/* ****************************************************************************
*
* Copyright (c) Microsoft Corporation.
*
* This source code is subject to terms and conditions of the Microsoft Public License. A
* copy of the license can be found in the License.html file at the root of this distribution. If
* you cannot locate the Microsoft Public License, please send an email to
* dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound
* by the terms of the Microsoft Public License.
*
* You must not remove this notice, or any other, from this software.
*
*
* ***************************************************************************/
using System;
using System.Diagnostics;
using System.Dynamic.Utils;
#if SILVERLIGHT
using System.Core;
#endif
#if CLR2
namespace Microsoft.Scripting.Ast{
#else
namespace System.Linq.Expressions {
#endif
/// <summary>
/// Specifies what kind of jump this <see cref="GotoExpression"/> represents.
/// </summary>
public enum GotoExpressionKind {
/// <summary>
/// A <see cref="GotoExpression"/> that represents a jump to some location.
/// </summary>
Goto,
/// <summary>
/// A <see cref="GotoExpression"/> that represents a return statement.
/// </summary>
Return,
/// <summary>
/// A <see cref="GotoExpression"/> that represents a break statement.
/// </summary>
Break,
/// <summary>
/// A <see cref="GotoExpression"/> that represents a continue statement.
/// </summary>
Continue,
}
/// <summary>
/// Represents an unconditional jump. This includes return statements, break and continue statements, and other jumps.
/// </summary>
#if !SILVERLIGHT
[DebuggerTypeProxy(typeof(Expression.GotoExpressionProxy))]
#endif
public sealed class GotoExpression : Expression {
private readonly GotoExpressionKind _kind;
private readonly Expression _value;
private readonly LabelTarget _target;
private readonly Type _type;
internal GotoExpression(GotoExpressionKind kind, LabelTarget target, Expression value, Type type) {
_kind = kind;
_value = value;
_target = target;
_type = type;
}
/// <summary>
/// Gets the static type of the expression that this <see cref="Expression" /> represents. (Inherited from <see cref="Expression"/>.)
/// </summary>
/// <returns>The <see cref="Type"/> that represents the static type of the expression.</returns>
public sealed override Type Type {
get { return _type; }
}
/// <summary>
/// Returns the node type of this <see cref="Expression" />. (Inherited from <see cref="Expression" />.)
/// </summary>
/// <returns>The <see cref="ExpressionType"/> that represents this expression.</returns>
public sealed override ExpressionType NodeType {
get { return ExpressionType.Goto; }
}
/// <summary>
/// The value passed to the target, or null if the target is of type
/// System.Void.
/// </summary>
public Expression Value {
get { return _value; }
}
/// <summary>
/// The target label where this node jumps to.
/// </summary>
public LabelTarget Target {
get { return _target; }
}
/// <summary>
/// The kind of the goto. For information purposes only.
/// </summary>
public GotoExpressionKind Kind {
get { return _kind; }
}
/// <summary>
/// Dispatches to the specific visit method for this node type.
/// </summary>
protected internal override Expression Accept(ExpressionVisitor visitor) {
return visitor.VisitGoto(this);
}
/// <summary>
/// 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.
/// </summary>
/// <param name="target">The <see cref="Target" /> property of the result.</param>
/// <param name="value">The <see cref="Value" /> property of the result.</param>
/// <returns>This expression if no children changed, or an expression with the updated children.</returns>
public GotoExpression Update(LabelTarget target, Expression value) {
if (target == Target && value == Value) {
return this;
}
return Expression.MakeGoto(Kind, target, value, Type);
}
}
public partial class Expression {
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a break statement.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Break,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>, and a null value to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Break(LabelTarget target) {
return MakeGoto(GotoExpressionKind.Break, target, null, typeof(void));
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a break statement. The value passed to the label upon jumping can be specified.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="value">The value that will be passed to the associated label upon jumping.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Break,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// and <paramref name="value"/> to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Break(LabelTarget target, Expression value) {
return MakeGoto(GotoExpressionKind.Break, target, value, typeof(void));
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a break statement with the specified type.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="type">An <see cref="System.Type"/> to set the <see cref="P:Expression.Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Break,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// and the <see cref="P:Expression.Type"/> property set to <paramref name="type"/>.
/// </returns>
public static GotoExpression Break(LabelTarget target, Type type) {
return MakeGoto(GotoExpressionKind.Break, target, null, type);
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a break statement with the specified type.
/// The value passed to the label upon jumping can be specified.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="value">The value that will be passed to the associated label upon jumping.</param>
/// <param name="type">An <see cref="System.Type"/> to set the <see cref="P:Expression.Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Break,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="P:Expression.Type"/> property set to <paramref name="type"/>,
/// and <paramref name="value"/> to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Break(LabelTarget target, Expression value, Type type) {
return MakeGoto(GotoExpressionKind.Break, target, value, type);
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a continue statement.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Continue,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// and a null value to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Continue(LabelTarget target) {
return MakeGoto(GotoExpressionKind.Continue, target, null, typeof(void));
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a continue statement with the specified type.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="type">An <see cref="System.Type"/> to set the <see cref="P:Expression.Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Continue,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="P:Expression.Type"/> property set to <paramref name="type"/>,
/// and a null value to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Continue(LabelTarget target, Type type) {
return MakeGoto(GotoExpressionKind.Continue, target, null, type);
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a return statement.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Return,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// and a null value to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Return(LabelTarget target) {
return MakeGoto(GotoExpressionKind.Return, target, null, typeof(void));
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a return statement with the specified type.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="type">An <see cref="System.Type"/> to set the <see cref="P:Expression.Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Return,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="P:Expression.Type"/> property set to <paramref name="type"/>,
/// and a null value to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Return(LabelTarget target, Type type) {
return MakeGoto(GotoExpressionKind.Return, target, null, type);
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a return statement. The value passed to the label upon jumping can be specified.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="value">The value that will be passed to the associated label upon jumping.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Continue,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// and <paramref name="value"/> to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Return(LabelTarget target, Expression value) {
return MakeGoto(GotoExpressionKind.Return, target, value, typeof(void));
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a return statement with the specified type.
/// The value passed to the label upon jumping can be specified.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="value">The value that will be passed to the associated label upon jumping.</param>
/// <param name="type">An <see cref="System.Type"/> to set the <see cref="P:Expression.Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Continue,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="P:Expression.Type"/> property set to <paramref name="type"/>,
/// and <paramref name="value"/> to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Return(LabelTarget target, Expression value, Type type) {
return MakeGoto(GotoExpressionKind.Return, target, value, type);
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a goto.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Goto,
/// the <see cref="P:GotoExpression.Target"/> property set to the specified value,
/// and a null value to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Goto(LabelTarget target) {
return MakeGoto(GotoExpressionKind.Goto, target, null, typeof(void));
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a goto with the specified type.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="type">An <see cref="System.Type"/> to set the <see cref="P:Expression.Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Goto,
/// the <see cref="P:GotoExpression.Target"/> property set to the specified value,
/// the <see cref="P:Expression.Type"/> property set to <paramref name="type"/>,
/// and a null value to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Goto(LabelTarget target, Type type) {
return MakeGoto(GotoExpressionKind.Goto, target, null, type);
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a goto. The value passed to the label upon jumping can be specified.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="value">The value that will be passed to the associated label upon jumping.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Goto,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// and <paramref name="value"/> to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Goto(LabelTarget target, Expression value) {
return MakeGoto(GotoExpressionKind.Goto, target, value, typeof(void));
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a goto with the specified type.
/// The value passed to the label upon jumping can be specified.
/// </summary>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="value">The value that will be passed to the associated label upon jumping.</param>
/// <param name="type">An <see cref="System.Type"/> to set the <see cref="P:Expression.Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to Goto,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="P:Expression.Type"/> property set to <paramref name="type"/>,
/// and <paramref name="value"/> to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression Goto(LabelTarget target, Expression value, Type type) {
return MakeGoto(GotoExpressionKind.Goto, target, value, type);
}
/// <summary>
/// Creates a <see cref="GotoExpression"/> representing a jump of the specified <see cref="GotoExpressionKind"/>.
/// The value passed to the label upon jumping can also be specified.
/// </summary>
/// <param name="kind">The <see cref="GotoExpressionKind"/> of the <see cref="GotoExpression"/>.</param>
/// <param name="target">The <see cref="LabelTarget"/> that the <see cref="GotoExpression"/> will jump to.</param>
/// <param name="value">The value that will be passed to the associated label upon jumping.</param>
/// <param name="type">An <see cref="System.Type"/> to set the <see cref="P:Expression.Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="P:GotoExpression.Kind"/> equal to <paramref name="kind"/>,
/// the <see cref="P:GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="P:Expression.Type"/> property set to <paramref name="type"/>,
/// and <paramref name="value"/> to be passed to the target label upon jumping.
/// </returns>
public static GotoExpression MakeGoto(GotoExpressionKind kind, LabelTarget target, Expression value, Type type) {
ValidateGoto(target, ref value, "target", "value");
return new GotoExpression(kind, target, value, type);
}
private static void ValidateGoto(LabelTarget target, ref Expression value, string targetParameter, string valueParameter) {
ContractUtils.RequiresNotNull(target, targetParameter);
if (value == null) {
if (target.Type != typeof(void)) throw Error.LabelMustBeVoidOrHaveExpression();
} else {
ValidateGotoType(target.Type, ref value, valueParameter);
}
}
// Standard argument validation, taken from ValidateArgumentTypes
private static void ValidateGotoType(Type expectedType, ref Expression value, string paramName) {
RequiresCanRead(value, paramName);
if (expectedType != typeof(void)) {
if (!TypeUtils.AreReferenceAssignable(expectedType, value.Type)) {
// C# autoquotes return values, so we'll do that here
if (TypeUtils.IsSameOrSubclass(typeof(LambdaExpression), expectedType) &&
expectedType.IsAssignableFrom(value.GetType())) {
value = Expression.Quote(value);
}
throw Error.ExpressionTypeDoesNotMatchLabel(value.Type, expectedType);
}
}
}
}
}
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