private bool TryInitialize(
TextSpan textSpan,
CancellationToken cancellationToken)
{
if (cancellationToken.IsCancellationRequested)
{
return(false);
}
var tree = Document.SyntaxTree;
var syntaxFacts = Document.Project.LanguageServices.GetService <ISyntaxFactsService>();
Expression = GetExpressionUnderSpan(tree, textSpan, cancellationToken);
if (Expression == null)
{
return(false);
}
var expressionType = Document.SemanticModel.GetTypeInfo(Expression, cancellationToken).Type;
if (expressionType is IErrorTypeSymbol)
{
return(false);
}
var containingType = Expression.AncestorsAndSelf()
.Select(n => Document.SemanticModel.GetDeclaredSymbol(n, cancellationToken))
.OfType <INamedTypeSymbol>()
.FirstOrDefault();
containingType ??= Document.SemanticModel.Compilation.ScriptClass;
if (containingType == null || containingType.TypeKind == TypeKind.Interface)
{
return(false);
}
if (!CanIntroduceVariable(textSpan.IsEmpty, cancellationToken))
{
return(false);
}
IsConstant = Document.SemanticModel.GetConstantValue(Expression, cancellationToken).HasValue;
// Note: the ordering of these clauses are important. They go, generally, from
// innermost to outermost order.
if (IsInQueryContext(cancellationToken))
{
if (CanGenerateInto <TQueryExpressionSyntax>(cancellationToken))
{
InQueryContext = true;
return(true);
}
return(false);
}
if (IsInConstructorInitializerContext(cancellationToken))
{
if (CanGenerateInto <TTypeDeclarationSyntax>(cancellationToken))
{
InConstructorInitializerContext = true;
return(true);
}
return(false);
}
var enclosingBlocks = _service.GetContainingExecutableBlocks(Expression);
if (enclosingBlocks.Any())
{
// If we're inside a block, then don't even try the other options (like field,
// constructor initializer, etc.). This is desirable behavior. If we're in a
// block in a field, then we're in a lambda, and we want to offer to generate
// a local, and not a field.
if (IsInBlockContext(cancellationToken))
{
InBlockContext = true;
return(true);
}
return(false);
}
/* NOTE: All checks from this point forward are intentionally ordered to be AFTER the check for Block Context. */
// If we are inside a block within an Expression bodied member we should generate inside the block,
// instead of rewriting a concise expression bodied member to its equivalent that has a body with a block.
if (_service.IsInExpressionBodiedMember(Expression))
{
if (CanGenerateInto <TTypeDeclarationSyntax>(cancellationToken))
{
InExpressionBodiedMemberContext = true;
return(true);
}
return(false);
}
if (_service.IsInAutoPropertyInitializer(Expression))
{
if (CanGenerateInto <TTypeDeclarationSyntax>(cancellationToken))
{
InAutoPropertyInitializerContext = true;
return(true);
}
return(false);
}
if (CanGenerateInto <TTypeDeclarationSyntax>(cancellationToken))
{
if (IsInParameterContext(cancellationToken))
{
InParameterContext = true;
return(true);
}
else if (IsInFieldContext(cancellationToken))
{
InFieldContext = true;
return(true);
}
else if (IsInAttributeContext(cancellationToken))
{
InAttributeContext = true;
return(true);
}
}
return(false);
}