                       Py_DECREF(elem);
+                       goto fail;
+               }
+               if (cmp == 0) {
                        Py_DECREF(elem);
                        continue;
                }