public void EvalAnd_ReturnTrue_WhenTailIsEmptyList()
{
var expr = BuiltIn.ListOf(ClSymbol.And);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(ClBool.True));
}
public override IContext Reduce(IContext ctx)
{
var funcName = BuiltIn.Head(Cdr);
var lambda = new ClCell(ClSymbol.Lambda, BuiltIn.Tail(Cdr));
return(BuiltIn.ListOf(ClSymbol.Define, funcName, lambda).Reduce(ctx));
}
public void EvalCond_ReturnFalse_WhenClausesAreMissed()
{
var expr = BuiltIn.ListOf(ClSymbol.Cond);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(ClBool.False));
}
public void EvalDefinition_ThrowException_WhenRighSideVariableDoesNotExist()
{
var expr = BuiltIn.ListOf(ClSymbol.Define, Var.Foo, Var.Bar);
Assert.That(() => expr.Reduce(_ctx),
Throws.Exception.TypeOf <UnboundVariableError>().With.Message.EqualTo("Unbound variable bar"));
}
public void EvalDefinition_CreateNewBinding()
{
var expr = BuiltIn.ListOf(ClSymbol.Define, Var.Foo, ClBool.True);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Env.Lookup(Var.Foo), Is.EqualTo(ClBool.True));
}
public void EvalBegin_ReturnNil_WhenTailIsEmptyList()
{
var expr = BuiltIn.ListOf(ClSymbol.Begin);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(ClCell.Nil));
}
public void EvalAnd_ReturnLastItem_WhenEachItemIsTrue()
{
var expr = BuiltIn.ListOf(ClSymbol.And, ClBool.True, Value.Foo);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(Value.Foo));
}
public void Eval_DoesNotCreateNewScope(Func <ClCell, ClCell> expr)
{
var define = BuiltIn.ListOf(ClSymbol.Define, Var.Foo, Value.Foo);
var ctx = expr.Invoke(define).Reduce(_ctx);
Assert.That(ctx.Env.Lookup(Var.Foo), Is.EqualTo(Value.Foo));
}
public void EvalIf_ReturnNil_WhenConditionIsFalseAndElseBranchIsMissed()
{
var expr = BuiltIn.ListOf(ClSymbol.If, ClBool.False, Value.One);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(ClCell.Nil));
}
public void EvalLet_LikeConstantFunction()
{
var expr = BuiltIn.ListOf(ClSymbol.Let, ClCell.Nil, Value.One);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(Value.One));
}
public void EvalAssignment_ThrowException_WhenEnvironmentDoesNotContainBinding()
{
var expr = BuiltIn.ListOf(ClSymbol.Set, Var.Foo, Value.Foo);
Assert.That(() => expr.Reduce(_ctx),
Throws.Exception.TypeOf <UnboundVariableError>().With.Message.EqualTo("Unbound variable foo"));
}
public void EvalIf_EvalThenBranch_WhenConditionIsTrue(ClObj predicate)
{
var expr = BuiltIn.ListOf(ClSymbol.If, predicate, Value.One, ClBool.False);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(Value.One));
}
public void EvalOr_ReturnFalse_WhenTailIsEmptyList()
{
var expr = BuiltIn.ListOf(ClSymbol.Or);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(ClBool.False));
}
public void EvalBegin_ReturnLastEvaluatedValue()
{
var expr = BuiltIn.ListOf(ClSymbol.Begin, ClBool.False, ClBool.True, Value.One);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(Value.One));
}
public void EvalDefinition_ReturnNil_WhenOperationIsSuccessful()
{
var expr = BuiltIn.ListOf(ClSymbol.Define, Var.Foo, ClBool.False);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Value, Is.EqualTo(ClCell.Nil));
}
static IEnumerable <ClObj> InvalidParameterTestCases()
{
yield return(Value.One);
yield return(Value.Foo);
yield return(BuiltIn.ListOf(ClSymbol.If, ClBool.True, Var.Foo, Var.Bar));
}
static IEnumerable <Func <ClCell, ClCell> > DoesNotCreateNewScopeTestCases()
{
yield return(new Func <ClCell, ClCell>(x => BuiltIn.ListOf(ClSymbol.If, x, ClBool.True, ClBool.False)));
yield return(new Func <ClCell, ClCell>(x => BuiltIn.ListOf(ClSymbol.And, x, ClBool.False)));
yield return(new Func <ClCell, ClCell>(x => BuiltIn.ListOf(ClSymbol.Or, x, ClBool.True)));
}
public void Env_InjectPredifinedEntities()
{
var env = new Env(BuiltIn.Env);
var nativeFn = env.Lookup(new ClSymbol("head")).Cast <NativeFn>();
var args = BuiltIn.ListOf(ClBool.True, ClBool.False);
Assert.That(nativeFn.Apply(args), Is.EqualTo(ClBool.True));
}
public void EvalLambda_ThrowException_WhenLambdaSpecialFormHasInvalidBody()
{
var expr = BuiltIn.ListOf(ClSymbol.Lambda, ClCell.Nil, ClBool.True, ClBool.False);
var errorMessage = "Invalid function body format";
Assert.That(() => expr.Reduce(_ctx),
Throws.Exception.TypeOf <SyntaxError>().With.Message.EqualTo(errorMessage));
}
public void Eval_IdentifiersAndKeywordsCoexistIndependently()
{
_env.Bind(ClSymbol.And, Value.One);
var expr = BuiltIn.ListOf(ClSymbol.And, ClBool.True, Value.Foo);
Assert.That(ClSymbol.And.Reduce(_ctx).Value, Is.EqualTo(Value.One));
Assert.That(expr.Reduce(_ctx).Value, Is.EqualTo(Value.Foo));
}
public override IContext Reduce(IContext ctx)
{
var identifier = BuiltIn.First(Cdr).Cast <ClSymbol>();
var newCtx = BuiltIn.Second(Cdr).Reduce(ctx);
newCtx.Env.Assign(identifier, newCtx.Value);
return(new Context(newCtx.Env));
}
public void EvalLambda_ThrowExceptionWhenParametersIsNotList()
{
var expr = BuiltIn.ListOf(ClSymbol.Lambda, Var.Foo, Var.Foo);
var errorMessage = "Invalid function parameters format";
Assert.That(() => expr.Reduce(_ctx),
Throws.Exception.TypeOf <SyntaxError>().With.Message.EqualTo(errorMessage));
}
public override IContext Reduce(IContext ctx)
{
var identifier = BuiltIn.First(Cdr).Cast <ClSymbol>();
var(value, env) = BuiltIn.Second(Cdr).Reduce(ctx);
env.Bind(identifier, value);
return(new Context(env));
}
public void SnippetsTest(string snippet, string expected)
{
using var source = new Source(snippet);
var reader = new Reader();
var(actual, _) = BuiltIn.Eval(reader.Read(source));
Assert.That(actual.ToString(), Is.EqualTo(expected));
}
public void EvalApplication_ThrowException_WhenBodyContainsUnboundVariable()
{
var procedure = BuiltIn.ListOf(ClSymbol.Lambda, ClCell.Nil, Var.Bar);
var expr = BuiltIn.ListOf(procedure);
Assert.That(() => expr.Reduce(_ctx),
Throws.Exception.TypeOf <UnboundVariableError>().With.Message.EqualTo("Unbound variable bar"));
}
public void Eval_ReturnUnreducedExpression_WhenItIsQuoted()
{
var cell = new ClCell(new ClInt(1), new ClInt(2));
var expr = BuiltIn.Quote(cell);
var ctx = expr.Reduce(_ctx);
Assert.That(Object.ReferenceEquals(ctx.Value, cell), Is.True);
}
public void EvalDefinition_CreateSharedReference()
{
_env.Bind(Var.Bar, Value.Bar);
var expr = BuiltIn.ListOf(ClSymbol.Define, Var.Foo, Var.Bar);
Ignore(expr.Reduce(_ctx));
Assert.That(Object.ReferenceEquals(_env.Lookup(Var.Foo), _env.Lookup(Var.Bar)), Is.True);
}
public void EvalDefinition_OverrideExistingBinding()
{
_env.Bind(Var.Foo, ClBool.True);
var expr = BuiltIn.ListOf(ClSymbol.Define, Var.Foo, Value.Foo);
var ctx = expr.Reduce(_ctx);
Assert.That(ctx.Env.Lookup(Var.Foo), Is.EqualTo(Value.Foo));
}
public void EvalApplication_ThrowInvalidFunctionCall_WhenCarIsNotCallable()
{
_env.Bind(Var.Fn, Value.One);
var expr = BuiltIn.ListOf(Var.Fn, Value.One);
var errorMessage = $"{nameof(ClInt)} is neither callable nor special from";
Assert.That(() => expr.Reduce(_ctx),
Throws.Exception.TypeOf <SyntaxError>().With.Message.EqualTo(errorMessage));
}
public void EvalApplication_ZeroArityFunction()
{
var constantFn = BuiltIn.ListOf(ClSymbol.Lambda, ClCell.Nil, Value.One);
var expr = BuiltIn.ListOf(constantFn);
var context = expr.Reduce(_ctx);
Assert.That(context.Value, Is.EqualTo(Value.One));
}
