index: don't include nullid in len()

index: don't include nullid in len()

I suspect the reason the nullid is in the index in the last position
is that it lets index[i] for regular revision number, even when index
was just a regular Python list. An alternative solution would have
been to reserve revision number 0 for the null revision. I don't know
why that wasn't done. Now that we have classes backing the index, we
can easily make index[-1] get the nullid without having to put it last
in the list and including it in the len().

This patch just hides the nullid -- it will still be accessible at
index[len(index)].

I realize that this will be annoying when checking out across this
commit for debugging (including bisection).

Differential Revision: https://phab.mercurial-scm.org/D4022

--- a/mercurial/cext/parsers.c	Wed Aug 01 10:57:14 2018 -0700
+++ b/mercurial/cext/parsers.c	Fri Jul 20 08:10:32 2018 -0700
@@ -713,7 +713,7 @@
 void manifest_module_init(PyObject *mod);
 void revlog_module_init(PyObject *mod);
 
-static const int version = 6;
+static const int version = 7;
 
 static void module_init(PyObject *mod)
 {

--- a/mercurial/cext/revlog.c	Wed Aug 01 10:57:14 2018 -0700
+++ b/mercurial/cext/revlog.c	Fri Jul 20 08:10:32 2018 -0700
@@ -77,8 +77,8 @@
 static Py_ssize_t index_length(const indexObject *self)
 {
 	if (self->added == NULL)
-		return self->length;
-	return self->length + PyList_GET_SIZE(self->added);
+		return self->length - 1;
+	return self->length + PyList_GET_SIZE(self->added) - 1;
 }
 
 static PyObject *nullentry;
@@ -155,7 +155,7 @@
 	int comp_len, uncomp_len, base_rev, link_rev, parent_1, parent_2;
 	const char *c_node_id;
 	const char *data;
-	Py_ssize_t length = index_length(self);
+	Py_ssize_t length = index_length(self) + 1;
 	PyObject *entry;
 
 	if (pos == -1 || pos == length - 1) {
@@ -225,7 +225,7 @@
  */
 static const char *index_node(indexObject *self, Py_ssize_t pos)
 {
-	Py_ssize_t length = index_length(self);
+	Py_ssize_t length = index_length(self) + 1;
 	const char *data;
 
 	if (pos == length - 1 || pos == -1)
@@ -285,7 +285,7 @@
 	if (node_check(PyTuple_GET_ITEM(obj, 7), &node) == -1)
 		return NULL;
 
-	len = index_length(self);
+	len = index_length(self) + 1;
 
 	if (self->added == NULL) {
 		self->added = PyList_New(0);
@@ -435,7 +435,7 @@
 {
 	PyObject *iter = NULL;
 	PyObject *iter_item = NULL;
-	Py_ssize_t min_idx = index_length(self) + 1;
+	Py_ssize_t min_idx = index_length(self) + 2;
 	long iter_item_long;
 
 	if (PyList_GET_SIZE(list) != 0) {
@@ -477,7 +477,7 @@
 	PyObject *reachable = NULL;
 
 	PyObject *val;
-	Py_ssize_t len = index_length(self) - 1;
+	Py_ssize_t len = index_length(self);
 	long revnum;
 	Py_ssize_t k;
 	Py_ssize_t i;
@@ -629,7 +629,7 @@
 	PyObject *phaseset = NULL;
 	PyObject *phasessetlist = NULL;
 	PyObject *rev = NULL;
-	Py_ssize_t len = index_length(self) - 1;
+	Py_ssize_t len = index_length(self);
 	Py_ssize_t numphase = 0;
 	Py_ssize_t minrevallphases = 0;
 	Py_ssize_t minrevphase = 0;
@@ -740,7 +740,7 @@
 		}
 	}
 
-	len = index_length(self) - 1;
+	len = index_length(self);
 	heads = PyList_New(0);
 	if (heads == NULL)
 		goto bail;
@@ -844,7 +844,7 @@
 	int stoprev, iterrev, baserev = -1;
 	int stopped;
 	PyObject *chain = NULL, *result = NULL;
-	const Py_ssize_t length = index_length(self);
+	const Py_ssize_t length = index_length(self) + 1;
 
 	if (!PyArg_ParseTuple(args, "iOi", &rev, &stoparg, &generaldelta)) {
 		return NULL;
@@ -1098,7 +1098,7 @@
 			return -1;
 		}
 		self->ntlength = 1;
-		self->ntrev = (int)index_length(self) - 1;
+		self->ntrev = (int)index_length(self);
 		self->ntlookups = 1;
 		self->ntmisses = 0;
 		if (nt_insert(self, nullid, -1) == -1) {
@@ -1393,7 +1393,7 @@
 
 	if (PyInt_Check(value)) {
 		long rev = PyInt_AS_LONG(value);
-		return rev >= -1 && rev < index_length(self);
+		return rev >= -1 && rev < index_length(self) + 1;
 	}
 
 	if (node_check(value, &node) == -1)
@@ -1673,7 +1673,7 @@
 	revs = PyMem_Malloc(argcount * sizeof(*revs));
 	if (argcount > 0 && revs == NULL)
 		return PyErr_NoMemory();
-	len = index_length(self) - 1;
+	len = index_length(self);
 
 	for (i = 0; i < argcount; i++) {
 		static const int capacity = 24;
@@ -1795,7 +1795,7 @@
 static int index_slice_del(indexObject *self, PyObject *item)
 {
 	Py_ssize_t start, stop, step, slicelength;
-	Py_ssize_t length = index_length(self);
+	Py_ssize_t length = index_length(self) + 1;
 	int ret = 0;
 
 /* Argument changed from PySliceObject* to PyObject* in Python 3. */

--- a/mercurial/policy.py	Wed Aug 01 10:57:14 2018 -0700
+++ b/mercurial/policy.py	Fri Jul 20 08:10:32 2018 -0700
@@ -69,7 +69,7 @@
     (r'cext', r'bdiff'): 3,
     (r'cext', r'mpatch'): 1,
     (r'cext', r'osutil'): 4,
-    (r'cext', r'parsers'): 6,
+    (r'cext', r'parsers'): 7,
 }
 
 # map import request to other package or module

--- a/mercurial/pure/parsers.py	Wed Aug 01 10:57:14 2018 -0700
+++ b/mercurial/pure/parsers.py	Fri Jul 20 08:10:32 2018 -0700
@@ -39,7 +39,7 @@
 
 class BaseIndexObject(object):
     def __len__(self):
-        return self._lgt + len(self._extra) + 1
+        return self._lgt + len(self._extra)
 
     def append(self, tup):
         self._extra.append(tup)
@@ -47,12 +47,12 @@
     def _fix_index(self, i):
         if not isinstance(i, int):
             raise TypeError("expecting int indexes")
-        if i < 0 or i >= len(self):
+        if i < 0 or i >= len(self) + 1:
             raise IndexError
         return i
 
     def __getitem__(self, i):
-        if i == -1 or i == len(self) - 1:
+        if i == -1 or i == len(self):
             return (0, 0, 0, -1, -1, -1, -1, nullid)
         i = self._fix_index(i)
         if i >= self._lgt:

--- a/mercurial/repoview.py	Wed Aug 01 10:57:14 2018 -0700
+++ b/mercurial/repoview.py	Fri Jul 20 08:10:32 2018 -0700
@@ -210,7 +210,7 @@
         unfichangelog = unfi.changelog
         # bypass call to changelog.method
         unfiindex = unfichangelog.index
-        unfilen = len(unfiindex) - 1
+        unfilen = len(unfiindex)
         unfinode = unfiindex[unfilen - 1][7]
 
         revs = filterrevs(unfi, self.filtername, self._visibilityexceptions)

--- a/mercurial/revlog.py	Wed Aug 01 10:57:14 2018 -0700
+++ b/mercurial/revlog.py	Fri Jul 20 08:10:32 2018 -0700
@@ -791,10 +791,8 @@
 indexformatv0_unpack = indexformatv0.unpack
 
 class revlogoldindex(list):
-    def __len__(self):
-        return list.__len__(self) + 1
     def __getitem__(self, i):
-        if i == -1 or i == len(self) - 1:
+        if i == -1 or i == len(self):
             return (0, 0, 0, -1, -1, -1, -1, nullid)
         return list.__getitem__(self, i)
 
@@ -1066,11 +1064,11 @@
                 yield fp
 
     def tip(self):
-        return self.node(len(self.index) - 2)
+        return self.node(len(self.index) - 1)
     def __contains__(self, rev):
         return 0 <= rev < len(self)
     def __len__(self):
-        return len(self.index) - 1
+        return len(self.index)
     def __iter__(self):
         return iter(pycompat.xrange(len(self)))
     def revs(self, start=0, stop=None):
@@ -1139,7 +1137,7 @@
             i = self.index
             p = self._nodepos
             if p is None:
-                p = len(i) - 2
+                p = len(i) - 1
             else:
                 assert p < len(i)
             for r in pycompat.xrange(p, -1, -1):