/// @cond DOXYGEN_SHOULD_SKIP_THIS
public override bool Equals(object obj)
{
Substitution s = obj as Substitution;
if (s == null)
{
return(false);
}
return(Variable.Equals(s.Variable) && SubValue.Equals(s.SubValue));
}
public void AddSubstitution(Substitution s)
{
Constraint c;
bool needsBuild = !m_constraints.TryGetValue(s.Variable, out c);
if (s.SubValue.Value.IsVariable)
{
Constraint c2;
if (m_constraints.TryGetValue(s.SubValue.Value, out c2))
{
if (needsBuild)
{
m_constraints[s.Variable] = c2;
c2.EquivalentVariables.Add(s.Variable);
}
else if (!Object.ReferenceEquals(c, c2))
{
c2.UnionWith(c);
foreach (var v in c2.EquivalentVariables)
{
m_constraints[v] = c2;
}
}
}
else
{
if (needsBuild)
{
c = new Constraint();
m_constraints[s.Variable] = c;
c.EquivalentVariables.Add(s.Variable);
}
m_constraints[s.SubValue.Value] = c;
c.EquivalentVariables.Add(s.SubValue.Value);
}
}
else
{
if (needsBuild)
{
c = new Constraint();
m_constraints[s.Variable] = c;
c.EquivalentVariables.Add(s.Variable);
}
c.Value = s.SubValue.Value;
}
m_substitutions.Add(s);
m_hashIsDirty = true;
}
public bool TestConflict(Substitution subs, SubstitutionSet set, out bool canAdd)
{
canAdd = true;
Constraint c;
if (!m_constraints.TryGetValue(subs.Variable, out c))
{
return(false);
}
Name G1 = c.Value;
Name G2;
if (subs.SubValue.Value.IsVariable)
{
if (c.EquivalentVariables.Contains(subs.SubValue.Value))
{
canAdd = false;
return(false);
}
Constraint c2;
if (!m_constraints.TryGetValue(subs.SubValue.Value, out c2))
{
return(false);
}
if (c.Value == null || c2.Value == null)
{
return(false);
}
G2 = c2.Value;
}
else
{
if (G1 == null)
{
return(false);
}
canAdd = false;
G2 = subs.SubValue.Value;
return(!G1.Equals(G2)); //Conflict!!!
}
G1 = G1.MakeGround(set);
G2 = G2.MakeGround(set);
return(!G1.Equals(G2)); //Conflict!!!
}
//return the idx jump on the valName or -1 if it can't add the substitution
private static int FindSubsAux(Literal var, Literal val, SimpleName valName, IDictionary <string, Substitution> bindings)
{
//first, analyse if the value is a composed name or a single parameter
string valDescription;
int valLiteralCount;
if (val.type == LiteralType.Root)
{
SimpleName auxName = null;
auxName = SimpleWFN.BuildNameFromContainedLiteral(valName, val);
valDescription = auxName.ToString();
valLiteralCount = auxName.literals.Count;
}
else
{
valDescription = val.description;
valLiteralCount = 1;
}
//check if a binding for the same variable already exists
Substitution existingSub = null;
bindings.TryGetValue(var.description, out existingSub);
if (existingSub != null)
{
if (existingSub.SubValue.ToString().RemoveWhiteSpace().EqualsIgnoreCase(valDescription))
{
return(valLiteralCount);
}
else
{
return(-1);
}
}
//if there was no existing binding to the variable
try
{
bindings[var.description] = new Substitution(var.description, valDescription);
return(valLiteralCount);
}
catch (BadSubstitutionException)
{
return(-1);
}
}
/// <summary>
/// Clone Constructor
/// </summary>
/// <param name="substitution">The substitution to clone</param>
private Substitution(Substitution substitution)
{
this.Variable = substitution.Variable;
this.SubValue = substitution.SubValue;
}
private static bool FindSubst(Name n1, Name n2, bool allowPartialTerms, SubstitutionSet bindings)
{
n1 = n1.MakeGround(bindings);
n2 = n2.MakeGround(bindings);
var t = GetTerms(n1, n2, allowPartialTerms);
if (t == null)
{
return(false);
}
foreach (var p in t)
{
Substitution candidate = null;
bool isVar1 = p.Item1.IsVariable;
bool isVar2 = p.Item2.IsVariable;
// Case 1: x = t, where t is not a variable and x is a variable, and create substitution x/t
if (isVar1 != isVar2)
{
Name variable = (isVar1 ? p.Item1 : p.Item2);
Name value = isVar1 ? p.Item2 : p.Item1;
if (value.ContainsVariable(variable)) //Occurs check to prevent cyclical evaluations
{
return(false);
}
candidate = new Substitution(variable, new ComplexValue(value));
}
else if (isVar1) //isVar1 == isVar2 == true
{
//Case 2: x = x, where x is a variable, ignore it. otherwise add the substitution
if (!(p.Item1 == p.Item2))
{
candidate = new Substitution(p.Item1, new ComplexValue(p.Item2));
}
}
else //isVar1 == isVar2 == false
{
// Case 3: t1 = t2, where t1,t2 are not variables.
// If they don't contain variables, compare them to see if they are equal. If they are not equal the unification fails.
if (p.Item1.IsGrounded && p.Item2.IsGrounded)
{
if (p.Item1 == p.Item2)
{
continue;
}
if (p.Item1 == Name.UNIVERSAL_SYMBOL || p.Item2 == Name.UNIVERSAL_SYMBOL)
{
continue;
}
return(false);
}
//If one or both contain variables, unify the terms
if (!FindSubst(p.Item1, p.Item2, allowPartialTerms, bindings))
{
return(false);
}
}
if (candidate != null)
{
// Step 4: check to see if the newly created substitution conflicts with any of the already created substitution.
// If it does, the unification fails.
if (!bindings.AddSubstitution(candidate))
{
return(false);
}
}
}
return(true);
}
