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/* ****************************************************************************
*
* Copyright (c) Microsoft Corporation.
*
* This source code is subject to terms and conditions of the Apache License, Version 2.0. A
* copy of the license can be found in the License.html file at the root of this distribution. If
* you cannot locate the Apache License, Version 2.0, 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 Apache License, Version 2.0.
*
* 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>
/// Represents an infinite loop. It can be exited with "break".
/// </summary>
#if !SILVERLIGHT
[DebuggerTypeProxy(typeof(Expression.LoopExpressionProxy))]
#endif
public sealed class LoopExpression : Expression {
private readonly Expression _body;
private readonly LabelTarget _break;
private readonly LabelTarget _continue;
internal LoopExpression(Expression body, LabelTarget @break, LabelTarget @continue) {
_body = body;
_break = @break;
_continue = @continue;
}
/// <summary>
/// Gets the static type of the expression that this <see cref="Expression" /> represents.
/// </summary>
/// <returns>The <see cref="Type"/> that represents the static type of the expression.</returns>
public sealed override Type Type {
get { return _break == null ? typeof(void) : _break.Type; }
}
/// <summary>
/// Returns the node type of this Expression. Extension nodes should return
/// ExpressionType.Extension when overriding this method.
/// </summary>
/// <returns>The <see cref="ExpressionType"/> of the expression.</returns>
public sealed override ExpressionType NodeType {
get { return ExpressionType.Loop; }
}
/// <summary>
/// Gets the <see cref="Expression"/> that is the body of the loop.
/// </summary>
public Expression Body {
get { return _body; }
}
/// <summary>
/// Gets the <see cref="LabelTarget"/> that is used by the loop body as a break statement target.
/// </summary>
public LabelTarget BreakLabel {
get { return _break; }
}
/// <summary>
/// Gets the <see cref="LabelTarget"/> that is used by the loop body as a continue statement target.
/// </summary>
public LabelTarget ContinueLabel {
get { return _continue; }
}
/// <summary>
/// Dispatches to the specific visit method for this node type.
/// </summary>
protected internal override Expression Accept(ExpressionVisitor visitor) {
return visitor.VisitLoop(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="breakLabel">The <see cref="BreakLabel" /> property of the result.</param>
/// <param name="continueLabel">The <see cref="ContinueLabel" /> property of the result.</param>
/// <param name="body">The <see cref="Body" /> property of the result.</param>
/// <returns>This expression if no children changed, or an expression with the updated children.</returns>
public LoopExpression Update(LabelTarget breakLabel, LabelTarget continueLabel, Expression body) {
if (breakLabel == BreakLabel && continueLabel == ContinueLabel && body == Body) {
return this;
}
return Expression.Loop(body, breakLabel, continueLabel);
}
}
public partial class Expression {
/// <summary>
/// Creates a <see cref="LoopExpression"/> with the given body.
/// </summary>
/// <param name="body">The body of the loop.</param>
/// <returns>The created <see cref="LoopExpression"/>.</returns>
public static LoopExpression Loop(Expression body) {
return Loop(body, null);
}
/// <summary>
/// Creates a <see cref="LoopExpression"/> with the given body and break target.
/// </summary>
/// <param name="body">The body of the loop.</param>
/// <param name="break">The break target used by the loop body.</param>
/// <returns>The created <see cref="LoopExpression"/>.</returns>
public static LoopExpression Loop(Expression body, LabelTarget @break) {
return Loop(body, @break, null);
}
/// <summary>
/// Creates a <see cref="LoopExpression"/> with the given body.
/// </summary>
/// <param name="body">The body of the loop.</param>
/// <param name="break">The break target used by the loop body.</param>
/// <param name="continue">The continue target used by the loop body.</param>
/// <returns>The created <see cref="LoopExpression"/>.</returns>
public static LoopExpression Loop(Expression body, LabelTarget @break, LabelTarget @continue) {
RequiresCanRead(body, "body");
if (@continue != null && @continue.Type != typeof(void)) throw Error.LabelTypeMustBeVoid();
return new LoopExpression(body, @break, @continue);
}
}
}
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