internal TermComparison CompareTo(TriggerTerm other)
{
if (this == other)
{
return(TermComparison.SameStrength);
}
else if (Expr.AllSubExpressions(true, true).Any(other.Expr.ExpressionEq))
{
return(TermComparison.Stronger);
}
else
{
return(TermComparison.NotStronger);
}
}
/// <summary>
/// Simple formulas like [P0(i) && P1(i) && P2(i) && P3(i) && P4(i)] yield very
/// large numbers of multi-triggers, most of which are useless. As it copies its
/// argument, this method updates various datastructures that allow it to
/// efficiently track ownership relations between formulae and bound variables,
/// and sets the IsRedundant flag of the returned set, allowing the caller to
/// discard that set of terms, and the ones that would have been built on top of
/// it, thus ensuring that the only sets of terms produced in the end are sets
/// of terms in which each element contributes (owns) at least one variable.
///
/// Note that this is trickier than just checking every term for new variables;
/// indeed, a new term that does bring new variables in can make an existing
/// term redundant (see redundancy-detection-does-its-job-properly.dfy).
/// </summary>
internal SetOfTerms CopyWithAdd(TriggerTerm term, ISet <BoundVar> relevantVariables)
{
var copy = new SetOfTerms();
copy.Terms = new List <TriggerTerm>(Terms);
copy.variables = new HashSet <BoundVar>(variables);
copy.termOwningAUniqueVar = new Dictionary <BoundVar, TriggerTerm>(termOwningAUniqueVar);
copy.uniqueVarsOwnedByATerm = new Dictionary <TriggerTerm, ISet <BoundVar> >(uniqueVarsOwnedByATerm);
copy.Terms.Add(term);
var varsInNewTerm = new HashSet <BoundVar>(term.BoundVars);
varsInNewTerm.IntersectWith(relevantVariables);
var ownedByNewTerm = new HashSet <BoundVar>();
// Check #0: does this term bring anything new?
copy.IsRedundant = IsRedundant || varsInNewTerm.All(bv => copy.variables.Contains(bv));
copy.variables.UnionWith(varsInNewTerm);
// Check #1: does this term claiming ownership of all its variables cause another term to become useless?
foreach (var v in varsInNewTerm)
{
TriggerTerm originalOwner;
if (copy.termOwningAUniqueVar.TryGetValue(v, out originalOwner))
{
var alsoOwnedByOriginalOwner = copy.uniqueVarsOwnedByATerm[originalOwner];
alsoOwnedByOriginalOwner.Remove(v);
if (!alsoOwnedByOriginalOwner.Any())
{
copy.IsRedundant = true;
}
}
else
{
ownedByNewTerm.Add(v);
copy.termOwningAUniqueVar[v] = term;
}
}
// Actually claim ownership
copy.uniqueVarsOwnedByATerm[term] = ownedByNewTerm;
return(copy);
}
private TriggerAnnotation AnnotatePotentialCandidate(Expression expr)
{
bool expr_is_killer = false;
HashSet <OldExpr> oldExprSet;
if (cache.exprsInOldContext.TryGetValue(expr, out oldExprSet))
{
// oldExpr has been set to the value found
}
else
{
oldExprSet = null;
}
var new_exprs = TriggerUtils.MaybeWrapInOld(TriggerUtils.PrepareExprForInclusionInTrigger(expr, out expr_is_killer), oldExprSet);
// We expect there to be at least one "new_exprs".
// We also expect that the computation of new_term.Variables, collected_terms, and children_contain_killers will be the
// same for each of the "new_exprs".
// Therefore, we use the values of these variables from the last iteration in the expression that is ultimately returned.
TriggerTerm new_term = null;
List <TriggerTerm> collected_terms = null;
var children_contain_killers = false;
foreach (var new_expr in new_exprs)
{
new_term = new TriggerTerm {
Expr = new_expr, OriginalExpr = expr, Variables = CollectVariables(expr)
};
collected_terms = CollectExportedCandidates(expr);
children_contain_killers = CollectIsKiller(expr);
if (!children_contain_killers)
{
// Add only if the children are not killers; the head has been cleaned up into non-killer form
collected_terms.Add(new_term);
}
}
Contract.Assert(new_term != null); // this checks our assumption that "new_exprs" contains at least one value.
// This new node is a killer if its children were killers, or if it's non-cleaned-up head is a killer
return(new TriggerAnnotation(children_contain_killers || expr_is_killer, new_term.Variables, collected_terms));
}
internal static bool Eq(TriggerTerm t1, TriggerTerm t2)
{
return(ExprExtensions.ExpressionEq(t1.Expr, t2.Expr));
}
private bool SubsetGenerationPredicate(TriggerUtils.SetOfTerms terms, TriggerTerm additionalTerm)
{
return(true); // FIXME Remove this
//return additionalTerm.Variables.Where(v => v is BoundVar && !terms.Any(t => t.Variables.Contains(v))).Any();
}