private async Task <CSharpSyntaxNode> ConvertToFunctionDeclarationOrNullAsync(VBSyntax.LambdaExpressionSyntax vbNode,
ParameterListSyntax param, BlockSyntax block,
ArrowExpressionClauseSyntax arrow)
{
if (!(_semanticModel.GetOperation(vbNode) is IAnonymousFunctionOperation anonFuncOp) || anonFuncOp.GetParentIgnoringConversions() is IDelegateCreationOperation dco && !dco.IsImplicit)
{
return(null);
}
var potentialAncestorDeclarationOperation = anonFuncOp.GetParentIgnoringConversions().GetParentIgnoringConversions();
// Could do: See if we can improve upon returning "object" for pretty much everything (which is what the symbols say)
// I believe that in general, special VB functions such as MultiplyObject are designed to work the same as integer when given two integers for example.
// If all callers currently pass an integer, perhaps it'd be more idiomatic in C# to specify "int", than to have Operators
var paramsWithTypes = anonFuncOp.Symbol.Parameters.Select(p => CommonConversions.CsSyntaxGenerator.ParameterDeclaration(p));
var paramListWithTypes = param.WithParameters(SyntaxFactory.SeparatedList(paramsWithTypes));
if (potentialAncestorDeclarationOperation is IFieldInitializerOperation fieldInit)
{
var fieldSymbol = fieldInit.InitializedFields.Single();
if (fieldSymbol.GetResultantVisibility() != SymbolVisibility.Public && !fieldSymbol.Type.IsDelegateReferencableByName() && await _solution.IsNeverWrittenAsync(fieldSymbol))
{
return(CreateMethodDeclaration(anonFuncOp, fieldSymbol, block, arrow));
}
}
if (potentialAncestorDeclarationOperation is IVariableInitializerOperation vio)
{
if (vio.GetParentIgnoringConversions().GetParentIgnoringConversions() is IVariableDeclarationGroupOperation go)
{
potentialAncestorDeclarationOperation = go.Declarations.First(d => d.Syntax.FullSpan.Contains(vbNode.FullSpan));
}
else
{
potentialAncestorDeclarationOperation = vio.Parent;
}
if (potentialAncestorDeclarationOperation is IVariableDeclarationOperation variableDeclaration)
{
var variableDeclaratorOperation = variableDeclaration.Declarators.Single();
if (!variableDeclaratorOperation.Symbol.Type.IsDelegateReferencableByName() &&
await _solution.IsNeverWrittenAsync(variableDeclaratorOperation.Symbol))
{
//Should do: Check no (other) write usages exist: SymbolFinder.FindReferencesAsync + checking if they're an assignment LHS or out parameter
return(CreateLocalFunction(anonFuncOp, variableDeclaratorOperation, paramListWithTypes, block,
arrow));
}
}
}
return(null);
}
public async Task <CSharpSyntaxNode> ConvertAsync(VBSyntax.LambdaExpressionSyntax vbNode,
ParameterListSyntax param, IReadOnlyCollection <StatementSyntax> convertedStatements)
{
BlockSyntax block = null;
ExpressionSyntax expressionBody = null;
ArrowExpressionClauseSyntax arrow = null;
if (!convertedStatements.TryUnpackSingleStatement(out StatementSyntax singleStatement))
{
convertedStatements = convertedStatements.Select(l => l.WithTrailingTrivia(SyntaxFactory.ElasticCarriageReturnLineFeed)).ToList();
block = SyntaxFactory.Block(convertedStatements);
}
else if (singleStatement.TryUnpackSingleExpressionFromStatement(out expressionBody))
{
arrow = SyntaxFactory.ArrowExpressionClause(expressionBody);
}
else
{
block = SyntaxFactory.Block(singleStatement);
}
var functionStatement = await ConvertToFunctionDeclarationOrNullAsync(vbNode, param, block, arrow);
if (functionStatement != null)
{
return(functionStatement);
}
var body = (CSharpSyntaxNode)block ?? expressionBody;
var isAnonAsync = _semanticModel.GetOperation(vbNode) is IAnonymousFunctionOperation a && a.Symbol.IsAsync;
var asyncKeyword = SyntaxFactory.Token(SyntaxKind.AsyncKeyword);
LambdaExpressionSyntax lambda;
if (param.Parameters.Count == 1 && param.Parameters.Single().Type == null)
{
var l = SyntaxFactory.SimpleLambdaExpression(param.Parameters[0], body);
lambda = isAnonAsync ? l.WithAsyncKeyword(asyncKeyword) : l;
}
else
{
var l = SyntaxFactory.ParenthesizedLambdaExpression(param, body);
lambda = isAnonAsync ? l.WithAsyncKeyword(asyncKeyword) : l;
}
return(lambda);
}
