org.getobjects.rules.RuleModel.java Source code

Introduction

Here is the source code for org.getobjects.rules.RuleModel.java

Source

/*
  Copyright (C) 2006-2007 Helge Hess
    
  This file is part of Go.
    
  Go is free software; you can redistribute it and/or modify it under
  the terms of the GNU Lesser General Public License as published by the
  Free Software Foundation; either version 2, or (at your option) any
  later version.
    
  Go is distributed in the hope that it will be useful, but WITHOUT ANY
  WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  License for more details.
    
  You should have received a copy of the GNU Lesser General Public
  License along with Go; see the file COPYING.  If not, write to the
  Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.
*/

package org.getobjects.rules;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.getobjects.eocontrol.EOBooleanQualifier;
import org.getobjects.eocontrol.EOCompoundQualifier;
import org.getobjects.eocontrol.EOQualifier;
import org.getobjects.foundation.NSObject;

/**
 * RuleModel
 * <p>
 * A rule model is a container for a set of rule objects (Rule). The model
 * will select candidate rules for a given key. Candidates rules are sorted
 * by various parameters.
 * 
 * @see Rule 
 */
public class RuleModel extends NSObject implements Comparator {
    protected static Log log = LogFactory.getLog("GoRules");

    protected Rule[] rules;

    public RuleModel(Rule[] _rules) {
        this.rules = _rules;
    }

    /* accessors */

    public void setRules(Rule[] _rules) {
        this.rules = _rules;
    }

    public Rule[] rules() {
        return this.rules;
    }

    public void addRule(Rule _rule) {
        if (_rule == null)
            return;
        if (this.rules == null)
            this.rules = new Rule[] { _rule };
        else {
            Rule[] oldRules = this.rules;
            this.rules = new Rule[oldRules.length + 1];

            System.arraycopy(oldRules, 0, this.rules, 0, oldRules.length);
            this.rules[oldRules.length] = _rule;
        }
    }

    public void addRules(Rule[] _rules) {
        if (_rules == null || _rules.length == 0)
            return;
        if (this.rules == null)
            this.rules = new Rule[0];

        Rule[] oldRules = this.rules;
        this.rules = new Rule[oldRules.length + _rules.length];

        System.arraycopy(oldRules, 0, this.rules, 0, oldRules.length);
        System.arraycopy(_rules, 0, this.rules, oldRules.length, _rules.length);
    }

    /* operations */

    @SuppressWarnings("unchecked")
    public Rule[] candidateRulesForKey(String _key) {
        if (this.rules == null)
            return null;

        List<Rule> candidatesList = new ArrayList<Rule>(4);
        for (int i = 0; i < this.rules.length; i++) {
            if (this.rules[i].isCandidateForKey(_key))
                candidatesList.add(this.rules[i]);
        }

        /* sort convertes to array anyway ... */
        Rule[] candidates = candidatesList.toArray(new Rule[0]);

        /* sort candidates */
        Arrays.sort(candidates, this);
        return candidates;
    }

    /* we act as a comparator for candidates */

    public int compare(Object _o1, Object _o2) {
        if (_o1 == _o2)
            return 0;
        if (_o2 == null)
            return 1;
        if (_o1 == null)
            return -1;

        Rule rule1 = (Rule) _o1, rule2 = (Rule) _o2;

        /* compare priorities */
        int pri1 = rule1.priority(), pri2 = rule2.priority();
        if (pri1 != pri2)
            return pri1 < pri2 ? 1 : -1;

        /* compare qualifier "width" */

        EOQualifier q = rule1.qualifier();
        if (q == null)
            pri1 = -1; /* very short */
        else if (q instanceof EOBooleanQualifier)
            pri1 = -1; /* very short */ // TODO: check whether its true!
        else if (q instanceof EOCompoundQualifier)
            pri1 = ((EOCompoundQualifier) q).qualifiers().length;
        else
            pri1 = 0;

        q = rule2.qualifier();
        if (q == null)
            pri2 = -1; /* very short */
        else if (q instanceof EOBooleanQualifier)
            pri2 = -1; /* very short */ // TODO: check whether its true!
        else if (q instanceof EOCompoundQualifier)
            pri2 = ((EOCompoundQualifier) q).qualifiers().length;
        else
            pri2 = 0;

        if (pri1 != pri2)
            return pri1 < pri2 ? 1 : -1;

        return 0 /* same priority */;
    }

    @Override
    public boolean equals(Object _obj) {
        return this == _obj;
    }

    @Override
    public void appendAttributesToDescription(StringBuilder _d) {
        super.appendAttributesToDescription(_d);

        if (this.rules == null || this.rules.length == 0)
            _d.append(" no-rules");
        else
            _d.append(" rules=" + Arrays.asList(this.rules));
    }
}