memory.java

symbman（大学作业）

import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import java.io.*;


public class Memory {
	private static Hashtable state = new Hashtable();
	
	public static Expression read(Symbol s) {
		return (Expression)state.get(s.getName());
	}

	public static void write(Symbol s, Expression e) {
		state.put(s.getName(), e);
	}
	
	public static void dump(String fn) throws IOException {
		FileOutputStream os = new FileOutputStream(fn);
		PrintWriter p = new PrintWriter(os);
		Iterator it = state.entrySet().iterator();
		
		while(it.hasNext()) {
			Map.Entry m = (Map.Entry)it.next();
			p.println((Symbol)m.getKey() + "=" + (Expression)m.getValue());
		}
		
		p.close();
		os.close();
	}
	
	public static void screenDump() throws IOException {
		Iterator it = state.entrySet().iterator();
		
		while(it.hasNext()) {
			Map.Entry m = (Map.Entry)it.next();
			System.out.println((String)m.getKey()+"=" + (Expression)m.getValue());
		}

		
	}
}