/*************************************************************************
** RangeMap.cpp **
** **
** This file is part of dvisvgm -- a fast DVI to SVG converter **
** Copyright (C) 2005-2024 Martin Gieseking <martin.gieseking@uos.de> **
** **
** 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 3 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, see <http://www.gnu.org/licenses/>. **
*************************************************************************/
#include <numeric>
#include "RangeMap.hpp"
using namespace std;
/** Tries to merge range r into this one. This is only possible if the ranges
* touch or overlap and if the assigned values match at the junction points.
* @param[in] r range to join
* @return true if join was successful */
bool RangeMap::Range::join (const Range &r) {
// check most common cases first
if (_max+1 < r._min || _min-1 > r._max) // disjoint ranges?
return false;
if (r._min-1 == _max) { // does r touch *this on the right?
if (valueAt(r._min) == r._minval) {
_max = r._max;
return true;
}
return false;
}
if (r._max+1 == _min) { // does r touch *this on the left
if (r.valueAt(_min) == _minval) {
setMinAndAdaptValue(r._min);
return true;
}
return false;
}
// the following cases should be pretty rare
if (r._min <= _min && r._max >= _max) { // does r overlap *this on both sides?
*this = r;
return true;
}
if (r._min < _min) { // left overlap only?
if (r.valueAt(_min) == _minval) {
_min = r._min;
_minval = r._minval;
return true;
}
return false;
}
if (r._max > _max) { // right overlap only?
if (valueAt(r._min) == r._minval) {
_max = r._max;
return true;
}
return false;
}
// r completely inside *this
return valueAt(r._min) == r._minval;
}
/** Adds a new number range. The range describes a mapping from c to v(c), where
* \f$c \in [cmin,cmax]\f$ and \f$v(cmin):=vmin, v(c):=vmin+c-cmin\f$.
* @param[in] cmin smallest number in the range
* @param[in] cmax largest number in the range
* @param[in] vmin map value of cmin */
void RangeMap::addRange (uint32_t cmin, uint32_t cmax, uint32_t vmin) {
if (cmin > cmax)
swap(cmin, cmax);
Range range(cmin, cmax, vmin);
if (_ranges.empty())
_ranges.push_back(std::move(range));
else {
// check for simple cases that can be handled pretty fast
Range &lrange = *_ranges.begin();
Range &rrange = *_ranges.rbegin();
if (cmin > rrange.max()) { // non-overlapping range at end of vector?
if (!rrange.join(range))
_ranges.push_back(std::move(range));
}
else if (cmax < lrange.min()) { // non-overlapping range at begin of vector?
if (!lrange.join(range))
_ranges.emplace(_ranges.begin(), std::move(range));
}
else {
// ranges overlap and/or must be inserted somewhere inside the vector
auto it = lower_bound(_ranges.begin(), _ranges.end(), range);
const bool at_end = (it == _ranges.end());
if (at_end)
--it;
if (!it->join(range) && (it == _ranges.begin() || !(it-1)->join(range))) {
if (it->min() < cmin && it->max() > cmax) { // new range completely inside an existing range?
//split existing range
uint32_t itmax = it->max();
it->max(cmin-1);
it = _ranges.emplace(it+1, Range(cmax+1, itmax, it->valueAt(cmax+1)));
}
else if (at_end) // does new range overlap right side of last range in vector?
it = _ranges.end(); // => append new range at end of vector
it = _ranges.emplace(it, std::move(range));
}
adaptNeighbors(it); // resolve overlaps
}
}
}
/** Adapts the left and right neighbor elements of a newly inserted range.
* The new range could overlap ranges in the neighborhood so that those must be
* adapted or removed. All ranges in the range vector are ordered ascendingly, i.e.
* [min_1, max_1],...,[min_n, max_n] where min_i < min_j for all i < j.
* @param[in] it pointer to the newly inserted range */
void RangeMap::adaptNeighbors (Ranges::iterator it) {
if (it != _ranges.end()) {
// adapt left neighbor
if (it != _ranges.begin() && it->min() <= (it-1)->max()) {
auto lit = it-1; // points to left neighbor
bool left_neighbor_valid = (it->min() > 0 && it->min()-1 >= lit->min());
if (left_neighbor_valid) // is adapted left neighbor valid?
lit->max(it->min()-1); // => assign new max value
if (!left_neighbor_valid || it->join(*lit))
it = _ranges.erase(lit);
}
// remove right neighbors completely overlapped by *it
auto rit = it+1; // points to right neighbor
while (rit != _ranges.end() && it->max() >= rit->max()) { // complete overlap?
_ranges.erase(rit);
rit = it+1;
}
// adapt rightmost range partially overlapped by *it
if (rit != _ranges.end()) {
if (it->max() >= rit->min())
rit->setMinAndAdaptValue(it->max()+1);
// try to merge right neighbor into *this
if (it->join(*rit))
_ranges.erase(rit); // remove merged neighbor
}
}
}
/** Finds the index of the range that contains a given value c.
* @param[in] c find range that contains this value
* @return index of the range found, or -1 if range was not found */
int RangeMap::lookup (uint32_t c) const {
// simple binary search
int left=0, right=_ranges.size()-1;
while (left <= right) {
int mid = (left+right)/2;
if (c < _ranges[mid].min())
right = mid-1;
else if (c > _ranges[mid].max())
left = mid+1;
else
return mid;
}
return -1;
}
uint32_t RangeMap::valueAt (uint32_t c) const {
int pos = lookup(c);
return pos < 0 ? 0 : _ranges[pos].valueAt(c);
}
/** Returns the number of values mapped. */
size_t RangeMap::numValues () const {
return std::accumulate(_ranges.begin(), _ranges.end(), size_t(0), [](size_t sum, const Range &range) {
return sum+range.max()-range.min()+1;
});
}
ostream& RangeMap::Range::write (ostream& os) const {
return os << '[' << _min << ',' << _max << "] => " << _minval;
}
ostream& RangeMap::write (ostream& os) const {
for (const Range &range : _ranges)
range.write(os) << '\n';
return os;
}