firstBucketOffset(), lastBucketOffset(): removed these functions. Their

purpose wasn't clear, and the few places that bothered to call them seemed
to be trying to cater to empty buckets.  But empty buckets aren't legitimate
in a BTree (or, if they are, lots of BTree code is broken).

BTreeItems struct:  finished figuring out what's in this, and documented it.

BTreeItems_seek():  rewrote and simplified, to avoid use of the now-
removed XYZBucketOffset() functions.  Repaired places where bucket access
time wasn't getting updated.  There are still insecurities in its use of
PreviousBucket() (for another day).

BTreeItems_slice():  now that I know what it is <wink>, create an empty
slice in the intended way.

NewBTreeItems():  documented its calling sequence, and added code to
protect against a NULL highbucket argument.

BTree_maxminKey():  no longer calls the XYZBucketOffset() functions.

src/BTrees/BTreeModuleTemplate.c

@@ -298,43 +298,6 @@ PreviousBucket(Bucket *current, Bucket *first, int i)
     }
 }
 
-static int
-firstBucketOffset(Bucket **bucket, int *offset)
-{
-  Bucket *b;
-
-  *offset = (*bucket)->len - 1;
-  while ((*bucket)->len < 1)
-    {
-      b=(*bucket)->next;
-      if (b==NULL) return 0;
-      Py_INCREF(b);
-      PER_ALLOW_DEACTIVATION((*bucket));
-      ASSIGNB((*bucket), b);
-      UNLESS (PER_USE(*bucket)) return -1;
-      *offset = 0;
-    }
-  return 1;
-}
-
-static int
-lastBucketOffset(Bucket **bucket, int *offset, Bucket *firstbucket, int i)
-{
-  Bucket *b;
-
-  *offset = (*bucket)->len - 1;
-  while ((*bucket)->len < 1)
-    {
-      b=PreviousBucket((*bucket), firstbucket, i);
-      if (b==NULL) return 0;
-      PER_ALLOW_DEACTIVATION((*bucket));
-      ASSIGNB((*bucket), b);
-      UNLESS (PER_USE(*bucket)) return -1;
-      *offset = (*bucket)->len - 1;
-    }
-  return 1;
-}
-
 static void *
 PyMalloc(size_t sz)
 {
@@ -409,7 +372,7 @@ static char BTree_module_documentation[] =
 "\n"
 MASTER_ID
 BTREEITEMSTEMPLATE_C
-"$Id: BTreeModuleTemplate.c,v 1.32 2002/06/17 19:21:39 tim_one Exp $\n"
+"$Id: BTreeModuleTemplate.c,v 1.33 2002/06/17 23:39:56 tim_one Exp $\n"
 BTREETEMPLATE_C
 BUCKETTEMPLATE_C
 KEYMACROS_H

src/BTrees/BTreeTemplate.c

@@ -12,7 +12,7 @@
 
  ****************************************************************************/
 
-#define BTREETEMPLATE_C "$Id: BTreeTemplate.c,v 1.59 2002/06/17 20:31:40 tim_one Exp $\n"
+#define BTREETEMPLATE_C "$Id: BTreeTemplate.c,v 1.60 2002/06/17 23:39:56 tim_one Exp $\n"
 
 /*
 ** _BTree_get
@@ -1100,19 +1100,8 @@ BTree_maxminKey(BTree *self, PyObject *args, int min)
   else if (min)
     {
       bucket = self->firstbucket;
-      PER_ALLOW_DEACTIVATION(self);
-      PER_ACCESSED(self);
-      UNLESS (PER_USE(bucket)) return NULL;
       Py_INCREF(bucket);
       offset = 0;
-      if (offset >= bucket->len)
-        {
-          switch (firstBucketOffset(&bucket, &offset))
-            {
-            case 0:  goto empty;
-            case -1: goto err;
-            }
-        }
     }
   else
     {
@@ -1124,16 +1113,8 @@ BTree_maxminKey(BTree *self, PyObject *args, int min)
           Py_DECREF(bucket);
           return NULL;
         }
-      if (bucket->len)
-        offset = bucket->len - 1;
-      else
-        {
-          switch (lastBucketOffset(&bucket, &offset, self->firstbucket, -1))
-            {
-            case 0:  goto empty;
-            case -1: goto err;
-            }
-        }
+      assert(bucket->len);
+      offset = bucket->len - 1;
     }
 
   COPY_KEY_TO_OBJECT(key, bucket->keys[offset]);