LambdaParser:解析字符串为Lambda表达式并编译为委托
最近刚刚离了职，便休息一会做点自己想做的事，于是花点时间写了这个解析字符串为Lambda表达式并编译为委托的模块：LambdaParser。
介绍
先举个最简单的例子让大家明白LambdaParser模块究竟做什么：
Func<int, string> f = ExpressionParserManager.ParseDelegate<Func<int, string>>(
"m=>2+m.ToString(\"000\")");
string result = f(2); // "2002"
"m=>2+m.ToString(\"000\")");
string result = f(2); // "2002"
简单的说，LambdaParser模块就是在运行时编译Lambda表达式。
原理
LambdaParser的最主要方法ParseDelegate接受一个代码字符串，返回一个委托。
LambdaParser会分析输入的代码字符串，然后一个一个构造Lambda Expression，最后编译成委托。
这样，我们就能动态编译并执行代码。
若是每次都这样，性能当然好不到哪里去，于是我在ExpressionParserManager做缓存，在下次调用时从缓存里取委托。
特点
在运行时编译Lambda表达式不是一个常规解决方案，但有时候很有用，它比反射更灵活，更快，更易懂。
一些说明
1.基于Lambda表达式，所以当然也不支持Lambda表达式不支持的，如：赋值操作等。
2.只支持Lambda表达式，不支持Lambda语句。也就是说不能写多条Lambda语句，所以if,for,while等肯定是不支持的。
3.理所当然，支持数字运算，支持字符串拼接。目前尚未做编译优化，比如：1+2这种常量运算本来是可以在编译的时候就计算出来，但现在是原原本本的编译出来，在运行时去计算。字符串的拼接也一样。
4.目前尚不支持checked运算。
5.由于我是看了老赵的《这下没理由嫌Eval的性能差了吧？》才有这想法的，对于那一段Expression代码 (DynamicPropertyAccessor构造函数)，当时花了N+M次的来回阅读，才勉强弄明白意思，于是计划写这个，所以我用老赵的思路也实 现了一个FastEval，由于我这个类库本来就是做解析的，所以对于FastEval的参数也就原生的支持表达式语句，而不仅仅是属性名，所以我认为我 这个FastEval实现比原本的Eval更快，更灵活：）
example:<%#FastEval("Sex?\"男\":\"女\"")%>
6.本打算同样用老赵的思想实现FastReflectionLib，但发现LambdaParser还有很多事要做，就先搁置。
7.如果本身的Lambda表达式写得有问题，那么报的错误可能会很奇怪，因为时间原因目前没有很友好的错误提示。
结束语
项目中必定会有不少bug，若是解析某个特定code时出意外，希望将输出的code发给我，可以在这里回复，或者发到我邮箱：zhucai+lambdaparser@gmail.com
今天只是简单介绍一下其功能及使用方法，之后有时间我再来详细谈谈设计过程。
我在sourceforge.net申请了个项目:https://sourceforge.net/projects/lambdaparser
但现在还不会玩：（
贴上所有已通过的测试用例，方便弄明白用法：
/// <summary>
/// 数字运算
/// </summary>
[TestMethod]
public void ParseDelegateTest_Number()
{
{
Func<int, string> f = ExpressionParserManager.ParseDelegate<Func<int, string>>(
"m=>2+m.ToString(\"000\")");
string result = f(2); // "2002"
Assert.AreEqual(result, "2002");
string code = "()=>1+2-3*4/2+20%7";
int expected = 1 + 2 - 3 * 4 / 2 + 20 % 7;
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2+3*4/2-4%(2+1)+32-43*(6-4)+3.3";
double expected = 2 + 3 * 4 / 2 - 4 % (2 + 1) + 32 - 43 * (6 - 4) + 3.3;
Func<double> func = ExpressionParserManager.ParseDelegate<Func<double>>(code);
double actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2+3*4/2-4%(2.4+1)+32-43*(6-4)+3.3*(322/(43-(3-1)))";
double expected = 2 + 3 * 4 / 2 - 4 % (2.4 + 1) + 32 - 43 * (6 - 4) + 3.3 * (322 / (43 - (3 - 1)));
Func<double> func = ExpressionParserManager.ParseDelegate<Func<double>>(code);
double actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 字符串拼接和函数调用
/// </summary>
[TestMethod]
public void ParseDelegateTest_StringAdd()
{
string code = "2.ToString()+3+(4*2)";
string expected = "238";
Func<string> func = ExpressionParserManager.ParseDelegate<Func<string>>(code);
string actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 成员访问，方法调用，构造函数(传参)
/// </summary>
[TestMethod]
public void ParseDelegateTest_Member_Method_Ctor()
{
string code = "()=>new Test_Zhucai.LambdaParser.TestClass(9,2).Member1";
string code2 = "()=>new Test_Zhucai.LambdaParser.TestClass(){Member1 = 5,Member2 = 4}.GetMemberAll()";
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
Func<int> func2 = ExpressionParserManager.ParseDelegate<Func<int>>(code2);
int actual = func();
int actual2 = func2();
Assert.AreEqual(actual, actual2);
}
/// <summary>
/// 委托传多个参数
/// </summary>
[TestMethod]
public void ParseDelegateTest_MultiLambdaParam()
{
string code = "(m,n,l)=>m+n+l"; // m:1 n:2 l:"3"
string expected = "33";
Func<int, int, string, string> func = ExpressionParserManager.ParseDelegate<Func<int, int, string, string>>(code);
string actual = func(1, 2, "3");
Assert.AreEqual(expected, actual);
}
/// <summary>
/// new数组，数组访问
/// </summary>
[TestMethod]
public void ParseDelegateTest_Array()
{
string code = "()=>new string[]{\"aa\",\"bb\"}[1]";
string expected = "bb";
Func<string> func = ExpressionParserManager.ParseDelegate<Func<string>>(code);
string actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// new数组，数组访问2
/// </summary>
[TestMethod]
public void ParseDelegateTest_Array2()
{
string code = "()=>new string[5].Length";
int expected = 5;
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// new多维数组
/// </summary>
[TestMethod]
public void ParseDelegateTest_ArrayMultiRank()
{
string code = "()=>new string[5,4].Rank";
int expected = 2;
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 索引器访问
/// </summary>
[TestMethod]
public void ParseDelegateTest_Indexer()
{
string code = "m=>(string)m[1]";
string expected = "bb";
Func<ArrayList, string> func = ExpressionParserManager.ParseDelegate<Func<ArrayList, string>>(code);
string actual = func(new ArrayList(new string[] { "aa", "bb" }));
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 重复生成
/// </summary>
[TestMethod]
public void ParseDelegateTest_Repeater()
{
string code = "m=>(string)m[1]";
string expected = "bb";
Func<ArrayList, string> func = ExpressionParserManager.ParseDelegate<Func<ArrayList, string>>(code);
func = ExpressionParserManager.ParseDelegate<Func<ArrayList, string>>(code);
string actual = func(new ArrayList(new string[] { "aa", "bb" }));
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 成员初始化
/// </summary>
[TestMethod]
public void ParseDelegateTest_MemberInit()
{
string code = "()=>new Test_Zhucai.LambdaParser.TestClass(){Member1 = 20}.ToString()";
string expected = "20";
Func<string> func = ExpressionParserManager.ParseDelegate<Func<string>>(code);
string actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 测试操作符typeof,sizeof
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorTypeofSizeof()
{
string code = "()=>typeof(string).FullName+sizeof(int)";
string expected = typeof(string).FullName + sizeof(int);
Func<string> func = ExpressionParserManager.ParseDelegate<Func<string>>(code);
string actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 测试操作符!
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorNot()
{
string code = "(m)=>!m";
bool expected = true;
Func<bool, bool> func = ExpressionParserManager.ParseDelegate<Func<bool, bool>>(code);
bool actual = func(false);
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 测试操作符~
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorBitNot()
{
string code = "()=>~9";
int expected = ~9;
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 测试操作符convert()
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorConvert()
{
string code = "()=>(int)(9.8+3.3)";
int expected = (int)(9.8 + 3.3);
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 测试操作符＞＞,＜＜
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorBitShift()
{
string code = "()=>(9>>3)-(5<<2)";
int expected = (9 >> 3) - (5 << 2);
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 测试操作符＞
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorGreaterThan()
{
{
string code = "()=>9>2";
bool expected = (9 > 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2>9";
bool expected = (2 > 9);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2>2";
bool expected = (2 > 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符＜
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorLessThan()
{
{
string code = "()=>9<2";
bool expected = (9 < 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2<9";
bool expected = (2 < 9);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2<2";
bool expected = (2 < 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符＜=
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorLessThanOrEqual()
{
{
string code = "()=>9<=2";
bool expected = (9 <= 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2<=2";
bool expected = (2 <= 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2<=9";
bool expected = (2 <= 9);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符＞=
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorGreaterThanOrEqual()
{
{
string code = "()=>9>=2";
bool expected = (9 >= 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2>=2";
bool expected = (2 >= 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2>=9";
bool expected = (2 >= 9);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符==
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorEqual()
{
{
string code = "()=>9==2";
bool expected = (9 == 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2==2";
bool expected = (2 == 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2==9";
bool expected = (2 == 9);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符!=
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorNotEqual()
{
{
string code = "()=>9!=2";
bool expected = (9 != 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2!=2";
bool expected = (2 != 2);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>2!=9";
bool expected = (2 != 9);
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符is
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorIs()
{
{
string code = "(m)=>((object)m) is int";
bool expected = ((object)2) is int;
Func<object, bool> func = ExpressionParserManager.ParseDelegate<Func<object, bool>>(code);
bool actual = func(2);
Assert.AreEqual(expected, actual);
}
{
string code = "()=>((object)\"abc\") is int";
bool expected = ((object)"abc") is int;
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符as
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorAs()
{
{
string code = "(m)=>((object)m) as string";
string expected = ((object)2) as string;
Func<object, string> func = ExpressionParserManager.ParseDelegate<Func<object, string>>(code);
string actual = func(2);
Assert.AreEqual(expected, actual);
}
{
string code = "()=>((object)\"abc\") as string";
string expected = ((object)"abc") as string;
Func<string> func = ExpressionParserManager.ParseDelegate<Func<string>>(code);
string actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符^
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorExclusiveOr()
{
string code = "()=>3^7";
int expected = 3 ^ 7;
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 测试操作符&
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorAnd()
{
string code = "()=>3&7";
int expected = 3 & 7;
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 测试操作符|
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorOr()
{
string code = "()=>3|7";
int expected = 3 | 7;
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 测试操作符&&
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorAndAlso()
{
{
string code = "()=>true&&false";
bool expected = true && false;
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>true&&true";
bool expected = true && true;
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>false && false";
bool expected = false && false;
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符||
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorOrElse()
{
{
string code = "()=>true||false";
bool expected = true || false;
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>true||true";
bool expected = true || true;
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>false||false";
bool expected = false || false;
Func<bool> func = ExpressionParserManager.ParseDelegate<Func<bool>>(code);
bool actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符?:
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorCondition()
{
{
string code = "()=>1==1?1:2";
int expected = 1 == 1 ? 1 : 2;
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = "()=>1==2?1:2";
int expected = 1 == 2 ? 1 : 2;
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
}
/// <summary>
/// 测试操作符??
/// </summary>
[TestMethod]
public void ParseDelegateTest_OperatorDoubleQuestionMark()
{
string code = "(m)=>m??\"bb\"";
string expected = "aa";
Func<string, string> func = ExpressionParserManager.ParseDelegate<Func<string, string>>(code);
string actual = func("aa");
Assert.AreEqual(expected, actual);
// use code to test 2
expected = "bb";
actual = func(null);
Assert.AreEqual(expected, actual);
}
/// <summary>
/// 测试一个复杂代码
/// </summary>
[TestMethod]
public void ParseDelegateTest_Other()
{
{
string code = @"()=>new Test_Zhucai.LambdaParser.TestClass()
{
Member1 = 3
}.Member1 == 3 ? new Test_Zhucai.LambdaParser.TestClass[]
{
new Test_Zhucai.LambdaParser.TestClass()
{
Member1 = 3
}
}[4-4].Member1 + 3 * new Test_Zhucai.LambdaParser.TestClass()
{
Member2 = 5
}.Member2 : new Test_Zhucai.LambdaParser.TestClass()
{
Member2 = 5,
Member1 = 9,
}.GetMemberAll();";
int expected = new Test_Zhucai.LambdaParser.TestClass()
{
Member1 = 3
}.Member1 == 3 ? new Test_Zhucai.LambdaParser.TestClass[]
{
new Test_Zhucai.LambdaParser.TestClass()
{
Member1 = 3
}
}[4 - 4].Member1 + 3 * new Test_Zhucai.LambdaParser.TestClass()
{
Member2 = 5
}.Member2 : new Test_Zhucai.LambdaParser.TestClass()
{
Member2 = 5,
Member1 = 9,
}.GetMemberAll();
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
{
string code = @"()=>new Test_Zhucai.LambdaParser.TestClass()
{
Member1 = 3
}.Member1 != 3 ? new Test_Zhucai.LambdaParser.TestClass[]
{
new Test_Zhucai.LambdaParser.TestClass()
{
Member1 = 3
}
}[new Test_Zhucai.LambdaParser.TestClass().Member1].Member1 + 3 * new Test_Zhucai.LambdaParser.TestClass()
{
Member2 = 5
}.Member2 : new Test_Zhucai.LambdaParser.TestClass()
{
Member2 = 5,
Member1 = 9,
}.GetMemberAll();";
int expected = new Test_Zhucai.LambdaParser.TestClass()
{
Member1 = 3
}.Member1 != 3 ? new Test_Zhucai.LambdaParser.TestClass[]
{
new Test_Zhucai.LambdaParser.TestClass()
{
Member1 = 3
}
}[new Test_Zhucai.LambdaParser.TestClass().Member1].Member1 + 3 * new Test_Zhucai.LambdaParser.TestClass()
{
Member2 = 5
}.Member2 : new Test_Zhucai.LambdaParser.TestClass()
{
Member2 = 5,
Member1 = 9,
}.GetMemberAll();
Func<int> func = ExpressionParserManager.ParseDelegate<Func<int>>(code);
int actual = func();
Assert.AreEqual(expected, actual);
}
}
public class TestClass
{
public int Member1 { get; set; }
public int Member2;
public TestClass()
{
}
public TestClass(int member, int member2)
{
this.Member1 = member;
this.Member2 = member2;
}
public int GetMemberAll()
{
return this.Member1 + this.Member2;
}
public override string ToString()
{
return Member1.ToString();
}
}
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