public static bool TryMatchPattern(
ISyntaxFactsService syntaxFacts,
IConditionalOperation ifOperation,
out ISimpleAssignmentOperation trueAssignment,
out ISimpleAssignmentOperation falseAssignment)
{
trueAssignment = null;
falseAssignment = null;
var trueStatement = ifOperation.WhenTrue;
var falseStatement = ifOperation.WhenFalse;
trueStatement = UseConditionalExpressionHelpers.UnwrapSingleStatementBlock(trueStatement);
falseStatement = UseConditionalExpressionHelpers.UnwrapSingleStatementBlock(falseStatement);
if (!TryGetAssignment(trueStatement, out trueAssignment) ||
!TryGetAssignment(falseStatement, out falseAssignment))
{
return(false);
}
// The left side of both assignment statements has to be syntactically identical (modulo
// trivia differences).
if (!syntaxFacts.AreEquivalent(trueAssignment.Target.Syntax, falseAssignment.Target.Syntax))
{
return(false);
}
return(UseConditionalExpressionHelpers.CanConvert(
syntaxFacts, ifOperation, trueAssignment, falseAssignment));
}
public static bool TryMatchPattern(
ISyntaxFactsService syntaxFacts,
IConditionalOperation ifOperation,
out IReturnOperation trueReturn,
out IReturnOperation falseReturn)
{
trueReturn = null;
falseReturn = null;
var trueStatement = ifOperation.WhenTrue;
var falseStatement = ifOperation.WhenFalse;
// we support:
//
// if (expr)
// return a;
// else
// return b;
//
// and
//
// if (expr)
// return a;
//
// return b;
if (falseStatement == null)
{
var parentBlock = ifOperation.Parent as IBlockOperation;
if (parentBlock == null)
{
return(false);
}
var ifIndex = parentBlock.Operations.IndexOf(ifOperation);
if (ifIndex < 0)
{
return(false);
}
if (ifIndex + 1 < parentBlock.Operations.Length)
{
falseStatement = parentBlock.Operations[ifIndex + 1];
if (falseStatement.IsImplicit)
{
return(false);
}
}
}
trueStatement = UseConditionalExpressionHelpers.UnwrapSingleStatementBlock(trueStatement);
falseStatement = UseConditionalExpressionHelpers.UnwrapSingleStatementBlock(falseStatement);
// Both return-statements must be of the form "return value"
if (!(trueStatement is IReturnOperation trueReturnOp) ||
!(falseStatement is IReturnOperation falseReturnOp) ||
trueReturnOp.ReturnedValue == null ||
falseReturnOp.ReturnedValue == null)
{
return(false);
}
if (trueReturnOp.Kind != falseReturnOp.Kind)
{
// Not allowed if these are different types of returns. i.e.
// "yield return ..." and "return ...".
return(false);
}
if (trueReturnOp.Kind == OperationKind.YieldBreak)
{
// This check is just paranoia. We likely shouldn't get here since we already
// checked if .ReturnedValue was null above.
return(false);
}
if (trueReturnOp.Kind == OperationKind.YieldReturn &&
ifOperation.WhenFalse == null)
{
// we have the following:
//
// if (...) {
// yield return ...
// }
//
// yield return ...
//
// It is *not* correct to replace this with:
//
// yield return ... ? ... ? ...
//
// as both yields need to be hit.
return(false);
}
trueReturn = trueReturnOp;
falseReturn = falseReturnOp;
return(UseConditionalExpressionHelpers.CanConvert(
syntaxFacts, ifOperation, trueReturn, falseReturn));
}