summaryrefslogtreecommitdiff
path: root/gnu/lib/libg++/g++-include/SkipMap.ccP
diff options
context:
space:
mode:
Diffstat (limited to 'gnu/lib/libg++/g++-include/SkipMap.ccP')
-rw-r--r--gnu/lib/libg++/g++-include/SkipMap.ccP307
1 files changed, 307 insertions, 0 deletions
diff --git a/gnu/lib/libg++/g++-include/SkipMap.ccP b/gnu/lib/libg++/g++-include/SkipMap.ccP
new file mode 100644
index 000000000000..8b6afe2eddf3
--- /dev/null
+++ b/gnu/lib/libg++/g++-include/SkipMap.ccP
@@ -0,0 +1,307 @@
+// This may look like C code, but it is really -*- C++ -*-
+/*
+Copyright (C) 1991 Free Software Foundation
+
+This file is part of the GNU C++ Library. This library is free
+software; you can redistribute it and/or modify it under the terms of
+the GNU Library General Public License as published by the Free
+Software Foundation; either version 2 of the License, or (at your
+option) any later version. This library is distributed in the hope
+that it will be useful, but WITHOUT ANY WARRANTY; without even the
+implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+PURPOSE. See the GNU Library General Public License for more details.
+You should have received a copy of the GNU Library General Public
+License along with this library; if not, write to the Free Software
+Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#ifdef __GNUG__
+#pragma implementation
+#endif
+
+#include <stream.h>
+#include <time.h>
+#include "<T>.<C>.SkipMap.h"
+
+/*
+ * Bags implemented via William Pugh SkipList algorithms.
+ * CACM, June 1990, p 668-676.
+ *
+ */
+
+MLCG* <T><C>SkipMap::gen = 0;
+int <T><C>SkipMapinit::count = 0;
+
+static int countbits(long bits)
+{
+ int n = 0;
+ while(bits>>=1) n++;
+ return n;
+}
+
+<T><C>SkipMap::<T><C>SkipMap(<C&> dflt, long size)
+: <T><C>Map(dflt),
+ level(0),
+ header(new <T><C>SkipMapNode (countbits(size)+1)),
+ max_levels (countbits(size)+1),
+ random_bits(gen->asLong()),
+ randoms_left(BITS_IN_RANDOM / 2)
+{
+ <T><C>SkipMapNodePtr *buffer_start = header->forward;
+ <T><C>SkipMapNodePtr *trav = &header->forward[max_levels];
+
+ count = 0;
+ while (trav > buffer_start)
+ *--trav = (<T><C>SkipMapNodePtr) header;
+}
+
+<T><C>SkipMap::<T><C>SkipMap(<T><C>SkipMap& b)
+: <T><C>Map(b.def),
+ level (0),
+ header (new <T><C>SkipMapNode (b.max_levels)),
+ max_levels (b.max_levels),
+ random_bits (gen->asLong()),
+ randoms_left (BITS_IN_RANDOM / 2)
+{
+ <T><C>SkipMapNodePtr *buffer_start = header->forward;
+ <T><C>SkipMapNodePtr *trav = &header->forward[max_levels];
+
+ count = 0;
+
+ while (trav > buffer_start)
+ *--trav = (<T><C>SkipMapNodePtr)header;
+
+ for (<T><C>SkipMapNodePtr t = b.leftmost(); t; t = b.succ(t))
+ (*this)[t->item] = t->cont;
+}
+
+<C>& <T><C>SkipMap::operator [] (<T&> item)
+{
+ <T><C>SkipMapNodePtr *update = new <T><C>SkipMapNodePtr[max_levels+1];
+ <T><C>SkipMapNodePtr curr =
+ (<T><C>SkipMapNodePtr) this->header;
+ int l = level;
+ <T><C>SkipMapNodePtr temp;
+
+ do
+ {
+ while ((temp = curr->forward[l])!=header &&
+ <T>CMP(temp->item, item) < 0)
+ curr = temp;
+ update[l] = curr;
+ }
+ while (--l >= 0);
+
+ if (temp != header && <T>CMP(temp->item, item) == 0)
+ {
+ delete update;
+ return temp->cont;
+ }
+
+ if ((l = random_level ()) > level)
+ {
+ l = ++level;
+ update[l] = (<T><C>SkipMapNodePtr)header;
+ };
+
+ temp = new <T><C>RealSkipMapNode (item, def, l);
+ <T><C>SkipMapNodePtr *temp_forward = temp->forward;
+
+ do
+ {
+ <T><C>SkipMapNodePtr *curr_forward = update[l]->forward;
+
+ temp_forward[l] = curr_forward[l];
+ curr_forward[l] = temp;
+ }
+ while (--l >= 0);
+
+ count++;
+ delete update;
+ return temp->cont;
+}
+
+void <T><C>SkipMap::del(<T&> key)
+{
+
+ int l = level;
+ int curr_level = level;
+ <T><C>SkipMapNodePtr *update = new <T><C>SkipMapNodePtr[max_levels+1];
+ <T><C>SkipMapNodePtr curr = (<T><C>SkipMapNodePtr)header;
+ <T><C>SkipMapNodePtr temp;
+
+ do
+ {
+ while ((temp = curr->forward[l])!=header
+ && <T>CMP(temp->item,key) < 0)
+ curr = temp;
+ update[l] = curr;
+ }
+ while (--l >= 0);
+
+ if (<T>CMP(temp->item,key)==0)
+ {
+ <T><C>SkipMapNodePtr *temp_forward = temp->forward;
+
+ for (l = 0;
+ l <= curr_level && (curr = update[l])->forward[l] == temp;
+ l++)
+ curr->forward[l] = temp_forward[l];
+
+ delete temp;
+
+ <T><C>SkipMapNodePtr *forward = header->forward;
+
+ while (forward[curr_level]==header && curr_level > 0)
+ curr_level--;
+
+ level = curr_level;
+ count--;
+ delete update;
+ return;
+ }
+}
+
+<T><C>SkipMapNodePtr <T><C>SkipMap::rightmost()
+{
+ <T><C>SkipMapNodePtr temp;
+ <T><C>SkipMapNode* curr = header;
+ int l = level;
+
+ do
+ while ((temp = curr->forward[l])!=header)
+ curr = temp;
+ while (--l >= 0);
+
+ return temp==header ? 0 : temp;
+}
+
+<T><C>SkipMapNodePtr <T><C>SkipMap::pred(<T><C>SkipMapNodePtr t)
+{
+ <T><C>SkipMapNodePtr temp, curr = (<T><C>SkipMapNodePtr) header;
+ int l = level;
+
+ do
+ while ((temp = curr->forward[l])!=t)
+ curr = temp;
+ while (--l >= 0);
+
+ return curr == header ? 0 : curr;
+}
+
+void <T><C>SkipMap::_kill()
+{
+ <T><C>SkipMapNode *p = this->header->forward[0];
+
+ while (p != header)
+ {
+ <T><C>SkipMapNodePtr q = p->forward[0];
+ delete p;
+ p = q;
+ }
+}
+
+void <T><C>SkipMap::clear()
+{
+ <T><C>SkipMapNodePtr *buffer_start = header->forward;
+ <T><C>SkipMapNodePtr *trav = &header->forward[level+1];
+ _kill();
+ count = 0;
+
+ while (trav > buffer_start)
+ *--trav = (<T><C>SkipMapNodePtr)header;
+}
+
+Pix <T><C>SkipMap::seek(<T&> key)
+{
+ <T><C>SkipMapNodePtr temp;
+ <T><C>SkipMapNode *curr = header;
+ int l = level;
+
+ do
+ {
+ while ((temp = curr->forward[l])!=header &&
+ <T>CMP(temp->item, key) < 0)
+ curr = temp;
+ }
+ while (--l >= 0);
+
+ if (<T>CMP(temp->item, key) != 0)
+ return 0;
+ else
+ {
+ return Pix(temp);
+ }
+}
+
+/*
+ * random function for probabilistic balancing
+ *
+ * Hardwired for p = .25. Not too flexible,
+ * but fast. Changing this would require a constructor
+ * that would accept a different value for p, etc.
+ * Perhaps someone else would like to implement this?
+ *
+ */
+int <T><C>SkipMap::random_level (void)
+{
+ int rlevel = 0;
+ int b;
+
+ do
+ {
+ b = random_bits & 3L;
+ if (!b)
+ rlevel++;
+ random_bits >>= 2;
+ if (--randoms_left == 0)
+ {
+ random_bits = gen->asLong();
+ randoms_left = BITS_IN_RANDOM / 2;
+ };
+ }
+ while (!b);
+
+ return rlevel > max_levels ? max_levels : rlevel;
+}
+
+int <T><C>SkipMap::OK()
+{
+ int v = 1;
+ if (header == 0)
+ v = 0;
+ else
+ {
+ int n = 0;
+ <T><C>SkipMapNodePtr trail = leftmost();
+ <T><C>SkipMapNodePtr t = 0;
+ if (trail) t = succ(trail);
+ if (t) n++;
+ while (t != 0)
+ {
+ ++n;
+ v &= <T>CMP(trail->item, t->item) < 0;
+ trail = t;
+ t = succ(t);
+ }
+ v &= n == count;
+ }
+ if (!v) error("invariant failure");
+ return v;
+}
+
+<T><C>SkipMapinit::<T><C>SkipMapinit()
+{
+ if (!count)
+ <T><C>SkipMap::gen = new MLCG(time(0));
+ count++;
+}
+
+<T><C>SkipMapinit::~<T><C>SkipMapinit()
+{
+ count--;
+ if (!count)
+ delete <T><C>SkipMap::gen;
+}
+
+
generated by cgit v1.2.3 (git 2.25.1) at 2025-08-05 04:18:45 +0000