CodeDom系列二

---程序基本结构--符号三角形问题

昨天一个同学叫我帮编写一个符号三角形的c代码，今天就把它改写成用CodeDom生成的c#代码。

符号三角形：在一组字符串里（只有用空格分割的+或者-组成的字符串），在每次的相邻的两个符号比较，如果相同就在中间空格插入+,否则就插入-。一直运行到字符串里只有一个+或者-时停止，输出的字符串为符号三角形。

由于是CodeDom些列，所以先介绍几个CodeDom表达式：

1：CodeConditionStatement：判断语句即是if（condition）{} else{}，看最全的那个构造函数：

public CodeConditionStatement(CodeExpression condition,//条件CodeStatement[] trueStatements,//为true的语句体CodeStatement[] falseStatements//为false语句体)

2：CodeIterationStatement()：表示 for 语句或语句块内的循环（使用测试表达式作为继续循环的条件）：

在codedom中没有提高while和dowhile但是For已经够用的

public CodeIterationStatement(CodeStatement initStatement,//for初始化CodeExpression testExpression,//条件表达式CodeStatement incrementStatement,//for变化体，增或减CodeStatement[] statements//循环体)

3：CodeBinaryOperatorExpression：表示一个表达式，该表达式包含在两个表达式间进行的二进制运算,

public CodeBinaryOperatorExpression(CodeExpression left,//表达式左边CodeBinaryOperatorType op,//操作符CodeExpression right//表达式右边)

4：CodeArrayIndexerExpression：表示对数组的索引的引用：

public CodeArrayIndexerExpression(CodeExpression targetObject,//数组对象CodeExpression[] indices//下标)

其他参见CodeDOM 快速参考：msdn.microsoft.com/zh-cn/library/f1dfsbhc(VS.80).aspx

code：

04
public CodeNamespace CreateNameSpace() 

05
{ 

06
public CodeNamespace CreateNameSpace() 

07
{ 

08
//Test 

09
CodeMemberMethod test = new CodeMemberMethod(); 

10
test.Name = "Test"; 

11
test.Attributes = MemberAttributes.Public | MemberAttributes.Final; 

12
test.Statements.Add(new CodeVariableDeclarationStatement(typeof(char[]), "ch",

`4`	`new CodeMethodInvokeExpression(new CodePrimitiveExpression("+ - + - + + - -"), "ToCharArray",`

`4`	`new CodeExpression[] { })));`

`5`	`test.Statements.Add(new CodeMethodInvokeExpression(new CodeMethodReferenceExpression`

`4`	`(new CodeThisReferenceExpression(), "FuHaoSanJiao"), new CodeExpression[] { new CodeVariableReferenceExpression("ch"),`

4
new CodePrimitiveExpression(0) })); 

5
test.Statements.Add(new CodeMethodInvokeExpression(new CodeTypeReferenceExpression("System.Console"), "Read")); 

6
//FuHaoSanJiao 

7
CodeMemberMethod fuHaoSanJiao = new CodeMemberMethod(); 

8
fuHaoSanJiao.Name = "FuHaoSanJiao"; 

9
fuHaoSanJiao.Parameters.Add(new CodeParameterDeclarationExpression(new CodeTypeReference(typeof(char[])),

4
"ch")); 

5
fuHaoSanJiao.Parameters.Add(new CodeParameterDeclarationExpression(new CodeTypeReference(typeof(int)), "start")); 

6
fuHaoSanJiao.Statements.Add(new CodeMethodInvokeExpression(new CodeTypeReferenceExpression("System.Console"),

`4`	`"WriteLine", new CodeExpression[] { new CodeObjectCreateExpression(typeof(string), new CodeArgumentReferenceExpression("ch")) }));`

`5`	`fuHaoSanJiao.Statements.Add(new CodeConditionStatement(new CodeBinaryOperatorExpression(`

`4`	`new CodeArgumentReferenceExpression("start"), CodeBinaryOperatorType.GreaterThanOrEqual,`

`5`	`(new CodeBinaryOperatorExpression(new CodePropertyReferenceExpression(`

4
new CodeArgumentReferenceExpression("ch"),"Length"), 

5
CodeBinaryOperatorType.Divide ,new CodePrimitiveExpression(2)))), 

6
new CodeMethodReturnStatement())); 

7
CodeBinaryOperatorExpression condition=new CodeBinaryOperatorExpression(

04
new CodeVariableReferenceExpression("i"), 

05
CodeBinaryOperatorType.LessThan, 

06
new CodeBinaryOperatorExpression(new CodeBinaryOperatorExpression(new CodePropertyReferenceExpression(new CodeArgumentReferenceExpression("ch"),"Length"), 

07
CodeBinaryOperatorType.Subtract ,new CodeArgumentReferenceExpression("start")), CodeBinaryOperatorType.Subtract, 

08
new CodePrimitiveExpression(1)));//for 条件 

09
CodeConditionStatement iterationBody=new CodeConditionStatement(new CodeBinaryOperatorExpression( 

10
new CodeArrayIndexerExpression(new CodeArgumentReferenceExpression("ch"),

`4`	`new CodeVariableReferenceExpression("i")),`

`5`	`CodeBinaryOperatorType.IdentityEquality, new CodeArrayIndexerExpression(`

`4`	`new CodeArgumentReferenceExpression("ch"),`

`5`	`new CodeBinaryOperatorExpression(new CodeVariableReferenceExpression("i"),`

4
CodeBinaryOperatorType.Add,new CodePrimitiveExpression(2)))), 

5
new CodeAssignStatement( 

6
new CodeArrayIndexerExpression(new CodeArgumentReferenceExpression("ch"),

`4`	`new CodeBinaryOperatorExpression(new CodeVariableReferenceExpression("i"), CodeBinaryOperatorType.Add,`

4
new CodePrimitiveExpression(1))), 

5
new CodePrimitiveExpression('+'))); 

6
iterationBody.FalseStatements.Add(new CodeAssignStatement( 

7
new CodeArrayIndexerExpression(new CodeArgumentReferenceExpression("ch"),

`4`	`new CodeBinaryOperatorExpression(new CodeVariableReferenceExpression("i"), CodeBinaryOperatorType.Add,`

4
new CodePrimitiveExpression(1))), 

5
new CodePrimitiveExpression('-'))); 

6
CodeAssignStatement iteerationbody2 = new CodeAssignStatement(new CodeArrayIndexerExpression(

4
new CodeArgumentReferenceExpression("ch"), new CodeVariableReferenceExpression("i")), 

5
new CodePrimitiveExpression(' ')); 

6
fuHaoSanJiao.Statements.Add(new CodeIterationStatement(new CodeVariableDeclarationStatement(typeof(int),

`4`	`"i", new CodeArgumentReferenceExpression("start")), condition,`

`5`	`new CodeAssignStatement(new CodeVariableReferenceExpression("i"),new CodeBinaryOperatorExpression(`

4
new CodeVariableReferenceExpression("i"), CodeBinaryOperatorType.Add, 

5
new CodePrimitiveExpression(2))), new CodeStatement[] { iterationBody, iteerationbody2 })); 

6
// ch[ch.Length - start - 1] = ' '; 

7
fuHaoSanJiao.Statements.Add(new CodeAssignStatement( 

8
new CodeArrayIndexerExpression(new CodeArgumentReferenceExpression("ch"),

`4`	`new CodeBinaryOperatorExpression(new CodeBinaryOperatorExpression(`

`4`	`new CodePropertyReferenceExpression(new CodeArgumentReferenceExpression("ch"), "Length"),`

`5`	`CodeBinaryOperatorType.Subtract ,new CodeArgumentReferenceExpression("start")),`

4
CodeBinaryOperatorType.Subtract, 

5
new CodePrimitiveExpression(1))),new CodePrimitiveExpression(' '))); 

6
//  FuHaoSanJiao(ch, start + 1); 

7
fuHaoSanJiao.Statements.Add(new CodeMethodInvokeExpression(new CodeThisReferenceExpression(),

`4`	`"FuHaoSanJiao",new CodeArgumentReferenceExpression("ch") ,`

`5`	`new CodeBinaryOperatorExpression(new CodeArgumentReferenceExpression("start"),`

04
CodeBinaryOperatorType.Add, new CodePrimitiveExpression(1)))); 

05
CodeTypeDeclaration codeDomDemo2 = new CodeTypeDeclaration("CodeDomDemo2"); 

06
codeDomDemo2.Members.Add(test); 

07
codeDomDemo2.Members.Add(fuHaoSanJiao); 

08
codeDomDemo2.Attributes = MemberAttributes.Public; 

09
codeDomDemo2.Comments.Add(new CodeCommentStatement("this code is from CodeDom!")); 

10
//codeDomDemo2.Members.AddRange(); 

11
CodeNamespace nspace = new CodeNamespace("CodeDomDemo2"); 

12
nspace.Imports.Add(new CodeNamespaceImport("System")); 

13
nspace.Types.Add(codeDomDemo2); 

14
return nspace; 

15
} 

16
} 

17
}

输出代码为：

04
namespace CodeDomDemo2 

05
{ 

06
using System; 

07
// this code is from CodeDom! 

08
public class CodeDomDemo2 

09
{ 

10
public void Test() 

11
{ 

12
char[] ch = "+ - + - + + - -".ToCharArray(); 

13
this.FuHaoSanJiao(ch, 0); 

14
System.Console.Read(); 

15
} 

16
private void FuHaoSanJiao(char[] ch, int start) 

17
{ 

18
System.Console.WriteLine(new string(ch)); 

19
if ((start 

20
>= (ch.Length / 2))) 

21
{ 

22
return; 

23
} 

24
for (int i = start; (i 

25
< ((ch.Length - start) 

26
- 1)); i = (i + 2)) 

27
{ 

28
if ((ch[i] == ch[(i + 2)])) 

29
{ 

30
ch[(i + 1)] = '+'; 

31
} else 

32
{ 

33
ch[(i + 1)] = '-'; 

34
} 

35
ch[i] = ' '; 

36
} 

37
ch[((ch.Length - start) 

38
- 1)] = ' '; 

39
this.FuHaoSanJiao(ch, (start + 1)); 

40
} 

41
} 

42
}

代码下载Demo1，Demo2

事件（event）定义和反射调用

CodeDom提供了对事件的支持，以及我们可以用反射机制对CodeDom生成的事件进行注册，以及调用。本节程序很简单，先贴上我将用CodeDom生成的代码：

view source

print ?

04 namespace CodeDomDemo3

05 {

06 using System;

07 public class CodeDomDemo3

08 {

09 public event System.EventHandler MyEvent;

10 protected virtual void OnHandle(System.EventArgs e)

11 {

12 if ((this.MyEvent != null))

13 {

14 this.MyEvent(this, e);

15 }

16 }

17 public void CallEvent()

18 {

19 this.OnHandle(EventArgs.Empty);

20 }

21 }

22 }

代码很简单哦，主要是看CodeDom的事件定义机制和反射调用CodeDom编译的类型方法事件。

CodeDom代码为：

view source

print ?

04 using System;

05 using System.Collections.Generic;

06 using System.Linq;

07 using System.Text;

08 using System.CodeDom;

09 namespace CodeDomDemo1

10 {

11 public class CodeDomDemo3

12 {

13 public CodeNamespace CreateCodeNamespcae()

14 {

15 CodeNamespace nspcae = new CodeNamespace("CodeDomDemo3");

16 nspcae.Imports.Add(new CodeNamespaceImport("System"));

17 nspcae.Types.Add(CrateClassType());

18 return nspcae;

19 }

20 public CodeTypeDeclaration CrateClassType()

21 {

22 //field event

23 CodeMemberEvent myevent = new CodeMemberEvent();

24 myevent.Attributes = MemberAttributes.Public;

25 myevent.Type = new CodeTypeReference(typeof(EventHandler));

26 myevent.Name = "MyEvent";

27 // event method OnHandle;

28 CodeMemberMethod method = new CodeMemberMethod();

29 method.Name = "OnHandle";

30 method.Attributes = MemberAttributes.Family;

31 method.Parameters.Add(new CodeParameterDeclarationExpression(new CodeTypeReference(typeof(EventArgs)), "e"));

32 method.Statements.Add(new CodeConditionStatement(new CodeBinaryOperatorExpression(new CodeEventReferenceExpression(

view source

print ?

4 new CodeThisReferenceExpression(),"MyEvent"),

5 CodeBinaryOperatorType.IdentityInequality,new CodePrimitiveExpression(null)),

6 new CodeExpressionStatement(new CodeDelegateInvokeExpression(new CodeEventReferenceExpression(

view source

print ?

04 new CodeThisReferenceExpression(),

05 "MyEvent"), new CodeExpression[] { new CodeThisReferenceExpression(), new CodeArgumentReferenceExpression("e"),

06 }))));

07 CodeMemberMethod callEvent = new CodeMemberMethod();

08 callEvent.Name = "CallEvent";

09 callEvent.Attributes = MemberAttributes.Public | MemberAttributes.Final;

10 callEvent.Statements.Add(new CodeMethodInvokeExpression(new CodeThisReferenceExpression(), "OnHandle", new CodeExpression[]

view source

print ?

04 {new CodePropertyReferenceExpression(new CodeTypeReferenceExpression("EventArgs"),"Empty") }));

05 CodeTypeDeclaration myclass = new CodeTypeDeclaration("CodeDomDemo3");

06 myclass.Attributes = MemberAttributes.Public;

07 myclass.Members.AddRange(new CodeTypeMember[] { myevent, method, callEvent });

08 return myclass;

09 }

10 }

11 }

view source

print ?

4 1:主要注意委托的调用：
public CodeDelegateInvokeExpression(CodeExpression targetObject,//事件的引用CodeExpression[] parameters//参数)
2:事件的添加（+=）：
public CodeAttachEventStatement(CodeExpression targetObject,//目标对象string eventName,//事件名CodeExpression listener//监听者)
3：事件的移除（-=）：
public CodeRemoveEventStatement(CodeExpression targetObject,//目标对象string eventName,//事件名CodeExpression listener//监听者)

   利用反射调用事件代码：

4
Type t = result.CompiledAssembly.GetType("CodeDomDemo3.CodeDomDemo3");//获取类型 

5
object obj= Activator.CreateInstance(t);//创建实例 

6
t.GetEvent("MyEvent").AddEventHandler(obj, new EventHandler(pro.CallEvent));//添加事件 

7
t.GetMethod("CallEvent").Invoke(obj, null);//触发事件

本示例代码下载：CodeDomDemo3