/// <summary>
/// Returns a compile-time constant default expression for the given type model.
/// </summary>
public static string GetTypeDefaultExpression(this ITypeModel typeModel)
{
if (typeModel.IsNonNullableClrValueType())
{
return($"default({typeModel.GetCompilableTypeName()})");
}
else
{
return("null");
}
}
/// <summary>
/// Returns a boolean expression that compares the given variable name to the given default value literal for inequality.
/// </summary>
public static string GetNotEqualToDefaultValueLiteralExpression(this ITypeModel typeModel, string variableName, string defaultValueLiteral)
{
if (typeModel.IsNonNullableClrValueType())
{
// Structs are really weird.
// Value types are not guaranteed to have an equality operator defined, so we can't just assume
// that '==' will work, so we do a little reflection, and use the operator if it is defined.
// otherwise, we assume that the operands are not equal no matter what.
var notEqualMethod = typeModel.ClrType.GetMethod("op_Inequality", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static);
if (notEqualMethod is not null || typeModel.ClrType.IsPrimitive || typeModel.ClrType.IsEnum)
{
// Let's hope that != is implemented rationally!
return($"{variableName} != {defaultValueLiteral}");
}
else
{
// structs without an inequality overload have to be assumed to be not equal.
return("true");
}
}
/// <summary>
/// Returns a boolean expression that compares the given variable name to the given default value literal for inequality.
/// </summary>
public static string GetNotEqualToDefaultValueLiteralExpression(this ITypeModel typeModel, string variableName, string defaultValueLiteral)
{
if (typeModel.IsNonNullableClrValueType())
{
if (typeModel.ClrType.IsPrimitive || typeModel.ClrType.IsEnum)
{
// Let's hope that != is implemented rationally!
return($"{variableName} != {defaultValueLiteral}");
}
else
{
// We assume non-primitive structs are not equal.
return("true");
}
}
else
{
// Nullable<T> and reference types are easy.
return($"!({variableName} is {defaultValueLiteral})");
}
}