arrayexpr.java

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// $Id: ArrayExpr.java,v 1.4 2000/10/10 15:47:50 mdeeds Exp $

package java6035.tools.IR;

/**
 * ArrayExpr represents an array reference.
 */

public class ArrayExpr extends Expression implements Lhs
{
    protected Rhs base;
    protected Rhs offset;

    /**
     * Constructs an Array Expression where @param(base) is the 
     * array variable, and @param(offset) is the index into the
     * array.
     *
     * Requires: base, offset are not null.
     **/
    public ArrayExpr(Rhs base, Rhs offset)
    {
	this.base = base;
	this.offset = offset;

	if (this.base == null)
	    throw new IRException
		("ArrayExpr: constructor: base null");

	if (this.offset == null)
	    throw new IRException
		("ArrayExpr: constructor: offset null");
    }

    /**
     * Returns the globally specified ID for this type of Expression.
     * (i.e. ARRAY_EXPR)
     **/
    protected int expkind()
    {
	return ARRAY_EXPR;
    }

    /**
     * Returns the base (array variable) of this.
     **/
    public Rhs getBase()
    {
	return base;
    }

    /**
     * Sets the base (array variable) of this.
     **/
    public void setBase(Rhs base)
    {
	this.base = base;

	if (this.base == null)
	    throw new IRException("ArrayExpr: setBase: base null");
    }

    /**
     * Returns the offset (index) of this.
     **/
    public Rhs getOffset()
    {
	return offset;
    }

    /**
     * Sets the offset (index) of this.
     **/
    public void setOffset(Rhs offset)
    {
	this.offset = offset;

	if (this.offset == null)
	    throw new IRException("ArrayExpr: setOffset: offset null");
    }

    /**
     * Walkable interface: returns the name of the node.
     **/
    public String getNodeName()
    {
	return "array_expr";
    }

    /**
     * Walkable interface: returns the number of neighbors (children)
     * in the IR tree.  These are the base and the offset.  i.e. 2.
     **/
    public int getNeighborCount()
    {
	return 2;
    }

    /**
     * Walkable interface: returns the specified neighbor.
     * specify 0 for base, and 1 for offset
     **/
    public Object getNeighbor(int index)
    {
	if (index == 0)
	    return base;
	else
	    return offset;
    }

    public String PPrint(int indent, boolean recursive)
    {
        String output = new String();
        for(int i=0;i<indent;i++) output += " ";
        output += "(array_expr\n";

        if (recursive) {
            output += base.PPrint(indent+2, true);
            output += offset.PPrint(indent+2, true);
        }

        for(int i=0;i<indent;i++) output += " ";
        output += ") /* array_expr */\n";

        return output;
    }
}