protected override object?Visit(Expression.If iff)
{
base.Visit(iff);
// Condition must be bool
var conditionType = System.TypeOf(iff.Condition);
if (!conditionType.Equals(Type.Bool))
{
System.Report(new ExpectedTypeError(Type.Bool, conditionType)
{
Context = "if condition",
Place = iff.Condition.ParseTreeNode,
});
}
// If there is an else branch, body types should match
if (iff.Else != null)
{
var thenType = System.TypeOf(iff.Then);
var elseType = System.TypeOf(iff.Else);
if (!thenType.Equals(elseType))
{
var thenRet = FindDeepestReturnValue(iff.Then)?.ParseTreeNode;
var elseRet = FindDeepestReturnValue(iff.Else)?.ParseTreeNode;
System.Report(new TypeMismatchError(thenType, elseType)
{
Context = "if expression",
Defined = thenRet,
Wrong = elseRet,
});
}
}
return(null);
}
public override Expression VisitEXPR_If([NotNull] S_ScriptParser.EXPR_IfContext context)
{
Expression x = this.Visit(context.expression()[0]);
Expression y = this.Visit(context.expression()[1]);
Expression z = (context.expression().Length == 2 ? null : this.Visit(context.expression()[2]));
Expression if_func = new Expression.If(this._Host, this._Master);
if_func.AddChild(x);
if_func.AddChild(y);
if_func.AddChild(z);
this._Master = if_func;
return(if_func);
}
protected override Value?Visit(Expression.If iff)
{
if (iff.Else == null)
{
// No chance for a return value
Builder.IfThen(
condition: b => VisitNonNull(iff.Condition),
then: b => Visit(iff.Then));
return(null);
}
else
{
var retType = TypeOf(iff);
if (retType.Equals(Semantic.Types.Type.Unit))
{
// There is no return value
Builder.IfThenElse(
condition: b => VisitNonNull(iff.Condition),
then: b => Visit(iff.Then),
@else: b => Visit(iff.Else));
return(null);
}
else
{
// There is a return value we need to take care of
// First we allocate space for the return value
var retSpace = Builder.Alloc(TranslateToLirType(retType));
// Compile it, storing the results in the respective blocks
Builder.IfThenElse(
condition: b => VisitNonNull(iff.Condition),
then: b =>
{
var result = VisitNonNull(iff.Then);
b.Store(retSpace, result);
},
@else: b =>
{
var result = VisitNonNull(iff.Else);
b.Store(retSpace, result);
});
// Load up the result
return(Builder.Load(retSpace));
}
}
}