public static RulesetFrame getRulesetFrame(string key)
{
RulesetFrame frame = (RulesetFrame)getInstance().rulesetFrames[key];
if (frame == null)
{
throw new FrameIsNotFound("The ruleset " + key + " is not found");
}
return((RulesetFrame)getInstance().rulesetFrames[key]);
}
public static bool forwardChaining(string rulesetName, string goal)
{
IList candidates1 = new ArrayList(); // candidates that have high proirity (first lane)
IList candidates2 = new ArrayList(); // candidates that have low priority (second lane)
RulesetFrame ruleset = CSharpExpertAbstract.getRulesetFrame(rulesetName);
if (!ruleset.isContextInitialized)
{
throw new KnowledgeException("Context of ruleset \"" + rulesetName + "\" must be initialized before consulting");
}
if (!ruleset.isParamsInitialized)
{
throw new KnowledgeException("Parameters of ruleset \"" + rulesetName + "\" must be set before consulting");
}
foreach (Rule rule in ruleset.getRules().Values)
{
if (rule.condition() == true &&
!((IList)statesByRule[rule.getName()]).Contains(ruleset.getParams()))
{
if (firedRules.Contains(rule))
{
candidates2.Add(rule);
}
else
{
candidates1.Add(rule);
}
}
}
if (candidates1.Count == 0 && candidates2.Count == 0)
{
ruleset.isContextInitialized = false;
ruleset.isParamsInitialized = false;
CSharpExpertAbstract.getOutputStream().WriteLine("Goal = \"{0}\" can't be calculated by using the set of rules \"{1}\"", goal, ruleset.getName());
return(false);
}
// method of conflict-resolution is very simple, just call first rule
ComparableDict parameters = ruleset.getParams();
Rule choosenRule = null;
if (candidates1.Count > 0)
{
choosenRule = ((Rule)candidates1[0]);
}
else if (candidates2.Count > 0)
{
choosenRule = ((Rule)candidates2[0]);
}
((IList)statesByRule[choosenRule.getName()]).Add(parameters);
object old_value_of_goal = parameters[goal];
choosenRule.if_statement(); // "if" block of chosen rule is fired
firedRules.Add(choosenRule);
if (showComments)
{
CSharpExpertAbstract.getOutputStream().WriteLine("Rule \"{0}\" has been fired:\n {1}", choosenRule.getName(), choosenRule.getComment());
}
foreach (Rule rule in ruleset.getRules().Values) // "else" blocks of all other rules are fired
{
if (rule != choosenRule)
{
rule.else_statement();
}
}
if (!ruleset.getParams()[goal].Equals(old_value_of_goal))
{
ruleset.isContextInitialized = false;
ruleset.isParamsInitialized = false;
CSharpExpertAbstract.getOutputStream().WriteLine("Goal is calculated: \"{0}\"={1}", goal, ruleset.getParams()[goal]);
return(true);
}
return(forwardChaining(rulesetName, goal));
}
public static void consult(string ruleset)
{
RulesetFrame frame = CSharpExpertAbstract.getRulesetFrame(ruleset);
consult(ruleset, frame.Goal);
}