TypeNode_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.ast;

import java.util.List;

import polyglot.frontend.SetResolverGoal;
import polyglot.types.*;
import polyglot.util.CodeWriter;
import polyglot.util.Position;
import polyglot.visit.*;

/**
 * A <code>TypeNode</code> is the syntactic representation of a 
 * <code>Type</code> within the abstract syntax tree.
 */
public abstract class TypeNode_c extends Term_c implements TypeNode
{
    /**
     * A reference to the computed type for the node. Is is VERY
     * important that this reference not change as the node is transformed.
     * Other TypeObjects have a copy of the reference. When the TypeNode is
     * disambiguated, the reference should be updated rather than a new
     * reference created.
     */
    protected Ref<? extends Type> type;

    public TypeNode_c(Position pos) {
    	super(pos);
    }
    
    /** Get the type as a qualifier. */
    public Ref<? extends Qualifier> qualifierRef() {
        return typeRef();
    }

    /** Get the type this node encapsulates. */
    public Ref<? extends Type> typeRef() {
	return this.type;
    }

    public Type type() {
        return Types.get(this.type);
    }

    /** Set the type this node encapsulates. */
    public TypeNode typeRef(Ref<? extends Type> type) {
	TypeNode_c n = (TypeNode_c) copy();
	assert(type != null);
	n.type = type;
	return n;
    }

    public Node buildTypes(TypeBuilder tb) {
        if (type == null) {
            TypeSystem ts = tb.typeSystem();
            return typeRef(Types.lazyRef(ts.unknownType(position()), new SetResolverGoal(tb.job()).intern(tb.job().extensionInfo().scheduler())));
        }
        else {
            return this;
        }
    }
    
    public void setResolver(Node parent, final TypeCheckPreparer v) {
    	if (typeRef() instanceof LazyRef<?>) {
    		LazyRef<Type> r = (LazyRef<Type>) typeRef();
    		TypeChecker tc = new TypeChecker(v.job(), v.typeSystem(), v.nodeFactory(), v.getMemo());
            // we use this resolver to disambiguate type nodes (e.g., the superclass, the superinterfaces)
            // therefore freezing is not needed (we only add more types and variables)
    		tc = (TypeChecker) tc.context(v.context().freeze());
    		r.setResolver(new TypeCheckTypeGoal(parent, this, tc, r, false));
    	}
    }
	
    public Term firstChild() {
        return null;
    }

    public <S> List<S> acceptCFG(CFGBuilder v, List<S> succs) {
        return succs;
    }

    public String toString() {
	if (type != null) {
	    return type.toString();
	}
	else {
	    return "<unknown type>";
	}
    }

    public abstract void prettyPrint(CodeWriter w, PrettyPrinter tr);

    public String nameString() {
        Type t = type();
        return t.name().toString();
    }
}