/*******************************************************************************
 * This file is part of the Polyglot extensible compiler framework.
 *
 * Copyright (c) 2000-2012 Polyglot project group, Cornell University
 * Copyright (c) 2006-2012 IBM Corporation
 * All rights reserved.
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License v1.0 which accompanies this
 * distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * This program and the accompanying materials are made available under
 * the terms of the Lesser GNU Public License v2.0 which accompanies this
 * distribution.
 * 
 * The development of the Polyglot project has been supported by a
 * number of funding sources, including DARPA Contract F30602-99-1-0533,
 * monitored by USAF Rome Laboratory, ONR Grants N00014-01-1-0968 and
 * N00014-09-1-0652, NSF Grants CNS-0208642, CNS-0430161, CCF-0133302,
 * and CCF-1054172, AFRL Contract FA8650-10-C-7022, an Alfred P. Sloan 
 * Research Fellowship, and an Intel Research Ph.D. Fellowship.
 *
 * See README for contributors.
 ******************************************************************************/
package polyglot.ext.jl7.ast;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import polyglot.ast.Ambiguous;
import polyglot.ast.Node;
import polyglot.ast.TypeNode;
import polyglot.ast.TypeNode_c;
import polyglot.ext.jl7.types.JL7TypeSystem;
import polyglot.types.ReferenceType;
import polyglot.types.SemanticException;
import polyglot.types.Type;
import polyglot.util.CodeWriter;
import polyglot.util.CollectionUtil;
import polyglot.util.Position;
import polyglot.util.SerialVersionUID;
import polyglot.visit.AmbiguityRemover;
import polyglot.visit.NodeVisitor;
import polyglot.visit.PrettyPrinter;

public class AmbUnionType extends TypeNode_c implements Ambiguous {
    private static final long serialVersionUID = SerialVersionUID.generate();

    private List<TypeNode> alternatives;

    public AmbUnionType(Position pos, List<TypeNode> alternatives) {
        super(pos);
        this.alternatives = alternatives;
    }

    protected AmbUnionType reconstruct(List<TypeNode> alternatives) {
        if (!CollectionUtil.equals(alternatives, this.alternatives)) {
            AmbUnionType aut = (AmbUnionType) this.copy();
            aut.alternatives = alternatives;
            return aut;
        }
        return this;
    }

    @Override
    public Node visitChildren(NodeVisitor v) {
        List<TypeNode> alternatives = new ArrayList<>(this.alternatives.size());
        for (TypeNode tn : this.alternatives) {
            alternatives.add(visitChild(tn, v));
        }
        return reconstruct(alternatives);
    }

    @Override
    public Node disambiguate(AmbiguityRemover sc) throws SemanticException {
        List<ReferenceType> types = new ArrayList<>(this.alternatives.size());
        for (TypeNode tn : this.alternatives) {
            if (!tn.isDisambiguated()) {
                return this;
            }
            types.add((ReferenceType) tn.type());
        }

        JL7TypeSystem ts = (JL7TypeSystem) sc.typeSystem();
        Type t;
        if (types.size() == 1) {
            t = types.get(0);
        }
        else {
            t = ts.lub(this.position(), types);
        }
        return sc.nodeFactory().CanonicalTypeNode(this.position, t);
    }

    @Override
    public void prettyPrint(CodeWriter w, PrettyPrinter tr) {
        Iterator<TypeNode> i = this.alternatives.iterator();
        while (i.hasNext()) {
            TypeNode a = i.next();
            tr.lang().prettyPrint(a, w, tr);
            if (i.hasNext()) {
                w.write("|");
            }
        }
    }
}
