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/* This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
This program 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.
*/
#include <cassert>
#include <climits>
#include <iostream>
#include <set>
#ifndef RANGE_TREE_DEBUG_PRINT_FUNCTION
# define RANGE_TREE_DEBUG_PRINT_FUNCTION 0
#endif
template <typename T>
struct RangeTree {
struct Range {
Range(T min_, T max_)
: min(min_), max(max_), single(min_ == max_) {
assert(min_ <= max_);
}
Range(T t)
: min(t), max(t), single(true)
{}
Range& operator=(const Range& v) {
*this = v;
return *this;
}
bool operator<(const Range& v) const {
return max < v.min;
}
const T min;
const T max;
const bool single;
};
typedef std::set<Range> Tree;
typedef typename Tree::iterator TreeIter;
typedef typename Tree::reverse_iterator TreeIterReverse;
typedef typename Tree::const_iterator TreeIterConst;
/* Initialize with a single range from 'min' to 'max', inclusive. */
RangeTree(T min, T max) {
tree.insert(Range(min, max));
}
/* Initialize with a single range from 0 to 'max', inclusive. */
RangeTree(T max) {
tree.insert(Range(0, max));
}
RangeTree(const RangeTree<T>& src) {
tree = src.tree;
}
/* Remove 't' from the associated range in the tree. Precondition:
a range including 't' must exist in the tree. */
void take(T t) {
#if RANGE_TREE_DEBUG_PRINT_FUNCTION
std::cout << __func__ << "(" << t << ")\n";
#endif
/* Find the range that includes 't' and its neighbors */
TreeIter iter = tree.find(Range(t));
assert(iter != tree.end());
Range cur = *iter;
/* Remove the original range (note that this does not
invalidate the prev/next iterators) */
tree.erase(iter);
/* Construct two new ranges that together cover the original
range, except for 't' */
if (t > cur.min)
tree.insert(Range(cur.min, t - 1));
if (t + 1 <= cur.max)
tree.insert(Range(t + 1, cur.max));
}
/* Take the first element out of the first range in the
tree. Precondition: tree must not be empty. */
T take_any() {
#if RANGE_TREE_DEBUG_PRINT_FUNCTION
std::cout << __func__ << "()\n";
#endif
/* Find the first element */
TreeIter iter = tree.begin();
assert(iter != tree.end());
T first = iter->min;
/* Take the first element */
take(first);
return first;
}
/* Return 't' to the tree, either expanding/merging existing
ranges or adding a range to cover it. Precondition: 't' cannot
be in an existing range. */
void release(T t) {
#if RANGE_TREE_DEBUG_PRINT_FUNCTION
std::cout << __func__ << "(" << t << ")\n";
#endif
/* TODO: these cases should be simplified/unified */
TreeIter right = tree.upper_bound(t);
if (right != tree.end()) {
TreeIter left = right;
if (left != tree.begin())
--left;
if (left == right) {
/* 't' lies before any existing ranges */
if (t + 1 == left->min) {
/* 't' lies directly before the first range,
resize and replace that range */
const Range r(t, left->max);
tree.erase(left);
tree.insert(r);
}
else {
/* There's a gap between 't' and the first range,
add a new range */
tree.insert(Range(t));
}
}
else if ((left->max + 1 == t) &&
(t + 1 == right->min)) {
/* 't' fills a hole. Remove left and right, and insert a
new range that covers both. */
const Range r(left->min, right->max);
tree.erase(left);
tree.erase(right);
tree.insert(r);
}
else if (left->max + 1 == t) {
/* 't' lies directly after 'left' range, resize and
replace that range */
const Range r(left->min, t);
tree.erase(left);
tree.insert(r);
}
else if (t + 1 == right->min) {
/* 't' lies directly before 'right' range, resize and
replace that range */
const Range r(t, right->max);
tree.erase(right);
tree.insert(r);
}
else {
/* There's a gap between 't' and both adjacent ranges,
add a new range */
tree.insert(Range(t));
}
}
else {
/* 't' lies after any existing ranges */
right = tree.end();
right--;
if (right->max + 1 == t) {
/* 't' lies directly after last range, resize and
replace that range */
const Range r(right->min, t);
tree.erase(right);
tree.insert(r);
}
else {
/* There's a gap between the last range and 't', add a
new range */
tree.insert(Range(t));
}
}
}
bool has(T t) const {
TreeIterConst iter = tree.find(Range(t));
return (iter != tree.end()) && (t <= iter->max);
}
bool has_range(T min, T max) const {
TreeIterConst iter = tree.find(Range(min, max));
return (iter != tree.end()) && (min == iter->min && max == iter->max);
}
bool empty() const {
return tree.empty();
}
int size() const {
return tree.size();
}
void print() const {
std::cout << "RangeTree:\n";
for (TreeIterConst iter = tree.begin(); iter != tree.end(); ++iter) {
const Range& r = *iter;
if (r.single)
std::cout << " [" << r.min << "]\n";
else
std::cout << " [" << r.min << ", " << r.max << "]\n";
}
if (empty())
std::cout << " <empty>";
std::cout << "\n";
}
unsigned int allocation_lower_bound() const {
return tree.size() * sizeof(Range);
}
private:
Tree tree;
};
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