/// <summary>
/// Optimizes an already-existing propnet by removing useless leaves. These are components that have no
/// outputs, but have no special meaning in GDL that requires them to stay.
/// </summary>
/// <param name="pn"></param>
public static void LopUselessLeaves(PropNet pn)
{
//Approach: Collect useful propositions based on a backwards
//search from goal/legal/terminal (passing through transitions)
var usefulComponents = new HashSet<IComponent>();
//TODO: Also try with queue?
var toAdd = new Stack<IComponent>();
toAdd.Push(pn.TerminalProposition);
usefulComponents.Add(pn.InitProposition); //Can't remove it...
IEnumerable<IProposition> goalProps = pn.GoalPropositions.Values.SelectMany(goalProp => goalProp);
foreach (IProposition prop in goalProps)
toAdd.Push(prop);
IEnumerable<IProposition> legalProps = pn.LegalPropositions.Values.SelectMany(legalProp => legalProp);
foreach (IProposition prop in legalProps)
toAdd.Push(prop);
while (toAdd.Any())
{
IComponent curComp = toAdd.Pop();
if (usefulComponents.Contains(curComp))
//We've already added it
continue;
usefulComponents.Add(curComp);
foreach (IComponent input in curComp.Inputs)
toAdd.Push(input);
}
//Remove the components not marked as useful
var allComponents = new List<IComponent>(pn.Components);
foreach (IComponent c in allComponents)
if (!usefulComponents.Contains(c))
pn.RemoveComponent(c);
}
public void Initialize(List<Expression> description)
{
_propNet = OptimizingPropNetFactory.Create(description, new BackComponentFactory());
_roles = _propNet.Roles;
//TODO: You need to ensure that propositions in your propnet are set to the correct initial state
// i.e init nodes set to true and propogated through. constant nodes set to there correct true/false value
}
/// <summary>
/// Potentially optimizes an already-existing propnet by removing propositions with no special meaning. The inputs and outputs
/// of those propositions are connected to one another. This is unlikely to improve performance unless values of every single
/// component are stored (outside the propnet).
/// </summary>
/// <param name="pn"></param>
public static void RemoveAnonymousPropositions(PropNet pn)
{
var toSplice = new List<IProposition>();
var toReplaceWithFalse = new List<IProposition>();
foreach (IProposition p in pn.Propositions)
{
//If it's important, continue to the next proposition
if (p.Inputs.Count == 1 && p.GetSingleInput() is ITransition)
//It's a base proposition
continue;
Fact sentence = p.Name;
Fact relation = sentence;
int name = relation.RelationName;
var parser = GameContainer.Parser;
if (name == parser.TokLegal || name == parser.TokGoal || name == parser.TokDoes || name == parser.TokInit ||
name == parser.TokTerminal
|| sentence.RelationName == GameContainer.SymbolTable["INIT"])
continue;
if (p.Inputs.Count < 1)
{
//Needs to be handled separately...
//because this is an always-false true proposition
//and it might have and gates as outputs
toReplaceWithFalse.Add(p);
continue;
}
if (p.Inputs.Count != 1)
throw new Exception(string.Format("Might have falsely declared {0} to be unimportant?", p.Name));
//Not important
//System.out.println("Removing " + p);
toSplice.Add(p);
}
foreach (IProposition p in toSplice)
{
//Get the inputs and outputs...
HashSet<IComponent> inputs = p.Inputs;
HashSet<IComponent> outputs = p.Outputs;
//Remove the proposition...
pn.RemoveComponent(p);
//And splice the inputs and outputs back together
if (inputs.Count > 1)
throw new Exception("Programmer made a bad assumption here... might lead to trouble?");
foreach (IComponent input in inputs)
foreach (IComponent output in outputs)
{
input.AddOutput(output);
output.AddInput(input);
}
}
foreach (IProposition p in toReplaceWithFalse)
throw new Exception(string.Format("Should be replacing {0} with false, but should do that in the OPNF, really; better equipped to do that there", p));
}
/// <summary>
/// Removes from the propnet all components that are discovered through type
/// inference to only ever be true or false, replacing them with their values
/// appropriately. This method may remove base and input propositions that are
/// shown to be always false (or, in the case of base propositions, those that
/// are always true).
/// </summary>
/// <param name="pn"></param>
/// <param name="basesTrueByInit">The set of base propositions that are true on the first turn of the game.</param>
public void RemoveUnreachableBasesAndInputs(PropNet pn, HashSet<IProposition> basesTrueByInit)
{
//If this doesn't contain a component, that's the equivalent of Type.NEITHER
var reachability = new Dictionary<IComponent, Type>();
//Keep track of the number of true inputs to AND gates and false inputs to
//OR gates.
var numTrueInputs = new Bag<IComponent>();
var numFalseInputs = new Bag<IComponent>();
var toAdd = new Stack<Tuple<IComponent, TypeCode>>();
//It's easier here if we get just the one-way version of the map
var legalsToInputs = new Dictionary<IProposition, IProposition>();
foreach (IProposition legalProp in pn.LegalPropositions.Values.SelectMany(v => v))
{
IProposition inputProp = pn.LegalInputMap[legalProp];
if (inputProp != null)
legalsToInputs[legalProp] = inputProp;
}
//All constants have their values
foreach (IComponent c in pn.Components) //ConcurrencyUtils.checkForInterruption();
if (c is IConstant)
toAdd.Push(c.Value ? Tuple.Create(c, TypeCode.True) : Tuple.Create(c, TypeCode.False));
//Every input can be false (we assume that no player will have just one move allowed all game)
foreach (IProposition p in pn.InputPropositions.Values)
toAdd.Push(Tuple.Create((IComponent)p, TypeCode.False));
//Every base with "init" can be true, every base without "init" can be false
foreach (IProposition baseProp in pn.BasePropositions.Values)
toAdd.Push(basesTrueByInit.Contains(baseProp)
? Tuple.Create((IComponent)baseProp, TypeCode.True)
: Tuple.Create((IComponent)baseProp, TypeCode.False));
//Keep INIT, for those who use it
IProposition initProposition = pn.InitProposition;
toAdd.Push(Tuple.Create((IComponent)initProposition, TypeCode.Both));
while (toAdd.Any())
{
//ConcurrencyUtils.checkForInterruption();
Tuple<IComponent, TypeCode> curEntry = toAdd.Pop();
IComponent curComp = curEntry.Item1;
var newInputType = new Type(curEntry.Item2);
Type oldType = reachability[curComp] ?? new Type(TypeCode.Neither);
//We want to send only the new addition to our children,
//for consistency in our parent-true and parent-false
//counts.
//Make sure we don't double-apply a type.
var typeToAdd = new Type(TypeCode.Neither); // Any new values that we discover we can have this iteration.
if (curComp is IProposition)
typeToAdd = newInputType;
else if (curComp is ITransition)
typeToAdd = newInputType;
else if (curComp is IConstant)
typeToAdd = newInputType;
else if (curComp is INot)
typeToAdd = new Type(newInputType.Opposite());
else if (curComp is IAnd)
{
if (newInputType.HasTrue)
{
numTrueInputs.Add(curComp);
if (numTrueInputs.Count(n => n == curComp) == curComp.Inputs.Count)
typeToAdd = new Type(TypeCode.True);
}
if (newInputType.HasFalse)
typeToAdd = new Type(typeToAdd.With(TypeCode.False));
}
else if (curComp is IOr)
{
if (newInputType.HasFalse)
{
numFalseInputs.Add(curComp);
if (numFalseInputs.Count(n => n == curComp) == curComp.Inputs.Count)
typeToAdd = new Type(TypeCode.False);
}
if (newInputType.HasTrue)
typeToAdd = new Type(typeToAdd.With(TypeCode.True));
}
else
throw new Exception("Unhandled component type " + curComp.GetType());
if (oldType.Includes(typeToAdd)) //We don't know anything new about curComp
continue;
reachability[curComp] = new Type(typeToAdd.With(oldType));
typeToAdd = new Type(typeToAdd.Minus(oldType));
if (typeToAdd == TypeCode.Neither)
throw new Exception("Something's messed up here");
//Add all our children to the stack
foreach (IComponent output in curComp.Outputs)
toAdd.Push(Tuple.Create(output, (TypeCode)typeToAdd));
if (legalsToInputs.ContainsKey((IProposition)curComp))
{
IProposition inputProp = legalsToInputs[(IProposition)curComp];
if (inputProp == null)
throw new Exception("IllegalState");
toAdd.Push(Tuple.Create((IComponent)inputProp, (TypeCode)typeToAdd));
}
}
IConstant trueConst = _componentFactory.CreateConstant(true);
IConstant falseConst = _componentFactory.CreateConstant(false);
pn.AddComponent(trueConst);
pn.AddComponent(falseConst);
//Make them the input of all false/true components
foreach (var entry in reachability)
{
TypeCode type = entry.Value;
if (type == TypeCode.True || type == TypeCode.False)
{
IComponent c = entry.Key;
if (c is IConstant) //Don't bother trying to remove this
continue;
//Disconnect from inputs
foreach (IComponent input in c.Inputs)
input.RemoveOutput(c);
c.RemoveAllInputs();
if (type == TypeCode.True ^ (c is INot))
{
c.AddInput(trueConst);
trueConst.AddOutput(c);
}
else
{
c.AddInput(falseConst);
falseConst.AddOutput(c);
}
}
}
OptimizingPropNetFactory.OptimizeAwayTrueAndFalse(pn, trueConst, falseConst);
}
/// <summary>
/// Optimizes an already-existing propnet by removing propositions of the form (init ?x). Does NOT remove the proposition "INIT".
/// </summary>
/// <param name="pn"></param>
public static void RemoveInits(PropNet pn)
{
var toRemove = (from p in pn.Propositions
let relation = p.Name
where relation.RelationName == GameContainer.Parser.TokInit
select p).ToList();
foreach (IProposition p in toRemove)
pn.RemoveComponent(p);
}
