private async Task <CSharpSyntaxNode> GetInitializerFromNameAndTypeAsync(ITypeSymbol typeSymbol,
VBSyntax.ModifiedIdentifierSyntax name, CSharpSyntaxNode initializer)
{
if (!SyntaxTokenExtensions.IsKind(name.Nullable, SyntaxKind.None))
{
if (typeSymbol.IsArrayType())
{
initializer = null;
}
}
var rankSpecifiers = await ConvertArrayRankSpecifierSyntaxesAsync(name.ArrayRankSpecifiers, name.ArrayBounds, false);
if (rankSpecifiers.Count > 0)
{
var rankSpecifiersWithSizes = await ConvertArrayRankSpecifierSyntaxesAsync(name.ArrayRankSpecifiers, name.ArrayBounds);
var arrayTypeSyntax = ((ArrayTypeSyntax)GetTypeSyntax(typeSymbol)).WithRankSpecifiers(rankSpecifiersWithSizes);
if (rankSpecifiersWithSizes.SelectMany(ars => ars.Sizes).Any(e => !e.IsKind(CSSyntaxKind.OmittedArraySizeExpression)))
{
initializer = SyntaxFactory.ArrayCreationExpression(arrayTypeSyntax);
}
else if (initializer is ImplicitArrayCreationExpressionSyntax iaces && iaces.Initializer != null)
{
initializer = SyntaxFactory.ArrayCreationExpression(arrayTypeSyntax, iaces.Initializer);
}
}
return(initializer);
}
/// <summary>
/// Returns true only if expressions static (i.e. doesn't reference the containing instance)
/// </summary>
public static bool IsDefinitelyStatic(this SemanticModel semanticModel, VBSyntax.ModifiedIdentifierSyntax vbName, VBSyntax.ExpressionSyntax vbInitValue)
{
var arrayBoundExpressions = vbName.ArrayBounds != null?vbName.ArrayBounds.Arguments.Select(a => a.GetExpression()) : Enumerable.Empty <VBSyntax.ExpressionSyntax>();
var expressions = vbInitValue.Yield().Concat(arrayBoundExpressions).Where(x => x != null).ToArray();
return(expressions.All(e => semanticModel.IsDefinitelyStatic(e)));
}
private async Task <EqualsValueClauseSyntax> ConvertEqualsValueClauseSyntaxAsync(
VariableDeclaratorSyntax vbDeclarator, VBSyntax.ModifiedIdentifierSyntax vbName,
VBSyntax.ExpressionSyntax vbInitValue,
ITypeSymbol declaredSymbolType,
ISymbol declaredSymbol, CSharpSyntaxNode initializerOrMethodDecl)
{
var csTypeSyntax = GetTypeSyntax(declaredSymbolType);
bool isField = vbDeclarator.Parent.IsKind(SyntaxKind.FieldDeclaration);
bool declaredConst = declaredSymbol is IFieldSymbol fieldSymbol && fieldSymbol.IsConst ||
declaredSymbol is ILocalSymbol localSymbol && localSymbol.IsConst;
EqualsValueClauseSyntax equalsValueClauseSyntax;
if (await GetInitializerFromNameAndTypeAsync(declaredSymbolType, vbName, initializerOrMethodDecl) is ExpressionSyntax
adjustedInitializerExpr)
{
var convertedInitializer = vbInitValue != null
? TypeConversionAnalyzer.AddExplicitConversion(vbInitValue, adjustedInitializerExpr, isConst : declaredConst)
: adjustedInitializerExpr;
if (isField && !declaredSymbol.IsStatic && !_semanticModel.IsDefinitelyStatic(vbName, vbInitValue))
{
if (_typeContext.Initializers.ShouldAddTypeWideInitToThisPart)
{
var lhs = SyntaxFactory.IdentifierName(ConvertIdentifier(vbName.Identifier, sourceTriviaMapKind: SourceTriviaMapKind.None));
_typeContext.Initializers.AdditionalInstanceInitializers.Add((lhs, CSSyntaxKind.SimpleAssignmentExpression, adjustedInitializerExpr));
equalsValueClauseSyntax = null;
}
else
{
var returnBlock = SyntaxFactory.Block(SyntaxFactory.ReturnStatement(adjustedInitializerExpr));
_typeContext.HoistedState.Hoist <HoistedParameterlessFunction>(new HoistedParameterlessFunction(GetInitialValueFunctionName(vbName), csTypeSyntax, returnBlock));
equalsValueClauseSyntax = null;
}
}
else
{
equalsValueClauseSyntax = SyntaxFactory.EqualsValueClause(convertedInitializer);
}
}
else if (isField || declaredSymbol != null && _semanticModel.IsDefinitelyAssignedBeforeRead(declaredSymbol, vbName))
{
equalsValueClauseSyntax = null;
}
else
{
// VB initializes variables to their default
equalsValueClauseSyntax = SyntaxFactory.EqualsValueClause(SyntaxFactory.DefaultExpression(csTypeSyntax));
}
return(equalsValueClauseSyntax);
}
/// <remarks>
/// In CS we need to lift non-static initializers to the constructor. But for partial classes these can be in different files.
/// Rather than re-architect to allow communication between files, we create an initializer function, and call it from the other part, and just hope the name doesn't clash.
/// </remarks>
public static string GetInitialValueFunctionName(VBSyntax.ModifiedIdentifierSyntax vbName)
{
return("initial" + vbName.Identifier.ValueText.ToPascalCase());
}
/// <summary>
/// This check is entirely to avoid some unnecessary default initializations so the code looks less cluttered and more like the VB did.
/// The caller should default to outputting an initializer which is always safe for equivalence/correctness.
/// </summary>
public static bool IsDefinitelyAssignedBeforeRead(this SemanticModel semanticModel,
ISymbol locallyDeclaredSymbol, VBSyntax.ModifiedIdentifierSyntax syntaxForSymbol)
{
var methodBlockBaseSyntax = syntaxForSymbol.GetAncestor <VBSyntax.MethodBlockBaseSyntax>();
var methodFlow = semanticModel.AnalyzeDataFlow(methodBlockBaseSyntax.Statements.First(), methodBlockBaseSyntax.Statements.Last());
return(DefiniteAssignmentAnalyzer.IsDefinitelyAssignedBeforeRead(locallyDeclaredSymbol, methodFlow));
}