/* Alloy Analyzer 4 -- Copyright (c) 2006-2009, Felix Chang
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
 * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package edu.mit.csail.sdg.alloy4compiler.ast;

import java.util.Collection;
import edu.mit.csail.sdg.alloy4.Pos;
import edu.mit.csail.sdg.alloy4.Err;
import edu.mit.csail.sdg.alloy4.ErrorWarning;
import edu.mit.csail.sdg.alloy4.JoinableList;
import static edu.mit.csail.sdg.alloy4compiler.ast.Type.EMPTY;

/** Immutable; represents a custom node.
 *
 * <p> <b>Invariant:</b>  this.type==EMPTY && this.errors.size()==1
 */

public abstract class ExprCustom extends Expr {

    /** {@inheritDoc} */
    @Override public Pos span() { return pos; }

    /** Constructs an ExprCustom object.
     * @param pos - the Pos for this expression (can be Pos.UNKNOWN if unknown)
     * @param error - the error to display if this node does not get desugared
     */
    public ExprCustom(Pos pos, Err error) {
        super(pos, null, false, EMPTY, 0, 0, new JoinableList<Err>(error));
        if (error==null) throw new NullPointerException();
    }

    /** {@inheritDoc} */
    @Override public Expr resolve(Type t, Collection<ErrorWarning> warns) { return this; }

    /** {@inheritDoc} */
    @Override public final<T> T accept(VisitReturn<T> visitor) throws Err { throw errors.pick(); }
}