public override ErlangValue Evaluate(ErlangProcess process)
{
var value = Expression.Evaluate(process);
if (value.Kind == ErlangValueKind.Error)
{
return(value);
}
foreach (var branch in Branches)
{
process.CallStack.CurrentFrame.IncreaseScopeLevel();
if (ErlangBinder.TryBindParameter(branch.Pattern, value, process.CallStack.CurrentFrame))
{
if (branch.Guard == null || ErlangAtom.IsTrue(branch.Guard.Evaluate(process)))
{
var result = branch.Evaluate(process);
process.CallStack.CurrentFrame.DecreaseScopeLevel();
return(result);
}
}
process.CallStack.CurrentFrame.DecreaseScopeLevel();
}
return(new ErlangError("bad match on case"));
}
public static bool TryBindParameters(ErlangProcess process, ErlangExpression[] parameters, ErlangValue[] values)
{
if (parameters.Length != values.Length)
{
return(false);
}
var frame = process.CallStack.CurrentFrame;
for (int i = 0; i < values.Length; i++)
{
if (!ErlangBinder.TryBindParameter(parameters[i], values[i], frame, true))
{
return(false);
}
}
return(true);
}
public override ErlangValue Evaluate(ErlangProcess process)
{
// variable assignment or pattern match
if (Operator == ErlangOperatorKind.Equals)
{
// first evaluate the right side
var right = Right.Evaluate(process);
if (right.Kind == ErlangValueKind.Error)
{
return(right);
}
// now match to the left
if (ErlangBinder.TryBindParameter(Left, right, process.CallStack.CurrentFrame))
{
return(right);
}
else
{
return(new ErlangError("bad match"));
}
}
var left = Left.Evaluate(process);
if (left.Kind == ErlangValueKind.Error)
{
return(left);
}
if (IsShortCircuitOperator(Operator))
{
switch (Operator)
{
case ErlangOperatorKind.AndAlso:
if (ErlangAtom.IsTrue(left))
{
return(Right.Evaluate(process));
}
else
{
return(ErlangAtom.False);
}
case ErlangOperatorKind.OrElse:
if (ErlangAtom.IsTrue(left))
{
return(left);
}
else
{
return(Right.Evaluate(process));
}
default:
throw new ArgumentException("invalid operator");
}
}
else
{
var right = Right.Evaluate(process);
if (right.Kind == ErlangValueKind.Error)
{
return(right);
}
switch (Operator)
{
case ErlangOperatorKind.Plus:
return(ErlangValue.Add(left, right));
case ErlangOperatorKind.Minus:
return(ErlangValue.Subtract(left, right));
case ErlangOperatorKind.Asterisk:
return(ErlangValue.Multiply(left, right));
case ErlangOperatorKind.Slash:
return(ErlangValue.Divide(left, right));
case ErlangOperatorKind.And:
return(ErlangValue.And(left, right));
case ErlangOperatorKind.Or:
return(ErlangValue.Or(left, right));
case ErlangOperatorKind.Less:
return(ErlangValue.Less(left, right));
case ErlangOperatorKind.EqualsLess:
return(ErlangValue.LessEquals(left, right));
case ErlangOperatorKind.Greater:
return(ErlangValue.Greater(left, right));
case ErlangOperatorKind.GreaterEquals:
return(ErlangValue.GreaterEquals(left, right));
case ErlangOperatorKind.EqualsEquals:
return(ErlangValue.EqualsEquals(left, right));
case ErlangOperatorKind.SlashEquals:
return(ErlangValue.SlashEquals(left, right));
case ErlangOperatorKind.EqualsColonEquals:
return(ErlangValue.EqualsColonEquals(left, right));
case ErlangOperatorKind.EqualsSlashEquals:
return(ErlangValue.EqualsSlashEquals(left, right));
case ErlangOperatorKind.PlusPlus:
return(ErlangValue.PlusPlus(left, right));
default:
throw new ArgumentException("invalid operator");
}
}
}
