/IronPython_Main/Runtime/Samples/ExpressionTree/UESamples/ConsoleApplication1/CLabel.cs

using System;

using System.Collections.Generic;

using System.Text;

using Microsoft.Scripting.Ast;



namespace Samples {

    class CLabel {

        //Expression.Label()

        static public void Label1() {

            //<Snippet1>

            // add the following directive to your file

            // using Microsoft.Scripting.Ast;  



            //This element defines a LabelTarget. The LabelTarget is used to associate Goto, Break and Continue

            //expressions with the desired Labels or loops.

            LabelTarget MyLabelTarget = Expression.Label();



            //This goto jumps over a throw expression:

            var MyBlock = Expression.Block(

                Expression.Goto(MyLabelTarget),

                Expression.Throw(Expression.Constant(new Exception())),

                Expression.Label(MyLabelTarget)

            );



            //No exception should be thrown.

            Expression.Lambda<Action>(MyBlock).Compile().Invoke();

            //</Snippet1>



        }



        //Expression.Label(LabelTarget)

        static public void Label2() {

            //<Snippet1>

            // add the following directive to your file

            // using Microsoft.Scripting.Ast;  



            //This element defines a LabelTarget. The LabelTarget is used to associate Goto, Break and Continue

            //expressions with the desired Labels or loops.

            LabelTarget MyLabelTarget = Expression.Label();



            //This element defines a Label. A label indentifies an execution point in the program, enabling 

            //execution to jump to it.

            LabelExpression MyLabel = Expression.Label(MyLabelTarget);



            //This goto jumps over a throw expression:

            var MyBlock = Expression.Block(

                Expression.Goto(MyLabelTarget),

                Expression.Throw(Expression.Constant(new Exception())),

                MyLabel

            );



            //No exception should be thrown.

            Expression.Lambda<Action>(MyBlock).Compile().Invoke();

            //</Snippet1>



        }



        //Expression.Label(LabelTarget, Expression)

        static public void Label3() {

            //<Snippet1>

            // add the following directive to your file

            // using Microsoft.Scripting.Ast;  



            //We need to create a label target to use with the label.

            LabelTarget MyLabelTarget = Expression.Label(typeof(int));



            //This element defines a Label. A label indentifies an execution point in the program, enabling 

            //execution to jump to it. It also has a default value.

            LabelExpression MyLabel = Expression.Label(

                MyLabelTarget,

                Expression.Constant(5)

            );



            //No exception should be thrown, 5 should be printed.

            Console.WriteLine(Expression.Lambda<Func<int>>(MyLabel).Compile().Invoke());

            //</Snippet1>



            //Validate sample

            if (Expression.Lambda<Func<int>>(MyLabel).Compile().Invoke() != 5) throw new Exception();



        }



        //Expression.Label(string)

        static public void Label4() {

            //<Snippet1>

            // add the following directive to your file

            // using Microsoft.Scripting.Ast;  



            //This element defines a LabelTarget. The LabelTarget is used to associate Goto, Break and Continue

            //expressions with the desired Labels or loops. It can use a name for debugging purposes.

            LabelTarget MyLabelTarget = Expression.Label("My Label Target");



            //This goto jumps over a throw expression:

            var MyBlock = Expression.Block(

                Expression.Goto(MyLabelTarget),

                Expression.Throw(Expression.Constant(new Exception())),

                Expression.Label(MyLabelTarget)

            );



            //No exception should be thrown.

            Expression.Lambda<Action>(MyBlock).Compile().Invoke();

            //</Snippet1>

        }







        //Expression.Label(Type)

        static public void Label5() {

            //<Snippet1>

            // add the following directive to your file

            // using Microsoft.Scripting.Ast;



            //This element defines a LabelTarget. The LabelTarget is used to associate Goto, Break and Continue

            //expressions with the desired Labels or loops. It can define a type, which labels associated with this

            //LabelTarget will have.

            LabelTarget MyLabelTarget = Expression.Label(typeof(int));



            //This element defines a Label. A label indentifies an execution point in the program, enabling 

            //execution to jump to it. It also has a default value, which matches the labeltarget's type.

            LabelExpression MyLabel = Expression.Label(

                MyLabelTarget,

                Expression.Constant(5)

            );



            //No exception should be thrown, 5 should be printed.

            Console.WriteLine(Expression.Lambda<Func<int>>(MyLabel).Compile().Invoke());

            //</Snippet1>



            //Validate sample

            if (Expression.Lambda<Func<int>>(MyLabel).Compile().Invoke() != 5) throw new Exception();



        }



        //Expression.Label(Type, string)

        static public void Label6() {

            //<Snippet1>

            // add the following directive to your file

            // using Microsoft.Scripting.Ast;



            //This element defines a LabelTarget. The LabelTarget is used to associate Goto, Break and Continue

            //expressions with the desired Labels or loops. It can define a type, which labels associated with this

            //LabelTarget will have.

            //It defines a name for debugging purposes.

            LabelTarget MyLabelTarget = Expression.Label(typeof(int), "MyLabelTarget");



            //This element defines a Label. A label indentifies an execution point in the program, enabling 

            //execution to jump to it. It also has a default value, which matches the labeltarget's type.

            LabelExpression MyLabel = Expression.Label(

                MyLabelTarget,

                Expression.Constant(5)

            );



            //No exception should be thrown, 5 should be printed.

            Console.WriteLine(Expression.Lambda<Func<int>>(MyLabel).Compile().Invoke());

            //</Snippet1>



            //Validate sample

            if (Expression.Lambda<Func<int>>(MyLabel).Compile().Invoke() != 5) throw new Exception();



        }

    }

}