HashMap中红黑树操作实现

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 // 红黑树操作方法实现, 从CLR引入        static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,                                              TreeNode<K,V> p) {        //左旋            TreeNode<K,V> r, pp, rl;            if (p != null && (r = p.right) != null) {                if ((rl = p.right = r.left) != null)                    rl.parent = p;                if ((pp = r.parent = p.parent) == null)                    (root = r).red = false;                else if (pp.left == p)                    pp.left = r;                else                    pp.right = r;                r.left = p;                p.parent = r;            }            return root;        }        static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,                                               TreeNode<K,V> p) {            //右旋            TreeNode<K,V> l, pp, lr;            if (p != null && (l = p.left) != null) {                if ((lr = p.left = l.right) != null)                    lr.parent = p;                if ((pp = l.parent = p.parent) == null)                    (root = l).red = false;                else if (pp.right == p)                    pp.right = l;                else                    pp.left = l;                l.right = p;                p.parent = l;            }            return root;        }        static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,                                                    TreeNode<K,V> x) {        //插入后调整平衡            x.red = true;            for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {                if ((xp = x.parent) == null) {                    x.red = false;                    return x;                }                else if (!xp.red || (xpp = xp.parent) == null)                    return root;                if (xp == (xppl = xpp.left)) {                    if ((xppr = xpp.right) != null && xppr.red) {                        xppr.red = false;                        xp.red = false;                        xpp.red = true;                        x = xpp;                    }                    else {                        if (x == xp.right) {                            root = rotateLeft(root, x = xp);                            xpp = (xp = x.parent) == null ? null : xp.parent;                        }                        if (xp != null) {                            xp.red = false;                            if (xpp != null) {                                xpp.red = true;                                root = rotateRight(root, xpp);                            }                        }                    }                }                else {                    if (xppl != null && xppl.red) {                        xppl.red = false;                        xp.red = false;                        xpp.red = true;                        x = xpp;                    }                    else {                        if (x == xp.left) {                            root = rotateRight(root, x = xp);                            xpp = (xp = x.parent) == null ? null : xp.parent;                        }                        if (xp != null) {                            xp.red = false;                            if (xpp != null) {                                xpp.red = true;                                root = rotateLeft(root, xpp);                            }                        }                    }                }            }        }        static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root, TreeNode<K,V> x) {    //删除后调整平衡            for (TreeNode<K,V> xp, xpl, xpr;;)  {                if (x == null || x == root)                    return root;                else if ((xp = x.parent) == null) {                    x.red = false;                    return x;                }                else if (x.red) {                    x.red = false;                    return root;                }                else if ((xpl = xp.left) == x) {                    if ((xpr = xp.right) != null && xpr.red) {                        xpr.red = false;                        xp.red = true;                        root = rotateLeft(root, xp);                        xpr = (xp = x.parent) == null ? null : xp.right;                    }                    if (xpr == null)                        x = xp;                    else {                        TreeNode<K,V> sl = xpr.left, sr = xpr.right;                        if ((sr == null || !sr.red) &&                            (sl == null || !sl.red)) {                            xpr.red = true;                            x = xp;                        }                        else {                            if (sr == null || !sr.red) {                                if (sl != null)                                    sl.red = false;                                xpr.red = true;                                root = rotateRight(root, xpr);                                xpr = (xp = x.parent) == null ?                                    null : xp.right;                            }                            if (xpr != null) {                                xpr.red = (xp == null) ? false : xp.red;                                if ((sr = xpr.right) != null)                                    sr.red = false;                            }                            if (xp != null) {                                xp.red = false;                                root = rotateLeft(root, xp);                            }                            x = root;                        }                    }                }                else { // symmetric                    if (xpl != null && xpl.red) {                        xpl.red = false;                        xp.red = true;                        root = rotateRight(root, xp);                        xpl = (xp = x.parent) == null ? null : xp.left;                    }                    if (xpl == null)                        x = xp;                    else {                        TreeNode<K,V> sl = xpl.left, sr = xpl.right;                        if ((sl == null || !sl.red) &&                            (sr == null || !sr.red)) {                            xpl.red = true;                            x = xp;                        }                        else {                            if (sl == null || !sl.red) {                                if (sr != null)                                    sr.red = false;                                xpl.red = true;                                root = rotateLeft(root, xpl);                                xpl = (xp = x.parent) == null ?                                    null : xp.left;                            }                            if (xpl != null) {                                xpl.red = (xp == null) ? false : xp.red;                                if ((sl = xpl.left) != null)                                    sl.red = false;                            }                            if (xp != null) {                                xp.red = false;                                root = rotateRight(root, xp);                            }                            x = root;                        }                    }                }            }        }
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