internal SubsumptionDiagnosticBuilder(Symbol enclosingSymbol,
Conversions conversions,
BoundExpression expression)
: base(enclosingSymbol, conversions)
{
_subsumptionTree = DecisionTree.Create(expression, expression.Type, enclosingSymbol);
}
private DecisionTree LowerToDecisionTree(
BoundExpression loweredExpression,
BoundPatternSwitchStatement node)
{
var loweredDecisionTree = DecisionTree.Create(loweredExpression, loweredExpression.Type, _enclosingSymbol);
BoundPatternSwitchLabel defaultLabel = null;
SyntaxNode defaultSection = null;
foreach (var section in node.SwitchSections)
{
var sectionSyntax = (SyntaxNode)section.Syntax;
foreach (var label in section.SwitchLabels)
{
var loweredLabel = LowerSwitchLabel(label);
if (loweredLabel.Syntax.Kind() == SyntaxKind.DefaultSwitchLabel)
{
if (defaultLabel != null)
{
// duplicate switch label will have been reported during initial binding.
}
else
{
defaultLabel = loweredLabel;
defaultSection = sectionSyntax;
}
}
else
{
Syntax = label.Syntax;
AddToDecisionTree(loweredDecisionTree, sectionSyntax, loweredLabel);
}
}
}
if (defaultLabel != null)
{
Add(loweredDecisionTree, (e, t) => new DecisionTree.Guarded(loweredExpression, loweredExpression.Type, default(ImmutableArray <KeyValuePair <BoundExpression, BoundExpression> >), defaultSection, null, defaultLabel));
}
// We discard use-site diagnostics, as they have been reported during initial binding.
_useSiteDiagnostics.Clear();
return(loweredDecisionTree);
}
internal DecisionTree ComputeDecisionTree()
{
Debug.Assert(_section == null);
var expression = _switchStatement.Expression;
if (expression.ConstantValue == null && expression.Kind != BoundKind.Local)
{
// unless the expression is simple enough, copy it into a local
var localSymbol = new SynthesizedLocal(_enclosingSymbol as MethodSymbol, expression.Type, SynthesizedLocalKind.PatternMatchingTemp, _switchStatement.Syntax, false, RefKind.None);
expression = new BoundLocal(expression.Syntax, localSymbol, null, expression.Type);
}
var result = DecisionTree.Create(_switchStatement.Expression, _switchStatement.Expression.Type, _enclosingSymbol);
var subsumptionTree = DecisionTree.Create(_switchStatement.Expression, _switchStatement.Expression.Type, _enclosingSymbol);
BoundPatternSwitchLabel defaultLabel = null;
BoundPatternSwitchSection defaultSection = null;
foreach (var section in _switchStatement.SwitchSections)
{
this._section = section;
foreach (var label in section.SwitchLabels)
{
if (label.Syntax.Kind() == SyntaxKind.DefaultSwitchLabel)
{
if (defaultLabel != null)
{
// duplicate switch label will have been reported during initial binding.
}
else
{
defaultLabel = label;
defaultSection = section;
}
}
else
{
this._syntax = label.Syntax;
// For purposes of subsumption, we do not take into consideration the value
// of the input expression. Therefore we consider null possible if the type permits.
var subsumedErrorCode = CheckSubsumed(label.Pattern, subsumptionTree, inputCouldBeNull: true);
if (subsumedErrorCode != 0 && subsumedErrorCode != ErrorCode.ERR_NoImplicitConvCast)
{
if (!label.HasErrors)
{
_diagnostics.Add(subsumedErrorCode, label.Pattern.Syntax.Location);
}
}
else
{
AddToDecisionTree(result, label);
if (label.Guard == null || label.Guard.ConstantValue == ConstantValue.True)
{
// Only unconditional switch labels contribute to subsumption
AddToDecisionTree(subsumptionTree, label);
}
}
}
}
}
if (defaultLabel != null)
{
Add(result, (e, t) => new DecisionTree.Guarded(_switchStatement.Expression, _switchStatement.Expression.Type, default(ImmutableArray <KeyValuePair <BoundExpression, BoundExpression> >), defaultSection, null, defaultLabel));
}
return(result);
}