public TState GetState(FlowLocation location)
{
int index = BinarySearchLowerBound(this.locations, location);
var nearestLocation = this.locations[index];
return(this.states[nearestLocation]);
}
public override void VisitWhileStatement(WhileStatementSyntax node)
{
var saveContinueLocation = this.continueLocation;
var saveBreakLocation = this.breakLocation;
// merge with any states that branch back to start (continue)
this.JoinState(node.StartLocation(), this.lexicalState);
TState trueState;
TState falseState;
this.VisitCondition(node.Condition, out trueState, out falseState);
this.continueLocation = node.StartLocation();
this.breakLocation = node.EndLocation();
// statement only executes when condition is true
this.SetState(node.Statement.StartLocation(), trueState);
this.Visit(node.Statement);
// at end of loop, branch back to top
this.BranchToLocation(this.continueLocation, this.lexicalState);
// merge with any states that branch to end (break & natural exit)
this.JoinState(node.EndLocation(), falseState);
this.continueLocation = saveContinueLocation;
this.breakLocation = saveBreakLocation;
}
private void BranchToLocation(FlowLocation location, FlowState state)
{
TState existingState;
if (this.joinStates.TryGetValue(location, out existingState))
{
this.joinStates = this.joinStates.SetItem(location, (TState)existingState.Join(this.lexicalState));
}
else
{
this.joinStates = this.joinStates.SetItem(location, this.lexicalState);
}
}
public void JoinState(FlowLocation location, TState state)
{
TState existingState;
if (this.joinStates.TryGetValue(location, out existingState))
{
this.lexicalState = (TState)existingState.Join(state);
}
else
{
this.lexicalState = state;
}
this.joinStates = this.joinStates.SetItem(location, this.lexicalState);
}
private static int BinarySearchLowerBound(FlowLocation[] array, FlowLocation value)
{
int low = 0;
int high = array.Length - 1;
while (low <= high)
{
int middle = low + ((high - low) >> 1);
if (array[middle].CompareTo(value) > 0)
{
high = middle - 1;
}
else
{
low = middle + 1;
}
}
return(high);
}
public void SetState(FlowLocation location, TState state)
{
this.lexicalState = state;
this.joinStates = this.joinStates.SetItem(location, state);
}