bufferaccess.java

来自「tinyos最新版」· Java 代码 · 共 83 行

/*									tab:4
 * "Copyright (c) 2000-2003 The Regents of the University  of California.  
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement is
 * hereby granted, provided that the above copyright notice, the following
 * two paragraphs and the author appear in all copies of this software.
 * 
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS."
 *
 * Copyright (c) 2002-2003 Intel Corporation
 * All rights reserved.
 *
 * This file is distributed under the terms in the attached INTEL-LICENSE     
 * file. If you do not find these files, copies can be found by writing to
 * Intel Research Berkeley, 2150 Shattuck Avenue, Suite 1300, Berkeley, CA, 
 * 94704.  Attention:  Intel License Inquiry.
 */
package net.tinyos.script.tree;

import java.io.*;
import java.util.*;
import java_cup.runtime.Symbol;
import net.tinyos.script.*;

public class BufferAccess extends Expression {
    private String name;
    private Expression index = null;
    private Symbol symbol;
    
    public BufferAccess(String name, Symbol s) {
	this.name = name;
	this.symbol = s;
    }
    
    public BufferAccess(String name, Symbol s, Expression index) {
	this.name = name;
	this.symbol = s;
	this.index = index;
    }
    
    public String toString() {
	String val = name + "[";
	if (index != null) {val+= index.toString();}
	val+="]";
	return val;
    }

    public void checkStatement(SymbolTable table) throws SemanticException {
	if (!table.bufferDeclared(name)) {
	    throw new SemanticException("Buffer " + name + " not declared: " + symbol.value + ".\n");
	}
    }

    public void generateCode(SymbolTable table, CodeWriter writer) throws IOException {
	int i = table.getBuffer(name);
	writer.writeInstr("bpush3 " + i);
	if (index != null) {
	    //if (index instanceof ConstantExpression) {
	    //ConstantExpression ce = (ConstantExpression) index;
	    //writer.writeInstr("bget " + ce.value());
	    //}
	    //else {
	    index.generateCode(table, writer);
	    writer.writeInstr("bread");
	    //}
	}
	else {
	    writer.writeInstr("btail");
	}	
    }
}