GotoExpression Class
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Represents an unconditional jump. This includes return statements, break and continue statements, and other jumps.
public ref class GotoExpression sealed : System::Linq::Expressions::Expression
public sealed class GotoExpression : System.Linq.Expressions.Expression
type GotoExpression = class
inherit Expression
Public NotInheritable Class GotoExpression
Inherits Expression
- Inheritance
The following example demonstrates how to create an expression that contains a GotoExpression object by using the Goto method.
// Add the following directive to your file:
// using System.Linq.Expressions;
// A label expression of the void type that is the target for the GotoExpression.
LabelTarget returnTarget = Expression.Label();
// This block contains a GotoExpression.
// It transfers execution to a label expression that is initialized with the same LabelTarget as the GotoExpression.
// The types of the GotoExpression, label expression, and LabelTarget must match.
BlockExpression blockExpr =
Expression.Block(
Expression.Call(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }), Expression.Constant("GoTo")),
Expression.Goto(returnTarget),
Expression.Call(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }), Expression.Constant("Other Work")),
Expression.Label(returnTarget)
);
// The following statement first creates an expression tree,
// then compiles it, and then runs it.
Expression.Lambda<Action>(blockExpr).Compile()();
// This code example produces the following output:
//
// GoTo
// "Other Work" is not printed because
// the GoTo expression transfers execution from Expression.GoTo(returnTarget)
// to Expression.Label(returnTarget).
' Add the following directive to your file:
' Imports System.Linq.Expressions
' A label expression of the void type that is the target for the GoToExpression.
Dim returnTarget As LabelTarget = Expression.Label()
' This block contains a GotoExpression.
' It transfers execution to a label expression that is initialized with the same LabelTarget as the GotoExpression.
' The types of the GotoExpression, label expression, and LabelTarget must match.
Dim blockExpr As BlockExpression =
Expression.Block(
Expression.Call(GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}), Expression.Constant("GoTo")),
Expression.Goto(returnTarget),
Expression.Call(GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}), Expression.Constant("Other Work")),
Expression.Label(returnTarget)
)
' The following statement first creates an expression tree,
' then compiles it, and then runs it.
Expression.Lambda(Of Action)(blockExpr).Compile()()
' This code example produces the following output:
'
' GoTo
' "Other Work" is not printed because
' the Return expression transfers execution from Expression.GoTo(returnTarget)
' to Expression.Label(returnTarget).
Can |
Indicates 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) |
Kind |
The kind of the "go to" expression. Serves information purposes only. |
Node |
Returns the node type of this Expression. |
Target |
The target label where this node jumps to. |
Type |
Gets the static type of the expression that this Expression represents. |
Value |
The value passed to the target, or null if the target is of type System.Void. |
Accept(Expression |
Dispatches to the specific visit method for this node type. For example, MethodCallExpression calls the VisitMethodCall(MethodCallExpression). (Inherited from Expression) |
Equals(Object) |
Determines whether the specified object is equal to the current object. (Inherited from Object) |
Get |
Serves as the default hash function. (Inherited from Object) |
Get |
Gets the Type of the current instance. (Inherited from Object) |
Memberwise |
Creates a shallow copy of the current Object. (Inherited from Object) |
Reduce() |
Reduces 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) |
Reduce |
Reduces 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) |
Reduce |
Reduces 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) |
To |
Returns a textual representation of the Expression. (Inherited from Expression) |
Update(Label |
Creates 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. |
Visit |
Reduces 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) |
מוצר | גירסאות |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
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