/// <summary>
/// Creates a new <see cref="ExpressionSyntax"/> that represents default value of the specified type symbol.
/// </summary>
/// <param name="typeSymbol"></param>
/// <param name="type"></param>
/// <param name="options"></param>
public static ExpressionSyntax GetDefaultValueSyntax(
this ITypeSymbol typeSymbol,
TypeSyntax type,
DefaultSyntaxOptions options = DefaultSyntaxOptions.None)
{
return(GetDefaultValueSyntax(typeSymbol, options, type, default(SymbolDisplayFormat)));
}
/// <summary>
/// Creates a new <see cref="ExpressionSyntax"/> that represents default value of the specified type symbol.
/// </summary>
/// <param name="typeSymbol"></param>
/// <param name="options"></param>
/// <param name="format"></param>
public static ExpressionSyntax GetDefaultValueSyntax(
this ITypeSymbol typeSymbol,
DefaultSyntaxOptions options = DefaultSyntaxOptions.None,
SymbolDisplayFormat format = null)
{
return(GetDefaultValueSyntax(typeSymbol, options, default(TypeSyntax), format));
}
internal static DefaultSyntaxOptions GetDefaultSyntaxOptions(this Document document, DefaultSyntaxOptions options = DefaultSyntaxOptions.None)
{
return((document.SupportsLanguageFeature(CSharpLanguageFeature.DefaultLiteral))
? options | DefaultSyntaxOptions.AllowDefaultLiteral
: options);
}
// https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/default-values-table
/// <summary>
/// Creates a new <see cref="ExpressionSyntax"/> that represents default value of the specified type symbol.
/// </summary>
/// <param name="typeSymbol"></param>
/// <param name="options"></param>
/// <param name="type"></param>
/// <param name="format"></param>
public static ExpressionSyntax GetDefaultValueSyntax(
this ITypeSymbol typeSymbol,
DefaultSyntaxOptions options = DefaultSyntaxOptions.None,
TypeSyntax type = null,
SymbolDisplayFormat format = null)
{
if (typeSymbol == null)
{
throw new ArgumentNullException(nameof(typeSymbol));
}
if ((options & DefaultSyntaxOptions.UseDefault) != 0)
{
return(CreateDefault());
}
if (typeSymbol.IsReferenceType ||
typeSymbol.TypeKind == TypeKind.Pointer ||
typeSymbol.IsNullableType())
{
return(NullLiteralExpression());
}
if (typeSymbol.TypeKind == TypeKind.Enum)
{
IFieldSymbol fieldSymbol = CSharpUtility.FindEnumDefaultField((INamedTypeSymbol)typeSymbol);
if (fieldSymbol != null)
{
return(SimpleMemberAccessExpression(GetTypeSyntax(), IdentifierName(fieldSymbol.Name)));
}
return(CastExpression(GetTypeSyntax(), NumericLiteralExpression(0)).WithSimplifierAnnotation());
}
switch (typeSymbol.SpecialType)
{
case SpecialType.System_Boolean:
return(FalseLiteralExpression());
case SpecialType.System_Char:
return(CharacterLiteralExpression('\0'));
case SpecialType.System_SByte:
case SpecialType.System_Byte:
case SpecialType.System_Int16:
case SpecialType.System_UInt16:
case SpecialType.System_Int32:
case SpecialType.System_UInt32:
case SpecialType.System_Int64:
case SpecialType.System_UInt64:
case SpecialType.System_Decimal:
case SpecialType.System_Single:
case SpecialType.System_Double:
return(NumericLiteralExpression(0));
}
return(CreateDefault());
TypeSyntax GetTypeSyntax()
{
return(type ?? typeSymbol.ToTypeSyntax(format).WithSimplifierAnnotation());
}
ExpressionSyntax CreateDefault()
{
if ((options & DefaultSyntaxOptions.AllowDefaultLiteral) != 0)
{
return(DefaultLiteralExpression());
}
return(DefaultExpression(GetTypeSyntax()));
}
}
