[PATCH 10/13] abt: Drop child parameters from 'reaugment' function.

[Ben Pfaff]

The function can simply inspect the 'down' members.
---
 src/libpspp/abt.c        |   10 +++++-----
 src/libpspp/abt.h        |   32 +++++++++++++-------------------
 src/libpspp/tower.c      |   32 ++++++++++++++------------------
 tests/libpspp/abt-test.c |   15 ++++++---------
 4 files changed, 38 insertions(+), 51 deletions(-)

diff --git a/src/libpspp/abt.c b/src/libpspp/abt.c
index c06047b..ae74618 100644
--- a/src/libpspp/abt.c
+++ b/src/libpspp/abt.c
@@ -351,7 +351,7 @@ void
 abt_reaugmented (const struct abt *abt, struct abt_node *p)
 {
   for (; p != NULL; p = p->up)
-    abt->reaugment (p, p->down[0], p->down[1], abt->aux);
+    abt->reaugment (p, abt->aux);
 }
 
 /* Moves P around in ABT to compensate for its key having
@@ -452,8 +452,8 @@ skew (struct abt *abt, struct abt_node *a)
       b->up = a->up;
       a->up = b;
 
-      abt->reaugment (a, a->down[0], a->down[1], abt->aux);
-      abt->reaugment (b, b->down[0], b->down[1], abt->aux);
+      abt->reaugment (a, abt->aux);
+      abt->reaugment (b, abt->aux);
 
       return b;
     }
@@ -483,8 +483,8 @@ split (struct abt *abt, struct abt_node *a)
 
       b->level++;
 
-      abt->reaugment (a, a->down[0], a->down[1], abt->aux);
-      abt->reaugment (b, b->down[0], b->down[1], abt->aux);
+      abt->reaugment (a, abt->aux);
+      abt->reaugment (b, abt->aux);
 
       return b;
     }
diff --git a/src/libpspp/abt.h b/src/libpspp/abt.h
index fa9d0dc..0e5b252 100644
--- a/src/libpspp/abt.h
+++ b/src/libpspp/abt.h
@@ -34,10 +34,9 @@
 
    The ABT data structure partially abstracts augmentation.  The
    client passes in a "reaugmentation" function that accepts a
-   node and its left and right children.  This function must
-   recalculate the node's augmentation data based on its own
-   contents and the contents of its children, and store the new
-   augmentation data in the node.
+   node.  This function must recalculate the node's augmentation
+   data based on its own contents and the contents of its
+   children, and store the new augmentation data in the node.
 
    The ABT automatically calls the reaugmentation function
    whenever it can tell that a node's augmentation data might
@@ -104,19 +103,16 @@
      }
 
      // Recalculates the count for NODE's subtree by adding up the
-     // counts for its LEFT and RIGHT child subtrees.
+     // counts for its left and right child subtrees.
      static void
-     reaugment_elements (struct abt_node *node_,
-                         const struct abt_node *left,
-                         const struct abt_node *right,
-                         const void *aux)
+     reaugment_elements (struct abt_node *node_, const void *aux)
      {
        struct element *node = node_to_element (node_);
        node->count = 1;
-       if (left != NULL)
-         node->count += node_to_element (left)->count;
-       if (right != NULL)
-         node->count += node_to_element (right)->count;
+       if (node->node.down[0] != NULL)
+         node->count += node_to_element (node->node.down[0])->count;
+       if (node->node.down[1] != NULL)
+         node->count += node_to_element (node->node.down[1])->count;
      }
 
      // Finds and returns the element in ABT that is in the given
@@ -173,12 +169,10 @@ typedef int abt_compare_func (const struct abt_node *a,
                               const struct abt_node *b,
                               const void *aux);
 
-/* Recalculates NODE's augmentation based on NODE's data and that
-   of its LEFT and RIGHT children, with the tree's AUX. */
-typedef void abt_reaugment_func (struct abt_node *node,
-                                 const struct abt_node *left,
-                                 const struct abt_node *right,
-                                 const void *aux);
+/* Recalculates NODE's augmentation based on NODE's data and that of its left
+   and right children NODE->down[0] and NODE[1], respectively, with the tree's
+   AUX. */
+typedef void abt_reaugment_func (struct abt_node *node, const void *aux);
 
 /* An augmented binary tree. */
 struct abt
diff --git a/src/libpspp/tower.c b/src/libpspp/tower.c
index 863da82..bdaaffb 100644
--- a/src/libpspp/tower.c
+++ b/src/libpspp/tower.c
@@ -33,10 +33,7 @@ static struct tower_node *prev_node (const struct tower *,
                                      const struct tower_node *);
 static unsigned long int get_subtree_size (const struct abt_node *);
 static unsigned long int get_subtree_count (const struct abt_node *);
-static void reaugment_tower_node (struct abt_node *,
-                                  const struct abt_node *,
-                                  const struct abt_node *,
-                                  const void *aux);
+static void reaugment_tower_node (struct abt_node *, const void *aux);
 
 /* Returns the height of the bottom of the given tower NODE.
 
@@ -351,27 +348,26 @@ get_subtree_count (const struct abt_node *p)
   return p != NULL ? abt_to_tower_node (p)->subtree_count : 0;
 }
 
-/* Recalculates the subtree_size of NODE based on its LEFT and
-   RIGHT children's subtree_sizes. */
+/* Recalculates the subtree_size of NODE based on the subtree_sizes of its
+   children. */
 static void
-reaugment_tower_node (struct abt_node *node_,
-                      const struct abt_node *left,
-                      const struct abt_node *right,
-                      const void *aux UNUSED)
+reaugment_tower_node (struct abt_node *node_, const void *aux UNUSED)
 {
   struct tower_node *node = abt_to_tower_node (node_);
   node->subtree_size = node->size;
   node->subtree_count = 1;
-  if (left != NULL) 
+
+  if (node->abt_node.down[0] != NULL)
     {
-      struct tower_node *left_node = abt_to_tower_node (left);
-      node->subtree_size += left_node->subtree_size;
-      node->subtree_count += left_node->subtree_count; 
+      struct tower_node *left = abt_to_tower_node (node->abt_node.down[0]);
+      node->subtree_size += left->subtree_size;
+      node->subtree_count += left->subtree_count;
     }
-  if (right != NULL) 
+
+  if (node->abt_node.down[1] != NULL)
     {
-      struct tower_node *right_node = abt_to_tower_node (right);
-      node->subtree_size += right_node->subtree_size;
-      node->subtree_count += right_node->subtree_count; 
+      struct tower_node *right = abt_to_tower_node (node->abt_node.down[1]);
+      node->subtree_size += right->subtree_size;
+      node->subtree_count += right->subtree_count;
     }
 }
diff --git a/tests/libpspp/abt-test.c b/tests/libpspp/abt-test.c
index 8bbe7d7..eae7d46 100644
--- a/tests/libpspp/abt-test.c
+++ b/tests/libpspp/abt-test.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2007, 2010 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2010, 2011 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -138,20 +138,17 @@ compare_elements (const struct abt_node *a_, const struct 
abt_node *b_,
 /* Recalculates the count for NODE's subtree by adding up the
    counts for its LEFT and RIGHT child subtrees. */
 static void
-reaugment_elements (struct abt_node *node_,
-                    const struct abt_node *left,
-                    const struct abt_node *right,
-                    const void *aux)
+reaugment_elements (struct abt_node *node_, const void *aux)
 {
   struct element *node = abt_node_to_element (node_);
 
   check (aux == &aux_data);
 
   node->count = 1;
-  if (left != NULL)
-    node->count += abt_node_to_element (left)->count;
-  if (right != NULL)
-    node->count += abt_node_to_element (right)->count;
+  if (node->node.down[0] != NULL)
+    node->count += abt_node_to_element (node->node.down[0])->count;
+  if (node->node.down[1] != NULL)
+    node->count += abt_node_to_element (node->node.down[1])->count;
 }
 
 /* Compares A and B and returns a strcmp-type return value. */
-- 
1.7.2.5