private static Expression <T> Stitch <T>(Expression binding, LambdaSignature <T> signature) where T : class
{
Type targetType = typeof(T);
Type siteType = typeof(CallSite <T>);
var body = new ReadOnlyCollectionBuilder <Expression>(3);
body.Add(binding);
var site = Expression.Parameter(typeof(CallSite), "$site");
var @params = signature.Parameters.AddFirst(site);
Expression updLabel = Expression.Label(CallSiteBinder.UpdateLabel);
#if DEBUG
// put the AST into the constant pool for debugging purposes
updLabel = Expression.Block(
Expression.Constant(binding, typeof(Expression)),
updLabel
);
#endif
body.Add(updLabel);
body.Add(
Expression.Label(
signature.ReturnLabel,
Expression.Condition(
Expression.Call(
typeof(CallSiteOps).GetMethod("SetNotMatched"),
@params.First()
),
Expression.Default(signature.ReturnLabel.Type),
Expression.Invoke(
Expression.Property(
Expression.Convert(site, siteType),
typeof(CallSite <T>).GetProperty("Update")
),
new TrueReadOnlyCollection <Expression>(@params)
)
)
)
);
return(new Expression <T>(
Expression.Block(body),
"CallSite.Target",
true, // always compile the rules with tail call optimization
new TrueReadOnlyCollection <ParameterExpression>(@params)
));
}
private static Expression <T> Stitch <T>(Expression binding, LambdaSignature <T> signature) where T : class
{
ParameterExpression expression;
Type type = typeof(CallSite <T>);
ReadOnlyCollectionBuilder <Expression> expressions = new ReadOnlyCollectionBuilder <Expression>(3)
{
binding
};
ParameterExpression[] source = signature.Parameters.AddFirst <ParameterExpression>(expression = Expression.Parameter(typeof(CallSite), "$site"));
Expression item = Expression.Label(UpdateLabel);
expressions.Add(item);
expressions.Add(Expression.Label(signature.ReturnLabel, Expression.Condition(Expression.Call(typeof(CallSiteOps).GetMethod("SetNotMatched"), source.First <ParameterExpression>()), Expression.Default(signature.ReturnLabel.Type), Expression.Invoke(Expression.Property(Expression.Convert(expression, type), typeof(CallSite <T>).GetProperty("Update")), new TrueReadOnlyCollection <Expression>(source)))));
return(new Expression <T>(Expression.Block(expressions), "CallSite.Target", true, new TrueReadOnlyCollection <ParameterExpression>(source)));
}
internal T BindCore <T>(CallSite <T> site, object[] args) where T : class
{
T local = this.BindDelegate <T>(site, args);
if (local != null)
{
return(local);
}
LambdaSignature <T> instance = LambdaSignature <T> .Instance;
Expression binding = this.Bind(args, instance.Parameters, instance.ReturnLabel);
if (binding == null)
{
throw Error.NoOrInvalidRuleProduced();
}
if (!AppDomain.CurrentDomain.IsHomogenous)
{
throw Error.HomogenousAppDomainRequired();
}
T target = Stitch <T>(binding, instance).Compile();
this.CacheTarget <T>(target);
return(target);
}
// TODO: This should be merged into CallSiteBinder.
private static LambdaExpression /*!*/ Stitch <T>(Expression binding, LambdaSignature <T> signature, LabelTarget returnLabel) where T : class
{
Expression updLabel = Expression.Label(CallSiteBinder.UpdateLabel);
var site = Expression.Parameter(typeof(CallSite), "$site");
var @params = ArrayUtils.Insert(site, signature.Parameters);
Expression body;
if (returnLabel != signature.ReturnLabel)
{
// TODO:
// This allows the binder to produce a strongly typed binding expression that gets boxed
// if the call site's return value is of type object.
// The current implementation of CallSiteBinder is too strict as it requires the two types to be reference-assignable.
var tmp = Expression.Parameter(typeof(object));
body = Expression.Convert(
Expression.Block(new[] { tmp },
binding,
updLabel,
Expression.Label(
returnLabel,
Expression.Condition(
Expression.NotEqual(
Expression.Assign(
tmp,
Expression.Invoke(
Expression.Property(
Expression.Convert(site, typeof(CallSite <T>)),
typeof(CallSite <T>).GetProperty("Update")
),
@params
)
),
AstUtils.Constant(null)
),
Expression.Convert(tmp, returnLabel.Type),
Expression.Default(returnLabel.Type)
)
)
),
typeof(object)
);
}
else
{
body = Expression.Block(
binding,
updLabel,
Expression.Label(
returnLabel,
Expression.Invoke(
Expression.Property(
Expression.Convert(site, typeof(CallSite <T>)),
typeof(CallSite <T>).GetProperty("Update")
),
@params
)
)
);
}
return(Expression.Lambda <T>(
body,
"CallSite.Target",
true, // always compile the rules with tail call optimization
@params
));
}
