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

}