class/System.ComponentModel.Composition/src/ComponentModel/System/ComponentModel/Composition/CompositionResultOfT.cs

   1 // -----------------------------------------------------------------------
   2 // Copyright (c) Microsoft Corporation.  All rights reserved.
   3 // -----------------------------------------------------------------------
   4 using System;
   5 using System.Collections.Generic;
   6 using System.Diagnostics.CodeAnalysis;
   7 using System.Linq;
   8 using Microsoft.Internal.Collections;
   9
  10 namespace System.ComponentModel.Composition
  11 {
  12     internal struct CompositionResult<T>
  13     {
  14         private readonly IEnumerable<CompositionError> _errors;
  15         private readonly T _value;
  16
  17         public CompositionResult(T value)
  18             : this(value, (CompositionError[])null)
  19         {
  20         }
  21
  22         public CompositionResult(params CompositionError[] errors)
  23             : this(default(T), (IEnumerable<CompositionError>)errors)
  24         {
  25         }
  26
  27         public CompositionResult(IEnumerable<CompositionError> errors)
  28             : this(default(T), errors)
  29         {
  30         }
  31
  32         internal CompositionResult(T value, IEnumerable<CompositionError> errors)
  33         {
  34             this._errors = errors;
  35             this._value = value;
  36         }
  37
  38         public bool Succeeded
  39         {
  40             get { return this._errors == null || !this._errors.FastAny(); }
  41         }
  42
  43         public IEnumerable<CompositionError> Errors
  44         {
  45             get { return this._errors ?? Enumerable.Empty<CompositionError>(); }
  46         }
  47
  48         /// <summary>
  49         ///     Gets the value from the result, throwing a CompositionException if there are any errors.
  50         /// </summary>
  51         public T Value
  52         {
  53             get
  54             {
  55                 ThrowOnErrors();
  56
  57                 return this._value;
  58             }
  59         }
  60
  61         internal CompositionResult<TValue> ToResult<TValue>()
  62         {
  63             return new CompositionResult<TValue>(this._errors);
  64         }
  65
  66         internal CompositionResult ToResult()
  67         {
  68             return new CompositionResult(this._errors);
  69         }
  70
  71         private void ThrowOnErrors()
  72         {
  73             if (!this.Succeeded)
  74             {
  75                 throw new CompositionException(this._errors);
  76             }
  77         }
  78     }
  79 }