(update_interval): Properly update `position' field of used intervals.

diff --git a/src/intervals.c b/src/intervals.c
index f52e6ea472720e37293d741e0eed919c591bbd06..c5dad6709266afcbe6cd512c2b2fefc8da6f827d 100644 (file)
--- a/src/intervals.c
+++ b/src/intervals.c
@@ -672,7 +672,8 @@ previous_interval (interval)
 }
 
 /* Find the interval containing POS given some non-NULL INTERVAL
-   in the same tree. */
+   in the same tree.  Note that we need to update interval->position
+   if we go down the tree.  */
 INTERVAL
 update_interval (i, pos)
      register INTERVAL i;
@@ -686,22 +687,31 @@ update_interval (i, pos)
       if (pos < i->position) 
        {
          /* Move left. */
-         if (pos >= i->position - TOTAL_LENGTH (i->left))
-           i = i->left;                /* Move to the left child */
+         if (pos >= i->position - TOTAL_LENGTH (i->left)) 
+           {
+             i->left->position = i->position - TOTAL_LENGTH (i->left)
+               + LEFT_TOTAL_LENGTH (i->left);
+             i = i->left;              /* Move to the left child */
+           }
          else if (NULL_PARENT (i)) 
            error ("Point before start of properties");
-         else  i = i->parent;
+         else  
+             i = i->parent;
          continue;
        }
       else if (pos >= INTERVAL_LAST_POS (i))
        {
          /* Move right. */
-         if (pos < INTERVAL_LAST_POS (i) + TOTAL_LENGTH (i->right))
-           i = i->right;               /* Move to the right child */
+         if (pos < INTERVAL_LAST_POS (i) + TOTAL_LENGTH (i->right)) 
+           {
+             i->right->position = INTERVAL_LAST_POS (i) +
+               LEFT_TOTAL_LENGTH (i->right);
+             i = i->right;             /* Move to the right child */
+           }
          else if (NULL_PARENT (i)) 
            error ("Point after end of properties");
          else 
-           i = i->parent;
+             i = i->parent;
          continue;
        }
       else