Expression.Continue 方法

定义

命名空间:

System.Linq.Expressions

程序集:

System.Linq.Expressions.dll

创建一个表示 continue 语句的 GotoExpression。

重载

Continue(LabelTarget)	创建一个表示 continue 语句的 GotoExpression。
Continue(LabelTarget, Type)	创建一个表示具有指定类型的 continue 语句的 GotoExpression。

Continue(LabelTarget)

Source:

GotoExpression.cs

创建一个表示 continue 语句的 GotoExpression。

public:
 static System::Linq::Expressions::GotoExpression ^ Continue(System::Linq::Expressions::LabelTarget ^ target);

public static System.Linq.Expressions.GotoExpression Continue (System.Linq.Expressions.LabelTarget target);

static member Continue : System.Linq.Expressions.LabelTarget -> System.Linq.Expressions.GotoExpression

Public Shared Function Continue (target As LabelTarget) As GotoExpression

参数

target

LabelTarget

LabelTarget 将跳至的 GotoExpression。

返回

GotoExpression

一个 GotoExpression，其 Kind 等于 Continue，其 Target 属性设置为 target，此外还有一个在跳转时将传递给目标标签的 null 值。

示例

以下示例演示如何创建使用 Continue 方法的循环表达式。

// 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

' 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

Continue(LabelTarget, Type)

Source:

GotoExpression.cs

创建一个表示具有指定类型的 continue 语句的 GotoExpression。

public:
 static System::Linq::Expressions::GotoExpression ^ Continue(System::Linq::Expressions::LabelTarget ^ target, Type ^ type);

public static System.Linq.Expressions.GotoExpression Continue (System.Linq.Expressions.LabelTarget target, Type type);

static member Continue : System.Linq.Expressions.LabelTarget * Type -> System.Linq.Expressions.GotoExpression

Public Shared Function Continue (target As LabelTarget, type As Type) As GotoExpression

参数

target

LabelTarget

LabelTarget 将跳至的 GotoExpression。

type

Type

要将 Type 属性设置为与其相等的 Type。

返回

GotoExpression

一个 GotoExpression，其 Kind 等于 Continue，其 Target 属性设置为 target，并且其 Type 属性设置为 type，此外还有一个在跳转时将传递给目标标签的 null 值。