opexpr.java

用Java实现的编译器。把源代码编译成SPARC汇编程序

// $Id: OpExpr.java,v 1.3 1999/09/29 06:20:44 deberg Exp $

package java6035.tools.IR;

/**
 * OpExpr represents an operation expression. The operation is defined as 
 * an integer opcode, meaningful to the program using this class.
 */

public class OpExpr extends Expression
{
    protected int opcode;
    protected Rhs left_operand;
    protected Rhs right_operand;

    /**
     * Constructs an operation with no operand.
     */
    public OpExpr(int opcode)
    {
	this.opcode = opcode;
	this.left_operand = null;
	this.right_operand = null;
    }

    /**
     * Constructs an unary expression.
     */
    public OpExpr(int opcode, Rhs operand)
    {
	this.opcode = opcode;
	this.left_operand = operand;
	this.right_operand = null;
    }

    /**
     * Constructs a binary expression.
     */
    public OpExpr(int opcode, Rhs left_operand, Rhs right_operand)
    {
	this.opcode = opcode;
	this.left_operand = left_operand;
	this.right_operand = right_operand;
    }

    protected int expkind()
    {
	return OP_EXPR;
    }

    /**
     * Returns true if expression is unary.
     */
    public boolean isUnary()
    {
	return (left_operand != null && right_operand == null);
    }

    /**
     * Returns the opcode.
     */
    public int getOpcode()
    {
	return opcode;
    }

    /**
     * Returns the left operand.
     */
    public Rhs getLeftOperand()
    {
	return left_operand;
    }

    /**
     * Sets the left operand.
     */
    public void setLeftOperand(Rhs l)
    {
	this.left_operand = l;
    }

    /**
     * Returns the right operand.
     */
    public Rhs getRightOperand()
    {
	return right_operand;
    }

    /**
     * Sets the left operand.
     */
    public void setRightOperand(Rhs r)
    {
	this.right_operand = r;
    }

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

    /**
     * Walkable interface: returns the number of neighbors.
     */
    public int getNeighborCount()
    {
	if (isUnary())
	    return 1;
	else
	    return 2;
    }

    /**
     * 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 left_operand;
	else if (index == 1 && !isUnary())
	    return right_operand;
	return null;
    }

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

        if (recursive) {
            if (left_operand != null) {
                output += this.left_operand.PPrint(indent+2, true);
            } else {
                for(int i=0;i<indent+2;i++) output += " ";
                output += "(no left operand)\n";
            }

            if (right_operand != null) {
                output += this.right_operand.PPrint(indent+2, true);
            } else {
                for(int i=0;i<indent+2;i++) output += " ";
                output += "(no right operand)\n";
            }
        }

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

        return output;
    }
}