/// <summary>
/// Evaluates a right-hand side expression if not evaluated yet.
/// </summary>
protected internal static EvaluationResult EvalExpression(Context context, ModuleLiteral env, EvaluationResult o, EvaluationStackFrame args)
{
var e = o.Value as Expression;
return(e?.Eval(context, env, args) ?? o);
}
/// <inheritdoc />
public override EvaluationResult GetOrEvalField(Context context, StringId name, bool recurs, ModuleLiteral origin, LineInfo location)
{
if (m_values.TryGetValue(name.Value, out EvaluationResult result))
{
return(result);
}
return(EvaluationResult.Undefined);
}
/// <summary>
/// Creates a task that runs GetOrEvalField taking into consideration concurrency settings
/// </summary>
protected Task <object> RunGetOrEvalFieldAsync(ImmutableContextBase context, ModuleLiteral origin, SymbolAtom name, ModuleBinding bindingValue)
{
return(context.EvaluationScheduler.EvaluateValue(() => Task.FromResult(GetOrEvalField(context, origin, name, bindingValue))));
}
/// <summary> /// Gets or evaluates field. /// </summary> /// <returns> /// Returns evaluated field or <see cref="UndefinedValue.Instance"/> if member is not found. /// Unfortunately there is no way to distinguish between type error or missing member, so in both /// cases this method will return the same - undefined. /// </returns> /// <remarks> /// Fields may need to be evaluated. This happens in the case of module fields that have thunked expressions. /// </remarks> public abstract EvaluationResult GetOrEvalField([NotNull] Context context, StringId name, bool recurs, [NotNull] ModuleLiteral origin, LineInfo location);
/// <nodoc />
protected static FullSymbol GetFullyQualifiedBindingName(SymbolTable symbolTable, ModuleLiteral owningModule, SymbolAtom name)
{
Contract.Requires(name.IsValid);
return(owningModule.Id.Name.Combine(symbolTable, name));
}
private void AddGetOrEvalFieldTasks(ImmutableContextBase context, List <Task <object> > list, ModuleLiteral origin)
{
Contract.Requires(origin.m_bindings != null);
foreach (var binding in origin.m_bindings)
{
SymbolAtom name = binding.Key;
ModuleBinding bindingValue = binding.Value;
list.Add(RunGetOrEvalFieldAsync(context, origin, name, bindingValue));
}
}
/// <summary>
/// Gets module or namespace based on module id.
/// </summary>
public EvaluationResult GetNamespace(ImmutableContextBase context, FullSymbol fullName, bool recurs, ModuleLiteral origin, LineInfo location)
{
ModuleBinding binding = GetNamespaceBinding(context, fullName, recurs);
if (binding == null)
{
context.Errors.ReportMissingNamespace(origin ?? this, fullName, this, location);
return(EvaluationResult.Error);
}
return(EvaluationResult.Create(binding.Body));
}
private EvaluationResult GetOrEvalField(Context context, SymbolAtom name, ModuleLiteral startEnv, bool recurs, ModuleLiteral origin, LineInfo location)
{
// This logic is still used only V1 evaluation
if (IsFileModule && name == context.ContextTree.CommonConstants.Qualifier)
{
// Someone references 'qualifier' on the file level.
return(EvaluationResult.Create(Qualifier.Qualifier));
}
ModuleBinding binding = null;
// TODO:ST: sounds reasonable to add "warning" if name was resolved but it is not exposed!
if (m_bindings?.TryGetValue(name, out binding) == true && (recurs || binding.IsExported))
{
return(GetOrEvalFieldBinding(context, name, binding, location));
}
if (recurs && OuterScope != null)
{
return(OuterScope.GetOrEvalField(context, name, startEnv, true, origin, location));
}
context.Errors.ReportMissingMember(origin ?? startEnv, name, startEnv, location);
return(EvaluationResult.Error);
}
/// <nodoc />
public sealed override EvaluationResult GetOrEvalField(Context context, SymbolAtom name, bool recurs, ModuleLiteral origin, LineInfo location)
{
Contract.Requires(name.IsValid);
return(GetOrEvalField(context, name, this, recurs: recurs, origin: origin, location: location));
}
/// <inheritdoc />
public sealed override bool TryProject(Context context, SymbolAtom name, ModuleLiteral origin, out EvaluationResult result, LineInfo location)
{
result = GetOrEvalField(context, name, recurs: false, origin: origin, location: Location);
return(true);
}
/// <inheritdoc />
protected override EvaluationResult DoEval(Context context, ModuleLiteral env, EvaluationStackFrame frame)
{
return(EvaluationResult.Create(this));
}
/// <summary>
/// Constructs module literal for namespace.
/// </summary>
protected static TypeOrNamespaceModuleLiteral CreateTypeOrNamespaceModule(FullSymbol namespaceName, ModuleLiteral outerScope, LineInfo location)
{
Contract.Requires(namespaceName.IsValid);
Contract.Requires(outerScope != null);
Contract.Requires(outerScope.IsFileOrGlobal);
ModuleLiteralId moduleId = outerScope.Id.WithName(namespaceName);
return(new TypeOrNamespaceModuleLiteral(moduleId, qualifier: QualifierValue.Unqualified,
outerScope: outerScope, location: location));
}
private EvaluationResult QualifiedEvaluateWithCycleDetection(ref object value, ImmutableContextBase context, ModuleLiteral env, Evaluation currentEvaluation, ref MutableContextFactory factory)
{
// Someone else is already busy evaluating this thunk. Let's wait...
EvaluationStatus result;
var cycleDetector = context.FrontEndHost.CycleDetector;
if (cycleDetector != null)
{
using (cycleDetector.AddValuePromiseChain(
valuePromiseChainGetter: () => GetValuePromiseChain(context, env),
cycleAnnouncer: () => currentEvaluation.Cancel(EvaluationStatus.Cycle)))
{
currentEvaluation.Wait(cycleDetector);
result = currentEvaluation.Result;
if ((result & EvaluationStatus.Value) != 0)
{
var currentValue = Volatile.Read(ref value);
Contract.Assert(currentValue is EvaluationResult);
return((EvaluationResult)currentValue);
}
}
}
else
{
currentEvaluation.Wait();
result = currentEvaluation.Result;
if ((result & EvaluationStatus.Value) != 0)
{
var currentValue = Volatile.Read(ref value);
Contract.Assert(currentValue is EvaluationResult);
return((EvaluationResult)currentValue);
}
}
// Evaluation got canceled --- we hit a cycle (or deadlock)!
if ((result & EvaluationStatus.Cycle) != 0)
{
context.Errors.ReportCycle(env, Expression.Location, factory.ContextName);
currentEvaluation.SetValue(ref value, EvaluationResult.Error);
return(EvaluationResult.Error);
}
// Evaluation crashed, which means that Expression.Eval had failed, and had thrown an exception.
if ((result & EvaluationStatus.Crash) != 0)
{
// Crash has been reported at the crash site.
currentEvaluation.SetValue(ref value, EvaluationResult.Error);
return(EvaluationResult.Error);
}
return(EvaluationResult.Error);
}
private EvaluationResult QualifiedEvaluate(
ref object value,
ImmutableContextBase context,
ModuleLiteral env,
EvaluationStackFrame args,
ref MutableContextFactory factory)
{
// Contract.Ensures(Contract.Result<object>() != null && !(Contract.Result<object>() is Evaluation));
// do we have a real value yet?
var currentValue = Volatile.Read(ref value);
var currentEvaluation = currentValue as Evaluation;
if (currentValue != currentEvaluation)
{
Contract.Assert(currentValue is EvaluationResult);
// so it's not null, and it's not an evaluation => we have a real value!
return((EvaluationResult)currentValue);
}
// no real value yet, let's try to create a new evaluation
if (currentEvaluation == null && !factory.ForceWaitForResult)
{
var newEvaluation = new Evaluation(
context.EvaluatorConfiguration.CycleDetectorStartupDelay,
context.EvaluatorConfiguration.CycleDetectorIncreasePriorityDelay);
currentValue = Interlocked.CompareExchange(ref value, newEvaluation, null);
currentEvaluation = currentValue as Evaluation;
if (currentValue != currentEvaluation)
{
Contract.Assert(currentValue is EvaluationResult);
// so it's not null, and it's not an evaluation => we have a real value! (and the CompareExchange must have failed)
return((EvaluationResult)currentValue);
}
if (currentValue == null)
{
using (var newLocalMutableContext = factory.Create(context))
{
try
{
var newValue = Expression.Eval(newLocalMutableContext, env, args);
// Evaluation got canceled --- we hit a cycle (or deadlock)!
if ((newEvaluation.Result & EvaluationStatus.Cycle) != 0)
{
newLocalMutableContext.Errors.ReportCycle(env, Expression.Location);
newEvaluation.SetValue(ref value, EvaluationResult.Error);
return(EvaluationResult.Error);
}
newEvaluation.SetValue(ref value, newValue);
return(newValue);
}
catch
{
// No actual value was ever set --- this means that Expression.Eval failed, and most likely threw an exception!
// Let's propagate this result, so that anyone else waiting for us gets unblocked.
newEvaluation.Cancel(EvaluationStatus.Crash);
throw;
}
finally
{
Contract.Assert(!newLocalMutableContext.HasChildren);
// just before the newly created context get disposed, we want to assert that all of its child contexts have already been disposed
}
}
}
// there's already an ongoing evaluation! (and the CompareExchange must have failed) we fall through...
}
if (factory.ForceWaitForResult)
{
while (currentEvaluation == null)
{
Thread.Sleep(TimeSpan.FromMilliseconds(10));
currentEvaluation = Volatile.Read(ref value) as Evaluation;
}
}
return(QualifiedEvaluateWithCycleDetection(ref value, context, env, currentEvaluation, ref factory));
}
/// <summary>
/// Evaluates this thunk in a new named context
/// </summary>
/// <remarks>
/// V1-specific. Still used to evaluate configuration-related files in V2 (and for the whole V1 legacy evaluation).
/// </remarks>
public EvaluationResult LegacyEvaluateWithNewNamedContext(ImmutableContextBase context, ModuleLiteral module, FullSymbol contextName, LineInfo location, bool forceWaitForResult = false)
{
// There is no captured template value in V1
var factory = new MutableContextFactory(this, contextName, module, templateValue: null, location: location, forceWaitForResult: forceWaitForResult);
return(EvaluateWithNewNamedContextAndTemplate(context, ref factory));
}