/// <summary>
/// Walks the lambda and produces a higher order function, which can be
/// used to bind the lambda to a closure array from the interpreter.
/// </summary>
/// <param name="lambda">The lambda to bind.</param>
/// <param name="closureVariables">Variables which are being accessed defined in the outer scope.</param>
/// <returns>A delegate that can be called to produce a delegate bound to the passed in closure array.</returns>
internal static Func <StrongBox <object>[], Delegate> BindLambda(LambdaExpression lambda, Dictionary <ParameterExpression, LocalVariable> closureVariables)
{
// 1. Create rewriter
var closure = Expression.Parameter(typeof(StrongBox <object>[]), "closure");
var visitor = new LightLambdaClosureVisitor(closureVariables, closure);
// 2. Visit the lambda
lambda = (LambdaExpression)visitor.Visit(lambda);
// 3. Create a higher-order function which fills in the parameters
var result = Expression.Lambda <Func <StrongBox <object>[], Delegate> >(lambda, closure);
// 4. Compile it
return(result.Compile());
}
/// <summary>
/// Create a compiled delegate for the LightLambda, and saves it so
/// future calls to Run will execute the compiled code instead of
/// interpreting.
/// </summary>
internal void Compile(object state)
{
if (_compiled != null)
{
return;
}
// Compilation is expensive, we only want to do it once.
lock (_compileLock) {
if (_compiled != null)
{
return;
}
PerfTrack.NoteEvent(PerfTrack.Categories.Compiler, "Interpreted lambda compiled");
// Interpreter needs a standard delegate type.
// So change the lambda's delegate type to Func<...> or
// Action<...> so it can be called from the LightLambda.Run
// methods.
LambdaExpression lambda = (_lambda as LambdaExpression) ?? (LambdaExpression)((LightLambdaExpression)_lambda).Reduce();
if (_interpreter != null)
{
_compiledDelegateType = GetFuncOrAction(lambda);
lambda = Expression.Lambda(_compiledDelegateType, lambda.Body, lambda.Name, lambda.Parameters);
}
if (HasClosure)
{
_compiled = LightLambdaClosureVisitor.BindLambda(lambda, _interpreter.ClosureVariables);
}
else
{
_compiled = lambda.Compile();
}
}
}
