internal static bool TryGetStringValue(this ArgumentSyntax argument, SemanticModel semanticModel, CancellationToken cancellationToken, out string result)
{
result = null;
if (argument?.Expression == null || semanticModel == null)
{
return(false);
}
if (argument.Expression.IsKind(SyntaxKind.NullLiteralExpression))
{
return(true);
}
if (argument.Expression.IsKind(SyntaxKind.StringLiteralExpression) ||
argument.Expression.IsNameOf())
{
var cv = semanticModel.GetConstantValueSafe(argument.Expression, cancellationToken);
if (cv.HasValue && cv.Value is string)
{
result = (string)cv.Value;
return(true);
}
}
var symbolInfo = semanticModel.GetSymbolSafe(argument.Expression, cancellationToken);
if (symbolInfo?.ContainingType?.Name == "String" &&
symbolInfo.Name == "Empty")
{
result = string.Empty;
return(true);
}
return(false);
}
/// <summary>
/// Try getting the GetConstantValue for the node.
/// Gets the semantic model for the tree if the node is not in the tree corresponding to <paramref name="semanticModel"/>.
/// </summary>
/// <typeparam name="T">The symbol.</typeparam>
/// <param name="semanticModel">The <see cref="SemanticModel"/>.</param>
/// <param name="node">The <see cref="SyntaxNode"/>.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/>.</param>
/// <param name="value">The symbol if found.</param>
/// <returns>True if a symbol was found.</returns>
public static bool TryGetConstantValue <T>(this SemanticModel semanticModel, SyntaxNode node, CancellationToken cancellationToken, out T value)
{
if (semanticModel.GetConstantValueSafe(node, cancellationToken) is Optional <object> optional &&
optional.HasValue)
{
if (optional.Value is T temp)
{
value = temp;
return(true);
}
if (optional.Value == null)
{
value = default(T);
return(default(T) == null);
}
// We can't use GetTypeInfo() here as it brings in System.Reflection.Extensions that does not work in VS.
if (default(T) is Enum &&
Enum.GetUnderlyingType(typeof(T)) == optional.Value.GetType())
{
// ReSharper disable once PossibleInvalidCastException
value = (T)optional.Value;
return(true);
}
}
value = default(T);
return(false);
}
internal static bool TryGetStringValue(this ArgumentSyntax argument, SemanticModel semanticModel, CancellationToken cancellationToken, out string result)
{
return(TryGetStringValue(argument?.Expression, out result));
bool TryGetStringValue(ExpressionSyntax expression, out string text)
{
text = null;
if (expression == null)
{
return(false);
}
if (expression is LiteralExpressionSyntax literal)
{
switch (literal.Kind())
{
case SyntaxKind.NullLiteralExpression:
return(true);
case SyntaxKind.StringLiteralExpression:
text = literal.Token.ValueText;
return(true);
}
}
if (expression.IsNameOf())
{
var cv = semanticModel.GetConstantValueSafe(expression, cancellationToken);
if (cv.HasValue &&
cv.Value is string)
{
text = (string)cv.Value;
return(true);
}
}
if (expression is MemberAccessExpressionSyntax memberAccess &&
memberAccess.Name.Identifier.ValueText == "Empty" &&
((memberAccess.Expression is PredefinedTypeSyntax predefinedType &&
predefinedType.Keyword.Text == "string") ||
(memberAccess.Expression is IdentifierNameSyntax identifierName &&
identifierName.Identifier.ValueText == "String")))
{
if (semanticModel.GetSymbolSafe(expression, cancellationToken) is IFieldSymbol field &&
field == KnownSymbol.String.Empty)
{
text = string.Empty;
return(true);
}
}
if (expression is CastExpressionSyntax castExpression)
{
return(TryGetStringValue(castExpression.Expression, out text));
}
return(false);
}
}
/// <summary>
/// Try getting the GetConstantValue for the node.
/// Gets the semantic model for the tree if the node is not in the tree corresponding to <paramref name="semanticModel"/>.
/// </summary>
/// <typeparam name="T">The symbol.</typeparam>
/// <param name="semanticModel">The <see cref="SemanticModel"/>.</param>
/// <param name="node">The <see cref="SyntaxNode"/>.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/>.</param>
/// <param name="value">The symbol if found.</param>
/// <returns>True if a symbol was found.</returns>
public static bool TryGetConstantValue <T>(this SemanticModel semanticModel, SyntaxNode node, CancellationToken cancellationToken, [MaybeNullWhen(false)] out T value)
{
if (semanticModel is null)
{
throw new ArgumentNullException(nameof(semanticModel));
}
if (node is null)
{
throw new ArgumentNullException(nameof(node));
}
if (semanticModel.GetConstantValueSafe(node, cancellationToken) is Optional <object> optional &&
optional.HasValue)
{
if (optional.Value is T temp)
{
value = temp;
return(true);
}
if (optional.Value is null)
{
value = default !;
/// <summary>
/// Try getting the GetConstantValue for the node.
/// Gets the semantic model for the tree if the node is not in the tree corresponding to <paramref name="semanticModel"/>.
/// </summary>
/// <typeparam name="T">The symbol.</typeparam>
/// <param name="semanticModel">The <see cref="SemanticModel"/>.</param>
/// <param name="node">The <see cref="SyntaxNode"/>.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/>.</param>
/// <param name="value">The symbol if found.</param>
/// <returns>True if a symbol was found.</returns>
public static bool TryGetConstantValue <T>(this SemanticModel semanticModel, SyntaxNode node, CancellationToken cancellationToken, [MaybeNullWhen(false)] out T value)
{
if (semanticModel is null)
{
throw new ArgumentNullException(nameof(semanticModel));
}
if (node is null)
{
throw new ArgumentNullException(nameof(node));
}
if (semanticModel.GetConstantValueSafe(node, cancellationToken) is { HasValue : true } optional)
{
if (optional.Value is T temp)
{
value = temp;
return(true);
}
// ReSharper disable ConditionIsAlwaysTrueOrFalse
if (optional.Value is null)
{
value = default !;
internal static bool TryGetArgumentStringValue(AttributeSyntax attribute, int argumentIndex, SemanticModel semanticModel, CancellationToken cancellationToken, out AttributeArgumentSyntax arg, out string result)
{
arg = null;
result = null;
if (attribute?.ArgumentList?.Arguments.TryGetAtIndex(argumentIndex, out arg) != true)
{
return(false);
}
if (!arg.Expression.IsKind(SyntaxKind.StringLiteralExpression))
{
return(false);
}
var constantValue = semanticModel.GetConstantValueSafe(arg.Expression, cancellationToken);
if (!constantValue.HasValue)
{
return(false);
}
result = (string)constantValue.Value;
return(true);
}