static Func<object, IInputData, object> GenCommand(MethodInfo methodInfo, IParameterBinders binders)
{
var parameters = methodInfo.GetParameters();
var controllerExpr = Expression.Parameter(typeof(object), "controller");
var inputDataExpr = Expression.Parameter(typeof(IInputData), "inputData");
List<ParameterExpression> varExprs = new List<ParameterExpression>();
IList<ParameterExpression> argExprs = new List<ParameterExpression>();
List<Expression> codeExprs = new List<Expression>();
#region handler parameters
foreach (var paraInfo in parameters)
{
var paramTypeInfo = paraInfo.ParameterType.GetTypeInfo();
var binder = binders.GetOrCreateBinder(paraInfo.ParameterType);
//var User user = null;
var paramValueExpr = Expression.Parameter(paraInfo.ParameterType, paraInfo.Name);
varExprs.Add(paramValueExpr);
argExprs.Add(paramValueExpr);
if (paramTypeInfo.IsClass)
{
// user = inputData.GetContextValue(typeof(User)) as User;
var getContextValueExpr = Expression.Convert(Expression.Call(controllerExpr, InputDataGetContextValueMethodInfo, Expression.Constant(paraInfo.ParameterType)), paraInfo.ParameterType);
var assignExpr = Expression.Assign(paramValueExpr, getContextValueExpr);
codeExprs.Add(assignExpr);
// if(user==null) user = binder.GetValue("user",inputData) as User;
var getBindValueExpr = Expression.Convert(
Expression.Call(Expression.Constant(binder), ParameterBinderGetValueMethodInfo, Expression.Constant(paraInfo.Name), inputDataExpr)
, paraInfo.ParameterType
);
var checkExpr = Expression.IfThen(
Expression.Equal(paramValueExpr, Expression.Constant(null))
, Expression.Assign(paramValueExpr, getBindValueExpr)
);
codeExprs.Add(checkExpr);
}
else
{
//var object userObj = null;
var paramValueObjExpr = Expression.Parameter(typeof(object), paraInfo.Name + "Obj");
varExprs.Add(paramValueObjExpr);
var getBindValueExpr = Expression.Call(Expression.Constant(binder), ParameterBinderGetValueMethodInfo, Expression.Constant(paraInfo.Name), inputDataExpr);
// userObj = binder.GetValue("user",inputData);
var assignExpr = Expression.Assign(paramValueObjExpr, getBindValueExpr);
codeExprs.Add(assignExpr);
if (paraInfo.HasDefaultValue)
{
//if(userObj==null) user = "******" else user = (string)userObj;
var checkDefault = Expression.IfThenElse(
Expression.Equal(paramValueObjExpr, Expression.Constant(null))
, Expression.Assign(paramValueExpr, Expression.Constant(paraInfo.DefaultValue))
, Expression.Assign(paramValueExpr, Expression.Convert(paramValueObjExpr, paraInfo.ParameterType))
);
codeExprs.Add(checkDefault);
}
}
}
#endregion
#region call and return
Expression resultExpr = null;
if (methodInfo.ReturnType != null && methodInfo.ReturnType != typeof(void))
{
resultExpr = Expression.Call(controllerExpr, methodInfo, argExprs);
}
else
{
resultExpr = Expression.Constant(null, typeof(object));
}
var labelTarget = Expression.Label(typeof(object));
var returnValueExpr = Expression.Convert(resultExpr, typeof(object));
var retExpr = Expression.Return(labelTarget, returnValueExpr);
var labelExpr = Expression.Label(labelTarget, resultExpr);
codeExprs.Add(retExpr);
codeExprs.Add(labelExpr);
#endregion
Expression block = Expression.Block(varExprs, codeExprs);
if (block.CanReduce)
{
block = block.ReduceAndCheck();
}
var lamda = Expression.Lambda<Func<object, IInputData, object>>(block, argExprs);
return lamda.Compile();
}
public Command(MethodInfo actionInfo,IParameterBinders binders) {
this.command = GenCommand(actionInfo,binders);
}