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GotoExpression.cs
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GotoExpression.cs
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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Diagnostics;
using System.Dynamic.Utils;
namespace System.Linq.Expressions
{
/// <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>
[DebuggerTypeProxy(typeof(GotoExpressionProxy))]
public sealed class GotoExpression : Expression
{
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="System.Type"/> that represents the static type of the expression.</returns>
public sealed override Type Type { get; }
/// <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 => ExpressionType.Goto;
/// <summary>
/// The value passed to the target, or null if the target is of type
/// System.Void.
/// </summary>
public Expression? Value { get; }
/// <summary>
/// The target label where this node jumps to.
/// </summary>
public LabelTarget Target { get; }
/// <summary>
/// The kind of the goto. For information purposes only.
/// </summary>
public GotoExpressionKind Kind { get; }
/// <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="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Break"/>,
/// the <see cref="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="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Break"/>,
/// the <see cref="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">A <see cref="System.Type"/> to set the <see cref="Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Break"/>,
/// the <see cref="GotoExpression.Target"/> property set to <paramref name="target"/>,
/// and the <see cref="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">A <see cref="System.Type"/> to set the <see cref="Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Break"/>,
/// the <see cref="GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="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="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Continue"/>,
/// the <see cref="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">A <see cref="System.Type"/> to set the <see cref="Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Continue"/>,
/// the <see cref="GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="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="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Return"/>,
/// the <see cref="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">A <see cref="System.Type"/> to set the <see cref="Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Return"/>,
/// the <see cref="GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="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="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Return"/>,
/// the <see cref="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">A <see cref="System.Type"/> to set the <see cref="Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Return"/>,
/// the <see cref="GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="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="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Goto"/>,
/// the <see cref="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">A <see cref="System.Type"/> to set the <see cref="Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Goto"/>,
/// the <see cref="GotoExpression.Target"/> property set to the specified value,
/// the <see cref="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="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Goto"/>,
/// the <see cref="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">A <see cref="System.Type"/> to set the <see cref="Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="GotoExpression.Kind"/> equal to <see cref="GotoExpressionKind.Goto"/>,
/// the <see cref="GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="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">A <see cref="System.Type"/> to set the <see cref="Type"/> property equal to.</param>
/// <returns>
/// A <see cref="GotoExpression"/> with <see cref="GotoExpression.Kind"/> equal to <paramref name="kind"/>,
/// the <see cref="GotoExpression.Target"/> property set to <paramref name="target"/>,
/// the <see cref="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, nameof(target), nameof(value), type);
return new GotoExpression(kind, target, value, type);
}
private static void ValidateGoto(LabelTarget target, ref Expression? value, string targetParameter, string valueParameter, Type? type)
{
ArgumentNullException.ThrowIfNull(target, targetParameter);
if (value == null)
{
if (target.Type != typeof(void)) throw Error.LabelMustBeVoidOrHaveExpression(nameof(target));
if (type != null)
{
TypeUtils.ValidateType(type, nameof(type));
}
}
else
{
ValidateGotoType(target.Type, ref value, valueParameter);
}
}
// Standard argument validation, taken from ValidateArgumentTypes
private static void ValidateGotoType(Type expectedType, ref Expression value, string paramName)
{
ExpressionUtils.RequiresCanRead(value, paramName);
if (expectedType != typeof(void))
{
if (!TypeUtils.AreReferenceAssignable(expectedType, value.Type))
{
// C# auto-quotes return values, so we'll do that here
if (!TryQuote(expectedType, ref value))
{
throw Error.ExpressionTypeDoesNotMatchLabel(value.Type, expectedType);
}
}
}
}
}
}