Expression.Loop Metoda

Definicja

Przestrzeń nazw:

System.Linq.Expressions

Zestaw:

System.Linq.Expressions.dll

Tworzy element LoopExpression.

Przeciążenia

Loop(Expression)	Tworzy element LoopExpression z daną treścią.
Loop(Expression, LabelTarget)	Tworzy element LoopExpression z daną treścią i elementem docelowym przerwania.
Loop(Expression, LabelTarget, LabelTarget)	Tworzy element LoopExpression z daną treścią.

Loop(Expression)

Źródło:

LoopExpression.cs

Tworzy element LoopExpression z daną treścią.

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

Parametry

body

Expression

Treść pętli.

Zwraca

LoopExpression

Utworzony element LoopExpression.

Loop(Expression, LabelTarget)

Źródło:

LoopExpression.cs

Tworzy element LoopExpression z daną treścią i elementem docelowym przerwania.

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

Parametry

body

Expression

Treść pętli.

break

LabelTarget

Cel przerwania używany przez treść pętli.

Zwraca

LoopExpression

Utworzony element LoopExpression.

Przykłady

W poniższym przykładzie pokazano, jak utworzyć wyrażenie blokowe LoopExpression zawierające obiekt.

// 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)

Źródło:

LoopExpression.cs

Tworzy element LoopExpression z daną treścią.

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

Parametry

body

Expression

Treść pętli.

break

LabelTarget

Cel przerwania używany przez treść pętli.

continue

LabelTarget

Obiekt docelowy kontynuacji używany przez treść pętli.

Zwraca

LoopExpression

Utworzony element LoopExpression.