mcs/class/referencesource/mscorlib/system/runtime/interopservices/windowsruntime/ireadonlydictionarytoimapviewadapter.cs

   1 // ==++==
   2 //
   3 //   Copyright (c) Microsoft Corporation.  All rights reserved.
   4 //
   5 // ==--==
   6 //
   7 // <OWNER>GPaperin</OWNER>
   8 // <OWNER>Microsoft</OWNER>
   9
  10 using System;
  11 using System.Security;
  12 using System.Collections;
  13 using System.Collections.Generic;
  14 using System.Diagnostics;
  15 using System.Diagnostics.Contracts;
  16 using System.Runtime.InteropServices;
  17 using System.Runtime.CompilerServices;
  18
  19 namespace System.Runtime.InteropServices.WindowsRuntime
  20 {
  21     // This is a set of stub methods implementing the support for the IMapView`2 interface on managed
  22     // objects that implement IReadOnlyDictionary`2. Used by the interop mashaling infrastructure.
  23     //
  24     // The methods on this class must be written VERY carefully to avoid introducing security holes.
  25     // That's because they are invoked with special "this"! The "this" object
  26     // for all of these methods are not IReadOnlyDictionaryToIMapViewAdapter objects. Rather, they are of type
  27     // IReadOnlyDictionary<K, V>. No actual IReadOnlyDictionaryToIMapViewAdapter object is ever instantiated. Thus, you will
  28     // see a lot of expressions that cast "this" to "IReadOnlyDictionary<K, V>".
  29     [DebuggerDisplay("Size = {Size}")]
  30     internal sealed class IReadOnlyDictionaryToIMapViewAdapter
  31     {
  32         private IReadOnlyDictionaryToIMapViewAdapter()
  33         {
  34             Contract.Assert(false, "This class is never instantiated");
  35         }
  36
  37         // V Lookup(K key)
  38         [SecurityCritical]
  39         internal V Lookup<K, V>(K key)
  40         {
  41             IReadOnlyDictionary<K, V> _this = JitHelpers.UnsafeCast<IReadOnlyDictionary<K, V>>(this);
  42             V value;
  43             bool keyFound = _this.TryGetValue(key, out value);
  44
  45             if (!keyFound)
  46             {
  47                 Exception e = new KeyNotFoundException(Environment.GetResourceString("Arg_KeyNotFound"));
  48                 e.SetErrorCode(__HResults.E_BOUNDS);
  49                 throw e;
  50             }
  51
  52             return value;
  53         }
  54
  55         // uint Size { get }
  56         [SecurityCritical]
  57         internal uint Size<K, V>()
  58         {
  59             IReadOnlyDictionary<K, V> _this = JitHelpers.UnsafeCast<IReadOnlyDictionary<K, V>>(this);
  60             return (uint)_this.Count;
  61         }
  62
  63         // bool HasKey(K key)
  64         [SecurityCritical]
  65         internal bool HasKey<K, V>(K key)
  66         {
  67             IReadOnlyDictionary<K, V> _this = JitHelpers.UnsafeCast<IReadOnlyDictionary<K, V>>(this);
  68             return _this.ContainsKey(key);
  69         }
  70
  71         // void Split(out IMapView<K, V> first, out IMapView<K, V> second)
  72         [SecurityCritical]
  73         internal void Split<K, V>(out IMapView<K, V> first, out IMapView<K, V> second)
  74         {
  75             IReadOnlyDictionary<K, V> _this = JitHelpers.UnsafeCast<IReadOnlyDictionary<K, V>>(this);
  76
  77             if (_this.Count < 2) {
  78                 first = null;
  79                 second = null;
  80                 return;
  81             }
  82
  83             ConstantSplittableMap<K, V> splittableMap = _this as ConstantSplittableMap<K, V>;
  84
  85             if (splittableMap == null)
  86                 splittableMap = new ConstantSplittableMap<K, V>(_this);
  87
  88             splittableMap.Split(out first, out second);
  89         }
  90     }
  91 }