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Generalising splayrotate operations into treerotates.

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Copied from Perforce
 Change: 184431
 ServerID: perforce.ravenbrook.com
This commit is contained in:
Richard Brooksby 2014-02-21 11:33:56 +00:00
parent c446abda38
commit 6bc35c5ca0
3 changed files with 56 additions and 62 deletions
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62
mps/code/splay.c
View file

@ -125,62 +125,6 @@ static void SplayLinkLeft(Tree *topIO, Tree *leftIO) {
}
/* SplayRotateLeft -- Rotate right child edge of node
*
* Rotates node, right child of node, and left child of right
* child of node, leftwards in the order stated.
*
* See <design/splay/#impl.rotate.left>.
*/
static void SplayRotateLeft(Tree *nodeIO, SplayTree tree) {
Tree nodeRight;
AVER(nodeIO != NULL);
AVERT(Tree, *nodeIO);
AVERT(Tree, TreeRight(*nodeIO));
AVERT(SplayTree, tree);
nodeRight = TreeRight(*nodeIO);
TreeSetRight(*nodeIO, TreeLeft(nodeRight));
TreeSetLeft(nodeRight, *nodeIO);
*nodeIO = nodeRight;
tree->updateNode(tree, TreeLeft(nodeRight));
/* Don't need to update new root because we know that we will */
/* do either a link or an assemble next, and that will sort it */
/* out. */
}
/* SplayRotateRight -- Rotate left child edge of node
*
* Rotates node, left child of node, and right child of left
* child of node, leftwards in the order stated.
*
* See <design/splay/#impl.rotate.right>.
*/
static void SplayRotateRight(Tree *nodeIO, SplayTree tree) {
Tree nodeLeft;
AVER(nodeIO != NULL);
AVERT(Tree, *nodeIO);
AVERT(Tree, TreeLeft(*nodeIO));
AVERT(SplayTree, tree);
nodeLeft = TreeLeft(*nodeIO);
TreeSetLeft(*nodeIO, TreeRight(nodeLeft));
TreeSetRight(nodeLeft, *nodeIO);
*nodeIO = nodeLeft;
tree->updateNode(tree, TreeRight(nodeLeft));
/* Don't need to update new root because we know that we will */
/* do either a link or an assemble next, and that will sort it */
/* out. */
}
/* SplayAssemble -- Assemble left right and top trees into one
*
* We do this by moving the children of the top tree to the last and
@ -336,7 +280,8 @@ static Bool SplaySplay(Tree *nodeReturn, SplayTree tree,
case CompareLESS: { /* zig-zig */
if (TreeLeft(topLeft) == TreeEMPTY)
goto terminalZig;
SplayRotateRight(&top, tree);
TreeRotateRight(&top);
tree->updateNode(tree, TreeRight(top));
SplayLinkRight(&top, &rightFirst);
} break;
@ -373,7 +318,8 @@ static Bool SplaySplay(Tree *nodeReturn, SplayTree tree,
case CompareGREATER: { /* zag-zag */
if (TreeRight(topRight) == TreeEMPTY)
goto terminalZag;
SplayRotateLeft(&top, tree);
TreeRotateLeft(&top);
tree->updateNode(tree, TreeLeft(top));
SplayLinkLeft(&top, &leftLast);
} break;

45
mps/code/tree.c
View file

@ -162,6 +162,51 @@ void TreeTraverseMorris(Tree tree, TreeVisitor visit,
}
/* TreeRotateLeft -- Rotate right child edge of node
*
* Rotates node, right child of node, and left child of right
* child of node, leftwards in the order stated.
*/
void TreeRotateLeft(Tree *treeIO)
{
Tree tree, right;
AVER(treeIO != NULL);
tree = *treeIO;
AVERT(Tree, tree);
right = TreeRight(tree);
AVERT(Tree, right);
TreeSetRight(tree, TreeLeft(right));
TreeSetLeft(right, tree);
*treeIO = right;
}
/* TreeRotateRight -- Rotate left child edge of node
*
* Rotates node, left child of node, and right child of left
* child of node, leftwards in the order stated.
*/
void TreeRotateRight(Tree *treeIO) {
Tree tree, left;
AVER(treeIO != NULL);
tree = *treeIO;
AVERT(Tree, tree);
left = TreeLeft(tree);
AVERT(Tree, left);
TreeSetLeft(*treeIO, TreeRight(left));
TreeSetRight(left, *treeIO);
*treeIO = left;
}
/* C. COPYRIGHT AND LICENSE
*
* Copyright (C) 2014 Ravenbrook Limited <http://www.ravenbrook.com/>.

11
mps/code/tree.h
View file

@ -71,12 +71,15 @@ extern Bool TreeCheckLeaf(Tree tree);
extern Compare TreeFind(Tree *treeReturn, Tree root,
TreeKey key, TreeCompare compare);
Bool TreeInsert(Tree *treeReturn, Tree root, Tree node,
TreeKey key, TreeCompare compare);
extern Bool TreeInsert(Tree *treeReturn, Tree root, Tree node,
TreeKey key, TreeCompare compare);
typedef void TreeVisitor(Tree tree, void *closureP, Size closureS);
void TreeTraverseMorris(Tree tree, TreeVisitor visit,
void *closureP, Size closureS);
extern void TreeTraverseMorris(Tree tree, TreeVisitor visit,
void *closureP, Size closureS);
extern void TreeRotateLeft(Tree *nodeIO);
extern void TreeRotateRight(Tree *nodeIO);
#endif /* tree_h */