source: fedd/abac-src/ttg/process/WeightTable.java @ eec716b

package com.nailabs.abac.process;

import edu.stanford.peer.rbtm.credential.*;
import java.util.*;
import java.io.*;

public class WeightTable {

    private int serialNo = 0;

    protected Hashtable table = new Hashtable(20);

    protected float p = 0.50f;

    protected final float SAT = 1.0f;

    protected final float FAIL = 0.0f;

    public float DEFAULT = 1.0f;

    public WeightTable(String file, float p) {
        this(file);
        this.p  = p;
    }

    public WeightTable(String file) { load(file);  }

    public void load(String filename) {
        try {
            BufferedReader in = new BufferedReader(new FileReader(filename));
            while(true) {
                String line = in.readLine();
                StringTokenizer st = new StringTokenizer(line, "=");
                EntityExpression expr = 
                    StaticCredential.getEntityExpression(st.nextToken());
                Float weight = new Float(st.nextToken());
                table.put(expr, weight);
            }
        } catch(Exception ex) {
            //ex.printStackTrace();
        }
    }
  
    public void save(String filename) {
        try {
            PrintStream out = new PrintStream(new FileOutputStream(filename));
            Iterator i = table.keySet().iterator();
            while(i.hasNext()) {
                EntityExpression key = (EntityExpression)i.next();
                Float entry = (Float)table.get(key);
                out.println(key + "=" + getWeight(key));
            }
        } catch(Exception ex) {
            ex.printStackTrace();
        }
    }

    public float getWeight(EntityExpression r) {
        Float val = (Float)table.get(r);
        if(val == null) {
            val = new Float(DEFAULT); 
            table.put(r, val);
        }
        return val.floatValue();
    }

    public void addSatisfied(EntityExpression r) { 
        Float val =  (Float)table.get(r);
        if(val == null) {
            val = new Float(DEFAULT);
        }
        val = new Float(update(val.floatValue(), SAT));
        table.put(r, val);
    }

    public void addFailed(EntityExpression r) {
        Float val =  (Float)table.get(r);
        if(val == null) {
            val = new Float(DEFAULT);
        }
        val = new Float(update(val.floatValue(), FAIL));
        table.put(r, val);
    }

    protected float update(float val, float u) {
        if(u == 1.0f) 
            return 1.0f;
        else 
            return (val * (1.0f - p) + u * p);
    }

}