protected override void VisitPatternSwitchSection(BoundPatternSwitchSection node, BoundExpression switchExpression, bool isLastSection)
{
foreach (var label in node.SwitchLabels)
{
NoteDeclaredPatternVariables(label.Pattern);
}
base.VisitPatternSwitchSection(node, switchExpression, isLastSection);
}
protected virtual void VisitPatternSwitchSection(BoundPatternSwitchSection node, BoundExpression switchExpression, bool isLastSection)
{
SetState(UnreachableState());
foreach (var label in node.SwitchLabels)
{
VisitLabel(label.Label, node);
}
VisitStatementList(node);
}
protected override void VisitPatternSwitchSection(BoundPatternSwitchSection node, BoundExpression switchExpression, bool isLastSection)
{
base.VisitPatternSwitchSection(node, switchExpression, isLastSection);
// Check for switch section fall through error
if (this.State.Alive)
{
var syntax = node.SwitchLabels.Last().Pattern.Syntax;
Diagnostics.Add(isLastSection ? ErrorCode.ERR_SwitchFallOut : ErrorCode.ERR_SwitchFallThrough,
new SourceLocation(syntax), syntax.ToString());
}
}
public Guarded(
BoundExpression expression,
TypeSymbol type,
ImmutableArray <KeyValuePair <BoundExpression, BoundExpression> > bindings,
BoundPatternSwitchSection section,
BoundExpression guard,
BoundPatternSwitchLabel label)
: base(expression, type, null)
{
this.Guard = guard;
this.Label = label;
this.Bindings = bindings;
this.Section = section;
Debug.Assert(guard?.ConstantValue != ConstantValue.False);
base.MatchIsComplete =
(guard == null) || (guard.ConstantValue == ConstantValue.True);
}
protected virtual void VisitPatternSwitchSection(BoundPatternSwitchSection node, BoundExpression switchExpression, bool isLastSection)
{
// visit switch section labels
var initialState = this.State;
var afterGuardState = UnreachableState();
foreach (var label in node.PatternSwitchLabels)
{
SetState(initialState.Clone());
VisitPattern(switchExpression, label.Pattern);
SetState(StateWhenTrue);
if (label.Guard != null)
{
VisitCondition(label.Guard);
SetState(StateWhenTrue);
}
IntersectWith(ref afterGuardState, ref this.State);
}
// visit switch section body
SetState(afterGuardState);
VisitStatementList(node);
}
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);
}
