varexpr.java

用Java实现的编译器。把源代码编译成SPARC汇编程序

// $Id: VarExpr.java,v 1.4 2000/10/21 22:44:34 mdeeds Exp $

package java6035.tools.IR;

/**
 * VarExpr represents a variable expression.
 */

public class VarExpr extends Expression
{
    protected VarDescriptor var;

    /**
     * Creates a new VarExpression for the @param var.
     * This should be the symboltable entry for @param var.
     **/
    public VarExpr(VarDescriptor var)
    {
        this.var = var;
    }

    /**
     * Returns the kind of this expression. (i.e. VAR_EXPR)
     **/
    protected int expkind()
    {
	return VAR_EXPR;
    }

    /**
     * Returns the variable descriptor.  (Not a clone.)
     **/
    public VarDescriptor getOperand()
    {
	return var;
    }

    /**
     * Sets the variable descriptor.
     **/
    public void setOperand(VarDescriptor v)
    {
	this.var = v;
    }

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

    /**
     * Walkable interface: returns the number of neighbors.
     */
    public int getNeighborCount()
    {
        return 1;
    }

    /**
     * Walkable interface: returns the specified neighbor: 0, left operand; 1,
     * right operand if operation is binary.
     */
    public Object getNeighbor(int index)
    {
	if (index == 0)
	    return var;
	return null;
    }

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

        if (recursive) output += var.PPrint(indent+2, true);

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

        return output;
    }
}