Examples with Formula kodkod.ast.Formula used on opensource projects

Example 61 with Formula

use of kodkod.ast.Formula in project org.alloytools.alloy by AlloyTools.

the class PrenexNFConverter method visit.

@Override
public Formula visit(BinaryFormula bf) {
    Formula ans;
    switch(bf.op()) {
        case AND:
        case OR:
            Formula left = bf.left().accept(this);
            Formula right = bf.right().accept(this);
            Pair p = new Pair(left, right);
            if (p.hasNoQuant() && left == bf.left() && right == bf.right())
                ans = bf;
            else
                ans = p.compose(bf.op());
            break;
        case IMPLIES:
            ans = bf.left().not().or(bf.right()).accept(this);
            break;
        case IFF:
            ans = bf.left().and(bf.right()).or(bf.left().not().and(bf.right().not())).accept(this);
            break;
        default:
            throw new IllegalStateException("Unknown BinaryFormula operator: " + bf.op());
    }
    return saveMapping(ans, bf);
}

Example 62 with Formula

use of kodkod.ast.Formula in project org.alloytools.alloy by AlloyTools.

the class Skolemizer method visit.

/**
 * If not cached, visits the formula's children with appropriate settings for
 * the negated flag and the skolemDepth parameter.
 *
 * @see kodkod.ast.visitor.AbstractReplacer#visit(kodkod.ast.BinaryFormula)
 */
@Override
public final Formula visit(BinaryFormula bf) {
    Formula ret = lookup(bf);
    if (ret != null)
        return ret;
    final FormulaOperator op = bf.op();
    final int oldDepth = skolemDepth;
    if (op == IFF || (negated && op == AND) || (!negated && (op == OR || op == IMPLIES))) {
        // cannot
        // skolemize
        // in
        // these
        // cases
        skolemDepth = -1;
    }
    final Formula left, right;
    if (negated && op == IMPLIES) {
        // !(a => b) = !(!a || b) = a && !b
        negated = !negated;
        left = bf.left().accept(this);
        negated = !negated;
        right = bf.right().accept(this);
    } else {
        left = bf.left().accept(this);
        right = bf.right().accept(this);
    }
    skolemDepth = oldDepth;
    ret = (left == bf.left() && right == bf.right()) ? bf : left.compose(op, right);
    return source(cache(bf, ret), bf);
}

Example 63 with Formula

use of kodkod.ast.Formula in project org.alloytools.alloy by AlloyTools.

the class Skolemizer method visit.

/**
 * Skolemizes the given formula, if possible, otherwise returns the result of
 * replacing its free variables according to the current replacement
 * environment.
 *
 * @see kodkod.ast.visitor.AbstractReplacer#visit(kodkod.ast.QuantifiedFormula)
 */
@Override
public final Formula visit(QuantifiedFormula qf) {
    Formula ret = lookup(qf);
    if (ret != null)
        return ret;
    final Environment<Expression, Expression> oldRepEnv = repEnv;
    final Quantifier quant = qf.quantifier();
    final Decls decls = qf.decls();
    if (skolemDepth >= 0 && (negated && quant == ALL || !negated && quant == SOME)) {
        // skolemizable
        // formula
        final List<Formula> rangeConstraints = new LinkedList<Formula>();
        final List<Formula> domConstraints = new LinkedList<Formula>();
        for (Decl decl : decls) {
            final Decl skolemDecl = visit(decl);
            Variable skVar = skolemDecl.variable();
            final Relation skolem = Relation.skolem("$" + skVar.name(), nonSkolems.size() + skVar.arity(), skVar, skolemDecl, quant);
            reporter.skolemizing(decl, skolem, nonSkolemsView);
            final Expression skolemExpr = skolemExpr(skolemDecl, skolem);
            final Multiplicity mult = decl.multiplicity();
            rangeConstraints.add(source(skolemExpr.in(skolemDecl.expression()), decl));
            if (mult != Multiplicity.SET) {
                rangeConstraints.add(source(skolemExpr.apply(mult), decl));
            }
            if (!nonSkolems.isEmpty())
                domConstraints.add(source(domainConstraint(skolemDecl, skolem), decl));
            repEnv = repEnv.extend(decl.variable(), decl.expression(), skolemExpr);
        }
        ret = source(Formula.and(rangeConstraints), decls).compose(negated ? IMPLIES : AND, qf.formula().accept(this));
        if (!domConstraints.isEmpty())
            topSkolemConstraints.add(source(Formula.and(domConstraints), decls));
    } else {
        // non-skolemizable formula
        final Decls newDecls = visit(qf.decls());
        if (skolemDepth >= nonSkolems.size() + newDecls.size()) {
            // below
            for (Decl d : newDecls) {
                nonSkolems.add(new DeclInfo(d));
            }
            final Formula domain = qf.domain().accept(this);
            final Formula body = qf.body().accept(this);
            ret = ((newDecls == decls && domain == qf.domain() && body == qf.body()) ? qf : body.quantify(quant, newDecls, domain));
            for (int i = newDecls.size(); i > 0; i--) {
                nonSkolems.remove(nonSkolems.size() - 1);
            }
        } else {
            // can't skolemize below
            final int oldDepth = skolemDepth;
            skolemDepth = -1;
            final Formula domain = qf.domain().accept(this);
            final Formula body = qf.body().accept(this);
            ret = ((newDecls == decls && domain == qf.domain() && body == qf.body()) ? qf : body.quantify(quant, newDecls, domain));
            skolemDepth = oldDepth;
        }
    }
    repEnv = oldRepEnv;
    if (repEnv.isEmpty() && !topSkolemConstraints.isEmpty()) {
        ret = source(Formula.and(topSkolemConstraints), qf).compose(negated ? IMPLIES : AND, ret);
    }
    return source(cache(qf, ret), qf);
}

Example 64 with Formula

use of kodkod.ast.Formula in project org.alloytools.alloy by AlloyTools.

the class Skolemizer method visit.

/**
 * Calls not.formula.accept(this) after flipping the negation flag and returns
 * the result.
 *
 * @see kodkod.ast.visitor.AbstractReplacer#visit(kodkod.ast.NotFormula)
 */
@Override
public final Formula visit(NotFormula not) {
    Formula ret = lookup(not);
    if (ret != null)
        return ret;
    // flip the negation flag
    negated = !negated;
    final Formula retChild = not.formula().accept(this);
    negated = !negated;
    return retChild == not.formula() ? cache(not, not) : source(cache(not, retChild.not()), not);
}

Example 65 with Formula

use of kodkod.ast.Formula in project org.alloytools.alloy by AlloyTools.

the class Skolemizer method visit.

/**
 * Calls super.visit(cf) after disabling skolemization and returns the result.
 *
 * @return super.visit(cf)
 */
@Override
public final Formula visit(ComparisonFormula cf) {
    final int oldDepth = skolemDepth;
    // cannot skolemize inside a comparison formula
    skolemDepth = -1;
    final Formula ret = super.visit(cf);
    skolemDepth = oldDepth;
    return source(ret, cf);
}