/* ****************************************************************************
*
* 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.
*
*
* ***************************************************************************/
#if !CLR2
using System.Linq.Expressions;
#else
using Microsoft.Scripting.Ast;
#endif
using System;
using System.Diagnostics;
using Microsoft.Scripting.Utils;
namespace Microsoft.Scripting.Actions{
/// <summary>
/// Encapsulates information about the result that should be produced when
/// a OldDynamicAction cannot be performed. The ErrorInfo can hold one of:
/// an expression which creates an Exception to be thrown
/// an expression which produces a value which should be returned
/// directly to the user and represents an error has occured (for
/// example undefined in JavaScript)
/// an expression which produces a value which should be returned
/// directly to the user but does not actually represent an error.
///
/// ErrorInfo's are produced by an ActionBinder in response to a failed
/// binding.
/// </summary>
public sealed class ErrorInfo {
private readonly Expression _value;
private readonly ErrorInfoKind _kind;
/// <summary>
/// Private constructor - consumers must use static From* factories
/// to create ErrorInfo objects.
/// </summary>
private ErrorInfo(Expression value, ErrorInfoKind kind) {
Debug.Assert(value != null);
_value = value;
_kind = kind;
}
/// <summary>
/// Creates a new ErrorInfo which represents an exception that should
/// be thrown.
/// </summary>
public static ErrorInfo FromException(Expression exceptionValue) {
ContractUtils.RequiresNotNull(exceptionValue, "exceptionValue");
ContractUtils.Requires(typeof(Exception).IsAssignableFrom(exceptionValue.Type), "exceptionValue", Strings.MustBeExceptionInstance);
return new ErrorInfo(exceptionValue, ErrorInfoKind.Exception);
}
/// <summary>
/// Creates a new ErrorInfo which represents a value which should be
/// returned to the user.
/// </summary>
public static ErrorInfo FromValue(Expression resultValue) {
ContractUtils.RequiresNotNull(resultValue, "resultValue");
return new ErrorInfo(resultValue, ErrorInfoKind.Error);
}
/// <summary>
/// Crates a new ErrorInfo which represents a value which should be returned
/// to the user but does not represent an error.
/// </summary>
/// <param name="resultValue"></param>
/// <returns></returns>
public static ErrorInfo FromValueNoError(Expression resultValue) {
ContractUtils.RequiresNotNull(resultValue, "resultValue");
return new ErrorInfo(resultValue, ErrorInfoKind.Success);
}
public ErrorInfoKind Kind {
get {
return _kind;
}
}
public Expression Expression {
get {
return _value;
}
}
}
public enum ErrorInfoKind {
/// <summary>
/// The ErrorInfo expression produces an exception
/// </summary>
Exception,
/// <summary>
/// The ErrorInfo expression produces a value which represents the error (e.g. undefined)
/// </summary>
Error,
/// <summary>
/// The ErrorInfo expression produces a value which is not an error
/// </summary>
Success
}
}
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