AScript是一个开源的C#动态脚本解析执行引擎,其中有两种数据类型比较特殊:匿名类型 和动态类型。
一、匿名类型
匿名类型是在编译时确定结构,适合固定数据结构,属性只读。
1 string s = @"
2 var a = new { Name='tony', Age=20 }
3 a.Name + ':' + a.Age
4 ";
5 var script = new Script();
6 Assert.AreEqual("tony:20", script.Eval(s));
7 dynamic a = script.Eval("a");
8 // 获取脚本中定义的匿名类型
9 var type = Script.AnonymousTypes.CreateType(new[] { "Name", "Age" }, new[] { typeof(string), typeof(int) });
10 Assert.IsInstanceOfType(a, type);
11 Assert.AreEqual("tony", a.Name);
12 Assert.AreEqual(20, a.Age);
13 Assert.AreEqual("{ Name = tony, Age = 20 }", a.ToString());
可以从 Script.AnonymousTypes 中获取脚本内定义的匿名类型。
匿名类型也常用于LINQ查询:
1 string s = @"
2 var q = from a in context.Persons
3 join b in context.AddressInfos on a.Id equals b.UserId into bb
4 from b in bb.DefaultIfEmpty()
5 select new { a.Id, a.Name, a.Age, MyAddress = b.Address };
6 q.ToList();
7 ";
8 var script = new Script();
9 // 数据库DbContext变量
10 script.Context.SetVar("context", context);
11 var list = script.Eval<IList>(s);
12 Console.WriteLine(JsonConvert.SerializeObject(list, Formatting.Indented));
匿名类型实现详见源码: AnonymousTypeManager
二、动态类型
动态类型 ExpandoObject ,运行时可动态添加属性,对应js中的写法: var a = { } 。
1 string s = @"
2 var a = new ExpandoObject();
3 a.Name = 'jim';
4 a.Age = 23;
5 a
6 ";
7 var script = new Script();
8 dynamic a = script.Eval(s);
9 Assert.IsInstanceOfType(a, typeof(ExpandoObject));
10 Assert.AreEqual("jim", a.Name);
11 Assert.AreEqual(23, a.Age);
使用初始化器创建动态类型:
1 string s = @"
2 var a = new ExpandoObject { Name = 'jim', Age = 23 };
3 a.Height= 170;
4 a
5 ";
6 var script = new Script();
7 dynamic a = script.Eval(s);
8 Assert.IsInstanceOfType(a, typeof(ExpandoObject));
9 Assert.AreEqual("jim", a.Name);
10 Assert.AreEqual(23, a.Age);
11 Assert.AreEqual(170, a.Height);
AScript 的匿名类型和动态类型为脚本提供了灵活的数据结构表达能力。