public static IExpression CreateFromExpression(string expression)
{
IExpression result = null;
if (ConstantExpression.IsMatch(expression))
{
result = new ConstantExpression();
}
else if (AddExpression.IsMatch(expression))
{
result = new AddExpression();
}
else if (SubExpression.IsMatch(expression))
{
result = new SubExpression();
}
else if (MulExpression.IsMatch(expression))
{
result = new MulExpression();
}
else if (DivExpression.IsMatch(expression))
{
result = new DivExpression();
}
else if (LetExpression.IsMatch(expression))
{
result = new LetExpression();
}
else if (VariableExpression.IsMatch(expression))
{
result = new VariableExpression();
}
return(result);
}
public TypeDenoter VisitLetExpression(LetExpression ast, Void arg)
{
_idTable.OpenScope();
ast.Declaration.Visit(this);
ast.Type = ast.Expression.Visit(this);
_idTable.CloseScope();
return(ast.Type);
}
public void EvaluateTests(string expression, int expectedResult)
{
var letExpression = new LetExpression();
int result = letExpression.Evaluate(expression);
Assert.That(result, Is.EqualTo(expectedResult));
}
public void ValidateExpressionTests(string expression, bool expectedResult, string expectedError)
{
var letExpression = new LetExpression();
bool result = letExpression.ValidateExpression(expression, out string error);
Assert.That(result, Is.EqualTo(expectedResult));
Assert.That(error, Is.EqualTo(expectedError));
}
public int VisitLetExpression(LetExpression ast, Frame frame)
{
ast.Type.Visit(this, null);
var extraSize = ast.Declaration.Visit(this, frame);
var valSize = ast.Expression.Visit(this, frame.Expand(extraSize));
if (extraSize > 0)
{
_emitter.Emit(OpCode.POP, valSize, extraSize);
}
return(valSize);
}
private Expression ParseLetExpression()
{
var letKeyword = ReadToken();
TokenInfo nameToken, assignToken;
List <Parameter> parameters = new List <Parameter>();
Expression assignedExpression = null;
if (!Eat(TokenKind.Identifier, out nameToken))
{
Diagnostics.AddError(Strings.Error_UnexpectedEndOfFile, nameToken.GetSpan());
}
TokenInfo token = PeekToken();
if (token.Kind != TokenKind.Assign && token.Kind == TokenKind.Identifier)
{
while (MaybeEat(TokenKind.Identifier, out token))
{
parameters.Add(new Parameter(token));
}
}
else
{
ReadToken();
Diagnostics.AddError(Strings.Error_ExpectedToken, token.GetSpan());
}
if (!Eat(TokenKind.Assign, out assignToken))
{
Diagnostics.AddError(Strings.Error_UnexpectedEndOfFile, assignToken.GetSpan());
}
token = PeekToken();
assignedExpression = ParseExpression();
if (assignedExpression == null)
{
Diagnostics.AddError(Strings.Error_ExpectedExpression, token.GetSpan());
}
var expr = new LetExpression(letKeyword, nameToken, assignToken, assignedExpression);
if (parameters.Any())
{
expr.Parameters.AddRange(parameters);
}
return(expr);
}
public static Fetch <B> Select <A, B>(this Fetch <A> self, Expression <Func <A, B> > f)
{
var isLet = LetExpression.IsLetExpression(f);
if (!isLet)
{
return(new Select <A, B>(self, f));
}
Expression <Func <A, Fetch <A> > > letBind = _ => self;
var letProject = LetExpression.RewriteLetExpression(f);
var letPair = new BindProjectPair(letBind, letProject);
return(new Bind <A, B, B>(self.CollectedExpressions.Append(letPair), self)
{
IsLet = true
});
}
static void Main(string[] args)
{
var input = File.ReadAllLines("test.in").First();
using (var sw = new StreamWriter(new FileStream("test.out", FileMode.Create)))
{
try
{
var id = new Abstraction(new Variable("x"), new Variable("x"));
var fst = new Abstraction(new Variable("x"), new Abstraction(new Variable("y"), new Variable("x")));
var lambda = new LetExpression(
new Variable("id"),
id,
new LetExpression(
new Variable("fst"),
fst,
new Application(
new Application(
new Variable("fst"),
new Application(new Variable("id"), new Variable("x"))
),
new Application(new Variable("id"), new Variable("y"))
)
)
);
var ev = new TypeInferer(Lambda.Parse(input));
sw.WriteLine(ev.GetLambdaType());
ev.PrintContext(sw);
}
catch (UnificatorUnresolvedExpection e)
{
sw.WriteLine("The lambda expression has no type");
}
}
}
ExpressionType TranslateExpression(LetExpression e)
{
Env.ValueEnvironment.BeginScope();
Env.TypeEnvironment.BeginScope();
ExpList eDec = null, p = null;
for (DeclarationList ptr = e.Decs; ptr != null; ptr = ptr.Tail)
{
if (eDec == null)
{
p = eDec = new ExpList(TranslateDeclaration(ptr.Head), null);
}
else
{
p = p.Tail = new ExpList(TranslateDeclaration(ptr.Head), null);
}
}
ExpressionType eBody = TranslateExpression(e.Body);
Env.ValueEnvironment.EndScope();
Env.TypeEnvironment.EndScope();
return(new ExpressionType(Translate.TranslateLetExp(eDec, eBody.Exp, eBody.Type.CoerceTo(Types.Type._void)), eBody.Type));
}
void PrintExpression(LetExpression e, int d)
{
Say("LetExpression("); SayLn("");
PrintDeclarationList(e.Decs, d + 1); SayLn(",");
PrintExpression(e.Body, d + 1); Say(")");
}
void PrintExpression(LetExpression e, int d)
{
Say("LetExpression("); SayLn("");
PrintDeclarationList(e.Decs, d + 1); SayLn(",");
PrintExpression(e.Body, d + 1); Say(")");
}
public void IsMatchTests(string expression, bool expectedResult)
{
bool result = LetExpression.IsMatch(expression);
Assert.That(result, Is.EqualTo(expectedResult));
}
public void ErrorEvaluateTests(string expression)
{
var letExpression = new LetExpression();
Assert.Throws(typeof(ArithmeticException), () => letExpression.Evaluate(expression));
}
public override string ToString()
{
return(string.Format("let {0} = {1}", ItemName, LetExpression.ToString()));
}