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动态表达式，dotnet版本eval

License: Apache License 2.0

C# 100.00%

dynamicexpression's Introduction

DynamicExpression

动态表达式，dotnet版本eval

目前还未成熟，正式项目中慎用。

悄咪咪的告诉你，DataTable中也有计算表达式的功能

var value = new DataTable().Compute("1+2",null);//3

回到我的动态表达式，是使用Roslyn解析表达式字符串，构建为表达式

依赖

是用的dotnet的Roslyn编译器，需要引用以下包

Microsoft.CodeAnalysis.CSharp

注意

这些例子里有关于类型的操作(创建对象、定义变量、静态方法调用)，都只有预设类型(int,string,double......)能用，其他类型需要在类型名称不重复的情况下，使用SetPredefinedType手动配置类型和名称，才能使用

调用例子

加减乘除

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
var func = expressionCompiler.Compile("1+2");
var result = func.DynamicInvoke();

比较

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
var func = expressionCompiler.Compile("1<2");
var result = func.DynamicInvoke();

带参

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value");
var func = expressionCompiler.Compile("value+2");
var result = func.DynamicInvoke(3);

方法调用

实例方法

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value1");
expressionCompiler.SetParameter<string>("value2");
var func = expressionCompiler.Compile("value1.ToString().Substring(2,2)+value2.Substring(2)");
var result = func.DynamicInvoke(12345,"67890");
//34890

静态方法

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<string>("value1");
expressionCompiler.SetParameter<string>("value2");
var func = expressionCompiler.Compile("string.Concat(value1, value2)");
var result = func.DynamicInvoke("12345","67890");
//1234567890

代码块

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value");
var func = expressionCompiler.Compile("{value = value + 2;return value;}");
var result = func.DynamicInvoke(3);

代码块内变量定义

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value");
var func = expressionCompiler.Compile("{int value1 = value+1;value = value1+1;value1 = value; return value1;}");
var result = func.DynamicInvoke(3);
//输出5
ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value");
var func = expressionCompiler.Compile("{int value1=1,value2=2; value1 =value1 + value2 + value; return value1;}");
var result = func.DynamicInvoke(3);
//输出6

其他逻辑运行

&&

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value1");
expressionCompiler.SetParameter<int>("value2");
var func = expressionCompiler.Compile("value1>1&&value2>3");
var result = func.DynamicInvoke(2,3);
//false

||

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value1");
expressionCompiler.SetParameter<int>("value2");
var func = expressionCompiler.Compile("value1>1||value2>3");
var result = func.DynamicInvoke(2,3);
//true

!

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value1");
expressionCompiler.SetParameter<int>("value2");
var func = expressionCompiler.Compile("!((value1+value2)>7");
var result = func.DynamicInvoke(3,4);
//true

位运行

^

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value1");
expressionCompiler.SetParameter<int>("value2");
var func = expressionCompiler.Compile("value1^value2");
var result = func.DynamicInvoke(3,4);
//7

|

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value1");
expressionCompiler.SetParameter<int>("value2");
var func = expressionCompiler.Compile("value1|value2");
var result = func.DynamicInvoke(6,10);
//14

&

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value1");
expressionCompiler.SetParameter<int>("value2");
var func = expressionCompiler.Compile("value1&value2");
var result = func.DynamicInvoke(6,10);
//2

>>

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value");
var func = expressionCompiler.Compile("value>>2");
var result = func.DynamicInvoke(14);
//3

<<

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int>("value");
var func = expressionCompiler.Compile("value<<2");
var result = func.DynamicInvoke(16);
//64

索引操作this[]

数组：

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int[]>("values");
var func = expressionCompiler.Compile("values[0]");//value[0,0] 多维数组/矩形数组 是在this中有多个参数的
var result = func.DynamicInvoke(new int[] { 1,2,3});
//result: 1

字符串

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<string>("values");
var func = expressionCompiler.Compile("values[0]");
var result = func.DynamicInvoke("123");
//result: '1'

自定义类型

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<Test>("values");
var func = expressionCompiler.Compile("values[0]");
var result = func.DynamicInvoke(new Test());
//result: null

多维数组

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int[][]>("values");
var func = expressionCompiler.Compile<Func<int[][], int[]>>("values[1]");//value[0,0] 多维数组/矩形数组 是在this中有多个参数的
int[][] value = new int[3][];
value[0] = new int[4] { 1, 2, 3, 4 };
value[1] = new int[3] { 5, 6, 7 };
value[2] = new int[3] { 8, 9, 0 };
var result = func.Invoke(value);
//result: { 5, 6, 7 }

多维数组作为入参时，需要编译为特定类型的表达式，使用Invoke方法而非DynamicInvoke。

可空类型处理

可空类型也是需要调用Invoke方法

??运算符

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int?>("value1");
var func = expressionCompiler.Compile<Func<int?,int?>>("value1??0");
var result1 = func.Invoke(null);//0
var result1 = func.Invoke(2);//2

?.

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int?>("value1");
var func = expressionCompiler.Compile<Func<int?, string>>("value1?.ToString()");
var result1 = func.Invoke(null);//null
var result1 = func.Invoke(2);//"2"

?[]

ExpressionCompiler expressionCompiler = new ExpressionCompiler();
expressionCompiler.SetParameter<int[]>("value1");

var func = expressionCompiler.Compile<Func<int[], int?>>("value1?[0]");//value[0,0] 多维数组/矩形
var result1 = func.Invoke(null);//null
var result1 = func.Invoke(new int[] { 10086, 110 });//10086

表达式合并

调用例子

ef中操作

string connectString = "Data Source=.;Initial Catalog=RportTest;Integrated Security=True";
var optionsBuilder = new DbContextOptionsBuilder<TestContext>();
optionsBuilder.UseSqlServer(connectString);
using (TestContext ctx = new TestContext(optionsBuilder.Options))
{

    Expression<Func<ReportData, bool>> epxr1 = report => report.ID == 2023;
    Expression<Func<ReportData, bool>> epxr2 = report => report.Name == "test1";

    var epxr3 = new List<Expression<Func<ReportData, bool>>>() { epxr1, epxr2 };

    var andPredicate = epxr3.AndAlso();
    var andQuery = ctx.ReportData.Where(andPredicate);
    string andSql = andQuery.ToQueryString();
    var andResult = andQuery.ToList();

    var orPredicate = epxr3.OrElse();
    var orQuery = ctx.ReportData.Where(orPredicate);
    string orSql = orQuery.ToQueryString();
    var orResult = orQuery.ToList();
}

多个参数表达式

多个表达式中的参数名不一致也没关系，最终会用第一个表达式的参数来代替。

Expression<Func<int,int, bool>> epxr1 = (value1,value2)=>value1+value2==4;
Expression<Func<int, int, bool>> epxr2 = (value3, value4) => value3 - value4 == 0;
var epxr3 = new List<Expression<Func<int,int, bool>>>() { epxr1, epxr2 };
var andPredicate = epxr3.AndAlso();
Func<int, int, bool> func = andPredicate.Compile();//(value1,value2)=>(value1 + value2 == 4) AndAlso (value1 - value2 == 0)
bool result1 = func(2, 2);//true
bool result2 = func(1, 3);//flase

支持列表

运算符

算数运算符

一元算数运算符 ++(递增) --(递减) +(正，一般不需要写) -(负)

二元： * / % + -

逻辑运算符

一元：！

二元：&& ||

位运算符

二元： & | ^ << >> ~按位求补

比较运算符

== ！= < > <= >=

成员访问运算符

. (访问属性、字段、方法)

[] 索引器运算符

赋值运算符

=

复合赋值

+= -= *= /= %= ^= &= |= ??=

??

三元条件运算符

? :

代码块

代码块

{.....;return x;}

定义变量

{int i=0;return i}

计划列表

  • 成员访问运算符 Null 条件运算符 ?. 和 ?[] 范围运算符..

    lambda表达式中不能有?. 和?[]操作: 表达式树lambda不能包含空传播运算符

  • 类型测试运算符 is as等

  • 浮点数写法 12d,12m,12f

  • 静态方法调用(已支持，但是只能调用System.Runtime程序集内的类型，类型相关的操作需要处理程序集加载问题)

  • new(延后，类型相关需要处理程序集)

  • 类型强制转换(延后，类型相关需要处理程序集)

一些不成熟的小想法

  • json转换为Expression用作EF的查询表达式

这种只能用在单表操作，不太好用在多表操作，并且这样会给前端太高的可操作性，数据安全性比较低。

  • Expression合并

Where查询的时候，可以通过不同的条件来添加Where筛选

if(!string.IsNullOfEmpty(name))
{
    query.Where(m=>m.Name == name);
}
......

多次判断的时候，多次调用Where，相当于多个条件的&&操作。有时候会需要||操作，就不太好弄

这里想重新构造多个Expression，合并生成一个新的Expression来操作

一些帮助摸鱼的小想法

  • 自动部署程序

某个项目中有很多的第三方dll，每次使用vs远程发布的时候，都需要传输大量文件，比较耗时

想法：在iis服务端进行应用的编译，发布，这个就涉及到从代码库中拉取代码->iis服务器编译->发布

相关资料

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