public T2 Assign()
{
T2 statement = default;
Token token = LookAheadToken;
MatchThenLookAhead(TokenTag.ID);
IdExpression idExpression = TopSymbol.Get(token);
if (idExpression is null)
{
Error($"{token} undeclared");
}
if (LookAheadToken?.Tag == '=')
{
LookAhead();
statement = (T2)Activator.CreateInstance(typeof(SetStatement), new object[] { idExpression, Boolean(), _emitterNode });
}
else
{
AccessingOperationExpression accessingOperationExpression = Offset(idExpression);
MatchThenLookAhead('=');
statement = (T2)Activator.CreateInstance(typeof(SetElementStatement), new object[] { accessingOperationExpression, Boolean(), _emitterNode });
}
MatchThenLookAhead(';');
return(statement);
}
public virtual void Declare()
{
while (LookAheadToken?.Tag == TokenTag.BASIC)
{
TypeToken typeToken = Type();
var token = LookAheadToken;
MatchThenLookAhead(TokenTag.ID);
MatchThenLookAhead(';');
IdExpression idExpression = new((WordToken)token, typeToken, Used, _emitterNode);
TopSymbol.Put(token, idExpression);
Used += typeToken.Width;
}
}
public T3 Factor()
{
T3 expression = default;
switch (LookAheadToken?.Tag)
{
case '(':
LookAhead();
expression = Boolean();
MatchThenLookAhead(')');
return(expression);
case TokenTag.NUMBER:
expression = (T3)Activator.CreateInstance(typeof(ConstantExpression), new object[] { LookAheadToken, TypeToken.INT, _emitterNode });
LookAhead();
return(expression);
case TokenTag.REAL:
expression = (T3)Activator.CreateInstance(typeof(ConstantExpression), new object[] { LookAheadToken, TypeToken.FLOAT, _emitterNode });
LookAhead();
return(expression);
case TokenTag.TRUE:
expression = (T3)Activator.CreateInstance(typeof(ConstantExpression), new object[] { WordToken.TRUE, TypeToken.BOOL, _emitterNode });
LookAhead();
return(expression);
case TokenTag.FALSE:
expression = (T3)Activator.CreateInstance(typeof(ConstantExpression), new object[] { WordToken.FALSE, TypeToken.BOOL, _emitterNode });
LookAhead();
return(expression);
case TokenTag.ID:
var idExpression = TopSymbol.Get(LookAheadToken);
if (idExpression == null)
{
Error($"{LookAheadToken} undeclared");
}
LookAhead();
if (LookAheadToken?.Tag != '[')
{
return((T3)Activator.CreateInstance(typeof(IdExpression), new object[] {
idExpression.Token,
idExpression.TypeToken,
idExpression.Offset,
idExpression.Node
}));
}
else
{
var accessingOperationExpression = Offset(idExpression);
return((T3)Activator.CreateInstance(typeof(AccessingOperationExpression), new object[] {
accessingOperationExpression.ArrayExpression,
accessingOperationExpression.IndexExpression,
accessingOperationExpression.TypeToken,
accessingOperationExpression.Node
}));
}
default:
Error("Syntax error");
return(expression);
}
}
