/// <inheritdoc /> public override bool Call(object[] arglist, TextBuffer output, BindingEnvironment env, MethodCallFrame predecessor, Step.Continuation k) => implementation(env.ResolveList(arglist)) && k(output, env.Unifications, env.State, predecessor);
/// <inheritdoc />
public override bool Call(object[] arglist, TextBuffer output, BindingEnvironment env, MethodCallFrame predecessor, Step.Continuation k)
{
ArgumentCountException.Check(Name, 0, arglist);
return(implementation() &&
k(output, env.Unifications, env.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 abstract bool Call(object[] arglist, TextBuffer output, BindingEnvironment env,
MethodCallFrame predecessor, Step.Continuation k);
/// <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);
}
/// <summary> /// Attempt to run this step. /// </summary> /// <param name="output">Output accumulated so far</param> /// <param name="e">Variable binding information to use in this step</param> /// <param name="k">Procedure to run if this step and the other steps in its chain are successful</param> /// <param name="predecessor">Predecessor frame</param> /// <returns>True if all steps in the chain, and the continuation are all successful. False means we're backtracking</returns> public abstract bool Try(TextBuffer output, BindingEnvironment e, Continuation k, MethodCallFrame predecessor);
/// <inheritdoc />
public override bool Call(object[] args, TextBuffer buffer, BindingEnvironment env, MethodCallFrame predecessor, Step.Continuation k)
{
ArgumentCountException.Check(Name, 1, args);
var arg = env.Resolve(args[0]);
var text = arg as string[];
if (buffer.WriteMode)
{
if (text == null)
{
text = renderer(arg);
}
return(k(buffer.Append(text), env.Unifications, env.State, predecessor));
}
// Read mode
if (arg is LogicVariable l)
{
var token = buffer.NextToken(out var newBuffer);
if (token == null)
{
return(false);
}
object value = token;
switch (token)
{
case "null":
value = null;
break;
case "true":
value = true;
break;
case "false":
value = false;
break;
default:
if (int.TryParse(token, out var iValue))
{
value = iValue;
}
else if (float.TryParse(token, out var fValue))
{
value = fValue;
}
break;
}
return(k(newBuffer,
BindingList <LogicVariable> .Bind(env.Unifications, l, value),
env.State, predecessor));
}
if (text == null)
{
text = renderer(arg);
}
return(buffer.Unify(text, out var result) &&
k(result, env.Unifications, env.State, predecessor));
}
/// <inheritdoc />
public override bool Call(object[] arglist, TextBuffer output, BindingEnvironment env, MethodCallFrame predecessor, Step.Continuation k)
{
return(k(output.Append(implementation(arglist, output, env, predecessor)),
env.Unifications, env.State, predecessor));
}