Expression基础体验

Posted 2020-07-28 Timeless

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;

namespace Unit
{
    class T
    {
        public void Test()
        {
            Console.WriteLine("Test Class!");
        }
    }
    class S
    {
        private List<int> ids = new List<int>();
        public string Name { set; get; }

        public List<int> Ids { set { ids = value; } get { return ids; } }
    }
    class ET
    {
        public void Run()
        {
            //add
            Add(4, 5);//+
            AddAssign(4, 5);
            Subtract(5, 4);//-
            SubtractAssign(5,4);
            Multiply(4,5);
            MultiplyAssign(4,5);
            Divide(4, 2);
            DivideAssign(4,2);
            Decrement(3);//i--;
            Increment(3);//++
            Modulo();
            
            And(true, false); //&
            AndAlso(true, false);  //&&
            Or(true, false);
            OrElse(true, false);  //||
            LessThan(4, 5);
            Coalesce(1, 2);
            Coalesce(null, 2);
            Is();
            If();
            IfElse();
            Condition();
            Switch(5);
            Loop(9);
            TypeAs();
            Convert();
            New();
            NewArray();
            NewArrayBounds();
            ListInit();
            ListBind();
        }
        /// <summary>
        /// +
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void Add(int a,int b)
        {
            var left = Expression.Parameter(typeof(int));
            var right = Expression.Parameter(typeof(int));
            Expression exp = Expression.Add(left, right);
            Expression<Func<int, int, int>> lambda = Expression.Lambda<Func<int, int, int>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }

        public static int Add2(int a,int b)
        {
            return 100;
        }

        /// <summary>
        /// 利用方法+
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void AddAssign(int a, int b)
        {
            var left = Expression.Parameter(typeof(int));
            var right = Expression.Parameter(typeof(int));
            Expression exp = Expression.AddAssign(left, right, this.GetType().GetMethod("Add2"));
            Expression<Func<int, int, int>> lambda = Expression.Lambda<Func<int, int, int>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }
        /// <summary>
        /// &
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void And(bool a, bool b)
        {
            var left = Expression.Parameter(typeof(bool));
            var right = Expression.Parameter(typeof(bool));
            Expression exp = Expression.And(left, right);
            Expression<Func<bool, bool, bool>> lambda = Expression.Lambda<Func<bool, bool, bool>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }
        /// <summary>
        /// &&
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void AndAlso(bool a, bool b)
        {
            var left = Expression.Parameter(typeof(bool));
            var right = Expression.Parameter(typeof(bool));
            Expression exp = Expression.AndAlso(left, right);
            Expression<Func<bool, bool, bool>> lambda = Expression.Lambda<Func<bool, bool, bool>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }
        /// <summary>
        /// |
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void Or(bool a, bool b)
        {
            var left = Expression.Parameter(typeof(bool));
            var right = Expression.Parameter(typeof(bool));
            Expression exp = Expression.Or(left, right);
            Expression<Func<bool, bool, bool>> lambda = Expression.Lambda<Func<bool, bool, bool>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }
        /// <summary>
        /// ||
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void OrElse(bool a, bool b)
        {
            var left = Expression.Parameter(typeof(bool));
            var right = Expression.Parameter(typeof(bool));
            Expression exp = Expression.OrElse(left, right);
            Expression<Func<bool, bool, bool>> lambda = Expression.Lambda<Func<bool, bool, bool>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }

        /// <summary>
        /// -
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void Subtract(int a, int b)
        {
            var left = Expression.Parameter(typeof(int));
            var right = Expression.Parameter(typeof(int));
            Expression exp = Expression.Subtract(left, right);
            Expression<Func<int, int, int>> lambda = Expression.Lambda<Func<int, int, int>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }
        private void SubtractAssign(int a, int b)
        {
            var left = Expression.Parameter(typeof(int));
            var right = Expression.Parameter(typeof(int));
            Expression exp = Expression.SubtractAssign(left, right, this.GetType().GetMethod("Add2"));
            Expression<Func<int, int, int>> lambda = Expression.Lambda<Func<int, int, int>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }

        /// <summary>
        /// *
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void Multiply(int a, int b)
        {
            var left = Expression.Parameter(typeof(int));
            var right = Expression.Parameter(typeof(int));
            Expression exp = Expression.Multiply(left, right);
            Expression<Func<int, int, int>> lambda = Expression.Lambda<Func<int, int, int>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }
        private void MultiplyAssign(int a, int b)
        {
            var left = Expression.Parameter(typeof(int));
            var right = Expression.Parameter(typeof(int));
            Expression exp = Expression.MultiplyAssign(left, right, this.GetType().GetMethod("Add2"));
            Expression<Func<int, int, int>> lambda = Expression.Lambda<Func<int, int, int>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }
        /// <summary>
        /// /
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void Divide(int a, int b)
        {
            var left = Expression.Parameter(typeof(int));
            var right = Expression.Parameter(typeof(int));
            Expression exp = Expression.Divide(left, right);
            Expression<Func<int, int, int>> lambda = Expression.Lambda<Func<int, int, int>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }
        /// <summary>
        /// a/=b
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void DivideAssign(int a, int b)
        {
            var left = Expression.Parameter(typeof(int));
            var right = Expression.Parameter(typeof(int));
            Expression exp = Expression.DivideAssign(left, right, this.GetType().GetMethod("Add2"));
            Expression<Func<int, int, int>> lambda = Expression.Lambda<Func<int, int, int>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }
        /// <summary>
        /// --
        /// </summary>
        /// <param name="a"></param>
        private void Decrement(int a)
        {
            var left = Expression.Parameter(typeof(int));
            Expression exp = Expression.Decrement(left);
            Expression<Func<int, int>> lambda = Expression.Lambda<Func<int, int>>(exp, new ParameterExpression[] { left });
            var l = lambda.Compile();
            var r = l(a);
            Console.WriteLine(r);
        }
        /// <summary>
        /// ++
        /// </summary>
        /// <param name="a"></param>
        private void Increment(int a)
        {
            var left = Expression.Parameter(typeof(int));
            Expression exp = Expression.Increment(left);
            Expression<Func<int, int>> lambda = Expression.Lambda<Func<int, int>>(exp, new ParameterExpression[] { left });
            var l = lambda.Compile();
            var r = l(a);
            Console.WriteLine(r);
        }
        /// <summary>
        /// >
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void LessThan(int a, int b)
        {
            var left = Expression.Parameter(typeof(int));
            var right = Expression.Parameter(typeof(int));
            Expression exp = Expression.LessThan(left, right);
            Expression<Func<int, int, bool>> lambda = Expression.Lambda<Func<int, int, bool>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a,b);
            Console.WriteLine(r);
        }
        /// <summary>
        /// ??
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        private void Coalesce(int? a, int b)
        {
            var left = Expression.Parameter(typeof(int?));
            var right = Expression.Parameter(typeof(int));

            var right2 = Expression.Assign(right, Expression.Default(typeof(int)));
            Expression exp = Expression.Coalesce(left, right2);
            Expression<Func<int?, int, int>> lambda = Expression.Lambda<Func<int?, int, int>>(exp, new ParameterExpression[] { left, right });
            var l = lambda.Compile();
            var r = l(a, b);
            Console.WriteLine(r);
        }

        public static bool IsFalse(bool flag){
           return false;
        }
        /// <summary>
        /// is
        /// </summary>
        private void Is()
        {
            var v1 = Expression.Parameter(typeof(bool));

            var v11 = Expression.Assign(v1,Expression.Constant(true));
            var v2 = Expression.IsFalse(v1, this.GetType().GetMethod("IsFalse"));
            Expression exp = Expression.IsFalse(v2);
            var v3=Expression.TypeIs(Expression.Constant(new List<int>()),typeof(IList<int>));
            Expression<Func<bool,bool>> lambda = Expression.Lambda<Func<bool,bool>>(exp, new ParameterExpression[] {v1 });
            var l = lambda.Compile();
            var r = l(true);
            Console.WriteLine(r);
            Expression<Func<bool>> lambda2 = Expression.Lambda<Func<bool>>(v3);
            var l2 = lambda2.Compile();
            Console.WriteLine(l2());
        }
        /// <summary>
        /// if
        /// </summary>
        private void If()
        {
            var v1 = Expression.Variable(typeof(int),"a");
            var v11 = Expression.Assign(v1, Expression.Constant(10));
            var v2 = Expression.GreaterThan(v11, Expression.Constant(9));
            Expression exp = Expression.IfThen(v2,Expression.Call(typeof(Console).GetMethod("WriteLine",new Type[]{typeof(int)}),v1));
            Expression exp2 = Expression.Block(new[]{v1},exp);
            Expression<Action> lambda = Expression.Lambda<Action>(exp2, new ParameterExpression[] { });
            var l = lambda.Compile();
            l();
        }

        /// <summary>
        /// if else
        /// </summary>
        private void IfElse()
        {
            var v1 = Expression.Variable(typeof(int), "a");
            var v11 = Expression.Assign(v1, Expression.Constant(10));
            var v2 = Expression.GreaterThan(v11, Expression.Constant(9));
            Expression exp = Expression.IfThenElse(v2, Expression.Call(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }), Expression.Constant("True")), Expression.Call(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }), Expression.Constant("False")));
            Expression exp2 = Expression.Block(new[] { v1 }, exp);
            Expression<Action> lambda = Expression.Lambda<Action>(exp2, new ParameterExpression[] { });
            var l = lambda.Compile();
            l();
        }

        /// <summary>
        /// trueTest?ifTrue:ifFalse;
        /// </summary>
        private void Condition()
        {
            var v1 = Expression.Variable(typeof(int), "a");
            var v11 = Expression.Assign(v1, Expression.Constant(10));
            var v2 = Expression.GreaterThan(v1, Expression.Constant(9));
            Expression exp = Expression.Condition(v2, Expression.Call(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }), Expression.Constant("True")), Expression.Call(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }), Expression.Constant("False")));
            Expression exp2 = Expression.Block(new[] { v1 },v11, exp);
            Expression<Action> lambda = Expression.Lambda<Action>(exp2, new ParameterExpression[] { });
            var l = lambda.Compile();
            l();
        }
        /// <summary>
        /// switch
        /// </summary>
        /// <param name="i"></param>
        private void Switch(int i)
        {
            var par = Expression.Parameter(typeof(int));
            var target = Expression.Label(typeof(int),"a");
            var exp = Expression.Switch(par, Expression.Break(target, Expression.Constant(-5)), Expression.SwitchCase(Expression.Break(target, par), Expression.Constant(1)));
            var lbl = Expression.Label(target, Expression.Constant(0));
            var block = Expression.Block(exp,lbl);
            Expression<Func<int, int>> lambda = Expression.Lambda<Func<int, int>>(block, new ParameterExpression[] { par });
            var l = lambda.Compile();
            Console.WriteLine(l(i));
        }
        /// <summary>
        /// while(true){}
        /// </summary>
        /// <param name="i"></param>
        private void Loop(int i)
        {
            var par = Expression.Parameter(typeof(int));
            var ret = Expression.Variable(typeof(int), "ret");
            var v11 = Expression.Assign(ret, Expression.Constant(0));
            var lbl = Expression.Label(typeof(int));
            var lbl2 = Expression.Label(lbl,Expression.Constant(0));
            var block1 = Expression.Block(Expression.AddAssign(ret,par),Expression.SubtractAssign(par,Expression.Constant(2)));
            var condition = Expression.IfThenElse(Expression.GreaterThan(par, Expression.Constant(0)),block1, Expression.Break(lbl, ret));
            var block2 = Expression.Block(new[] { ret }, v11, Expression.Loop(condition), lbl2);// Expression.Block(new[] { ret }, v11, Expression.Loop(condition,lbl))  可以达到一样的效果
            Expression<Func<int, int>> lambda = Expression.Lambda<Func<int, int>>(block2, new ParameterExpression[] { par });
            var l = lambda.Compile();
            Console.WriteLine(l(i));
        }

        /// <summary>
        /// as
        /// </summary>
        private void TypeAs()
        {
            Expression s = Expression.Constant(1);
            var t=Expression.TypeAs(s, typeof(object));
            var call = Expression.Call(typeof(Console).GetMethod("WriteLine", new[] { typeof(int) }), Expression.Unbox(t, typeof(int)));
            Expression<Action> lambda = Expression.Lambda<Action>(call);
            var l=lambda.Compile();
            l();
        }

        /// <summary>
        /// 强转  class定义TypeConverter,TypeConverterAttribute
        /// </summary>
        private void Convert()
        {
            Expression s = Expression.Constant(7.5);
            var t = Expression.Convert(s, typeof(int));
            var call = Expression.Call(typeof(Console).GetMethod("WriteLine", new[] { typeof(int) }),t);
            Expression<Action> lambda = Expression.Lambda<Action>(call);
            var l = lambda.Compile();
            l();
        }

        /// <summary>
        /// %
        /// </summary>
        private void Modulo()
        {
            Expression s1 = Expression.Constant(7);
            Expression s2 = Expression.Constant(4);
            var t = Expression.Modulo(s1,s2);

            Expression<Func<int>> lambda = Expression.Lambda<Func<int>>(t);
            var l = lambda.Compile();
            Console.WriteLine(l());
        }

        /// <summary>
        /// new
        /// </summary>
        private void New()
        {
            Expression s = Expression.Constant(7);
            var t = Expression.New(typeof(T));
            var call = Expression.Call(t, typeof(T).GetMethod("Test"));
            Expression<Action> lambda = Expression.Lambda<Action>(call);
            var l = lambda.Compile();
            l();
        }

        /// <summary>
        /// 初始化数组对象new int[]{7}
        /// </summary>
        private void NewArray()
        {
            Expression s = Expression.Constant(7);
            var t = Expression.NewArrayInit(typeof(int),s);
            var call = Expression.Call(t, typeof(int[]).GetProperty("Length").GetGetMethod());
            Expression<Func<int>> lambda = Expression.Lambda<Func<int>>(call);
            var l = lambda.Compile();
            Console.WriteLine(l());
        }

        /// <summary>
        /// new int[7]
        /// </summary>
        private void NewArrayBounds()
        {
            Expression s = Expression.Constant(7);
            var t = Expression.NewArrayBounds(typeof(int), s);
            var call = Expression.Call(t, typeof(int[]).GetProperty("Length").GetGetMethod());
            Expression<Func<int>> lambda = Expression.Lambda<Func<int>>(call);
            var l = lambda.Compile();
            Console.WriteLine(l());
        }
        /// <summary>
        /// new List<int>(){5}
        /// </summary>
        private void ListInit()
        {
            Expression s = Expression.Constant(5);
            var lst = Expression.New(typeof(List<int>));
            var t = Expression.ListInit(lst,s);
            var call = Expression.Call(t, typeof(List<int>).GetProperty("Count").GetGetMethod());
            Expression<Func<int>> lambda = Expression.Lambda<Func<int>>(call);
            var l = lambda.Compile();
            Console.WriteLine(l());
        }
        /// <summary>
        /// var s=new S();s.Ids.Add(5);s.Ids.Add(7);
        /// </summary>
        private void ListBind()
        {
            Type s = typeof(S);
            var n=Expression.New(s);
            var ids=s.GetProperty("Ids");
            var l=typeof(List<int>);
            var n2 = Expression.New(l);
            var e1 = Expression.ElementInit(l.GetMethod("Add"), Expression.Constant(5));
            var e2 = Expression.ElementInit(l.GetMethod("Add"), Expression.Constant(7));
            var lst = Expression.ListBind(ids,e1,e2);
            var init=Expression.MemberInit(n,lst);
            Expression<Func<S>> lambda = Expression.Lambda<Func<S>>(init);
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