https://github.com/mozilla/gecko-dev
Tip revision: b2c372d1aa1949a560004ea3dbc4dfc0f5785a24 authored by Christian Legnitto on 15 December 2011, 23:47:29 UTC
ckout c3081b5db3d1 (bug 572652) and 4c77addce789 (bug 655628), as they cause bug 657153 and we are worried about the impact. The reward for keeping this in seems really low as well. a=LegNeato
ckout c3081b5db3d1 (bug 572652) and 4c77addce789 (bug 655628), as they cause bug 657153 and we are worried about the impact. The reward for keeping this in seems really low as well. a=LegNeato
Tip revision: b2c372d
interval_map.h
/* -*- Mode: C++ -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is ``interval_map''
*
* The Initial Developer of the Original Code is Netscape
* Communications Corp. Portions created by the Initial Developer are
* Copyright (C) 2001 the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Chris Waterson <waterson@netscape.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef interval_map_h__
#define interval_map_h__
/*
A utility class that maps an interval to an object, allowing clients
to look up the object by a point within the interval.
*/
// TODO:
// - removing intervals
// - container iterators
#include <fstream>
#include <assert.h>
template<class coord, class T>
class interval_map {
protected:
class const_iterator;
friend class const_iterator;
struct node {
T m_data;
coord m_min;
coord m_max;
node *m_before; // intervals before this one
node *m_within; // intervals within this one
node *m_after; // intervals after this one
int m_bal;
};
public:
/**
* A unidirectional const iterator that is used to enumerate the
* intervals that overlap a specific point.
*/
class const_iterator {
protected:
const node *m_node;
const coord m_point;
friend class interval_map;
const_iterator(const node *n, const coord &point)
: m_node(n), m_point(point) {}
void advance();
public:
const_iterator() : m_node(0), m_point(0) {}
const_iterator(const const_iterator &iter)
: m_node(iter.m_node), m_point(iter.m_point) {}
const_iterator &
operator=(const const_iterator &iter) {
m_node = iter.m_node;
m_point = iter.m_point; }
const T &
operator*() const { return m_node->m_data; }
const T *
operator->() const { return &m_node->m_data; }
const_iterator &
operator++() { advance(); return *this; }
const_iterator
operator++(int) {
const_iterator temp(*this);
advance();
return temp; }
bool
operator==(const const_iterator &iter) const {
return m_node == iter.m_node; }
bool
operator!=(const const_iterator &iter) const {
return !iter.operator==(*this); }
};
interval_map() : m_root(0) {}
~interval_map() { delete m_root; }
/**
* Insert aData for the interval [aMin, aMax]
*/
void put(coord min, coord max, const T &data) {
put_into(&m_root, min, max, data);
#ifdef DEBUG
verify(m_root, 0);
#endif
}
/**
* Return an iterator that will enumerate the data for all intervals
* intersecting |aPoint|.
*/
const_iterator get(coord point) const;
/**
* Return an iterator that marks the end-point of iteration.
*/
const_iterator end() const {
return const_iterator(0, 0); }
protected:
void put_into(node **link, coord min, coord max, const T &data, bool *subsumed = 0);
void left_rotate(node **link, node *node);
void right_rotate(node **link, node *node);
#ifdef DEBUG
void verify(node *node, int depth);
#endif
node *m_root;
};
template<class coord, class T>
void
interval_map<coord, T>::put_into(node **root, coord min, coord max, const T &data, bool *subsumed)
{
assert(min < max);
node *interval = *root;
if (interval) {
bool before = min < interval->m_min;
bool after = max > interval->m_max;
if (!before || !after) {
// The interval we're adding does not completely subsume
// the |interval|. So we've got one of these situations:
//
// |======| |======| |======|
// |------| |--| |------|
//
// where |==| is the existing interval, and |--| is the
// new interval we're inserting. If there's left or right
// slop, then we ``split'' the new interval in half:
//
// |======| |======|
// |--|---| |---|--|
//
// and insert it both in the ``within'' and ``before'' (or
// ``after'') subtrees.
//
if (before) {
if (max > interval->m_min) {
put_into(&interval->m_within, interval->m_min, max, data);
max = interval->m_min;
}
bool was_subsumed = true;
put_into(&interval->m_before, min, max, data, &was_subsumed);
if (! was_subsumed) {
if (interval->m_bal < 0) {
if (interval->m_before->m_bal > 0)
left_rotate(&interval->m_before, interval->m_before);
right_rotate(root, interval);
}
else
--interval->m_bal;
if (subsumed)
*subsumed = (interval->m_bal == 0);
}
return;
}
if (after) {
if (min < interval->m_max) {
put_into(&interval->m_within, min, interval->m_max, data);
min = interval->m_max;
}
bool was_subsumed = true;
put_into(&interval->m_after, min, max, data, &was_subsumed);
if (! was_subsumed) {
if (interval->m_bal > 0) {
if (interval->m_after->m_bal < 0)
right_rotate(&interval->m_after, interval->m_after);
left_rotate(root, interval);
}
else
++interval->m_bal;
if (subsumed)
*subsumed = (interval->m_bal == 0);
}
return;
}
put_into(&interval->m_within, min, max, data);
return;
}
// If we get here, the interval we're adding completely
// subsumes |interval|. We'll go ahead and insert a new
// interval immediately above |interval|, with |interval| as
// the new interval's |m_within|.
}
if (subsumed)
*subsumed = false;
node *n = new node();
n->m_data = data;
n->m_before = n->m_after = 0;
n->m_min = min;
n->m_max = max;
n->m_within = interval;
n->m_bal = 0;
*root = n;
}
/*
* (*link) (*link)
* | == left rotate ==> |
* (x) (y)
* / \ / \
* a (y) <== right rotate == (x) c
* / \ / \
* b c a b
*/
template<class coord, class T>
void
interval_map<coord, T>::left_rotate(node **link, node *x)
{
node *y = x->m_after;
x->m_after = y->m_before;
*link = y;
y->m_before = x;
--x->m_bal;
--y->m_bal;
}
template<class coord, class T>
void
interval_map<coord, T>::right_rotate(node **link, node *y)
{
node *x = y->m_before;
y->m_before = x->m_after;
*link = x;
x->m_after = y;
++y->m_bal;
++x->m_bal;
}
template<class coord, class T>
interval_map<coord, T>::const_iterator
interval_map<coord, T>::get(coord point) const
{
node *interval = m_root;
while (interval) {
if (point < interval->m_min)
interval = interval->m_before;
else if (point > interval->m_max)
interval = interval->m_after;
else
break;
}
return const_iterator(interval, point);
}
template<class coord, class T>
void
interval_map<coord, T>::const_iterator::advance()
{
assert(m_node);
m_node = m_node->m_within;
while (m_node) {
if (m_point < m_node->m_min)
m_node = m_node->m_before;
else if (m_point > m_node->m_max)
m_node = m_node->m_after;
else
break;
}
}
#ifdef DEBUG
template<class coord, class T>
void
interval_map<coord, T>::verify(node<coord, T> *node, int depth)
{
if (node->m_after)
verify(node->m_after, depth + 1);
for (int i = 0; i < depth; ++i)
cout << " ";
hex(cout);
cout << node << "(";
dec(cout);
cout << node->m_bal << ")";
hex(cout);
cout << "[" << node->m_min << "," << node->m_max << "]";
cout << "@" << node->m_data;
cout << endl;
if (node->m_before)
verify(node->m_before, depth + 1);
}
#endif // DEBUG
#endif // interval_map_h__