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/*
* vim: ts=4 sw=4 et tw=0 wm=0
*
* libvpsc - A solver for the problem of Variable Placement with
* Separation Constraints.
*
* Copyright (C) 2005-2012 Monash University
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
* See the file LICENSE.LGPL distributed with the library.
*
* 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.
*
* Author(s): Tim Dwyer
* Michael Wybrow
*/
/*
* @brief A block structure defined over the variables
*
* A block structure defined over the variables such that each block contains
* 1 or more variables, with the invariant that all constraints inside a block
* are satisfied by keeping the variables fixed relative to one another
*/
#include "libvpsc/blocks.h"
#include "libvpsc/block.h"
#include "libvpsc/constraint.h"
#include "libvpsc/variable.h"
#include "libvpsc/assertions.h"
#ifdef LIBVPSC_LOGGING
#include <fstream>
using std::ios;
using std::ofstream;
using std::endl;
#endif
using std::vector;
using std::iterator;
using std::list;
using std::copy;
#define __NOTNAN(p) (p)==(p)
namespace vpsc {
Blocks::Blocks(vector<Variable*> const &vs) : vs(vs),nvs(vs.size()) {
blockTimeCtr=0;
m_blocks.resize(nvs);
for(size_t i=0;i<nvs;i++) {
m_blocks[i] = new Block(this, vs[i]);
}
}
Blocks::~Blocks(void)
{
blockTimeCtr=0;
size_t length = m_blocks.size();
for (size_t i = 0; i < length; ++i)
{
delete m_blocks[i];
}
m_blocks.clear();
}
/*
* returns a list of variables with total ordering determined by the constraint
* DAG
*/
list<Variable*> *Blocks::totalOrder() {
list<Variable*> *order = new list<Variable*>;
for(size_t i=0;i<nvs;i++) {
vs[i]->visited=false;
}
for(size_t i=0;i<nvs;i++) {
if(vs[i]->in.size()==0) {
dfsVisit(vs[i],order);
}
}
return order;
}
// Recursive depth first search giving total order by pushing nodes in the DAG
// onto the front of the list when we finish searching them
void Blocks::dfsVisit(Variable *v, list<Variable*> *order) {
v->visited=true;
vector<Constraint*>::iterator it=v->out.begin();
for(;it!=v->out.end();++it) {
Constraint *c=*it;
if(!c->right->visited) {
dfsVisit(c->right, order);
}
}
#ifdef LIBVPSC_LOGGING
ofstream f(LOGFILE,ios::app);
f<<" order="<<*v<<endl;
#endif
order->push_front(v);
}
/*
* Processes incoming constraints, most violated to least, merging with the
* neighbouring (left) block until no more violated constraints are found
*/
void Blocks::mergeLeft(Block *r) {
#ifdef LIBVPSC_LOGGING
ofstream f(LOGFILE,ios::app);
f<<"mergeLeft called on "<<*r<<endl;
#endif
r->timeStamp=++blockTimeCtr;
r->setUpInConstraints();
Constraint *c=r->findMinInConstraint();
while (c != nullptr && c->slack()<0) {
#ifdef LIBVPSC_LOGGING
f<<"mergeLeft on constraint: "<<*c<<endl;
#endif
r->deleteMinInConstraint();
Block *l = c->left->block;
if (l->in==nullptr) l->setUpInConstraints();
double dist = c->right->offset - c->left->offset - c->gap;
if (r->vars->size() < l->vars->size()) {
dist=-dist;
std::swap(l, r);
}
blockTimeCtr++;
r->merge(l, c, dist);
r->mergeIn(l);
r->timeStamp=blockTimeCtr;
removeBlock(l);
c=r->findMinInConstraint();
}
#ifdef LIBVPSC_LOGGING
f<<"merged "<<*r<<endl;
#endif
}
/*
* Symmetrical to mergeLeft
*/
void Blocks::mergeRight(Block *l) {
#ifdef LIBVPSC_LOGGING
ofstream f(LOGFILE,ios::app);
f<<"mergeRight called on "<<*l<<endl;
#endif
l->setUpOutConstraints();
Constraint *c = l->findMinOutConstraint();
while (c != nullptr && c->slack()<0) {
#ifdef LIBVPSC_LOGGING
f<<"mergeRight on constraint: "<<*c<<endl;
#endif
l->deleteMinOutConstraint();
Block *r = c->right->block;
r->setUpOutConstraints();
double dist = c->left->offset + c->gap - c->right->offset;
if (l->vars->size() > r->vars->size()) {
dist=-dist;
std::swap(l, r);
}
l->merge(r, c, dist);
l->mergeOut(r);
removeBlock(r);
c=l->findMinOutConstraint();
}
#ifdef LIBVPSC_LOGGING
f<<"merged "<<*l<<endl;
#endif
}
void Blocks::removeBlock(Block *doomed) {
doomed->deleted=true;
//erase(doomed);
}
// Clears up deleted blocks from the blocks list.
void Blocks::cleanup(void)
{
// We handle removal of items in-place by doing a single linear pass over
// the vector. We use two indexes, j to refer to elements we've checked
// from the original list and i to refer to the current position we are
// writing in the updated list.
size_t i = 0;
// For all items in the current blocks list...
size_t length = m_blocks.size();
for (size_t j = 0; j < length; )
{
if (m_blocks[j]->deleted)
{
// The element is deleted, so free it and increment j.
delete m_blocks[j];
++j;
}
else
{
// The current element is still valid.
if (j > i)
{
// If we've not looking at same element, then copy from j to i.
m_blocks[i] = m_blocks[j];
}
// Increment both indexes.
++i;
++j;
}
}
m_blocks.resize(i);
}
/*
* Splits block b across constraint c into two new blocks, l and r (c's left
* and right sides respectively)
*/
void Blocks::split(Block *b, Block *&l, Block *&r, Constraint *c) {
b->split(l,r,c);
m_blocks.push_back(l);
m_blocks.push_back(r);
#ifdef LIBVPSC_LOGGING
ofstream f(LOGFILE,ios::app);
f<<"Split left: "<<*l<<endl;
f<<"Split right: "<<*r<<endl;
#endif
r->posn = b->posn;
//COLA_ASSERT(r->weight!=0);
//r->wposn = r->posn * r->weight;
mergeLeft(l);
// r may have been merged!
r = c->right->block;
r->updateWeightedPosition();
//r->posn = r->wposn / r->weight;
mergeRight(r);
removeBlock(b);
COLA_ASSERT(__NOTNAN(l->posn));
COLA_ASSERT(__NOTNAN(r->posn));
}
/*
* returns the cost total squared distance of variables from their desired
* positions
*/
double Blocks::cost() {
double c = 0;
size_t length = m_blocks.size();
for (size_t i = 0; i < length; ++i)
{
c += m_blocks[i]->cost();
}
return c;
}
}
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