public LambdaExpression Decompiler(bool enableNullSafe)
{
LambdaExpression lambdaExpression = this.RegisterCore(enableNullSafe);
var newparameter1 = Expression.Variable(parameterTuple.Destination.Type, parameterTuple.Destination.Name);
var newparameter2 = Expression.Parameter(parameterTuple.Source.Type, parameterTuple.Source.Name);
var newparameter3 = Expression.Parameter(parameterTuple.ErrorMsg.Type.MakeByRefType(), parameterTuple.ErrorMsg.Name);
ParameterTuple newParameterTuple = new ParameterTuple(newparameter1, newparameter2, newparameter3);
var body = this.Body;
var newBody = ParameterReplacer.Replace(body, parameterTuple.Collect().ToArray(), newParameterTuple.Collect().ToArray()) as BlockExpression;
ReturnTargetRewriter returnTargetRewriter = null;
if (hasReturnLabel)
{
returnTargetRewriter = new ReturnTargetRewriter(parameterTuple.Destination.Type, Expression.Default(parameterTuple.Destination.Type));
newBody = returnTargetRewriter.Visit(newBody) as BlockExpression;
}
//初始化临时变量并构造新的lambda表达式
//去掉原来lambda表达式最后的return true
var initExpression = Expression.Assign(newparameter1, Expression.New(newparameter1.Type));
Expression returnExpression = null;
int exprCount = newBody.Expressions.Count - 1;
if (hasReturnLabel)
{
returnExpression = Expression.Label(returnTargetRewriter.LabelTarget, returnTargetRewriter.DefaultValue);
++exprCount;
}
else
{
returnExpression = newparameter1;
}
var newBlockExpression = Expression.Block(new[] { newparameter1 }.Concat(newBody.Variables), new[] { initExpression }.Concat(newBody.Expressions.Take(exprCount)).Concat(new[] { returnExpression }));
return(Expression.Lambda(newBlockExpression, newParameterTuple.Source, newParameterTuple.ErrorMsg));
}
protected override Expression VisitMethodCall(MethodCallExpression node)
{
//判断调用方法的实例是否为AutoCopy<>的派生类
if (node.Object != null && IsAssignableToGenericType(node.Object.Type, typeof(AutoCopy <,>)))
{
//获取调用方法的实例
var member = (MemberExpression)node.Object;
var argument = Visit(node.Arguments[0]);
var constant = (ConstantExpression)member.Expression;
var anonymousClassInstance = constant.Value;
var calledClassField = (FieldInfo)member.Member;
var calledClass = calledClassField.GetValue(anonymousClassInstance);
//调用实例的RegisterCore方法，获取Lambda表达式
var autoCopyType = calledClass.GetType();
object lambda = autoCopyType.InvokeMember("RegisterCore", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.InvokeMethod, null, calledClass, new object[] { false });;
LambdaExpression lambdaExpression = (LambdaExpression)lambda;
//获取表达式的形参并根据类型定义新的形参
var parameter1 = lambdaExpression.Parameters[0];
var newparameter1 = Expression.Variable(parameter1.Type, "p1");
var parameter2 = lambdaExpression.Parameters[1];
var newparameter2 = Expression.Parameter(parameter2.Type, "p2");
//去掉lambda表达式最外层的try catch
var body = (BlockExpression)((TryExpression)lambdaExpression.Body).Body;
//遍历表达式的body，替换原来的两个参数为新定义的参数
body = ParameterReplacer.Replace(body, parameter1, newparameter1) as BlockExpression;
body = ParameterReplacer.Replace(body, parameter2, newparameter2) as BlockExpression;
//初始化临时变量并构造新的lambda表达式
//去掉原来lambda表达式第一行的Expression.Coalesce运算和最后的return true
var initExpression = Expression.Assign(newparameter1, Expression.New(newparameter1.Type));
var returnExpression = newparameter1;
var newBlockExpression = Expression.Block(new[] { newparameter1 }.Concat(body.Variables), new[] { initExpression }.Concat(body.Expressions.Skip(1).Take(body.Expressions.Count - 2)).Concat(new[] { returnExpression }));
var newLambda = Expression.Lambda(newBlockExpression, newparameter2);
return(Expression.Invoke(newLambda, argument));
}
return(base.VisitMethodCall(node));
}
