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LoopExpression Class

Represents an infinite loop. It can be exited with "break".

System.Object
  System.Linq.Expressions.Expression
    System.Linq.Expressions.LoopExpression

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

public sealed class LoopExpression : Expression

The LoopExpression type exposes the following members.

  NameDescription
Public propertyBodyGets the Expression that is the body of the loop.
Public propertyBreakLabelGets the LabelTarget that is used by the loop body as a break statement target.
Public propertyCanReduceIndicates that the node can be reduced to a simpler node. If this returns true, Reduce() can be called to produce the reduced form. (Inherited from Expression.)
Public propertyContinueLabelGets the LabelTarget that is used by the loop body as a continue statement target.
Public propertyNodeTypeReturns the node type of this expression. Extension nodes should return Extension when overriding this method. (Overrides Expression.NodeType.)
Public propertyTypeGets the static type of the expression that this Expression represents. (Overrides Expression.Type.)
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  NameDescription
Protected methodAcceptDispatches to the specific visit method for this node type. For example, MethodCallExpression calls the VisitMethodCall. (Inherited from Expression.)
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodReduceReduces this node to a simpler expression. If CanReduce returns true, this should return a valid expression. This method can return another node which itself must be reduced. (Inherited from Expression.)
Public methodReduceAndCheckReduces this node to a simpler expression. If CanReduce returns true, this should return a valid expression. This method can return another node which itself must be reduced. (Inherited from Expression.)
Public methodReduceExtensionsReduces the expression to a known node type (that is not an Extension node) or just returns the expression if it is already a known type. (Inherited from Expression.)
Public methodToStringReturns a textual representation of the Expression. (Inherited from Expression.)
Public methodUpdateCreates a new expression that is like this one, but using the supplied children. If all of the children are the same, it will return this expression.
Protected methodVisitChildrenReduces the node and then calls the visitor delegate on the reduced expression. The method throws an exception if the node is not reducible. (Inherited from Expression.)
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The following example demonstrates how to create a block expression that contains a LoopExpression object by using the Loop method.


// 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);

outputBlock.Text += factorial + "\n";

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


Silverlight

Supported in: 5, 4

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

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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