/** Partially evaluate the right-hand side and the conditions of a specified rule. */
private static Rule evaluateRule(Rule rule, TermContext termContext) {
try {
// TODO(AndreiS): some evaluation is required in the LHS as well
// TODO(YilongL): cannot simply uncomment the following code because it
// may evaluate the LHS using the rule itself
// Term leftHandSide = rule.leftHandSide().evaluate(termContext);
Rule origRule = rule;
Term rightHandSide = rule.rightHandSide().evaluate(termContext);
List<Term> requires = new ArrayList<>();
for (Term term : rule.requires()) {
requires.add(term.evaluate(termContext));
}
List<Term> ensures = new ArrayList<>();
for (Term term : rule.ensures()) {
ensures.add(term.evaluate(termContext));
}
ConjunctiveFormula lookups = ConjunctiveFormula.of(termContext);
for (Equality equality : rule.lookups().equalities()) {
lookups =
lookups.add(
equality.leftHandSide().evaluate(termContext),
equality.rightHandSide().evaluate(termContext));
}
Map<CellLabel, Term> rhsOfWriteCell = null;
if (rule.isCompiledForFastRewriting()) {
rhsOfWriteCell = new HashMap<>();
for (Map.Entry<CellLabel, Term> entry : rule.rhsOfWriteCell().entrySet()) {
rhsOfWriteCell.put(entry.getKey(), entry.getValue().evaluate(termContext));
}
}
Rule newRule =
new Rule(
rule.label(),
rule.leftHandSide(),
rightHandSide,
requires,
ensures,
rule.freshConstants(),
rule.freshVariables(),
lookups,
rule.isCompiledForFastRewriting(),
rule.lhsOfReadCell(),
rhsOfWriteCell,
rule.cellsToCopy(),
rule.matchingInstructions(),
rule,
termContext);
return newRule.equals(rule) ? origRule : newRule;
} catch (KEMException e) {
e.exception.addTraceFrame(
"while compiling rule at location " + rule.getSource() + rule.getLocation());
throw e;
}
}
@Override
public void visit(Rule rule) {
rule.leftHandSide().accept(this);
rule.rightHandSide().accept(this);
rule.lookups().accept(this);
for (Term term : rule.requires()) {
term.accept(this);
}
for (Term term : rule.ensures()) {
term.accept(this);
}
for (Variable variable : rule.freshVariables()) {
variable.accept(this);
}
}
private void narrowByRule(ConstrainedTerm constrainedTerm, Rule rule) {
stopwatch.reset();
stopwatch.start();
constrainedTermResults = new ArrayList<ConstrainedTerm>();
SymbolicConstraint leftHandSideConstraint =
new SymbolicConstraint(constrainedTerm.termContext());
leftHandSideConstraint.addAll(rule.requires());
for (Variable variable : rule.freshVariables()) {
leftHandSideConstraint.add(variable, IntToken.fresh());
}
ConstrainedTerm leftHandSide =
new ConstrainedTerm(
rule.leftHandSide(),
rule.lookups().getSymbolicConstraint(constrainedTerm.termContext()),
leftHandSideConstraint,
constrainedTerm.termContext());
for (SymbolicConstraint constraint : constrainedTerm.unify(leftHandSide)) {
constraint.addAll(rule.ensures());
/* rename rule variables in the constraints */
Map<Variable, Variable> freshSubstitution = constraint.rename(rule.variableSet());
Term result = rule.rightHandSide();
/* rename rule variables in the rule RHS */
result = result.substituteWithBinders(freshSubstitution, constrainedTerm.termContext());
/* apply the constraints substitution on the rule RHS */
result =
result.substituteWithBinders(constraint.substitution(), constrainedTerm.termContext());
/* evaluate pending functions in the rule RHS */
result = result.evaluate(constrainedTerm.termContext());
/* eliminate anonymous variables */
constraint.eliminateAnonymousVariables();
/* compute all results */
constrainedTermResults.add(
new ConstrainedTerm(result, constraint, constrainedTerm.termContext()));
}
stopwatch.stop();
}
// apply rule by matching
private void rewriteByRule(Term term, Rule rule) {
stopwatch.reset();
stopwatch.start();
termResults = new ArrayList<Term>();
TermContext context = TermContext.of(definition);
ConstrainedTerm constrainedTerm = new ConstrainedTerm(term, context);
SymbolicConstraint leftHandSideConstraint = new SymbolicConstraint(context);
leftHandSideConstraint.addAll(rule.requires());
for (Variable variable : rule.freshVariables()) {
leftHandSideConstraint.add(variable, IntToken.fresh());
}
ConstrainedTerm leftHandSide =
new ConstrainedTerm(
rule.leftHandSide(),
rule.lookups().getSymbolicConstraint(context),
leftHandSideConstraint,
context);
for (SymbolicConstraint constraint : constrainedTerm.unify(leftHandSide)) {
if (!constraint.isMatching(leftHandSide)) {
continue;
}
constraint.orientSubstitution(leftHandSide.variableSet());
Term result = rule.rightHandSide();
/* apply the constraints substitution on the rule RHS */
result = result.substituteAndEvaluate(constraint.substitution(), context);
/* compute all results */
termResults.add(result);
}
stopwatch.stop();
}