static bool AreVariablesOnlyWrittenInsideDeclaration(LocalDeclarationStatementSyntax declaration, SemanticModel semanticModel)
{
var dfa = semanticModel.AnalyzeDataFlow(declaration);
var symbols = from variable in declaration.Declaration.Variables
select semanticModel.GetDeclaredSymbol(variable);
var result = !symbols.Any(s => dfa.WrittenOutside.Contains(s));
return result;
}
private static bool MethodShouldBeStatic(MethodDeclarationSyntax method, SemanticModel semanticModel)
{
if (method.Body == null) return false;
var dataFlow = semanticModel.AnalyzeDataFlow(method.Body);
var variablesDeclared = dataFlow.VariablesDeclared.ToList();
var variablesRead = dataFlow.ReadInside.Union(dataFlow.ReadOutside).ToList();
if (variablesDeclared.Any(c => c.Name == "this"))
{
return false;
}
if (variablesRead.Any(c => c.Name == "this"))
{
return false;
}
return true;
protected override ImmutableArray<ISymbol> GetCapturedVariables(SemanticModel model, SyntaxNode memberBody)
{
Debug.Assert(memberBody.IsKind(SyntaxKind.Block) || memberBody is ExpressionSyntax);
return model.AnalyzeDataFlow(memberBody).Captured;
}
private static bool UsedOutsideParentBlock(SemanticModel semanticModel, StatementSyntax expressionStatement, ISymbol identitySymbol)
{
var block = expressionStatement.FirstAncestorOrSelf<BlockSyntax>();
var method = expressionStatement.FirstAncestorOrSelf<MethodDeclarationSyntax>();
var methodBlock = method.Body;
if (methodBlock.Equals(block)) return false;
var collectionOfStatementsAfter = GetStatementsInBlocksAfter(block);
foreach (var allStatementsAfterBlock in collectionOfStatementsAfter)
{
if (!allStatementsAfterBlock.Any()) continue;
var dataFlowAnalysis = semanticModel.AnalyzeDataFlow(allStatementsAfterBlock.First(), allStatementsAfterBlock.Last());
if (!dataFlowAnalysis.Succeeded) continue;
var isUsed = dataFlowAnalysis.ReadInside.Contains(identitySymbol)
|| dataFlowAnalysis.WrittenInside.Contains(identitySymbol);
if (isUsed) return true;
}
return false;
}
private static IEnumerable<ISymbol> GetReadSymbolsCondition(ForStatementSyntax forNode,
SemanticModel semanticModel)
{
if (forNode.Condition == null)
{
return new ISymbol[0];
}
var dataFlowAnalysis = semanticModel.AnalyzeDataFlow(forNode.Condition);
return dataFlowAnalysis.Succeeded
? dataFlowAnalysis.ReadInside.Distinct()
: new ISymbol[0];
}
private static bool CanBeMadeConst(LocalDeclarationStatementSyntax localDeclaration, SemanticModel semanticModel)
{
// already const?
if (localDeclaration.Modifiers.Any(SyntaxKind.ConstKeyword))
{
return false;
}
// Ensure that all variables in the local declaration have initializers that
// are assigned with constant values.
foreach (var variable in localDeclaration.Declaration.Variables)
{
var initializer = variable.Initializer;
if (initializer == null)
{
return false;
}
var constantValue = semanticModel.GetConstantValue(initializer.Value);
if (!constantValue.HasValue)
{
return false;
}
var variableTypeName = localDeclaration.Declaration.Type;
var variableType = semanticModel.GetTypeInfo(variableTypeName).ConvertedType;
// Ensure that the initializer value can be converted to the type of the
// local declaration without a user-defined conversion.
var conversion = semanticModel.ClassifyConversion(initializer.Value, variableType);
if (!conversion.Exists || conversion.IsUserDefined)
{
return false;
}
// Special cases:
// * If the constant value is a string, the type of the local declaration
// must be System.String.
// * If the constant value is null, the type of the local declaration must
// be a reference type.
if (constantValue.Value is string)
{
if (variableType.SpecialType != SpecialType.System_String)
{
return false;
}
}
else if (variableType.IsReferenceType && constantValue.Value != null)
{
return false;
}
}
// Perform data flow analysis on the local declaration.
var dataFlowAnalysis = semanticModel.AnalyzeDataFlow(localDeclaration);
// Retrieve the local symbol for each variable in the local declaration
// and ensure that it is not written outside of the data flow analysis region.
foreach (var variable in localDeclaration.Declaration.Variables)
{
var variableSymbol = semanticModel.GetDeclaredSymbol(variable);
if (dataFlowAnalysis.WrittenOutside.Contains(variableSymbol))
{
return false;
}
}
return true;
}
public static DataFlowAnalysis AnalyzeDataFlow(this SemanticModel semanticModel, SyntaxNode statementOrExpression)
{
return(semanticModel.AnalyzeDataFlow(statementOrExpression));
}
public static DataFlowAnalysis AnalyzeDataFlow(this SemanticModel semanticModel, SyntaxNode firstStatement, SyntaxNode lastStatement)
{
return(semanticModel.AnalyzeDataFlow(firstStatement, lastStatement));
}
static bool ContainsLocalReferences(SemanticModel context, SyntaxNode expr, SyntaxNode body)
{
var dataFlowAnalysis = context.AnalyzeDataFlow(expr);
return dataFlowAnalysis.Captured.Any();
}