gecko-dev/ef/Utilities/General/Tree.h

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* The contents of this file are subject to the Netscape Public License
* Version 1.0 (the "NPL"); you may not use this file except in
* compliance with the NPL. You may obtain a copy of the NPL at
* http://www.mozilla.org/NPL/
*
* Software distributed under the NPL is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
* for the specific language governing rights and limitations under the
* NPL.
*
* The Initial Developer of this code under the NPL is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All Rights
* Reserved.
*/
#ifndef TREE_H
#define TREE_H
#include "Fundamentals.h"
// --- PRIVATE ----------------------------------------------------------------
struct TreeNodeImpl
{
private:
TreeNodeImpl *parent; // This node's parent or nil if this is the root
TreeNodeImpl *children[2]; // This node's left (0) and right (1) children
bool red BOOL_8; // This node is black if false, red if true
bool right BOOL_8; // This node is a left child if false, right if true
#ifdef DEBUG
bool linked BOOL_8; // True if this node is linked into a tree
#endif
public:
#ifdef DEBUG
TreeNodeImpl(): linked(false) {}
~TreeNodeImpl() {assert(!linked);}
#endif
void link() {assert(!linked); DEBUG_ONLY(linked = true);}
void unlink() {assert(linked); DEBUG_ONLY(linked = false);}
TreeNodeImpl *getParent() const {assert(linked); return parent;}
TreeNodeImpl *getChild(bool right) const {assert(linked); return children[right];}
bool isBlack() const {assert(linked); return !red;}
bool isRed() const {assert(linked); return red;}
bool isLeft() const {assert(linked); return !right;}
bool isRight() const {assert(linked); return right;}
void setParent(TreeNodeImpl *p) {assert(linked); parent = p;}
void setChild(bool right, TreeNodeImpl *c) {assert(linked); children[right] = c;}
void setBlack() {assert(linked); red = false;}
void setRed(bool red = true) {assert(linked); TreeNodeImpl::red = red;}
void setLeft() {assert(linked); right = false;}
void setRight(bool right = true) {assert(linked); TreeNodeImpl::right = right;}
void move(TreeNodeImpl &src);
TreeNodeImpl &extremeNode(bool right);
TreeNodeImpl *prev();
TreeNodeImpl *next();
};
// Base class for Tree. Do not use directly.
class TreeImpl
{
TreeNodeImpl *root; // The tree's root or nil if the tree is empty
Uint32 nNodes; // Current number of nodes linked into the tree
public:
TreeImpl(): root(0), nNodes(0) {}
TreeNodeImpl *getRoot() const {return root;}
TreeNodeImpl *firstNode() const {return root ? &root->extremeNode(false) : 0;}
TreeNodeImpl *lastNode() const {return root ? &root->extremeNode(true) : 0;}
TreeNodeImpl *next(TreeNodeImpl *n) const {return n ? n->next() : firstNode();}
TreeNodeImpl *prev(TreeNodeImpl *n) const {return n ? n->prev() : lastNode();}
Uint32 getNNodes() const {return nNodes;}
private:
void linkNode(TreeNodeImpl *node, TreeNodeImpl *parent, bool right);
void rotate(TreeNodeImpl &node, bool right);
void addNode(TreeNodeImpl &node, TreeNodeImpl *parent, bool right);
public:
void attach(TreeNodeImpl &node, TreeNodeImpl *where, bool right);
void insertAfter(TreeNodeImpl &node, TreeNodeImpl *where);
void insertBefore(TreeNodeImpl &node, TreeNodeImpl *where);
void remove(TreeNodeImpl &node);
void substitute(TreeNodeImpl &newNode, TreeNodeImpl &oldNode);
#ifdef DEBUG
private:
static bool verifySubtree(TreeNodeImpl *node, TreeNodeImpl *parent, bool rightChild, Uint32 &nNodes, Uint32 &blackDepth);
public:
void verify() const;
#endif
};
// --- PUBLIC -----------------------------------------------------------------
// Derive Tree nodes from this class. Node is the node class, which should
// be a subclass of this class.
template<class Node>
class TreeNode: public TreeNodeImpl
{
#ifdef DEBUG
TreeNode(const TreeNode<Node> &); // Copying forbidden
void operator=(const TreeNode<Node> &); // Copying forbidden
public:
TreeNode() {}
#endif
public:
Node *getParent() const {return static_cast<Node *>(TreeNodeImpl::getParent());}
Node *getChild(bool right) const {return static_cast<Node *>(TreeNodeImpl::getChild(right));}
Node *prev() {return static_cast<Node *>(TreeNodeImpl::prev());}
Node *next() {return static_cast<Node *>(TreeNodeImpl::next());}
};
//
// A balanced binary tree with nodes of class Node, which must be a subclass of TreeNode<Node>.
//
// Only insert, remove, and substitute operations are provided. It is up to the user
// to determine the proper place to insert a node. The Tree also does not do storage
// management (allocation or deallocation) of its nodes; the user should do so explicitly
// if needed.
//
template<class Node>
class Tree: private TreeImpl
{
public:
Node *getRoot() const {return static_cast<Node *>(TreeImpl::getRoot());}
Node *firstNode() const {return static_cast<Node *>(TreeImpl::firstNode());}
Node *lastNode() const {return static_cast<Node *>(TreeImpl::lastNode());}
Node *next(Node *n) const {return n ? n->next() : firstNode();}
Node *prev(Node *n) const {return n ? n->prev() : lastNode();}
TreeImpl::getNNodes;
void attach(Node &node, Node *where, bool right) {TreeImpl::attach(node, where, right);}
void insertAfter(Node &node, Node *where) {TreeImpl::insertAfter(node, where);}
void insertBefore(Node &node, Node *where) {TreeImpl::insertBefore(node, where);}
void remove(Node &node) {TreeImpl::remove(node);}
void substitute(Node &newNode, Node &oldNode) {TreeImpl::substitute(newNode, oldNode);}
#ifdef DEBUG
TreeImpl::verify;
#endif
};
//
// A sorted balanced binary tree with nodes of class Node, which must be a subclass of
// TreeNode<Node>. Each Node has a key of class Key.
//
// Each Key must support the following methods:
//
// Key(const Key &);
// void operator=(const Key &);
// Copy constructor and assignment.
//
// bool operator<(const Key &key2) const;
// Comparisons. These comparisons must induce a full order on all Keys. In particular:
// For any key key1, key1<key1 must be false;
// At most one of key1<key2 or key2<key1 can be true;
// If key1<key2 and key2<key3 then key1<key3 must be true;
// If !(key1<key2) and !(key2<key3) then key1<key3 must be false.
//
// In addition to deriving from TreeNode<Node>, each Node must support the following methods:
//
// Key getKey() const or
// const Key &getKey() const;
// Returns the node's key.
//
// Find, insert, remove, and substitute operations are provided. The SortedTree does not
// do storage management (allocation or deallocation) of its nodes; the user should do so
// explicitly if needed.
//
template<class Node, class Key>
class SortedTree: public Tree<Node>
{
#ifdef DEBUG
static bool isBetween(Node &node, Node *prev, Node *next);
bool immediatelyAfter(Node &node, Node *prev) const;
bool immediatelyBefore(Node &node, Node *next) const;
#endif
public:
Node *find(Key key) const;
Node *find(Key key, Node *&where, bool &right) const;
Node *findAfter(Key key) const;
Node *findBefore(Key key) const;
void attach(Node &node, Node *where, bool right);
void insert(Node &node);
void insertAfter(Node &node, Node *where) {assert(immediatelyAfter(node, where)); Tree<Node>::insertAfter(node, where);}
void insertBefore(Node &node, Node *where) {assert(immediatelyBefore(node, where)); Tree<Node>::insertBefore(node, where);}
void substitute(Node &newNode, Node &oldNode);
#ifdef DEBUG
void verify() const;
#endif
};
// --- TEMPLATES --------------------------------------------------------------
#ifdef DEBUG
//
// Return true if key(prev) <= key(node) <= key(next), where comparisons against a nil
// node's key always succeed.
//
template<class Node, class Key>
inline bool SortedTree<Node, Key>::isBetween(Node &node, Node *prev, Node *next)
{
return !(prev && node.getKey() < prev->getKey() || next && next->getKey() < node.getKey());
}
//
// Return true if node can be inserted immediately after prev
// without violating the key ordering of the tree.
//
template<class Node, class Key>
bool SortedTree<Node, Key>::immediatelyAfter(Node &node, Node *prev) const
{
return isBetween(node, prev, next(prev));
}
//
// Return true if node can be inserted immediately before next
// without violating the key ordering of the tree.
//
template<class Node, class Key>
bool SortedTree<Node, Key>::immediatelyBefore(Node &node, Node *next) const
{
return isBetween(node, prev(next), next);
}
#endif
//
// Find and return a node that contains the given key. If there is no such node,
// return nil. If there is more than one node with the given key in the tree,
// pick one arbitrarily.
//
template<class Node, class Key>
Node *SortedTree<Node, Key>::find(Key key) const
{
Node *p = getRoot();
while (p)
if (key < p->getKey())
p = p->getChild(false);
else if (p->getKey() < key)
p = p->getChild(true);
else
break;
return p;
}
//
// Find and return a node that contains the given key. If there is no such node,
// return nil and store a node in where and a flag in right that can be passed to
// attach to add a node with the given key to the tree. If there is more than one
// node with the given key in the tree, pick one arbitrarily.
// where and right are undefined if the node has been found.
//
template<class Node, class Key>
Node *SortedTree<Node, Key>::find(Key key, Node *&where, bool &right) const
{
Node *p = getRoot();
Node *parent = 0;
bool rightChild = false;
while (p) {
if (key < p->getKey())
rightChild = false;
else if (p->getKey() < key)
rightChild = true;
else
return p;
parent = p;
p = p->getChild(rightChild);
}
where = parent;
right = rightChild;
return 0;
}
//
// Find and return a node that contains the given key. If there is no such node,
// return the tree node with the lowest key greater than the given key; if there
// still is no such node (i.e. the given key is greater than the keys of all nodes
// in the tree), return nil. If there is more than one node with the given key in
// the tree, pick one arbitrarily.
//
template<class Node, class Key>
Node *SortedTree<Node, Key>::findAfter(Key key) const
{
Node *where;
bool right;
Node *p = find(key, where, right);
if (!p && where) {
assert(!where->getChild(right));
if (right)
p = where->next();
else
p = where;
}
return p;
}
//
// Find and return a node that contains the given key. If there is no such node,
// return the tree node with the greatest key less than the given key; if there
// still is no such node (i.e. the given key is lower than the keys of all nodes
// in the tree), return nil. If there is more than one node with the given key in
// the tree, pick one arbitrarily.
//
template<class Node, class Key>
Node *SortedTree<Node, Key>::findBefore(Key key) const
{
Node *where;
bool right;
Node *p = find(key, where, right);
if (!p && where) {
assert(!where->getChild(right));
if (right)
p = where;
else
p = where->prev();
}
return p;
}
//
// Attach the node at the position (where, right) returned by find.
//
template<class Node, class Key>
inline void SortedTree<Node, Key>::attach(Node &node, Node *where, bool right)
{
assert(right ? immediatelyAfter(node, where) : immediatelyBefore(node, where));
Tree<Node>::attach(node, where, right);
}
//
// Insert node into the proper place in the tree. Rebalance the tree as needed.
// If there already are nodes with an equal key in the tree, the new node will be
// inserted arbitrarily either before, after, or between such nodes.
// node should not be part of any tree on entry.
//
template<class Node, class Key>
void SortedTree<Node, Key>::insert(Node &node)
{
Node *where;
bool right;
Node *p = find(node.getKey(), where, right);
if (p)
insertAfter(node, p);
else
attach(node, where, right);
}
//
// Splice newNode into oldNode's position in the tree. oldNode is removed from
// the tree.
//
template<class Node, class Key>
inline void SortedTree<Node, Key>::substitute(Node &newNode, Node &oldNode)
{
assert(isBetween(newNode, oldNode.prev(), oldNode.next()));
Tree<Node>::substitute(newNode, oldNode);
}
#ifdef DEBUG
//
// Verify that the tree is internally consistent and that the entries in it are
// still sorted. Assert if anything wrong is found.
//
template<class Node, class Key>
void SortedTree<Node, Key>::verify() const
{
Tree<Node>::verify();
Node *p = firstNode();
if (p) {
Node *q;
while ((q = p->next()) != 0) {
assert(!(q->getKey() < p->getKey()));
p = q;
}
}
}
#endif
#endif