How to use Expression Tree in .Net 3.5

The below blog explains on how the use of Expression Tree in .net 3.5 which is self explanatory!!

using System;

`02`	`using` `System.Linq.Expressions;`

03

`04`	`namespace` `Sample`

05 {

`06`	`class` `Program`

07 {

`08`	`private` `static` `void` `DisplayTree(int` `indent,` `string` `message, Expression expression)`

09 {

`10`	`string` `output = String.Format("{0} {1} ! NodeType: {2}; Expr: {3} ",`

`11`	`"".PadLeft(indent,` `'>'), message, expression.NodeType, expression);`

12

`13`	`indent++;`

`14`	`switch` `(expression.NodeType)`

15 {

`16`	`case` `ExpressionType.Lambda:`

`17`	`Console.WriteLine(output);`

`18`	`LambdaExpression lambdaExpr = (LambdaExpression)expression;`

`19`	`foreach` `(var parameter` `in` `lambdaExpr.Parameters)`

20 {

`21`	`DisplayTree(indent,` `"Parameter", parameter);`

22 }

`23`	`DisplayTree(indent,` `"Body", lambdaExpr.Body);`

24 break;

`25`	`case` `ExpressionType.Constant:`

`26`	`ConstantExpression constExpr = (ConstantExpression)expression;`

`27`	`Console.WriteLine("{0} Const Value: {1}", output, constExpr.Value);`

28 break;

`29`	`case` `ExpressionType.Parameter:`

`30`	`ParameterExpression paramExpr = (ParameterExpression)expression;`

`31`	`Console.WriteLine("{0} Param Type: {1}", output, paramExpr.Type.Name);`

32 break;

`33`	`case` `ExpressionType.Equal:`

`34`	`case` `ExpressionType.AndAlso:`

`35`	`case` `ExpressionType.GreaterThan:`

`36`	`BinaryExpression binExpr = (BinaryExpression)expression;`

`37`	`if` `(binExpr.Method !=` `null)`

38 {

`39`	`Console.WriteLine("{0} Method: {1}", output, binExpr.Method.Name);`

40 }

41 else

42 {

`43`	`Console.WriteLine(output);`

44 }

`45`	`DisplayTree(indent,` `"Left", binExpr.Left);`

`46`	`DisplayTree(indent,` `"Right", binExpr.Right);`

47 break;

`48`	`case` `ExpressionType.MemberAccess:`

`49`	`MemberExpression memberExpr = (MemberExpression)expression;`

`50`	`Console.WriteLine("{0} Member Name: {1}, Type: {2}", output,`

`51`	`memberExpr.Member.Name, memberExpr.Type.Name);`

`52`	`DisplayTree(indent,` `"Member Expr", memberExpr.Expression);`

53 break;

`54`	`default:`

`55`	`Console.WriteLine();`

`56`	`Console.WriteLine("{0} {1}", expression.NodeType, expression.Type.Name);`

57 break;

58 }

59 }

60

61

`62`	`static` `void` `Main()`

63 {

`64`	`Expression<Func<Racer,` `bool>> expression = r => r.Country ==` `"UK"` `&& r.Wins > 6;`

65

`66`	`DisplayTree(0,` `"Lambda", expression);`

67

68 }

69 }

70 }