private DecisionTree Add(DecisionTree.Guarded guarded, DecisionMaker makeDecision)
{
if (guarded.Default != null)
{
if (guarded.Default.MatchIsComplete)
{
return(null);
}
var result = Add(guarded.Default, makeDecision);
if (guarded.Default.MatchIsComplete)
{
guarded.MatchIsComplete = true;
}
return(result);
}
else
{
var result = guarded.Default = makeDecision(guarded.Expression, guarded.Type);
if (guarded.Default.MatchIsComplete)
{
guarded.MatchIsComplete = true;
}
return(result);
}
}
private void VisitGuardedDecisionTree(DecisionTree.Guarded guarded)
{
var initialState = this.State;
SetState(initialState.Clone());
// assign pattern variables
VisitGuardedPattern(guarded);
if (guarded.Guard != null)
{
VisitCondition(guarded.Guard);
SetState(StateWhenTrue);
// discard StateWhenFalse
}
// goto the label for the switch block
_pendingBranches.Add(new PendingBranch(guarded.Label, this.State));
// put the state back where we found it for the next case
SetState(initialState);
// Handle the "default" case when the guard fails
VisitDecisionTree(guarded.Default);
}
private void LowerDecisionTree(DecisionTree.Guarded guarded)
{
var sectionBuilder = this.SwitchSections[guarded.Section];
var targetLabel = guarded.Label.Label;
Debug.Assert(guarded.Guard?.ConstantValue != ConstantValue.False);
if (guarded.Guard == null || guarded.Guard.ConstantValue == ConstantValue.True)
{
// unconditional
if (guarded.Bindings.IsDefaultOrEmpty)
{
_loweredDecisionTree.Add(_factory.Goto(targetLabel));
}
else
{
// with bindings
var matched = _factory.GenerateLabel("matched");
_loweredDecisionTree.Add(_factory.Goto(matched));
sectionBuilder.Add(_factory.Label(matched));
AddBindings(sectionBuilder, guarded.Bindings);
sectionBuilder.Add(_factory.Goto(targetLabel));
}
}
else
{
var checkGuard = _factory.GenerateLabel("checkGuard");
_loweredDecisionTree.Add(_factory.Goto(checkGuard));
sectionBuilder.Add(_factory.Label(checkGuard));
AddBindings(sectionBuilder, guarded.Bindings);
sectionBuilder.Add(_factory.ConditionalGoto(LocalRewriter.VisitExpression(guarded.Guard), targetLabel, true));
var guardFailed = _factory.GenerateLabel("guardFailed");
sectionBuilder.Add(_factory.Goto(guardFailed));
_loweredDecisionTree.Add(_factory.Label(guardFailed));
}
}
private void LowerDecisionTree(DecisionTree.Guarded guarded)
{
var sectionBuilder = this.SwitchSections[guarded.Section];
var targetLabel = guarded.Label.Label;
Debug.Assert(guarded.Guard?.ConstantValue != ConstantValue.False);
if (guarded.Guard == null || guarded.Guard.ConstantValue == ConstantValue.True)
{
// unconditional
Debug.Assert(guarded.Default == null);
if (guarded.Bindings.IsDefaultOrEmpty)
{
_loweredDecisionTree.Add(_factory.Goto(targetLabel));
}
else
{
// with bindings
var matched = _factory.GenerateLabel("matched");
_loweredDecisionTree.Add(_factory.Goto(matched));
sectionBuilder.Add(_factory.Label(matched));
AddBindings(sectionBuilder, guarded.Bindings);
sectionBuilder.Add(_factory.Goto(targetLabel));
}
}
else
{
var checkGuard = _factory.GenerateLabel("checkGuard");
_loweredDecisionTree.Add(_factory.Goto(checkGuard));
sectionBuilder.Add(_factory.Label(checkGuard));
AddBindings(sectionBuilder, guarded.Bindings);
var guardTest = _factory.ConditionalGoto(LocalRewriter.VisitExpression(guarded.Guard), targetLabel, true);
// Only add instrumentation (such as a sequence point) if the node is not compiler-generated.
if (!guarded.Guard.WasCompilerGenerated && this.LocalRewriter.Instrument)
{
guardTest = this.LocalRewriter._instrumenter.InstrumentPatternSwitchWhenClauseConditionalGotoBody(guarded.Guard, guardTest);
}
sectionBuilder.Add(guardTest);
var guardFailed = _factory.GenerateLabel("guardFailed");
sectionBuilder.Add(_factory.Goto(guardFailed));
_loweredDecisionTree.Add(_factory.Label(guardFailed));
LowerDecisionTree(guarded.Expression, guarded.Default);
}
}
private DecisionTree AddByNull(DecisionTree.Guarded guarded, DecisionMaker makeDecision)
{
if (guarded.Default == null)
{
guarded.Default = new DecisionTree.ByType(guarded.Expression, guarded.Type, null);
}
var result = AddByNull(guarded.Default, makeDecision);
if (guarded.Default.MatchIsComplete)
{
guarded.MatchIsComplete = true;
}
return(result);
}
private DecisionTree AddByValue(DecisionTree.Guarded guarded, BoundConstantPattern value, DecisionMaker makeDecision)
{
if (guarded.Default != null)
{
Debug.Assert(!guarded.Default.MatchIsComplete); // otherwise we would have given a subsumption error
}
else
{
// There is no default at this branch of the decision tree, so we create one.
// Before the decision tree can match by value, it needs to test if the input is of the required type.
// So we create a ByType node to represent that test.
guarded.Default = new DecisionTree.ByType(guarded.Expression, guarded.Type, null);
}
return(AddByValue(guarded.Default, value, makeDecision));
}
private DecisionTree AddByValue(DecisionTree.Guarded guarded, BoundConstantPattern value, DecisionMaker makeDecision)
{
if (guarded.Default != null)
{
if (guarded.Default.MatchIsComplete)
{
return(null);
}
}
else
{
guarded.Default = new DecisionTree.ByValue(guarded.Expression, guarded.Type, null);
}
return(AddByValue(guarded.Default, value, makeDecision));
}
private DecisionTree AddByValue(DecisionTree.Guarded guarded, BoundExpression value, DecisionMaker makeDecision, bool hasErrors)
{
if (guarded.Default != null)
{
if (guarded.Default.MatchIsComplete)
{
return(null);
}
}
else
{
guarded.Default = new DecisionTree.ByValue(guarded.Expression, guarded.Type, null);
}
return(AddByValue(guarded.Default, value, makeDecision, hasErrors));
}
private DecisionTree Add(DecisionTree.Guarded guarded, DecisionMaker makeDecision)
{
if (guarded.Default != null)
{
Debug.Assert(!guarded.Default.MatchIsComplete); // otherwise we would have given a subsumption error
var result = Add(guarded.Default, makeDecision);
if (guarded.Default.MatchIsComplete)
{
guarded.MatchIsComplete = true;
}
return(result);
}
else
{
var result = guarded.Default = makeDecision(guarded.Expression, guarded.Type);
if (guarded.Default.MatchIsComplete)
{
guarded.MatchIsComplete = true;
}
return(result);
}
}
protected virtual void VisitGuardedPattern(DecisionTree.Guarded guarded)
{
}
