public static IEnumerable<ReplaceAction> GetSimplifications(ForEachStatementSyntax forLoop, ISemanticModel model, Assumptions assume, CancellationToken cancellationToken = default(CancellationToken))
{
var body = forLoop.Statement.Statements();
if (body.None()) yield break;
var unconditionalStatements = body.Skip(1);
var conditionalStatement = body.First() as IfStatementSyntax;
if (conditionalStatement == null) yield break;
var trueBranch = conditionalStatement.Statement.Statements().AppendUnlessJumps(unconditionalStatements).Block();
var falseBranch = conditionalStatement.ElseStatementOrEmptyBlock().Statements().AppendUnlessJumps(unconditionalStatements).Block();
var falseIsEmpty = falseBranch.HasSideEffects(model, assume) == false;
var trueIsEmpty = trueBranch.HasSideEffects(model, assume) == false;
if (falseIsEmpty == trueIsEmpty) yield break;
var condition = falseIsEmpty ? conditionalStatement.Condition : conditionalStatement.Condition.Inverted();
var conditionalActions = falseIsEmpty ? trueBranch : falseBranch;
var query = forLoop.Expression.Accessing("Where").Invoking(forLoop.Identifier.Lambdad(condition).Args1());
var forWhereDo = forLoop.WithExpression(query).WithStatement(conditionalActions);
yield return new ReplaceAction(
"Filter collection",
forLoop,
forWhereDo);
}
private async Task <Document> ConvertVariableAssignmentToLINQ(Document document, VariableDeclaratorSyntax variableDeclarator, ForEachStatementSyntax foreachStatement, CancellationToken c)
{
var generator = SyntaxGenerator.GetGenerator(document);
var oldVariableName = foreachStatement.Identifier.Text;
var newVariableName = variableDeclarator.Identifier.Text;
var oldVariables = variableDeclarator.Initializer.Value.DescendantNodesAndSelf().OfType <IdentifierNameSyntax>().Where(x => x.Identifier.Text == oldVariableName);
var selectCall = generator.InvocationExpression(
generator.MemberAccessExpression(foreachStatement.Expression, "Select"),
generator.Argument(
generator.ValueReturningLambdaExpression(
new[] { generator.LambdaParameter("x") },
variableDeclarator.Initializer.Value.ReplaceNodes(oldVariables, (x, y) => generator.IdentifierName("x")))));
var root = await document.GetSyntaxRootAsync(c);
Debug.WriteLine(variableDeclarator.Parent);
var restOfForeachBody = foreachStatement.Statement
.RemoveNode(variableDeclarator, SyntaxRemoveOptions.AddElasticMarker)
.WithAdditionalAnnotations(Formatter.Annotation);
var newFeStatement = foreachStatement
.WithExpression((ExpressionSyntax)selectCall)
.WithIdentifier(generator.IdentifierName(newVariableName).GetFirstToken())
.WithStatement(restOfForeachBody);
var newRoot = root.ReplaceNode(foreachStatement, newFeStatement);
var withEmptyVariableDeclarationsRemoved = new RemoveEmptyVariableDeclarationSyntax().Visit(newRoot);
return(document.WithSyntaxRoot(withEmptyVariableDeclarationsRemoved));
}
private async Task <Document> ConvertIfContinueToLINQ(Document document, IfStatementSyntax ifStatement, ForEachStatementSyntax foreachStatement, CancellationToken c)
{
var generator = SyntaxGenerator.GetGenerator(document);
var oldVariables = ifStatement.Condition.DescendantNodesAndSelf().OfType <IdentifierNameSyntax>().Where(x => x.Identifier.Text == foreachStatement.Identifier.Text);
var whereCall = generator.InvocationExpression(
generator.MemberAccessExpression(foreachStatement.Expression, "Where"),
generator.Argument(
generator.ValueReturningLambdaExpression(
new[] { generator.LambdaParameter("x") },
generator.LogicalNotExpression(
ifStatement.Condition.ReplaceNodes(oldVariables, (x, y) => generator.IdentifierName("x"))))));
var root = await document.GetSyntaxRootAsync(c);
var restOfForeachBody = foreachStatement.Statement
.ReplaceNode(ifStatement, ifStatement.Else?.Statement)
.WithAdditionalAnnotations(Formatter.Annotation);
var newFeStatement = foreachStatement
.WithExpression((ExpressionSyntax)whereCall)
.WithStatement(restOfForeachBody);
var newRoot = root.ReplaceNode(foreachStatement, newFeStatement);
return(document.WithSyntaxRoot(newRoot));
}
public static IEnumerable<ReplaceAction> GetSimplifications(ForEachStatementSyntax forLoop, ISemanticModel model, Assumptions assume, CancellationToken cancellationToken = default(CancellationToken))
{
// loop uses iterator once?
var declaredSymbol = model.GetDeclaredSymbol(forLoop);
var singleRead = forLoop.Statement.DescendantNodes()
.OfType<SimpleNameSyntax>()
.Where(e => model.GetSymbolInfo(e).Symbol == declaredSymbol)
.SingleOrDefaultAllowMany();
if (singleRead == null) yield break;
// safe iterator projection?
var guaranteedProjectionPerIteration = forLoop.Statement.CompleteExecutionGuaranteesChildExecutedExactlyOnce(singleRead);
var projection = singleRead.AncestorsAndSelf()
.TakeWhile(e => !(e is StatementSyntax))
.OfType<ExpressionSyntax>()
.TakeWhile(e => model.GetTypeInfo(e).Type.SpecialType != SpecialType.System_Void)
.TakeWhile(e => guaranteedProjectionPerIteration == true || e.HasSideEffects(model, assume) == false)
.LastOrDefault();
if (projection == null) yield break;
if (projection.TryEvalAlternativeComparison(singleRead, model, assume) == true) yield break;
// build replacement loop
var projectedCollection = forLoop.Expression
.Accessing("Select")
.Invoking(forLoop.Identifier.Lambdad(projection).Args1());
var newBody = forLoop.Statement.ReplaceNode(projection, singleRead);
var replacedLoop = forLoop.WithExpression(projectedCollection).WithStatement(newBody);
// expose as code action/issue
yield return new ReplaceAction(
"Project collection",
forLoop,
replacedLoop);
}
public override SyntaxNode VisitForEachStatement(ForEachStatementSyntax node)
{
if (node != this.ContainerOfStatementsOrFieldToReplace)
{
return(base.VisitForEachStatement(node));
}
return(node.WithExpression(VisitNode(node.Expression))
.WithStatement(ReplaceStatementIfNeeded(node.Statement)));
}