/// <summary>
/// Provides the value of the function
/// </summary>
/// <param name="context"></param>
/// <param name="actuals"></param>
/// <param name="explain"></param>
/// <returns>The value for the function application</returns>
public virtual IValue Evaluate(InterpretationContext context, Dictionary<Actual, IValue> actuals,
ExplanationPart explain)
{
IValue retVal = null;
bool useCache = EFSSystem.CacheFunctions;
ExplainedValue explainedValue = null;
// Only use the cached value when the EFSSystem indicates that caches should be used
// This condition has been added to handle the fact that the user changes the status
// of EFSSystem.CacheFunctions within a test session
if (useCache)
{
if (_cachedResult == null)
{
_cachedResult = new CurryCache(this);
}
explainedValue = _cachedResult.GetValue(actuals);
}
if (explainedValue == null)
{
int token = context.LocalScope.PushContext();
AssignParameters(context, actuals);
if (Cases.Count > 0)
{
bool preConditionSatisfied = false;
// Statically defined function
foreach (Case aCase in Cases)
{
// Evaluate the function
ExplanationPart subExplanation = ExplanationPart.CreateSubExplanation(explain, aCase);
preConditionSatisfied = aCase.EvaluatePreConditions(context, subExplanation);
ExplanationPart.SetNamable(subExplanation,
preConditionSatisfied ? EFSSystem.BoolType.True : EFSSystem.BoolType.False);
if (preConditionSatisfied)
{
retVal = aCase.Expression.GetValue(context, subExplanation);
break;
}
}
if (!preConditionSatisfied)
{
ExplanationPart.CreateSubExplanation(explain, "Partial function called outside its domain");
AddError("Partial function called outside its domain");
}
}
else if (Surface != null && FormalParameters.Count == 2)
{
double x = 0.0;
double y = 0.0;
Parameter formal1 = (Parameter) FormalParameters[0];
Parameter formal2 = (Parameter) FormalParameters[1];
foreach (KeyValuePair<Actual, IValue> pair in actuals)
{
if (pair.Key.Parameter == formal1)
{
x = GetDoubleValue(pair.Value);
}
if (pair.Key.Parameter == formal2)
{
y = GetDoubleValue(pair.Value);
}
}
retVal = new DoubleValue(EFSSystem.DoubleType, Surface.Val(x, y));
}
else if (Graph != null && FormalParameters.Count < 2)
{
if (FormalParameters.Count == 0)
{
retVal = new DoubleValue(EFSSystem.DoubleType, Graph.Evaluate(0));
}
else if (FormalParameters.Count == 1)
{
double x = 0.0;
Parameter formal = (Parameter) FormalParameters[0];
foreach (KeyValuePair<Actual, IValue> pair in actuals)
{
if (pair.Key.Parameter == formal)
{
x = GetDoubleValue(pair.Value);
}
}
retVal = new DoubleValue(EFSSystem.DoubleType, Graph.Evaluate(x));
}
}
context.LocalScope.PopContext(token);
ExplanationPart.SetNamable(explain, retVal);
if (useCache)
{
_cachedResult.SetValue(actuals, retVal, explain);
}
}
else
{
retVal = explainedValue.Value;
ExplanationPart subExplain = ExplanationPart.CreateSubExplanation(explain, "Cached result = ");
ExplanationPart.SetNamable(subExplain, retVal);
// Reuse the explanation of the return value computation
// Topmost entry is the function call, useless, so don't provide it
if (explainedValue.Explanation != null)
{
foreach (ExplanationPart part in explainedValue.Explanation.SubExplanations)
{
ExplanationPart.AddSubExplanation(subExplain, part);
}
}
}
return retVal;
}
/// <summary>
/// Clears the caches for this function
/// </summary>
public override void ClearCache()
{
base.ClearCache();
_cachedResult = null;
Graph = null;
Surface = null;
}
