public override bool Try(TextBuffer output, BindingEnvironment e, Continuation k,
MethodCallFrame predecessor)
{
if (!e.TryCopyGround(Value.Eval(e), out var expValue))
{
// You can't set a variable to a non-ground value
throw new ArgumentInstantiationException("set", e,
new[] { (object)GlobalVariable, Value });
}
if (LocalVariable == null)
{
return(Continue(output,
new BindingEnvironment(e,
e.Unifications,
e.State.Bind(GlobalVariable, expValue)),
k, predecessor));
}
if (e.Unify(LocalVariable, expValue, out var result))
{
return(Continue(output,
new BindingEnvironment(e, result, e.State),
k, predecessor));
}
return(false);
}
public override bool Try(TextBuffer output, BindingEnvironment e, Continuation k, MethodCallFrame predecessor)
{
var collectionValue = e.Resolve(collectionVariable);
switch (collectionValue)
{
case Cons list:
{
return(list != Cons.Empty &&
e.Unify(element, list.First, out var bindings) &&
Continue(output,
new BindingEnvironment(e,
bindings,
e.State.Bind(collectionVariable, list.Rest)),
k, predecessor));
}
case ImmutableStack <object> stack:
{
return(!stack.IsEmpty &&
e.Unify(element, stack.Peek(), out var bindings) &&
Continue(output,
new BindingEnvironment(e,
bindings,
e.State.Bind(collectionVariable, stack.Pop())),
k, predecessor));
}
case ImmutableQueue <object> queue:
{
return(!queue.IsEmpty &&
e.Unify(element, queue.Peek(), out var bindings) &&
Continue(output,
new BindingEnvironment(e,
bindings,
e.State.Bind(collectionVariable, queue.Dequeue())),
k, predecessor));
}
default:
throw new ArgumentTypeException("removeNext", typeof(Cons), collectionValue,
new[] { "removeNext", collectionValue });
}
}
/// <inheritdoc />
protected override IEnumerable <BindingList <LogicVariable> > Iterator(object[] args, BindingEnvironment env)
{
ArgumentCountException.Check(Name, 2, args);
var input = ArgumentTypeException.Cast <TIn>(Name, env.Resolve(args[0]), args);
var result = implementation(input);
if (env.Unify(args[1], result, out var bindings))
{
return new[] { bindings }
}
;
return(EmptyBindingListArray);
}
}
/// <inheritdoc />
protected override IEnumerable <BindingList <LogicVariable> > Iterator(object[] args, BindingEnvironment env)
{
ArgumentCountException.Check(Name, 4, args);
var input1 = ArgumentTypeException.Cast <TIn1>(Name, args[0], args);
var input2 = ArgumentTypeException.Cast <TIn2>(Name, args[1], args);
var input3 = ArgumentTypeException.Cast <TIn3>(Name, args[2], args);
var result = implementation(input1, input2, input3);
if (env.Unify(args[3], result, out var bindings))
{
return new[] { bindings }
}
;
return(EmptyBindingListArray);
}
}
/// <inheritdoc />
protected override IEnumerable <BindingList <LogicVariable> > Iterator(object[] args, BindingEnvironment env)
{
ArgumentCountException.CheckAtLeast(Name, 1, args);
var fArgs = new object[args.Length - 1];
Array.Copy(args, fArgs, args.Length - 1);
var result = implementation(fArgs);
if (env.Unify(args[args.Length - 1], result, out var bindings))
{
return new[] { bindings }
}
;
return(EmptyBindingListArray);
}
}
private static bool TaskSubtask(object[] args, TextBuffer o, BindingEnvironment e, MethodCallFrame predecessor, Step.Continuation k)
{
ArgumentCountException.Check("TaskSubtask", 2, args);
var task = ArgumentTypeException.Cast <CompoundTask>("TaskSubtask", args[0], args);
foreach (var callExpression in e.Module.Subtasks(task))
{
if (e.Unify(args[1], callExpression, out var unifications))
{
if (k(o, unifications, e.State, predecessor))
{
return(true);
}
}
}
return(false);
}
private static bool PreviousCall(object[] args, TextBuffer output, BindingEnvironment env,
MethodCallFrame predecessor, Step.Continuation k)
{
ArgumentCountException.Check(nameof(PreviousCall), 1, args);
if (args[0] is LogicVariable)
{
// [PreviousCall ?var]
foreach (var priorGoal in predecessor.GoalChain)
{
var e = priorGoal.CallExpression;
if (env.Unify(args[0], e, out BindingList <LogicVariable> unifications) &&
k(output, unifications, env.State, predecessor))
{
return(true);
}
}
return(false);
}
// [PreviousCall [Task ?args]]
var call = ArgumentTypeException.Cast <object[]>(nameof(PreviousCall), args[0], args);
foreach (var priorGoal in predecessor.GoalChain)
{
if (priorGoal.Method.Task != call[0])
{
// Don't bother making the call expression and trying to unify.
continue;
}
var e = priorGoal.CallExpression;
if (call.Length == e.Length &&
env.UnifyArrays(call, e, out BindingList <LogicVariable> unifications) &&
k(output, unifications, env.State, predecessor))
{
return(true);
}
}
return(false);
}
private static bool SaveText(object[] args, TextBuffer o, BindingEnvironment e, MethodCallFrame predecessor, Step.Continuation k)
{
ArgumentCountException.Check("SaveText", 2, args);
var textVar = e.Resolve(args[1]);
if (textVar == null)
{
throw new ArgumentInstantiationException("SaveText", e, args);
}
var invocation = args[0] as object[];
if (invocation == null || invocation.Length == 0)
{
throw new ArgumentTypeException("SaveText", typeof(Call), args[0], args);
}
var arglist = new object[invocation.Length - 1];
Array.Copy(invocation, 1, arglist, 0, arglist.Length);
var call = new Call(invocation[0], arglist, null);
var initialLength = o.Length;
string[] chunk = null;
var frame = predecessor;
if (call.Try(o, e,
(output, b, d, p) =>
{
frame = p;
chunk = new string[output.Length - initialLength];
Array.Copy(o.Buffer, initialLength, chunk, 0, output.Length - initialLength);
return(true);
},
predecessor) &&
e.Unify(textVar, chunk, e.Unifications, out var newUnifications))
{
return(k(o, newUnifications, e.State, frame));
}
return(false);
}
private static bool FindUnique(object[] args, TextBuffer o, BindingEnvironment e, MethodCallFrame predecessor, Step.Continuation k)
{
ArgumentCountException.Check("FindUnique", 3, args);
var solution = args[0];
var call = args[1] as object[];
if (call == null || call.Length == 0)
{
throw new ArgumentException("Invalid goal expression");
}
var task = ArgumentTypeException.Cast <Task>("FindUnique", call[0], args);
var taskArgs = call.Skip(1).ToArray();
var result = args[2];
var resultSet = new HashSet <object>();
task.Call(taskArgs, o, e, predecessor, (newO, u, s, p) =>
{
resultSet.Add(e.Resolve(solution, u));
return(false);
});
return(e.Unify(result, resultSet.ToArray(), out var final) &&
k(o, final, e.State, predecessor));
}
private bool CallTask(TextBuffer output, BindingEnvironment env, Continuation k, object target, object[] arglist,
object originalTarget, MethodCallFrame predecessor)
{
switch (target)
{
case Task p:
return(p.Call(arglist, output, env, predecessor,
(newOutput, u, s, newPredecessor) => Continue(newOutput, new BindingEnvironment(env, u, s), k, newPredecessor)));
case string[] text:
return(Continue(output.Append(text), env, k, predecessor));
case IDictionary d:
ArgumentCountException.Check(d, 2, arglist);
var arg0 = arglist[0];
var v0 = arg0 as LogicVariable;
var arg1 = arglist[1];
if (v0 == null)
{
return(d.Contains(arg0) &&
env.Unify(arg1, d[arg0], out var u) &&
Continue(output,
new BindingEnvironment(env, u, env.State), k, predecessor));
}
else
{
// Arg 0 is out
foreach (DictionaryEntry e in d)
{
if (env.Unify(arg0, e.Key, out var unif1) &&
env.Unify(arg1, e.Value, unif1, out var unif2) &&
Continue(output, new BindingEnvironment(env, unif2, env.State), k, predecessor))
{
return(true);
}
}
}
return(false);
case IList l:
// If it's a list in the operator position, pretend it's a call to member
if (arglist.Length != 1)
{
throw new ArgumentCountException("<list member>", 1, arglist);
}
if (arglist[0] is LogicVariable l0)
{
foreach (var e in l)
{
if (Continue(output,
new BindingEnvironment(env, BindingList <LogicVariable> .Bind(env.Unifications, l0, e),
env.State),
k,
predecessor))
{
return(true);
}
}
}
else
{
if (l.Contains(arglist[0]) && Continue(output, env, k, predecessor))
{
return(true);
}
}
return(false);
case LogicVariable v:
throw new ArgumentException($"Attempt to call an unbound variable {v}");
case null:
throw new ArgumentException($"Null is not a valid task in call {CallSourceText(originalTarget, arglist)}");
case bool b:
if (arglist.Length != 0)
{
throw new ArgumentCountException(b, 0, arglist);
}
return(b && Continue(output, env, k, predecessor));
default:
if (arglist.Length == 0)
{
var hook = env.Module.FindTask(MentionHook, 1, false);
if (hook != null)
{
return(MakeCall(hook, target, Next).Try(output, env, k, predecessor));
}
return(Continue(output.Append(target.ToString()), env, k, predecessor));
}
throw new ArgumentException($"Unknown task {target} in call {CallSourceText(originalTarget, arglist)}");
}
}
private static bool UniqueCall(object[] args, TextBuffer output, BindingEnvironment env,
MethodCallFrame predecessor, Step.Continuation k)
{
ArgumentCountException.CheckAtLeast(nameof(UniqueCall), 1, args);
var call = ArgumentTypeException.Cast <object[]>(nameof(PreviousCall), args[0], args);
if (!(call[0] is Task task))
{
throw new InvalidOperationException(
"Task argument to UniqueCall must be a task.");
}
var taskArgs = new object[call.Length - 1 + args.Length - 1];
var i = 0;
for (var callIndex = 1; callIndex < call.Length; callIndex++)
{
taskArgs[i++] = call[callIndex];
}
for (var argsIndex = 1; argsIndex < args.Length; argsIndex++)
{
taskArgs[i++] = args[argsIndex];
}
var fullCall = call;
if (args.Length > 1)
{
fullCall = new object[taskArgs.Length + 1];
fullCall[0] = task;
for (var j = 0; j < taskArgs.Length; j++)
{
fullCall[j + 1] = taskArgs[j];
}
}
if (task.Call(taskArgs, output, env, predecessor,
(o, u, s, newPredecessor) =>
{
foreach (var priorGoal in predecessor.GoalChain)
{
if (priorGoal.Method.Task != task)
{
// Don't bother making the call expression and trying to unify.
continue;
}
if (env.Unify(fullCall, priorGoal.CallExpression, u, out BindingList <LogicVariable> _))
{
// We already did a call that matches this call
// So have the continuation return false, forcing the task.Call above to backtrack
// and try to generate a new solution
return(false);
}
}
return(k(o, u, s, newPredecessor));
}))
{
return(true);
}
return(false);
}
private static bool LastMethodCallFrame(object[] args, TextBuffer o, BindingEnvironment e, MethodCallFrame predecessor, Step.Continuation k)
{
ArgumentCountException.Check("LastMethodCallFrame", 1, args);
return(e.Unify(args[0], predecessor, out var u) &&
k(o, u, e.State, predecessor));
}
/// <summary>
/// Call this task with the specified arguments
/// </summary>
/// <param name="arglist">Task arguments</param>
/// <param name="output">Output accumulated so far</param>
/// <param name="env">Binding environment</param>
/// <param name="predecessor">Most recently succeeded MethodCallFrame</param>
/// <param name="k">Continuation</param>
/// <returns>True if task succeeded and continuation succeeded</returns>
/// <exception cref="CallFailedException">If the task fails</exception>
public override bool Call(object[] arglist, TextBuffer output, BindingEnvironment env, MethodCallFrame predecessor, Step.Continuation k)
{
string lastToken = null;
if (Suffix)
{
(lastToken, output) = output.Unappend();
arglist = new object[] { lastToken };
}
ArgumentCountException.Check(this, this.ArgCount, arglist);
var successCount = 0;
if (ReadCache)
{
// Check for a hit in the cache. If we find one, we're done.
if (Cache.TryGetValue(env.State, arglist, out var result))
{
if (result.Success)
{
if (Function)
{
// We got a hit, and since this is a function, it's the only allowable hit.
// So we succeed deterministically.
return(env.Unify(arglist[arglist.Length - 1], result.FunctionValue,
out BindingList <LogicVariable> u) &&
k(output.Append(result.Text), u, env.State, predecessor));
}
else
{
successCount++;
if (k(output.Append(result.Text), env.Unifications, env.State, predecessor))
{
return(true);
}
}
}
else
{
// We have a match on a cached fail result, so force a failure, skipping over the methods.
goto failed;
}
}
else if (arglist.Any(x => x is LogicVariable))
{
foreach (var pair in Cache.Bindings(env.State))
{
if (pair.Value.Success &&
env.UnifyArrays((object[])pair.Key, arglist,
out BindingList <LogicVariable> unifications))
{
successCount++;
if (k(output.Append(pair.Value.Text), unifications, env.State, predecessor))
{
return(true);
}
}
}
}
}
if (ContainsCoolStep)
{
var s = env.State;
s = CallCounts.SetItem(s, this, CallCount(s) + 1);
env = new BindingEnvironment(env, env.Unifications, s);
}
var methods = this.EffectiveMethods;
for (var index = 0; index < methods.Count && !(this.Deterministic && successCount > 0); index++)
{
var method = methods[index];
if (method.Try(arglist, output, env, predecessor,
(o, u, s, newPredecessor) =>
{
successCount++;
if (WriteCache)
{
var final = env.ResolveList(arglist, u);
if (Term.IsGround(final))
{
s = StoreResult(s, final, new CachedResult(true,
Function?final[final.Length - 1]:null,
TextBuffer.Difference(output, o)));
}
}
return(k(o, u, s, newPredecessor));
}))
{
return(true);
}
if (Suffix)
{
// Undo any overwriting that the method might have done
output.Buffer[output.Length - 1] = lastToken;
}
}
failed:
var currentFrame = MethodCallFrame.CurrentFrame = env.Frame;
if (currentFrame != null)
{
currentFrame.BindingsAtCallTime = env.Unifications;
}
if (successCount == 0 && this.MustSucceed)
{
throw new CallFailedException(this, arglist);
}
if (currentFrame != null)
{
env.Module.TraceMethod(Module.MethodTraceEvent.CallFail, currentFrame.Method, currentFrame.Arglist, output,
env);
MethodCallFrame.CurrentFrame = currentFrame.Predecessor;
}
// Failure
return(false);
}