public void AddRule(Rule rule)
{
_ruleSet.Add(rule);
}
private bool CheckRule(Rule rule)
{
var arg = string.Empty;
return CheckPattern(rule, ref arg) && FireRule(rule, arg);
}
private bool FireRule(Rule rule, string arg)
{
var retval = false;
var newCons = string.Empty;
foreach(var walker in rule.Consequents)
{
var terms = GetTerms(walker.Element);
switch (terms[0])
{
case "(add":
ConstructElement(ref newCons, terms[1], arg);
retval = PerformAddCommand(newCons);
break;
case "(delete":
ConstructElement(ref newCons, terms[1], arg);
retval = PerformDeleteCommand(newCons);
break;
case "(disable-rule":
rule.IsActive = false;
retval = true;
break;
case "(print":
retval = PerformPrintCommand(terms[1]);
break;
case "(enable-timer":
retval = PerformEnableCommand(walker.Element);
break;
case "(quit":
EndRun = true;
break;
}
}
return retval;
}
private bool CheckPattern(Rule rule, ref string arg)
{
var found = false;
var chain = new Stack<MemoryElement>();
foreach (var terms in rule.Antecedents.Select(antecedent => GetTerms(antecedent.Element)))
{
if (string.IsNullOrEmpty(terms[1]))
{
throw new InvalidOperationException("Argument can't be null!");
}
/* If the antecedent element is variable, find the matches
* in the working memory and store the matched terms.
*/
if (terms[1][0] != '?') continue;
for (var i = 0; i < _memoryStore.Length; i++)
{
if (!_memoryStore[i].IsActive) continue;
var wmTerms = GetTerms(_memoryStore[i].Element);
if (!terms[0].Equals(wmTerms[0])) continue;
var newElement = new MemoryElement { Element = wmTerms[1] };
chain.Push(newElement);
}
}
/* Now that we have the replacement strings, walk through the rules trying
* the replacement string when necessary.
*/
do
{
//var curRule = rule.Antecedent;
string[] terms = null;
foreach(var curRule in rule.Antecedents)
{
terms = GetTerms(curRule.Element);
if (terms[0].IndexOf("(true", StringComparison.Ordinal) == 0)
{
found = true;
break;
}
if ((terms[1][0] == '?') && (chain.Count > 0))
{
terms[1] = chain.Peek().Element;
}
found = SearchWorkingMemory(terms[0], terms[1]);
if (!found) break;
}
if (found)
{
/* Cleanup the replacement string chain */
arg = terms[1];
chain.Clear();
break;
}
if(chain.Count > 0 )
{
chain.Pop();
}
} while (chain.Count > 0);
return found;
}