/// <summary>
/// Restrict the leaf predicates with psi
/// </summary>
BDG <T, S> RestrictLeaves(T psi)
{
var key = new Tuple <T, BDG <T, S> >(psi, this);
BDG <T, S> val;
if (!algebra.restrictLeafCache.TryGetValue(key, out val))
{
if (this.IsLeaf)
{
val = this.algebra.MkLeaf(this.algebra.leafAlgebra.MkAnd(this.LeafCondition, psi), true);
}
else
{
var t = TrueCase.RestrictLeaves(psi);
var f = FalseCase.RestrictLeaves(psi);
if (t == TrueCase && f == FalseCase)
{
val = this;
}
else
{
val = this.algebra.MkNode(this.BranchCondition, t, f);
}
}
algebra.restrictLeafCache[key] = val;
}
return(val);
}
/// <summary>
/// Maintains the node invariant: sat(path & nodePred) and sat(path & ~nodePred)
/// </summary>
BDG <T, S> MkAnd(S path, BDG <T, S> that)
{
var key = new Tuple <S, BDG <T, S>, BDG <T, S> >(path, this, that);
BDG <T, S> val;
if (!algebra.MkAndCache.TryGetValue(key, out val))
{
if (this.IsLeaf)
{
if (path.Equals(algebra.nodeAlgebra.True))
{
val = that.RestrictLeaves(this.LeafCondition);
}
else
{
val = that.Restrict(path, this.LeafCondition);
}
}
else if (that.IsLeaf)
{
val = this.RestrictLeaves(that.LeafCondition); //path is not relevant
}
else
{
var path_and_thatCond = algebra.nodeAlgebra.MkAnd(path, that.BranchCondition);
if (!algebra.nodeAlgebra.IsSatisfiable(path_and_thatCond))
{
//path implies ~that.BranchCondition
var t = this.TrueCase.MkAnd(algebra.nodeAlgebra.MkAnd(path, this.BranchCondition), that.FalseCase);
var f = this.FalseCase.MkAnd(algebra.nodeAlgebra.MkAnd(path, algebra.nodeAlgebra.MkNot(this.BranchCondition)), that.FalseCase);
if (t == this.TrueCase && f == this.FalseCase)
{
val = this;
}
else
{
val = this.algebra.MkNode(this.BranchCondition, t, f);
}
}
else
{
var path_and_not_thatCond = algebra.nodeAlgebra.MkAnd(path, algebra.nodeAlgebra.MkNot(that.BranchCondition));
if (!algebra.nodeAlgebra.IsSatisfiable(path_and_not_thatCond))
{
//path implies that.BranchCondition
var t = this.TrueCase.MkAnd(algebra.nodeAlgebra.MkAnd(path, this.BranchCondition), that.TrueCase);
var f = this.FalseCase.MkAnd(algebra.nodeAlgebra.MkAnd(path, algebra.nodeAlgebra.MkNot(this.BranchCondition)), that.TrueCase);
if (t == this.TrueCase && f == this.FalseCase)
{
val = this;
}
else
{
val = this.algebra.MkNode(this.BranchCondition, t, f);
}
}
else
{ //both cases are possible
var t = this.TrueCase.MkAnd(algebra.nodeAlgebra.MkAnd(path, this.BranchCondition), that);
var f = this.FalseCase.MkAnd(algebra.nodeAlgebra.MkAnd(path, algebra.nodeAlgebra.MkNot(this.BranchCondition)), that);
if (t == this.TrueCase && f == this.FalseCase)
{
val = this;
}
else
{
val = this.algebra.MkNode(this.BranchCondition, t, f);
}
}
}
}
algebra.MkAndCache[key] = val;
}
return(val);
}