public static bool TryGetCompileTimeString(
this ExpressionSyntax expression,
SemanticModelDecorator semanticModel,
[NotNullWhen(true)] out string?result
)
{
if (expression is null)
{
throw new ArgumentNullException(nameof(expression));
}
if (semanticModel is null)
{
throw new ArgumentNullException(nameof(semanticModel));
}
if (expression is LiteralExpressionSyntax literal)
{
result = literal.Token.ValueText;
return(true);
}
var constant = semanticModel.GetConstantValue(expression);
if (constant.HasValue)
{
result = constant.Value !.ToString() !;
return(true);
}
result = null;
return(false);
}
private void CheckForAllowedSyntaxForConstantBinding(
)
{
var child = _constantClause.ChildNodes().FirstOrDefault();
if (child == null)
{
throw new DpdtException(
DpdtExceptionTypeEnum.InternalError,
$"Unknown error during validation a target in 'constant' binding."
);
}
var cconstant = _semanticModel.GetConstantValue(child);
if (cconstant.HasValue)
{
//it's a true constant, keep going!
return;
}
var ilsymbol = _semanticModel.GetSymbolInfo(child).Symbol;
if (ilsymbol is null)
{
throw new DpdtException(
DpdtExceptionTypeEnum.InternalError,
$"Unknown error during validation a target in 'constant' binding."
);
}
if (ilsymbol.Kind != SymbolKind.Field)
{
throw new DpdtException(
DpdtExceptionTypeEnum.InternalError,
$"Unsupported type of 'constant' binding. Allowed compile-time constants, readonly fields and readonly static fields only."
);
}
var filsymbol = ilsymbol as IFieldSymbol;
if (filsymbol is null)
{
throw new DpdtException(
DpdtExceptionTypeEnum.InternalError,
$"Unknown error during validation a target in 'constant' binding."
);
}
if (!filsymbol.IsReadOnly)
{
throw new DpdtException(
DpdtExceptionTypeEnum.InternalError,
$"Unsupported type of 'constant' binding. Allowed compile-time constants, readonly fields and readonly static fields only."
);
}
}
