mcs/class/System.ComponentModel.Composition/src/ComponentModel/System/ComponentModel/Composition/ReflectionModel/ImportingItem.cs

   1 // -----------------------------------------------------------------------\r
   2 // Copyright (c) Microsoft Corporation.  All rights reserved.\r
   3 // -----------------------------------------------------------------------\r
   4 using System;\r
   5 using System.Collections;\r
   6 using System.Collections.Generic;\r
   7 using System.ComponentModel.Composition.Hosting;\r
   8 using System.ComponentModel.Composition.Primitives;\r
   9 using System.Globalization;\r
  10 using System.Linq;\r
  11 using Microsoft.Internal;\r
  12 using Microsoft.Internal.Collections;\r
  13 \r
  14 namespace System.ComponentModel.Composition.ReflectionModel\r
  15 {\r
  16     internal abstract class ImportingItem\r
  17     {\r
  18         private readonly ContractBasedImportDefinition _definition;\r
  19         private readonly ImportType _importType;\r
  20 \r
  21         protected ImportingItem(ContractBasedImportDefinition definition, ImportType importType)\r
  22         {\r
  23             Assumes.NotNull(definition);\r
  24 \r
  25             this._definition = definition;\r
  26             this._importType = importType;\r
  27         }\r
  28 \r
  29         public ContractBasedImportDefinition Definition\r
  30         {\r
  31             get { return this._definition; }\r
  32         }\r
  33 \r
  34         public ImportType ImportType\r
  35         {\r
  36             get { return this._importType; }\r
  37         }\r
  38 \r
  39         public object CastExportsToImportType(Export[] exports)\r
  40         {\r
  41             if (this.Definition.Cardinality == ImportCardinality.ZeroOrMore)\r
  42             {\r
  43                 return CastExportsToCollectionImportType(exports);\r
  44             }\r
  45             else\r
  46             {\r
  47                 return CastExportsToSingleImportType(exports);\r
  48             }\r
  49         }\r
  50 \r
  51         private object CastExportsToCollectionImportType(Export[] exports)\r
  52         {\r
  53             Assumes.NotNull(exports);\r
  54 \r
  55             // Element type could be null if the actually import type of the member is not a collection\r
  56             // This particular case will end up failing when we set the member.\r
  57             Type elementType = this.ImportType.ElementType ?? typeof(object);\r
  58 \r
  59             Array array = Array.CreateInstance(elementType, exports.Length);\r
  60 \r
  61             for (int i = 0; i < array.Length; i++)\r
  62             {\r
  63                 object value = CastSingleExportToImportType(elementType, exports[i]);\r
  64 \r
  65                 array.SetValue(value, i);\r
  66             }\r
  67 \r
  68             return array;\r
  69         }\r
  70 \r
  71         private object CastExportsToSingleImportType(Export[] exports)\r
  72         {\r
  73             Assumes.NotNull(exports);\r
  74             Assumes.IsTrue(exports.Length < 2);\r
  75 \r
  76             if (exports.Length == 0)\r
  77             {   \r
  78                 return null;\r
  79             }\r
  80 \r
  81             return CastSingleExportToImportType(this.ImportType.ActualType, exports[0]);\r
  82         }\r
  83 \r
  84         private object CastSingleExportToImportType(Type type, Export export)\r
  85         {\r
  86             if (this.ImportType.CastExport != null)\r
  87             {\r
  88                 return this.ImportType.CastExport(export);\r
  89             }\r
  90 \r
  91             return Cast(type, export);\r
  92         }\r
  93 \r
  94         private object Cast(Type type, Export export)\r
  95         {\r
  96             // TODO: Need to catch CompositionException to provide\r
  97             // additional information about what member we're setting\r
  98             // and the current dependency graph.\r
  99             object value = export.Value;\r
 100 \r
 101             object result;\r
 102             if (!ContractServices.TryCast(type, value, out result))\r
 103             {\r
 104                 throw new ComposablePartException(\r
 105                     CompositionErrorId.ReflectionModel_ImportNotAssignableFromExport,\r
 106                     String.Format(CultureInfo.CurrentCulture,\r
 107                         Strings.ReflectionModel_ImportNotAssignableFromExport,\r
 108                         export.ToElement().DisplayName,\r
 109                         type.FullName),\r
 110                     this.Definition.ToElement());\r
 111             }\r
 112 \r
 113             return result;\r
 114         }\r
 115     }\r
 116 }