//todo working on scope for better emit
public System.Delegate Compile(System.Type target, IExpressionVisitor <object> visitor)
{
//pass scoped arguments // refer System.Linq.Expression.Compiler folder
var context = TypeContext.Default;
System.Type returnType;
if (ReturnSyntax != null)
{
returnType = ReturnSyntax.ResolveType(context);
}
else
{
returnType = TypeProvider.AnyType;
}
var names = Parameters.Map(para => para.Name).AddFirst("closure");
int length = Parameters.Count;
System.Type[] types = new System.Type[length];
var parameters = new ParameterInfo[length];
for (int i = 0; i < Parameters.Count; i++)
{
var para = Parameters[i];
System.Type type = para.Type == null ? TypeProvider.AnyType : para.Type.ResolveType(context);
parameters[i] = new ParameterInfo(para.Name, i + 1, type, para.IsVarArgs);
types[i] = type;
}
// Emit First Argument
var lamdaVisit = new LamdaVisitor(names);
Body.Accept(lamdaVisit);
var parameterTypes = types.AddFirst(typeof(Closure));
var method = new System.Reflection.Emit.DynamicMethod("lambda_method", returnType, parameterTypes, true);
var methodGen = new Generators.DynamicMethodGenerator(method, parameters, target)
{
SyntaxBody = Body,
Context = context
};
methodGen.EmitParameterInfo();
var bodyGen = new MethodBodyGenerator(methodGen, method.GetILGenerator());
object[] values = new object[lamdaVisit.HoistedLocals.Count];
if (values.Length > 0)
{
int index = 0;
var field = typeof(Closure).GetField("Values");
foreach (var item in lamdaVisit.HoistedLocals)
{
var value = item.Value;
values[index] = value.Accept(visitor);
var variable = bodyGen.DeclareVariable(value.Type, item.Key);
bodyGen.LoadArgument(0);
bodyGen.LoadField(field);
bodyGen.LoadInt32(index);
bodyGen.LoadArrayElement(typeof(object));
bodyGen.UnboxObject(value.Type);
bodyGen.StoreVariable(variable);
index++;
}
}
bodyGen.Compile();
var delgateType = DelegateGen.MakeNewDelegate(types, returnType);
Type = delgateType;
return(method.CreateDelegate(delgateType, new Runtime.Closure(values)));
}