/// <summary>
/// Convert a Step term to a string as it would appear in the source code.
/// </summary>
public static string TermToString(object term, BindingList <LogicVariable> bindings = null)
{
var b = new StringBuilder();
void WriteCompound(char before, IEnumerable objects, char after)
{
b.Append(before);
var firstOne = true;
foreach (var e in objects)
{
if (firstOne)
{
firstOne = false;
}
else
{
b.Append(' ');
}
Walk(e);
}
b.Append(after);
}
void Walk(object o)
{
switch (o)
{
case Cons list:
if (list == Cons.Empty)
{
b.Append("Empty");
}
else
{
WriteCompound('(', list, ')');
}
break;
case object[] tuple:
WriteCompound('[', tuple, ']');
break;
case LogicVariable l:
var d = BindingEnvironment.Deref(l, bindings);
if (d == l)
{
// Unbound variable
b.Append(l);
}
else
{
Walk(d);
}
break;
case IDictionary dict:
WriteDictionary(dict);
break;
case IList l:
WriteList(l);
break;
default:
b.Append(o);
break;
}
}
void WriteDictionary(IDictionary d)
{
b.Append("{");
var count = 0;
foreach (DictionaryEntry pair in d)
{
if (count++ == 20)
{
b.Append(" ... }");
return;
}
if (count != 1)
{
b.Append(" ");
}
b.Append(pair.Key);
b.Append(":");
var v = pair.Value;
WriteFlat(v);
}
b.Append("}");
}
void WriteList(IList d)
{
b.Append("[");
var count = 0;
foreach (var elt in d)
{
if (count++ == 20)
{
b.Append(" ... ]");
return;
}
if (count != 1)
{
b.Append(" ");
}
WriteFlat(elt);
}
b.Append("]");
}
void WriteFlat(object v)
{
switch (v)
{
case IDictionary d:
b.Append(d.Count == 0 ? "{ }" : "{ ... }");
break;
case IList l:
b.Append(l.Count == 0 ? "[]" : "[ ... ]");
break;
default:
b.Append(v);
break;
}
}
Walk(term);
return(b.ToString());
}