public static bool IsMemberDeclarationContext(
this SyntaxTree syntaxTree,
int position,
CSharpSyntaxContext contextOpt,
ISet<SyntaxKind> validModifiers,
ISet<SyntaxKind> validTypeDeclarations,
bool canBePartial,
CancellationToken cancellationToken)
{
var typeDecl = contextOpt != null
? contextOpt.ContainingTypeOrEnumDeclaration
: syntaxTree.GetContainingTypeOrEnumDeclaration(position, cancellationToken);
if (typeDecl == null)
{
return false;
}
if (!validTypeDeclarations.Contains(typeDecl.Kind()))
{
return false;
}
validTypeDeclarations = validTypeDeclarations ?? SpecializedCollections.EmptySet<SyntaxKind>();
// Check many of the simple cases first.
var leftToken = contextOpt != null
? contextOpt.LeftToken
: syntaxTree.FindTokenOnLeftOfPosition(position, cancellationToken);
if (syntaxTree.IsMemberDeclarationContext(position, leftToken, cancellationToken))
{
return true;
}
var token = contextOpt != null
? contextOpt.TargetToken
: leftToken.GetPreviousTokenIfTouchingWord(position);
// A member can also show up after certain types of modifiers
if (canBePartial &&
token.IsKindOrHasMatchingText(SyntaxKind.PartialKeyword))
{
return true;
}
var modifierTokens = contextOpt != null
? contextOpt.PrecedingModifiers
: syntaxTree.GetPrecedingModifiers(position, leftToken, cancellationToken);
if (!modifierTokens.Any())
{
return false;
}
validModifiers = validModifiers ?? SpecializedCollections.EmptySet<SyntaxKind>();
if (modifierTokens.IsSubsetOf(validModifiers))
{
var member = token.Parent;
if (token.HasMatchingText(SyntaxKind.AsyncKeyword))
{
// second appearance of "async", not followed by modifier: treat it as type
if (syntaxTree.GetPrecedingModifiers(token.SpanStart, token, cancellationToken).Any(x => x == SyntaxKind.AsyncKeyword))
{
return false;
}
// rule out async lambdas inside a method
if (token.GetAncestor<StatementSyntax>() == null)
{
member = token.GetAncestor<MemberDeclarationSyntax>();
}
}
// cases:
// public |
// async |
// public async |
return member != null &&
member.Parent is BaseTypeDeclarationSyntax;
}
return false;
}
public static bool IsTypeDeclarationContext(
this SyntaxTree syntaxTree,
int position,
CSharpSyntaxContext contextOpt,
ISet<SyntaxKind> validModifiers,
ISet<SyntaxKind> validTypeDeclarations,
bool canBePartial,
CancellationToken cancellationToken)
{
// We only allow nested types inside a class or struct, not inside a
// an interface or enum.
var typeDecl = contextOpt != null
? contextOpt.ContainingTypeDeclaration
: syntaxTree.GetContainingTypeDeclaration(position, cancellationToken);
validTypeDeclarations = validTypeDeclarations ?? SpecializedCollections.EmptySet<SyntaxKind>();
if (typeDecl != null)
{
if (!validTypeDeclarations.Contains(typeDecl.Kind()))
{
return false;
}
}
// Check many of the simple cases first.
var leftToken = contextOpt != null
? contextOpt.LeftToken
: syntaxTree.FindTokenOnLeftOfPosition(position, cancellationToken);
if (syntaxTree.IsTypeDeclarationContext(position, leftToken, cancellationToken))
{
return true;
}
// If we're touching the right of an identifier, move back to
// previous token.
var token = contextOpt != null
? contextOpt.TargetToken
: leftToken.GetPreviousTokenIfTouchingWord(position);
// A type can also show up after certain types of modifiers
if (canBePartial &&
token.IsKindOrHasMatchingText(SyntaxKind.PartialKeyword))
{
return true;
}
// using static | is never a type declaration context
if (token.IsStaticKeywordInUsingDirective())
{
return false;
}
var modifierTokens = contextOpt != null
? contextOpt.PrecedingModifiers
: syntaxTree.GetPrecedingModifiers(position, leftToken, cancellationToken);
if (!modifierTokens.Any())
{
return false;
}
validModifiers = validModifiers ?? SpecializedCollections.EmptySet<SyntaxKind>();
if (modifierTokens.IsProperSubsetOf(validModifiers))
{
// the parent is the member
// the grandparent is the container of the member
var container = token.Parent.GetParent();
if (container.IsKind(SyntaxKind.CompilationUnit) ||
container.IsKind(SyntaxKind.NamespaceDeclaration) ||
container.IsKind(SyntaxKind.ClassDeclaration) ||
container.IsKind(SyntaxKind.StructDeclaration))
{
return true;
}
}
return false;
}
SyntaxContext(CSharpSyntaxContext ctx, List<ITypeSymbol> inferredTypes)
{
this.inferredTypes = inferredTypes;
this.ctx = ctx;
}