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rbtree: Simplify insert and extract

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Simplify _RBTree_Insert() and _RBTree_Extract().  Remove more
superfluous NULL pointer checks.  Change _RBTree_Is_root() to use only
the node.  Add parent parameter to _RBTree_Sibling().  Delete
_RBTree_Grandparent() and _RBTree_Parent_sibling().
This commit is contained in:
Sebastian Huber
2014-07-23 13:03:54 +02:00
parent 4752550f80
commit 993f5acd25
6 changed files with 86 additions and 99 deletions
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12
cpukit/sapi/include/rtems/rbtree.h
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@@ -195,9 +195,7 @@ RTEMS_INLINE_ROUTINE rtems_rbtree_node *rtems_rbtree_right(
}
/**
* @brief Return pointer to the parent child node from this node.
*
* This function returns a pointer to the parent node of @a the_node.
* @copydoc _RBTree_Parent()
*/
RTEMS_INLINE_ROUTINE rtems_rbtree_node *rtems_rbtree_parent(
const rtems_rbtree_node *the_node
@@ -248,17 +246,13 @@ RTEMS_INLINE_ROUTINE bool rtems_rbtree_is_max(
}
/**
* @brief Is this node the RBTree root.
*
* This function returns true if @a the_node is the root of @a the_rbtree and
* false otherwise.
* @copydoc _RBTree_Is_root()
*/
RTEMS_INLINE_ROUTINE bool rtems_rbtree_is_root(
const rtems_rbtree_control *the_rbtree,
const rtems_rbtree_node *the_node
)
{
return _RBTree_Is_root( the_rbtree, the_node );
return _RBTree_Is_root( the_node );
}
/**

44
cpukit/score/include/rtems/score/rbtree.h
View File

@@ -300,9 +300,16 @@ RTEMS_INLINE_ROUTINE bool _RBTree_Is_node_off_tree(
}
/**
* @brief Return pointer to RBTree's root node.
* @brief Returns a pointer to root node of the red-black tree.
*
* This function returns a pointer to the root node of @a the_rbtree.
* The root node may change after insert or extract operations.
*
* @param[in] the_rbtree The red-black tree control.
*
* @retval NULL The tree is empty.
* @retval root The root node.
*
* @see _RBTree_Is_root().
*/
RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Root(
const RBTree_Control *the_rbtree
@@ -326,15 +333,21 @@ RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_First(
}
/**
* @brief Return pointer to the parent of this node.
* @brief Returns a pointer to the parent of this node.
*
* This function returns a pointer to the parent node of @a the_node.
* The node must have a parent, thus it is invalid to use this function for the
* root node or a node that is not part of a tree. To test for the root node
* compare with _RBTree_Root() or use _RBTree_Is_root().
*
* @param[in] the_node The node of interest.
*
* @retval parent The parent of this node.
* @retval undefined The node is the root node or not part of a tree.
*/
RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Parent(
const RBTree_Node *the_node
)
{
if (!the_node->parent->parent) return NULL;
return the_node->parent;
}
@@ -409,20 +422,25 @@ RTEMS_INLINE_ROUTINE bool _RBTree_Is_first(
}
/**
* @brief Is this node the RBTree root.
*
* This function returns true if @a the_node is the root of @a the_rbtree and
* @brief Returns true if this node is the root node of a red-black tree, and
* false otherwise.
*
* @retval true @a the_node is the root of @a the_rbtree.
* @retval false @a the_node is not the root of @a the_rbtree.
* The root node may change after insert or extract operations. In case the
* node is not a node of a tree, then this function yields unpredictable
* results.
*
* @param[in] the_node The node of interest.
*
* @retval true The node is the root node.
* @retval false Otherwise.
*
* @see _RBTree_Root().
*/
RTEMS_INLINE_ROUTINE bool _RBTree_Is_root(
const RBTree_Control *the_rbtree,
const RBTree_Node *the_node
const RBTree_Node *the_node
)
{
return (the_node == _RBTree_Root(the_rbtree));
return _RBTree_Parent( _RBTree_Parent( the_node ) ) == NULL;
}
/**

53
cpukit/score/include/rtems/score/rbtreeimpl.h
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@@ -107,56 +107,23 @@ RTEMS_INLINE_ROUTINE bool _RBTree_Is_red(
}
/**
* @brief Return a pointer to node's grandparent.
* @brief Returns the sibling of the node.
*
* This function returns a pointer to the grandparent of @a the_node if it
* exists, and NULL if not.
*/
RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Grandparent(
const RBTree_Node *the_node
)
{
if(!the_node) return NULL;
if(!(the_node->parent)) return NULL;
if(!(the_node->parent->parent)) return NULL;
if(!(the_node->parent->parent->parent)) return NULL;
return(the_node->parent->parent);
}
/**
* @brief Return a pointer to node's sibling.
* @param[in] the_node The node of interest.
* @param[in] parent The parent of the node. The parent must exist, thus it is
* invalid to use this function for the root node.
*
* This function returns a pointer to the sibling of @a the_node if it
* exists, and NULL if not.
* @retval NULL No sibling exists.
* @retval sibling The sibling of the node.
*/
RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Sibling(
const RBTree_Node *the_node
const RBTree_Node *the_node,
const RBTree_Node *parent
)
{
if(!the_node) return NULL;
if(!(the_node->parent)) return NULL;
if(!(the_node->parent->parent)) return NULL;
RBTree_Node *left_child = parent->child[ RBT_LEFT ];
if(the_node == the_node->parent->child[RBT_LEFT])
return the_node->parent->child[RBT_RIGHT];
else
return the_node->parent->child[RBT_LEFT];
}
/**
* @brief Return a pointer to node's parent's sibling.
*
* This function returns a pointer to the sibling of the parent of
* @a the_node if it exists, and NULL if not.
*/
RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Parent_sibling(
const RBTree_Node *the_node
)
{
if(!the_node) return NULL;
if(_RBTree_Grandparent(the_node) == NULL) return NULL;
return _RBTree_Sibling(the_node->parent);
return the_node == left_child ? parent->child[ RBT_RIGHT ] : left_child;
}
RTEMS_INLINE_ROUTINE bool _RBTree_Is_equal(

7
cpukit/score/src/rbtreeextract.c
View File

@@ -22,7 +22,7 @@
*/
static void _RBTree_Extract_validate( RBTree_Node *the_node )
{
RBTree_Node *parent, *sibling;
RBTree_Node *parent;
RBTree_Direction dir;
parent = the_node->parent;
@@ -30,10 +30,10 @@ static void _RBTree_Extract_validate( RBTree_Node *the_node )
if ( !parent->parent )
return;
sibling = _RBTree_Sibling( the_node );
/* continue to correct tree as long as the_node is black and not the root */
while ( !_RBTree_Is_red( the_node ) && parent->parent ) {
RBTree_Node *sibling = _RBTree_Sibling( the_node, parent );
/* if sibling is red, switch parent (black) and sibling colors,
* then rotate parent left, making the sibling be the_node's grandparent.
* Now the_node has a black sibling and red parent. After rotation,
@@ -59,7 +59,6 @@ static void _RBTree_Extract_validate( RBTree_Node *the_node )
the_node = parent; /* done if parent is red */
parent = the_node->parent;
sibling = _RBTree_Sibling( the_node );
} else {
/* at least one of sibling's children is red. we now proceed in two
* cases, either the_node is to the left or the right of the parent.

55
cpukit/score/src/rbtreeinsert.c
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@@ -32,40 +32,55 @@ RTEMS_STATIC_ASSERT(
*/
static void _RBTree_Validate_insert( RBTree_Node *the_node )
{
RBTree_Node *u, *g;
RBTree_Node *parent = _RBTree_Parent( the_node );
RBTree_Node *grandparent = _RBTree_Parent( parent );
/* note: the insert root case is handled already */
/* if the parent is black, nothing needs to be done
* otherwise may need to loop a few times */
while ( _RBTree_Is_red( _RBTree_Parent( the_node ) ) ) {
u = _RBTree_Parent_sibling( the_node );
g = the_node->parent->parent;
while ( parent->color == RBT_RED ) {
/* The root is black, so the grandparent must exist */
RBTree_Node *uncle = _RBTree_Sibling( parent, grandparent );
/* if uncle is red, repaint uncle/parent black and grandparent red */
if ( _RBTree_Is_red( u ) ) {
the_node->parent->color = RBT_BLACK;
u->color = RBT_BLACK;
g->color = RBT_RED;
the_node = g;
} else { /* if uncle is black */
RBTree_Direction dir = the_node != the_node->parent->child[ 0 ];
RBTree_Direction pdir = the_node->parent != g->child[ 0 ];
/*
* If uncle exists and is red, repaint uncle/parent black and grandparent
* red.
*/
if ( uncle != NULL && uncle->color == RBT_RED ) {
parent->color = RBT_BLACK;
uncle->color = RBT_BLACK;
grandparent->color = RBT_RED;
the_node = grandparent;
parent = _RBTree_Parent( the_node );
grandparent = _RBTree_Parent( parent );
if ( grandparent == NULL )
break;
} else { /* If uncle does not exist or is black */
RBTree_Direction dir = _RBTree_Direction( the_node, parent );
RBTree_Direction parentdir = _RBTree_Direction( parent, grandparent );
/* ensure node is on the same branch direction as parent */
if ( dir != pdir ) {
_RBTree_Rotate( the_node->parent, pdir );
the_node = the_node->child[ pdir ];
if ( dir != parentdir ) {
RBTree_Node *oldparent = parent;
parent = the_node;
the_node = oldparent;
_RBTree_Rotate( oldparent, parentdir );
}
the_node->parent->color = RBT_BLACK;
g->color = RBT_RED;
parent->color = RBT_BLACK;
grandparent->color = RBT_RED;
/* now rotate grandparent in the other branch direction (toward uncle) */
_RBTree_Rotate( g, ( 1 - pdir ) );
_RBTree_Rotate( grandparent, _RBTree_Opposite_direction( parentdir ) );
grandparent = _RBTree_Parent( parent );
break;
}
}
if ( !the_node->parent->parent )
if ( grandparent == NULL )
the_node->color = RBT_BLACK;
}

14
testsuites/sptests/sprbtree01/init.c
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@@ -816,13 +816,13 @@ static bool visit_nodes(
rtems_test_assert( td->key == tn->key );
if ( td->parent == NULL ) {
rtems_test_assert( td->parent == tn->Node.parent->parent );
rtems_test_assert( rtems_rbtree_is_root( &tn->Node ) );
} else {
rtems_test_assert( td->parent == tn->Node.parent );
rtems_test_assert( td->parent == rtems_rbtree_parent( &tn->Node ) );
}
rtems_test_assert( td->left == tn->Node.child[ RBT_LEFT ] );
rtems_test_assert( td->right == tn->Node.child[ RBT_RIGHT ] );
rtems_test_assert( td->left == rtems_rbtree_left( &tn->Node ) );
rtems_test_assert( td->right == rtems_rbtree_right( &tn->Node ) );
rtems_test_assert( td->color == tn->Node.color );
++ctx->current;
@@ -1194,12 +1194,6 @@ rtems_task Init( rtems_task_argument ignored )
rtems_test_exit(0);
}
if ( _RBTree_Sibling( NULL ) != NULL )
puts ( "INIT - ERROR ON RBTREE NULL SIBLING MISMATCH" );
if ( _RBTree_Sibling( rbtree1.root ) != NULL )
puts ( "INIT - ERROR ON RBTREE NULL SIBLING MISMATCH" );
if ( _RBTree_Grandparent( NULL ) != NULL )
puts ( "INIT - ERROR ON RBTREE NULL GRANDPARENT MISMATCH" );
if ( _RBTree_Is_red( NULL ) != 0 )
puts ( "INIT - ERROR ON RBTREE NULL IS RED MISMATCH" );
if ( _RBTree_Is_red( rbtree1.root ) != 0 )