使用C# 2.0实现语言无关的代码生成器

    在数据表类中每个属性代表数据表的一个字段，名子就是字段名。这些属性和保存字段的全局变量一一对应。下面是具体的实现代码：
private
void GenerateProperties(){String fieldname =
"", fieldtype =
"";foreach (XmlNode xn in m_Xml.DocumentElement.ChildNodes){fieldname = xn.Name;fieldtype = xn.Attributes["type"].Value;CodeMemberProperty property =
new CodeMemberProperty();property.Attributes = MemberAttributes.Public | MemberAttributes.Final;property.Name = fieldname;property.Type =
new CodeTypeReference(fieldtype);property.HasGet =
true;property.HasSet =
true;CodeVariableReferenceExpression field =
new CodeVariableReferenceExpression("m_"
+ fieldname);// 产生 return m_property
        CodeMethodReturnStatement propertyReturn =
new CodeMethodReturnStatement(field);property.GetStatements.Add(propertyReturn);// 产生 m_property = value;
        CodeAssignStatement propertyAssignment =
new CodeAssignStatement(field, new CodePropertySetValueReferenceExpression());property.SetStatements.Add(propertyAssignment);m_Class.Members.Add(property);}}


    这些生成的属性是可读写的。这就需要将HasGet和HasSet两个属性设为true，然后分别将get和set方法中的语句分别加到GetStatements和SetStatements中。

构造函数的生成

    构造函数的主要工作是打开数据表。如果数据表不存在，就创建这个数据表文件。在编写代码之前，需要先定义三个全局变量。因为这三个全局变量在程序中会多次 用到。它们的类型都是CodeVariableReferenceExpression。这个类型变量其实在生成源码中的作用就是对某一个变量的引用。具 体的实现代码如下：

private
void GenerateMethods(){CodeTypeReference voidReference =
new CodeTypeReference("System.void");//产生Add方法
    CodeMemberMethod add =
new CodeMemberMethod();add.ReturnType = voidReference;add.Name =
"add";add.Attributes = MemberAttributes.Public | MemberAttributes.Final;CodeAssignStatement assignAddTrue =
new CodeAssignStatement(m_AddFlagExpression, new CodePrimitiveExpression(true));add.Statements.Add(assignAddTrue);m_Class.Members.Add(add);//产生Save方法
    CodeMemberMethod save =
new CodeMemberMethod();save.ReturnType = voidReference;save.Name =
"save";save.Attributes = MemberAttributes.Public | MemberAttributes.Final;System.Collections.Generic.List<CodeStatement> ifStatements =
new System.Collections.Generic.List<CodeStatement>();//产生 "XmlNode xn = m_xml.CreateNode(XmlNodeType.Element, "item", "");"
CodeVariableDeclarationStatement xmlNode =
new CodeVariableDeclarationStatement("System.Xml.XmlNode", "xn");CodeMethodInvokeExpression createNode =
new CodeMethodInvokeExpression(m_XmlExpression, "CreateNode", new CodeExpression[] {new CodeVariableReferenceExpression("System.Xml.XmlNodeType.Element"), new CodePrimitiveExpression("item"), new CodePrimitiveExpression("") });xmlNode.InitExpression = createNode;ifStatements.Add(xmlNode);//产生 "XmlAttribute xa = null; "
   CodeVariableDeclarationStatement xmlAttr =
new CodeVariableDeclarationStatement("System.Xml.XmlAttribute", "xa");xmlAttr.InitExpression =
new CodePrimitiveExpression(null);ifStatements.Add(xmlAttr);//产生字段属性
   CodeStatementCollection statements =
new CodeStatementCollection();foreach (XmlNode xn in m_Xml.DocumentElement.ChildNodes){CodeMethodInvokeExpression createAttribute =
new CodeMethodInvokeExpression(m_XmlExpression,"CreateAttribute", new CodePrimitiveExpression(xn.Name));CodeAssignStatement assignxa =
new CodeAssignStatement(new CodeVariableReferenceExpression("xa"), createAttribute);CodeMethodInvokeExpression invokeToString =
new CodeMethodInvokeExpression(new CodeVariableReferenceExpression("m_"
+ xn.Name), "ToString");CodeAssignStatement assignValue =
new CodeAssignStatement(new CodeVariableReferenceExpression("xa.Value"), invokeToString);CodeMethodInvokeExpression invokeAppend =
new CodeMethodInvokeExpression(new CodeVariableReferenceExpression("xn.Attributes"), "Append", newCodeVariableReferenceExpression("xa"));statements.Add(invokeAppend);ifStatements.Add(assignxa);ifStatements.Add(assignValue);ifStatements.Add(statements[0]);}// 产生 "m_xml.DocumentElement.AppendChild(xn);"
   CodeMethodInvokeExpression invokeAppendChild =
new CodeMethodInvokeExpression(new CodeVariableReferenceExpression("m_xml.DocumentElement"), "AppendChild", new CodeVariableReferenceExpression("xn"));statements.Clear();statements.Add(invokeAppendChild);ifStatements.Add(statements[0]);// 产生 "m_xml.Save(m_XmlFile);"
    CodeMethodInvokeExpression invokeSave =
new CodeMethodInvokeExpression(m_XmlExpression, "Save", m_XmlFileExpression);statements.Clear();statements.Add(invokeSave);ifStatements.Add(statements[0]);// 产生 "m_AddFlag = false;"
    CodeAssignStatement assignAddFalse =
new CodeAssignStatement(m_AddFlagExpression, new CodePrimitiveExpression(false));ifStatements.Add(assignAddFalse);// 产生if语句: "if (m_AddFlag)"
    CodeConditionStatement ifStatement =
new CodeConditionStatement(m_AddFlagExpression, ifStatements.ToArray());save.Statements.Add(ifStatement);m_Class.Members.Add(save);}