Expression.Loop Метод

Определение

Создает объект LoopExpression.Creates a LoopExpression.

Перегрузки

Loop(Expression)

Создает объект LoopExpression с заданным телом.Creates a LoopExpression with the given body.

Loop(Expression, LabelTarget)

Создает объект LoopExpression с заданным телом и целью оператора break.Creates a LoopExpression with the given body and break target.

Loop(Expression, LabelTarget, LabelTarget)

Создает объект LoopExpression с заданным телом.Creates a LoopExpression with the given body.

Loop(Expression)

Создает объект LoopExpression с заданным телом.Creates a LoopExpression with the given body.

public:
 static System::Linq::Expressions::LoopExpression ^ Loop(System::Linq::Expressions::Expression ^ body);
public static System.Linq.Expressions.LoopExpression Loop (System.Linq.Expressions.Expression body);
static member Loop : System.Linq.Expressions.Expression -> System.Linq.Expressions.LoopExpression
Public Shared Function Loop (body As Expression) As LoopExpression

Параметры

body
Expression

Тело цикла.The body of the loop.

Возвращаемое значение

Созданный LoopExpression.The created LoopExpression.

Loop(Expression, LabelTarget)

Создает объект LoopExpression с заданным телом и целью оператора break.Creates a LoopExpression with the given body and break target.

public:
 static System::Linq::Expressions::LoopExpression ^ Loop(System::Linq::Expressions::Expression ^ body, System::Linq::Expressions::LabelTarget ^ break);
public static System.Linq.Expressions.LoopExpression Loop (System.Linq.Expressions.Expression body, System.Linq.Expressions.LabelTarget break);
static member Loop : System.Linq.Expressions.Expression * System.Linq.Expressions.LabelTarget -> System.Linq.Expressions.LoopExpression
Public Shared Function Loop (body As Expression, break As LabelTarget) As LoopExpression

Параметры

body
Expression

Тело цикла.The body of the loop.

break
LabelTarget

Цель оператора break, используемая телом цикла.The break target used by the loop body.

Возвращаемое значение

Созданный LoopExpression.The created LoopExpression.

Примеры

В следующем примере показано, как создать блочное выражение, содержащее объект LoopExpression.The following example demonstrates how to create a block expression that contains a LoopExpression object.

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

// Creating a parameter expression.
ParameterExpression value = Expression.Parameter(typeof(int), "value");

// Creating an expression to hold a local variable. 
ParameterExpression result = Expression.Parameter(typeof(int), "result");

// Creating a label to jump to from a loop.
LabelTarget label = Expression.Label(typeof(int));

// Creating a method body.
BlockExpression block = Expression.Block(
    new[] { result },
    Expression.Assign(result, Expression.Constant(1)),
        Expression.Loop(
           Expression.IfThenElse(
               Expression.GreaterThan(value, Expression.Constant(1)),
               Expression.MultiplyAssign(result,
                   Expression.PostDecrementAssign(value)),
               Expression.Break(label, result)
           ),
       label
    )
);

// Compile and run an expression tree.
int factorial = Expression.Lambda<Func<int, int>>(block, value).Compile()(5);

Console.WriteLine(factorial);

// This code example produces the following output:
//
// 120
' Add the following directive to the file:
' Imports System.Linq.Expressions  

' Creating a parameter expression.
Dim value As ParameterExpression =
    Expression.Parameter(GetType(Integer), "value")

' Creating an expression to hold a local variable. 
Dim result As ParameterExpression =
    Expression.Parameter(GetType(Integer), "result")

' Creating a label to jump to from a loop.
Dim label As LabelTarget = Expression.Label(GetType(Integer))

' Creating a method body.
Dim block As BlockExpression = Expression.Block(
    New ParameterExpression() {result},
    Expression.Assign(result, Expression.Constant(1)),
    Expression.Loop(
        Expression.IfThenElse(
            Expression.GreaterThan(value, Expression.Constant(1)),
            Expression.MultiplyAssign(result,
                Expression.PostDecrementAssign(value)),
            Expression.Break(label, result)
        ),
        label
    )
)

' Compile an expression tree and return a delegate.
Dim factorial As Integer =
    Expression.Lambda(Of Func(Of Integer, Integer))(block, value).Compile()(5)

Console.WriteLine(factorial)

' This code example produces the following output:
'
' 120

Loop(Expression, LabelTarget, LabelTarget)

Создает объект LoopExpression с заданным телом.Creates a LoopExpression with the given body.

public:
 static System::Linq::Expressions::LoopExpression ^ Loop(System::Linq::Expressions::Expression ^ body, System::Linq::Expressions::LabelTarget ^ break, System::Linq::Expressions::LabelTarget ^ continue);
public static System.Linq.Expressions.LoopExpression Loop (System.Linq.Expressions.Expression body, System.Linq.Expressions.LabelTarget break, System.Linq.Expressions.LabelTarget continue);
static member Loop : System.Linq.Expressions.Expression * System.Linq.Expressions.LabelTarget * System.Linq.Expressions.LabelTarget -> System.Linq.Expressions.LoopExpression
Public Shared Function Loop (body As Expression, break As LabelTarget, continue As LabelTarget) As LoopExpression

Параметры

body
Expression

Тело цикла.The body of the loop.

break
LabelTarget

Цель оператора break, используемая телом цикла.The break target used by the loop body.

continue
LabelTarget

Цель оператора continue, используемая телом цикла.The continue target used by the loop body.

Возвращаемое значение

Созданный LoopExpression.The created LoopExpression.

Применяется к