Статья
11/18/2011

Expression.Continue Method (LabelTarget)

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Creates a GotoExpression representing a continue statement.

Namespace: System.Linq.Expressions
Assembly: System.Core (in System.Core.dll)

Syntax

'Declaration
Public Shared Function Continue ( _
    target As LabelTarget _
) As GotoExpression

public static GotoExpression Continue(
    LabelTarget target
)

Parameters

target
Type: System.Linq.Expressions.LabelTarget
The LabelTarget that the GotoExpression will jump to.

Return Value

Type: System.Linq.Expressions.GotoExpression
A GotoExpression with Kind equal to Continue, the Target property set to target, and a null value to be passed to the target label upon jumping.

Examples

The following example demonstrates how to create a loop expression that uses the Continue method.

' Add the following directive to your file:
' Imports System.Linq.Expressions  

' A label that is used by a break statement and a loop. 
Dim breakLabel As LabelTarget = Expression.Label()

' A label that is used by the Continue statement and the loop it refers to.
Dim continueLabel As LabelTarget = Expression.Label()

' This expression represents a Continue statement.
Dim continueExpr As Expression = Expression.Continue(continueLabel)

' A variable that triggers the exit from the loop.
Dim count As ParameterExpression = Expression.Parameter(GetType(Integer))

' A loop statement.
Dim loopExpr As Expression = Expression.Loop(
       Expression.Block(
           Expression.IfThen(
               Expression.GreaterThan(count, Expression.Constant(3)),
               Expression.Break(breakLabel)
           ),
           Expression.PreIncrementAssign(count),
           Expression.Call(
                       Nothing,
                       GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
                       Expression.Constant("Loop")
                   ),
           continueExpr,
           Expression.PreDecrementAssign(count)
       ),
       breakLabel,
       continueLabel
   )

' The following statement first creates an expression tree,
' then compiles it, and then runs it.
' Without the Continue statement, the loop would go on forever.
Expression.Lambda(Of Action(Of Integer))(loopExpr, count).Compile()(1)

' This code example produces the following output:
'
' Loop
' Loop
' Loop

// Add the following directive to your file:
// using System.Linq.Expressions;  

// A label that is used by a break statement and a loop. 
LabelTarget breakLabel = Expression.Label();

// A label that is used by the Continue statement and the loop it refers to.
LabelTarget continueLabel = Expression.Label();

// This expression represents a Continue statement.
Expression continueExpr = Expression.Continue(continueLabel);

// A variable that triggers the exit from the loop.
ParameterExpression count = Expression.Parameter(typeof(int));

// A loop statement.
Expression loopExpr = Expression.Loop(
    Expression.Block(
        Expression.IfThen(
            Expression.GreaterThan(count, Expression.Constant(3)),
            Expression.Break(breakLabel)
        ),
        Expression.PreIncrementAssign(count),
        Expression.Call(
                    null,
                    typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
                    Expression.Constant("Loop")
                ),
        continueExpr,
        Expression.PreDecrementAssign(count)
    ),
    breakLabel,
    continueLabel
);

// The following statement first creates an expression tree,
// then compiles it, and then runs it.
// Without the Continue statement, the loop would go on forever.
Expression.Lambda<Action<int>>(loopExpr, count).Compile()(1);

// This code example produces the following output:
//
// Loop
// Loop
// Loop

Version Information

Silverlight

Supported in: 5, 4

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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