/// <inheritdoc />
public override bool Call(object[] arglist, TextBuffer output, BindingEnvironment env, MethodCallFrame predecessor, Step.Continuation k)
{
ArgumentCountException.Check(this, Arity, arglist);
// Check types and find the shortest list of candidate tuples that match
var candidateTuples = tuples;
for (var i = 0; i < Arity; i++)
{
var arg = arglist[i];
if (arg is LogicVariable)
{
continue;
}
ArgumentTypeException.Check(this, Signature[i], arg, arglist);
var index = indices[i];
if (index != null)
{
if (!index.TryGetValue(arg, out var indexedTuples))
{
// There are literally no tuples with the specified argument value
return(false);
}
if (indexedTuples.Count < candidateTuples.Count)
{
candidateTuples = indexedTuples;
}
}
}
// Attempt to unify each candidate tuple with the argument list
foreach (var t in Shuffler(candidateTuples))
{
if (env.UnifyArrays(arglist, t, out BindingList <LogicVariable> unifications))
{
if (k(output, unifications, env.State, predecessor))
{
return(true);
}
}
}
return(false);
}
private static bool TaskCalls(object[] args, TextBuffer o, BindingEnvironment e, MethodCallFrame predecessor, Step.Continuation k)
{
var m = e.Module;
ArgumentCountException.Check(nameof(TaskCalls), 2, args);
ArgumentTypeException.Check(nameof(TaskCalls), typeof(CompoundTask), args[0], args, true);
var callerVar = args[0] as LogicVariable;
var callerTask = args[0] as CompoundTask;
var callee = args[1];
var calleeVar = callee as LogicVariable;
if (callerVar == null)
{
// First arg is input
if (calleeVar == null)
{
// in in
if (m.TaskCalls(callerTask, callee))
{
return(k(o, e.Unifications, e.State, predecessor));
}
}
else
{
// in out
foreach (var c in m.Callees(callerTask))
{
if (k(o, BindingList <LogicVariable> .Bind(e.Unifications, calleeVar, c), e.State, predecessor))
{
return(true);
}
}
}
}
else
{
// First arg is output
if (calleeVar == null)
{
// out in
foreach (var caller in m.DefinedTasks)
{
if (m.TaskCalls(caller, callee))
{
if (k(o, BindingList <LogicVariable> .Bind(e.Unifications, callerVar, caller), e.State,
predecessor))
{
return(true);
}
}
}
}
else
{
// out out
foreach (var caller in m.DefinedTasks)
{
foreach (var c in m.Callees(caller))
{
if (k(o,
BindingList <LogicVariable> .Bind(e.Unifications, callerVar, caller).Bind(calleeVar, c),
e.State, predecessor))
{
return(true);
}
}
}
}
}
return(false);
}