// This is the standard DeltaBlue benchmark. A long chain of
// equality constraints is constructed with a stay constraint on
// one end. An edit constraint is then added to the opposite end
// and the time is measured for adding and removing this
// constraint, and extracting and executing a constraint
// satisfaction plan. There are two cases. In case 1, the added
// constraint is stronger than the stay constraint and values must
// propagate down the entire length of the chain. In case 2, the
// added constraint is weaker than the stay constraint so it cannot
// be accomodated. The cost in this case is, of course, very
// low. Typical situations lie somewhere between these two
// extremes.
//
private void chainTest(int n)
{
planner = new Planner();
Variable prev = null, first = null, last = null;
// Build chain of n equality constraints
for (int i = 0; i <= n; i++)
{
String name = "v" + i;
Variable v = new Variable(name);
if (prev != null)
new EqualityConstraint(prev, v, Strength.required);
if (i == 0) first = v;
if (i == n) last = v;
prev = v;
}
new StayConstraint(last, Strength.strongDefault);
Constraint editC = new EditConstraint(first, Strength.preferred);
ArrayList editV = new ArrayList();
editV.Add(editC);
Plan plan = planner.extractPlanFromConstraints(editV);
for (int i = 0; i < 100; i++)
{
first.value = i;
plan.execute();
if (last.value != i)
error("Chain test failed!");
}
editC.destroyConstraint();
deltablue.chains++;
}
// Update the walkabout strengths and stay flags of all variables
// downstream of the given constraint. Answer a collection of
// unsatisfied constraints sorted in order of decreasing strength.
//
public ArrayList removePropagateFrom(Variable outvar)
{
outvar.determinedBy = null;
outvar.walkStrength = Strength.weakest;
outvar.stay = true;
ArrayList unsatisfied = new ArrayList();
ArrayList todo = new ArrayList();
todo.Add(outvar);
while (!(todo.Count == 0))
{
#if USE_STACK
Variable v = (Variable)todo[todo.Count - 1];
todo.RemoveAt(todo.Count - 1);
#else
Variable v= (Variable)todo[0];
todo.RemoveAt(0);
#endif
for (int i = 0; i < v.constraints.Count; ++i)
{
Constraint c = (Constraint)v.constraints[i];
if (!c.isSatisfied())
unsatisfied.Add(c);
}
Constraint determiningC = v.determinedBy;
for (int i = 0; i < v.constraints.Count; ++i)
{
Constraint nextC = (Constraint)v.constraints[i];
if (nextC != determiningC && nextC.isSatisfied())
{
nextC.recalculate();
todo.Add(nextC.output());
}
}
}
return unsatisfied;
}
public void addConstraintsConsumingTo(Variable v, ArrayList coll)
{
Constraint determiningC = v.determinedBy;
ArrayList cc = v.constraints;
for (int i = 0; i < cc.Count; ++i)
{
Constraint c = (Constraint)cc[i];
if (c != determiningC && c.isSatisfied())
coll.Add(c);
}
}
public Variable offset; // offset input variable
// Install a scale constraint with the given strength on the given variables.
public ScaleConstraint(Variable src, Variable scale, Variable offset,
Variable dest, Strength strength)
{
// Curse this wretched language for insisting that constructor invocation
// must be the first thing in a method...
// ..because of that, we must copy the code from the inherited
// constructors.
this.strength = strength;
v1 = src;
v2 = dest;
direction = nodirection;
this.scale = scale;
this.offset = offset;
addConstraint();
}
// The given variable has changed. Propagate new values downstream.
public void propagateFrom(Variable v)
{
ArrayList todo = new ArrayList();
addConstraintsConsumingTo(v, todo);
while (!(todo.Count == 0))
{
#if USE_STACK
Constraint c = (Constraint)todo[todo.Count - 1];
todo.RemoveAt(0);
#else
Constraint c= (Constraint)todo[todo.Count-1];
todo.RemoveAt(0);
#endif
c.execute();
addConstraintsConsumingTo(c.output(), todo);
}
}
public BinaryConstraint() { } // this has to be here because of
// Java's constructor idiocy.
public BinaryConstraint(Variable var1, Variable var2, Strength strength)
: base(strength)
{
v1 = var1;
v2 = var2;
direction = nodirection;
addConstraint();
}
// Install a constraint with the given strength equating the given variables.
public EqualityConstraint(Variable var1, Variable var2, Strength strength)
: base(var1, var2, strength)
{
}
// Install a stay constraint with the given strength on the given variable.
public StayConstraint(Variable v, Strength str) : base(v, str) { }
public EditConstraint(Variable v, Strength str) : base(v, str) { }
public Boolean satisfied; // true if I am currently satisfied
public UnaryConstraint(Variable v, Strength strength) : base(strength)
{
myOutput = v;
satisfied = false;
addConstraint();
}
private void change(Variable var, int newValue)
{
EditConstraint editC = new EditConstraint(var, Strength.preferred);
ArrayList editV = new ArrayList();
editV.Add(editC);
Plan plan = planner.extractPlanFromConstraints(editV);
for (int i = 0; i < 10; i++)
{
var.value = newValue;
plan.execute();
}
editC.destroyConstraint();
}
// This test constructs a two sets of variables related to each
// other by a simple linear transformation (scale and offset). The
// time is measured to change a variable on either side of the
// mapping and to change the scale and offset factors.
//
private void projectionTest(int n)
{
planner = new Planner();
Variable scale = new Variable("scale", 10);
Variable offset = new Variable("offset", 1000);
Variable src = null, dst = null;
ArrayList dests = new ArrayList();
for (int i = 0; i < n; ++i)
{
src = new Variable("src" + i, i);
dst = new Variable("dst" + i, i);
dests.Add(dst);
new StayConstraint(src, Strength.normal);
new ScaleConstraint(src, scale, offset, dst, Strength.required);
}
change(src, 17);
if (dst.value != 1170) error("Projection test 1 failed!");
change(dst, 1050);
if (src.value != 5) error("Projection test 2 failed!");
change(scale, 5);
for (int i = 0; i < n - 1; ++i)
{
if (((Variable)dests[i]).value != i * 5 + 1000)
error("Projection test 3 failed!");
}
change(offset, 2000);
for (int i = 0; i < n - 1; ++i)
{
if (((Variable)dests[i]).value != i * 5 + 2000)
error("Projection test 4 failed!");
}
deltablue.projections++;
}
