public List <UnificationResult> GetUnifier(TrsTermBase ruleHead, TrsTermBase matchTerm)
{
List <UnificationResult> unifiers = new List <UnificationResult>();
for (int i = 0; i < 1; i++)
{
var tempResult = new UnificationResult();
tempResult.Unifier = new List <Substitution>();
foreach (var variable in ruleHead.GetVariables())
{
tempResult.Unifier.Add(new Substitution {
SubstitutionTerm = new TrsNumber(i.ToString()), Variable = variable
});
}
tempResult.Succeed = true;
unifiers.Add(tempResult);
}
return(unifiers);
}
/// <summary>
/// NB: this is not a general solution, only for c = b + x where + can be -, / or * and, b and x can be swapped arround.
/// c is the match term. The rest is the head term.
/// </summary>
public List <UnificationResult> GetUnifier(TrsTermBase termHead, TrsTermBase matchTerm)
{
UnificationResult result = new UnificationResult();
result.Succeed = false;
// Check input
Substitution sRhs = new Substitution
{
Variable = new TrsVariable("exp_r"),
SubstitutionTerm = termHead
};
Substitution sLhs = new Substitution
{
Variable = new TrsVariable("exp_l"),
SubstitutionTerm = matchTerm
};
var headTerm = termHead as TrsTerm;
if (!interpreter.TypeChecker.IsSubstitutionValid(sLhs) ||
!interpreter.TypeChecker.IsSubstitutionValid(sRhs))
{
return(new List <UnificationResult> {
result
});
}
// Load problem
interpreter.ClearExecutionCache();
interpreter.LoadTerms(new []
{
new TrsTerm("rhs", new [] { termHead }),
new TrsTerm("lhs", new [] { matchTerm })
});
// Solve
while (interpreter.ExecuteRewriteStep())
{
}
;
// Extract answer
var runResults = interpreter.GetCurrentRewriteResult();
foreach (var stm in runResults.ProgramOut.Statements)
{
var resEq = stm as TrsTerm;
if (resEq != null &&
resEq.Name == "eq" &&
resEq.Arguments.Count == 2 &&
resEq.Arguments[0] is TrsNumber &&
resEq.Arguments[1] is TrsVariable)
{
result.Succeed = true;
result.Unifier = new List <Substitution>();
result.Unifier.Add(new Substitution()
{
Variable = resEq.Arguments[1] as TrsVariable,
SubstitutionTerm = resEq.Arguments[0]
});
}
}
return(new List <UnificationResult> {
result
});
}
static void Main(string[] args)
{
System.Console.WriteLine(UnificationResult.Unify(Term.NewAtom("42"), Term.NewAtom("42")));
}
