public static void ThrowsWhenEvaluated <TException>(ILispValue expression, ILispEnvironment environment = null) where TException : LispException
{
Assert.IsNotNull(expression);
try
{
ILispValue actual = Evaluator.Evaluate(expression, environment ?? new GlobalEnvironment());
throw new AssertFailedException(string.Format(
"Expression returned value instead of throwing: {1}{0}Expected: {2}, Actual: {3}",
System.Environment.NewLine,
expression,
typeof(TException).FullName,
actual));
}
catch (LispException ex)
{
if (!(ex is TException))
{
throw new AssertFailedException(string.Format(
"Expression threw incorrect exception type: {1}{0}Expected: {2}{0}Actual: {3}",
System.Environment.NewLine,
expression,
typeof(TException).FullName,
ex));
}
}
}
private static ILispValue EvaluateProgn(IList <ILispValue> args, ILispEnvironment environment)
{
ILispValue result = Nil.Instance;
foreach (ILispValue arg in args)
{
result = Evaluate(arg, environment);
}
return(result);
}
private static ILispValue EvaluateQuote(IList <ILispValue> args, ILispEnvironment environment)
{
if (args.Count == 0)
{
throw new SignatureMismatchException("missing argument to 'quote'");
}
if (args.Count > 1)
{
throw new SignatureMismatchException("too many arguments supplied");
}
return(args[0]);
}
public static void EvaluatesTo(ILispValue expected, ILispValue expression, ILispEnvironment environment = null)
{
Assert.IsNotNull(expected);
Assert.IsNotNull(expression);
ILispValue actual = Evaluator.Evaluate(expression, environment ?? new GlobalEnvironment());
if (!EqualityComparer <ILispValue> .Default.Equals(expected, actual))
{
throw new AssertFailedException(string.Format(
"Computed incorrect value while evaluating {1}.{0}Expected: {2}, Actual: {3}",
System.Environment.NewLine,
expression,
expected,
actual));
}
}
private static ILispValue EvaluateList(List list, ILispEnvironment environment)
{
if (list.IsEmpty)
{
return(list);
}
ILispValue head = list.GetHead();
IList <ILispValue> parameters = list.CollectProperList().Skip(1).ToList();
if (head.Type == LispValueType.Symbol)
{
// Look for special forms and process them, um..., specially.
switch (((Symbol)head).Name)
{
case "quote":
return(EvaluateQuote(parameters, environment));
case "if":
return(EvaluateIf(parameters, environment));
case "progn":
return(EvaluateProgn(parameters, environment));
case "set!":
return(EvaluateSet(parameters, environment));
case "lambda":
return(EvaluateLambdaDefinition(parameters, environment));
default:
return(EvaluateInvocation((Symbol)head, parameters, environment));
}
}
else
{
head = Evaluate(head, environment);
if (head.Type != LispValueType.Symbol)
{
throw new TypeMismatchException(new Symbol("function"), LispValueType.Symbol, head.Type);
}
return(EvaluateInvocation((Symbol)head, parameters, environment));
}
}
public static ILispValue Evaluate(ILispValue value, ILispEnvironment environment)
{
switch (value.Type)
{
case LispValueType.Boolean:
case LispValueType.Char:
case LispValueType.Lambda:
case LispValueType.Number:
case LispValueType.String:
default:
return(value);
case LispValueType.Symbol:
return(environment.Lookup((Symbol)value));
case LispValueType.List:
return(EvaluateList((List)value, environment));
}
}
private static ILispValue EvaluateSet(IList <ILispValue> args, ILispEnvironment environment)
{
if (args.Count < 2)
{
throw new SignatureMismatchException("too few arguments supplied");
}
if (args.Count > 2)
{
throw new SignatureMismatchException("too many arguments supplied");
}
// this is a special form since we do not evaluate the first argument, which must be a symbol
if (args[0].Type != LispValueType.Symbol)
{
throw new TypeMismatchException(new Symbol("variable"), LispValueType.Symbol, args[0].Type);
}
ILispValue value = Evaluate(args[1], environment);
environment.Set((Symbol)args[0], value);
return(value);
}
private static ILispValue EvaluateIf(IList <ILispValue> args, ILispEnvironment environment)
{
if (args.Count < 3)
{
throw new SignatureMismatchException("too few arguments supplied");
}
if (args.Count > 3)
{
throw new SignatureMismatchException("too many arguments supplied");
}
ILispValue test = Evaluate(args[0], environment);
switch (test.Type)
{
case LispValueType.Boolean:
if (!((TiaLisp.Values.Boolean)test).Value)
{
return(Evaluate(args[2], environment));
}
else
{
return(Evaluate(args[1], environment));
}
case LispValueType.List:
if (((List)test).IsEmpty)
{
return(Evaluate(args[2], environment));
}
else
{
return(Evaluate(args[1], environment));
}
default:
// Any other value than #f or () is considered true:
return(Evaluate(args[1], environment));
}
}
internal LocalEnvironment(ILispEnvironment parentEnvironment)
{
this._ParentEnvironment = parentEnvironment;
}
public static void ThrowsWhenEvaluated(ILispValue expression, ILispEnvironment environment = null)
{
ThrowsWhenEvaluated <LispException>(expression, environment);
}
private static ILispValue EvaluateInvocation(Symbol funcName, IList <ILispValue> args, ILispEnvironment environment)
{
ILispValue func = environment.Lookup(funcName);
if (func.Type != LispValueType.Lambda)
{
throw new TypeMismatchException(new Symbol("function"), LispValueType.Lambda, func.Type);
}
ILispLambda lambda = (ILispLambda)func;
IList <ILispValue> parameterValues = args.Select(arg => Evaluate(arg, environment)).ToList();
return(lambda.Execute(BindParameters(lambda, parameterValues)));
}
private static ILispValue EvaluateLambdaDefinition(IList <ILispValue> args, ILispEnvironment environment)
{
throw new NotImplementedException();
}
