ListInitExpression 類別

定義

代表具有集合初始設定式的建構函式呼叫。Represents a constructor call that has a collection initializer.

public ref class ListInitExpression sealed : System::Linq::Expressions::Expression
public sealed class ListInitExpression : System.Linq.Expressions.Expression
type ListInitExpression = class
    inherit Expression
Public NotInheritable Class ListInitExpression
Inherits Expression
繼承
ListInitExpression

範例

下列範例 ListInitExpression 會建立,代表具有兩個索引鍵/值組之新字典實例的初始化。The following example creates a ListInitExpression that represents the initialization of a new dictionary instance that has two key-value pairs.

string tree1 = "maple";
string tree2 = "oak";

System.Reflection.MethodInfo addMethod = typeof(Dictionary<int, string>).GetMethod("Add");

// Create two ElementInit objects that represent the
// two key-value pairs to add to the Dictionary.
System.Linq.Expressions.ElementInit elementInit1 =
    System.Linq.Expressions.Expression.ElementInit(
        addMethod,
        System.Linq.Expressions.Expression.Constant(tree1.Length),
        System.Linq.Expressions.Expression.Constant(tree1));
System.Linq.Expressions.ElementInit elementInit2 =
    System.Linq.Expressions.Expression.ElementInit(
        addMethod,
        System.Linq.Expressions.Expression.Constant(tree2.Length),
        System.Linq.Expressions.Expression.Constant(tree2));

// Create a NewExpression that represents constructing
// a new instance of Dictionary<int, string>.
System.Linq.Expressions.NewExpression newDictionaryExpression =
    System.Linq.Expressions.Expression.New(typeof(Dictionary<int, string>));

// Create a ListInitExpression that represents initializing
// a new Dictionary<> instance with two key-value pairs.
System.Linq.Expressions.ListInitExpression listInitExpression =
    System.Linq.Expressions.Expression.ListInit(
        newDictionaryExpression,
        elementInit1,
        elementInit2);

Console.WriteLine(listInitExpression.ToString());

// This code produces the following output:
//
// new Dictionary`2() {Void Add(Int32, System.String)(5,"maple"),
// Void Add(Int32, System.String)(3,"oak")}
Dim tree1 As String = "maple"
Dim tree2 As String = "oak"

Dim addMethod As System.Reflection.MethodInfo = _
    Type.GetType("System.Collections.Generic.Dictionary`2[System.Int32, System.String]").GetMethod("Add")

' Create two ElementInit objects that represent the
' two key-value pairs to add to the Dictionary.
Dim elementInit1 As System.Linq.Expressions.ElementInit = _
    System.Linq.Expressions.Expression.ElementInit( _
        addMethod, _
        System.Linq.Expressions.Expression.Constant(tree1.Length), _
        System.Linq.Expressions.Expression.Constant(tree1))
Dim elementInit2 As System.Linq.Expressions.ElementInit = _
    System.Linq.Expressions.Expression.ElementInit( _
        addMethod, _
        System.Linq.Expressions.Expression.Constant(tree2.Length), _
        System.Linq.Expressions.Expression.Constant(tree2))

' Create a NewExpression that represents constructing
' a new instance of Dictionary(Of Integer, String).
Dim newDictionaryExpression As System.Linq.Expressions.NewExpression = _
    System.Linq.Expressions.Expression.[New](Type.GetType("System.Collections.Generic.Dictionary`2[System.Int32, System.String]"))

' Create a ListInitExpression that represents initializing
' a new Dictionary(Of T) instance with two key-value pairs.
Dim listInitExpression As System.Linq.Expressions.ListInitExpression = _
    System.Linq.Expressions.Expression.ListInit( _
        newDictionaryExpression, _
        elementInit1, _
        elementInit2)

Console.WriteLine(listInitExpression.ToString())

' This code produces the following output:
'
' new Dictionary`2() {Void Add(Int32, System.String)(5,"maple"),
' Void Add(Int32, System.String)(3,"oak")

備註

使用 ListInit factory 方法來建立 ListInitExpressionUse the ListInit factory methods to create a ListInitExpression.

NodeType 屬性值 ListInitExpressionListInitThe value of the NodeType property of a ListInitExpression is ListInit.

屬性

CanReduce

取得值,指出是否可以減少運算式樹狀架構的節點。Gets a value that indicates whether the expression tree node can be reduced.

CanReduce

表示節點可精簡為更簡單的節點。Indicates that the node can be reduced to a simpler node. 如果傳回 true,則可呼叫 Reduce() 以產生精簡的形式。If this returns true, Reduce() can be called to produce the reduced form.

(繼承來源 Expression)
Initializers

取得可用來初始化集合的項目初始化設定式。Gets the element initializers that are used to initialize a collection.

NewExpression

取得運算式,這個運算式包含對集合型別之建構函式的呼叫。Gets the expression that contains a call to the constructor of a collection type.

NodeType

傳回這個 Expression 的節點類型。Returns the node type of this Expression.

NodeType

取得這個 Expression 的節點類型。Gets the node type of this Expression.

(繼承來源 Expression)
Type

取得此 Expression 代表之運算式的靜態類型。Gets the static type of the expression that this Expression represents.

Type

取得此 Expression 代表之運算式的靜態類型。Gets the static type of the expression that this Expression represents.

(繼承來源 Expression)

方法

Accept(ExpressionVisitor)

分派給這個節點類型的特定造訪方法。Dispatches to the specific visit method for this node type. 例如,MethodCallExpression 會呼叫 VisitMethodCall(MethodCallExpression)For example, MethodCallExpression calls the VisitMethodCall(MethodCallExpression).

(繼承來源 Expression)
Equals(Object)

判斷指定的物件是否等於目前的物件。Determines whether the specified object is equal to the current object.

(繼承來源 Object)
GetHashCode()

做為預設雜湊函式。Serves as the default hash function.

(繼承來源 Object)
GetType()

取得目前執行個體的 TypeGets the Type of the current instance.

(繼承來源 Object)
MemberwiseClone()

建立目前 Object 的淺層複製。Creates a shallow copy of the current Object.

(繼承來源 Object)
Reduce()

將二進位運算式節點精簡為更簡單的運算式。Reduces the binary expression node to a simpler expression.

Reduce()

將這個節點精簡為更簡單的運算式。Reduces this node to a simpler expression. 如果 CanReduce 傳回 true,則應該傳回有效的運算式。If CanReduce returns true, this should return a valid expression. 這個方法可以傳回其他本身必須精簡的節點。This method can return another node which itself must be reduced.

(繼承來源 Expression)
ReduceAndCheck()

將這個節點精簡為更簡單的運算式。Reduces this node to a simpler expression. 如果 CanReduce 傳回 true,則應該傳回有效的運算式。If CanReduce returns true, this should return a valid expression. 這個方法可以傳回其他本身必須精簡的節點。This method can return another node which itself must be reduced.

(繼承來源 Expression)
ReduceExtensions()

將運算式精簡為已知的節點類型 (不是 Extension 節點),如果已經是已知的類型,則僅傳回運算式。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.

(繼承來源 Expression)
ToString()

傳回 Expression 的文字表示。Returns a textual representation of the Expression.

(繼承來源 Expression)
Update(NewExpression, IEnumerable<ElementInit>)

建立類似這個運算式的新運算式,但使用提供的子系。Creates a new expression that is like this one, but using the supplied children. 如果所有子系都相同,則會傳回這個運算式。If all of the children are the same, it will return this expression.

VisitChildren(ExpressionVisitor)

精簡節點,然後呼叫精簡後的運算式上的訪問項委派。Reduces the node and then calls the visitor delegate on the reduced expression. 如果節點無法縮減,此方法會擲回例外狀況。The method throws an exception if the node is not reducible.

(繼承來源 Expression)

適用於