Expression.SwitchCase Method (Expression, IEnumerable<Expression>)
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Creates a SwitchCase object to be used in a SwitchExpression object.
Namespace: System.Linq.Expressions
Assembly: System.Core (in System.Core.dll)
Syntax
'Declaration
Public Shared Function SwitchCase ( _
body As Expression, _
testValues As IEnumerable(Of Expression) _
) As SwitchCase
public static SwitchCase SwitchCase(
Expression body,
IEnumerable<Expression> testValues
)
Parameters
- body
Type: System.Linq.Expressions.Expression
The body of the case.
- testValues
Type: System.Collections.Generic.IEnumerable<Expression>
The test values of the case.
Return Value
Type: System.Linq.Expressions.SwitchCase
The created SwitchCase.
Remarks
All SwitchCase objects in a SwitchExpression object must have the same type, unless the SwitchExpression has the type void.
Each SwitchCase object has an implicit break statement, which means that there is no implicit fall through from one case label to another.
Examples
The following example demonstrates how to create an expression that represents a swtich statement that has a default case.
' Add the following directive to the file:
' Imports System.Linq.Expressions
' An expression that represents the switch value.
Dim switchValue As ConstantExpression = Expression.Constant(3)
' This expression represents a switch statement
' that has a default case.
Dim switchExpr As SwitchExpression =
Expression.Switch(
switchValue,
Expression.Call(
Nothing,
GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
Expression.Constant("Default")
),
New SwitchCase() {
Expression.SwitchCase(
Expression.Call(
Nothing,
GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
Expression.Constant("First")
),
Expression.Constant(1)
),
Expression.SwitchCase(
Expression.Call(
Nothing,
GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
Expression.Constant("Second")
),
Expression.Constant(2)
)
}
)
' The following statement first creates an expression tree,
' then compiles it, and then runs it.
Expression.Lambda(Of Action)(switchExpr).Compile()()
' This code example produces the following output:
'
' Default
// Add the following directive to the file:
// using System.Linq.Expressions;
// An expression that represents the switch value.
ConstantExpression switchValue = Expression.Constant(3);
// This expression represents a switch statement
// that has a default case.
SwitchExpression switchExpr =
Expression.Switch(
switchValue,
Expression.Call(
null,
typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
Expression.Constant("Default")
),
new SwitchCase[] {
Expression.SwitchCase(
Expression.Call(
null,
typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
Expression.Constant("First")
),
Expression.Constant(1)
),
Expression.SwitchCase(
Expression.Call(
null,
typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
Expression.Constant("Second")
),
Expression.Constant(2)
)
}
);
// The following statement first creates an expression tree,
// then compiles it, and then runs it.
Expression.Lambda<Action>(switchExpr).Compile()();
// This code example produces the following output:
//
// Default
Version Information
Silverlight
Supported in: 5, 4
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.