While_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.types.*;
import polyglot.util.CodeWriter;
import polyglot.util.Position;
import polyglot.visit.*;

/**
 * An immutable representation of a Java language <code>while</code>
 * statement.  It contains a statement to be executed and an expression
 * to be tested indicating whether to reexecute the statement.
 */ 
public abstract class While_c extends Loop_c implements While
{
    protected Expr cond;
    protected Stmt body;

    public While_c(Position pos, Expr cond, Stmt body) {
	super(pos);
	assert(cond != null && body != null);
	this.cond = cond;
	this.body = body;
    }

    /** Get the conditional of the statement. */
    public Expr cond() {
	return this.cond;
    }

    /** Set the conditional of the statement. */
    public While cond(Expr cond) {
	While_c n = (While_c) copy();
	n.cond = cond;
	return n;
    }

    /** Get the body of the statement. */
    public Stmt body() {
	return this.body;
    }

    /** Set the body of the statement. */
    public While body(Stmt body) {
	While_c n = (While_c) copy();
	n.body = body;
	return n;
    }

    /** Reconstruct the statement. */
    protected While_c reconstruct(Expr cond, Stmt body) {
	if (cond != this.cond || body != this.body) {
	    While_c n = (While_c) copy();
	    n.cond = cond;
	    n.body = body;
	    return n;
	}

	return this;
    }

    /** Visit the children of the statement. */
    public Node visitChildren(NodeVisitor v) {
	Expr cond = (Expr) visitChild(this.cond, v);
	Node body = visitChild(this.body, v);
        if (body instanceof NodeList) body = ((NodeList) body).toBlock();
	return reconstruct(cond, (Stmt) body);
    }

    /** Type check the statement. */
    public abstract Node typeCheck(ContextVisitor tc);

    public String toString() {
	return "while (" + cond + ") ...";
    }

    /** Write the statement to an output file. */
    public void prettyPrint(CodeWriter w, PrettyPrinter tr) {
	w.write("while (");
	printBlock(cond, w, tr);
	w.write(")");
	printSubStmt(body, w, tr);
    }

    public Term firstChild() {
        return cond;
    }

    public <S> List<S> acceptCFG(CFGBuilder v, List<S> succs) {
        if (condIsConstantTrue()) {
            v.visitCFG(cond, body, ENTRY);
        }
        else {
            v.visitCFG(cond, FlowGraph.EDGE_KEY_TRUE, body, 
                             ENTRY, FlowGraph.EDGE_KEY_FALSE, this, EXIT);
        }

        v.push(this).visitCFG(body, cond, ENTRY);

        return succs;
    }

    public Term continueTarget() {
        return cond;
    }
    

}