TypeObject_c.java

/*
 *  This file is part of the X10 project (http://x10-lang.org).
 *
 *  This file is licensed to You under the Eclipse Public License (EPL);
 *  You may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *      http://www.opensource.org/licenses/eclipse-1.0.php
 *
 * This file was originally derived from the Polyglot extensible compiler framework.
 *
 *  (C) Copyright 2000-2007 Polyglot project group, Cornell University
 *  (C) Copyright IBM Corporation 2007-2012.
 */

package polyglot.types;

import java.io.*;

import polyglot.util.*;

/**
 * Abstract implementation of a type object.  Contains a reference to the
 * type system and to the object's position in the code.
 */  
public abstract class TypeObject_c implements TypeObject
{
    private static final long serialVersionUID = -8428041030408667923L;

    protected transient TypeSystem ts;
    protected Position position;
    protected Position errorPosition;

    /** Used for deserializing types. */
    protected TypeObject_c() {
    }
    
    /** Creates a new type in the given a TypeSystem. */
    public TypeObject_c(TypeSystem ts) {
        this(ts, null, null);
    }

    public TypeObject_c(TypeSystem ts, Position pos, Position errorPos) {
	this.ts = ts;
	this.position = pos;
	this.errorPosition = errorPos;
    }

    public Object copy() {
        try {
            return (TypeObject_c) super.clone();
        }
        catch (CloneNotSupportedException e) {
            throw new InternalCompilerError("Java clone() weirdness.");
        }
    }

    @SuppressWarnings("unchecked") // Casting to a generic type parameter
    public <T> T copyGeneric() {
        return (T) copy();
    }

    public TypeSystem typeSystem() {
        return ts;
    }

    public Position position() {
        return position;
    }
    
    public Position errorPosition() {
    	return errorPosition;
    }

    private void writeObject(ObjectOutputStream out) throws IOException {
        out.defaultWriteObject();
    }

    private void readObject(ObjectInputStream in) throws IOException,
					       ClassNotFoundException {
	if (in instanceof TypeInputStream) {
	    ts = ((TypeInputStream) in).getTypeSystem();
	}

        in.defaultReadObject();
    }
    

    /**
     * Return whether o is structurally equivalent to o.
     * Implementations should override equalsImpl().
     */
    public final boolean equals(Object o) {
        return o instanceof TypeObject && ts.equals(this, (TypeObject) o);
    }

    public int hashCode() {
        return super.hashCode();
    }
    
    /**
     * Default implementation is pointer equality.
     */
    public boolean equalsImpl(TypeObject t) {
        return t == this;
    }

    /**
     * Overload equalsImpl to find inadvertent overriding errors.
     * Make package-scope and void to break callers.
     */ 
    public final void equals(TypeObject t) { assert false; }
    public final void equals(Type t) { assert false; }
    public final void equalsImpl(Type t) { assert false; }
    public final void equalsImpl(Object o) { assert false; }
    public final void typeEqualsImpl(Object o) { assert false; }
    public final void typeEqualsImpl(TypeObject o) { assert false; }
}