// This may look like C code, but it is really -*- C++ -*- /* Copyright (C) 1988 Free Software Foundation written by Doug Lea (dl@rocky.oswego.edu) This file is part of GNU CC. GNU CC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY. No author or distributor accepts responsibility to anyone for the consequences of using it or for whether it serves any particular purpose or works at all, unless he says so in writing. Refer to the GNU CC General Public License for full details. Everyone is granted permission to copy, modify and redistribute GNU CC, but only under the conditions described in the GNU CC General Public License. A copy of this license is supposed to have been given to you along with GNU CC so you can know your rights and responsibilities. It should be in a file named COPYING. Among other things, the copyright notice and this notice must be preserved on all copies. */ #ifdef __GNUG__ #pragma implementation #endif #include #include #include ".SplaySet.h" /* struct to simulate the special `null' node in the Sleater & Tarjan JACM 1985 splay tree algorithms All routines use a version of their `simple top-down' splay alg. (p 669) */ struct _dummySplayNode { SplayNode* lt; SplayNode* rt; SplayNode* par; } _dummy_null; /* traversal primitives */ SplayNode* SplaySet::leftmost() { SplayNode* t = root; if (t != 0) while (t->lt != 0) t = t->lt; return t; } SplayNode* SplaySet::rightmost() { SplayNode* t = root; if (t != 0) while (t->rt != 0) t = t->rt; return t; } SplayNode* SplaySet::succ(SplayNode* t) { if (t == 0) return 0; if (t->rt != 0) { t = t->rt; while (t->lt != 0) t = t->lt; return t; } else { for (;;) { if (t->par == 0 || t == t->par->lt) return t->par; else t = t->par; } } } SplayNode* SplaySet::pred(SplayNode* t) { if (t == 0) return 0; else if (t->lt != 0) { t = t->lt; while (t->rt != 0) t = t->rt; return t; } else { for (;;) { if (t->par == 0 || t == t->par->rt) return t->par; else t = t->par; } } } Pix SplaySet::seek( key) { SplayNode* t = root; if (t == 0) return 0; int comp = CMP(key, t->item); if (comp == 0) return Pix(t); SplayNode* dummy = (SplayNode*)(&_dummy_null); SplayNode* l = dummy; SplayNode* r = dummy; dummy->rt = dummy->lt = dummy->par = 0; while (comp != 0) { if (comp > 0) { SplayNode* tr = t->rt; if (tr == 0) break; else { comp = CMP(key, tr->item); if (comp <= 0 || tr->rt == 0) { l->rt = t; t->par = l; l = t; t = tr; if (comp >= 0) break; } else { if ((t->rt = tr->lt) != 0) t->rt->par = t; tr->lt = t; t->par = tr; l->rt = tr; tr->par = l; l = tr; t = tr->rt; comp = CMP(key, t->item); } } } else { SplayNode* tl = t->lt; if (tl == 0) break; else { comp = CMP(key, tl->item); if (comp >= 0 || tl->lt == 0) { r->lt = t; t->par = r; r = t; t = tl; if (comp <= 0) break; } else { if ((t->lt = tl->rt) != 0) t->lt->par = t; tl->rt = t; t->par = tl; r->lt = tl; tl->par = r; r = tl; t = tl->lt; comp = CMP(key, t->item); } } } } if ((r->lt = t->rt) != 0) r->lt->par = r; if ((l->rt = t->lt) != 0) l->rt->par = l; if ((t->lt = dummy->rt) != 0) t->lt->par = t; if ((t->rt = dummy->lt) != 0) t->rt->par = t; t->par = 0; root = t; return (comp == 0) ? Pix(t) : 0; } Pix SplaySet::add( item) { SplayNode* t = root; if (t == 0) { ++count; root = new SplayNode(item); return Pix(root); } int comp = CMP(item, t->item); if (comp == 0) return Pix(t); SplayNode* dummy = (SplayNode*)(&_dummy_null); SplayNode* l = dummy; SplayNode* r = dummy; dummy->rt = dummy->lt = dummy->par = 0; while (comp != 0) { if (comp > 0) { SplayNode* tr = t->rt; if (tr == 0) { ++count; tr = new SplayNode(item); comp = 0; } else comp = CMP(item, tr->item); if (comp <= 0) { l->rt = t; t->par = l; l = t; t = tr; } else { SplayNode* trr = tr->rt; if (trr == 0) { ++count; trr = new SplayNode(item); comp = 0; } else comp = CMP(item, trr->item); if ((t->rt = tr->lt) != 0) t->rt->par = t; tr->lt = t; t->par = tr; l->rt = tr; tr->par = l; l = tr; t = trr; } } else { SplayNode* tl = t->lt; if (tl == 0) { ++count; tl = new SplayNode(item); comp = 0; } else comp = CMP(item, tl->item); if (comp >= 0) { r->lt = t; t->par = r; r = t; t = tl; } else { SplayNode* tll = tl->lt; if (tll == 0) { ++count; tll = new SplayNode(item); comp = 0; } else comp = CMP(item, tll->item); if ((t->lt = tl->rt) != 0) t->lt->par = t; tl->rt = t; t->par = tl; r->lt = tl; tl->par = r; r = tl; t = tll; } } } if ((r->lt = t->rt) != 0) r->lt->par = r; if ((l->rt = t->lt) != 0) l->rt->par = l; if ((t->lt = dummy->rt) != 0) t->lt->par = t; if ((t->rt = dummy->lt) != 0) t->rt->par = t; t->par = 0; root = t; return Pix(root); } void SplaySet::del( key) { SplayNode* t = (SplayNode*)(seek(key)); if (t == 0) return; SplayNode* p = t->par; --count; if (t->rt == 0) { if (t == root) { if ((root = t->lt) != 0) root->par = 0; } else if (t == p->lt) { if ((p->lt = t->lt) != 0) p->lt->par = p; } else if ((p->rt = t->lt) != 0) p->rt->par = p; } else { SplayNode* r = t->rt; SplayNode* l = r->lt; for(;;) { if (l == 0) { if (t == root) { root = r; r->par = 0; } else if (t == p->lt) { p->lt = r; r->par = p; } else { p->rt = r; r->par = p; } if ((r->lt = t->lt) != 0) r->lt->par = r; break; } else { if ((r->lt = l->rt) != 0) r->lt->par = r; l->rt = r; r->par = l; r = l; l = l->lt; } } } delete t; } void SplaySet::_kill(SplayNode* t) { if (t != 0) { _kill(t->lt); _kill(t->rt); delete t; } } SplayNode* SplaySet::_copy(SplayNode* t) { if (t != 0) { SplayNode* l = _copy(t->lt); SplayNode* r = _copy(t->rt); SplayNode* x = new SplayNode(t->item, l, r); if (l != 0) l->par = x; if (r != 0) r->par = x; return x; } else return 0; } /* relationals */ int SplaySet::operator == (SplaySet& y) { if (count != y.count) return 0; else { SplayNode* t = leftmost(); SplayNode* u = y.leftmost(); for (;;) { if (t == 0) return 1; else if (!EQ(t->item, u->item)) return 0; else { t = succ(t); u = y.succ(u); } } } } int SplaySet::operator <= (SplaySet& y) { if (count > y.count) return 0; else { SplayNode* t = leftmost(); SplayNode* u = y.leftmost(); for (;;) { if (t == 0) return 1; else if (u == 0) return 0; int cmp = CMP(t->item, u->item); if (cmp == 0) { t = succ(t); u = y.succ(u); } else if (cmp < 0) return 0; else u = y.succ(u); } } } void SplaySet::operator |=(SplaySet& y) { if (&y == this) return; SplayNode* u = y.leftmost(); while (u != 0) { add(u->item); u = y.succ(u); } } void SplaySet::operator &= (SplaySet& y) { if (y.count == 0) clear(); else if (&y != this && count != 0) { SplayNode* t = leftmost(); while (t != 0) { SplayNode* s = succ(t); if (y.seek(t->item) == 0) del(t->item); t = s; } } } void SplaySet::operator -=(SplaySet& y) { if (&y == this) clear(); else if (y.count != 0) { SplayNode* t = leftmost(); while (t != 0) { SplayNode* s = succ(t); if (y.seek(t->item) != 0) del(t->item); t = s; } } } int SplaySet::OK() { int v = 1; if (root == 0) v = count == 0; else { int n = 1; SplayNode* trail = leftmost(); SplayNode* t = succ(trail); while (t != 0) { ++n; v &= CMP(trail->item, t->item) < 0; trail = t; t = succ(t); } v &= n == count; } if (!v) error("invariant failure"); return v; }