public void UnionWith(SubstitutionCollection other)
{
Substitutions.AddRange(other.Substitutions);
NextRelation = (NextRelation, other.NextRelation) switch
{
(NullLogicalValue _, var v) => v,
(var v, NullLogicalValue _) => v,
(var v1, var v2) => new LogicalDisjunctionValue(v1, v2)
};
}
private List <Path> GeneratePaths(
IBlock currentBlock,
ILogicalValue currentRelation,
Path currentPath,
HashSet <IBlock> cutSet,
HashSet <IBlock> visited)
{
var paths = new List <Path>();
var substitutionCollection = new SubstitutionCollection(Enumerable.Empty <ValueSubstitution>(), new NullLogicalValue());
List <IBlock> successors;
while (true)
{
visited.Add(currentBlock);
substitutionCollection.UnionWith(substitutionGenerator.GenerateSubstitutions(currentBlock));
successors = currentBlock.GetSuccessors().ToList();
if (successors.Count != 1)
{
break;
}
currentBlock = successors[0];
}
currentPath = currentPath.Combine(new Path(currentRelation, substitutionCollection.Substitutions));
// If we reached the end of the CFG, just return the current paths.
if (successors.Count == 0)
{
paths.Add(new Path(currentRelation, substitutionCollection.Substitutions));
return(paths);
}
// If we have an unusual number of successors, throw an exception.
if (successors.Count != 2)
{
throw new InvalidOperationException(
$"Expected a block to have 2 successors, found {successors.Count}.");
}
// If the next relation is unknown, throw an exception.
if (substitutionCollection.NextRelation is NullLogicalValue)
{
throw new InvalidOperationException(
"A block had successors, but the next relation was unknown.");
}
Path nextPath;
if (cutSet.Contains(currentBlock))
{
// If we reached a cut point, end the current path.
nextPath = new Path();
paths.Add(currentPath);
}
else
{
// Otherwise, extend the current path.
nextPath = currentPath;
}
if (!visited.Contains(successors[0]))
{
paths.AddRange(GeneratePaths(successors[0], substitutionCollection.NextRelation, nextPath, cutSet, visited));
}
if (!visited.Contains(successors[1]))
{
paths.AddRange(GeneratePaths(successors[1], new LogicalNotValue(substitutionCollection.NextRelation), nextPath, cutSet, visited));
}
return(paths);
}