public static LambdaCapturedVariable Create(ClosureEnvironment frame, Symbol captured, ref int uniqueId)
{
Debug.Assert(captured is LocalSymbol || captured is ParameterSymbol);
string fieldName = GetCapturedVariableFieldName(captured, ref uniqueId);
TypeSymbol type = GetCapturedVariableFieldType(frame, captured);
return(new LambdaCapturedVariable(frame, type, fieldName, IsThis(captured)));
}
private void MakeAndAssignEnvironments()
{
VisitScopeTree(ScopeTree, scope =>
{
// Currently all variables declared in the same scope are added
// to the same closure environment
var variablesInEnvironment = scope.DeclaredVariables;
// Don't create empty environments
if (variablesInEnvironment.Count == 0)
{
return;
}
// First walk the nested scopes to find all closures which
// capture variables from this scope. They all need to capture
// this environment. This includes closures which captured local
// functions that capture those variables, so multiple passes may
// be needed. This will also decide if the environment is a struct
// or a class.
bool isStruct = true;
var closures = new SetWithInsertionOrder <Closure>();
bool addedItem;
// This loop is O(n), where n is the length of the chain
// L_1 <- L_2 <- L_3 ...
// where L_1 represents a local function that directly captures the current
// environment, L_2 represents a local function that directly captures L_1,
// L_3 represents a local function that captures L_2, and so on.
//
// Each iteration of the loop runs a visitor that is proportional to the
// number of closures in nested scopes, so we hope that the total number
// of nested functions and function chains is small in any real-world code.
do
{
addedItem = false;
VisitClosures(scope, (closureScope, closure) =>
{
if (!closures.Contains(closure) &&
(closure.CapturedVariables.Overlaps(scope.DeclaredVariables) ||
closure.CapturedVariables.Overlaps(closures.Select(c => c.OriginalMethodSymbol))))
{
closures.Add(closure);
addedItem = true;
isStruct &= CanTakeRefParameters(closure.OriginalMethodSymbol);
}
});
} while (addedItem == true);
// Next create the environment and add it to the declaration scope
var env = new ClosureEnvironment(variablesInEnvironment, isStruct);
scope.DeclaredEnvironments.Add(env);
_topLevelMethod.TryGetThisParameter(out var thisParam);
foreach (var closure in closures)
{
closure.CapturedEnvironments.Add(env);
if (thisParam != null && env.CapturedVariables.Contains(thisParam))
{
closure.CapturesThis = true;
}
}
});
}
internal LambdaFrameConstructor(ClosureEnvironment frame)
: base(frame)
{
}