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AspClassic.VBScript/Runtime/DynamicObjectHelpers.cs

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+using System;
+using System.Collections.Generic;
+//using System.Text;
+using System.Reflection;
+using System.Dynamic;
+#if USE35
+using AspClassic.Scripting.Ast;
+using AspClassic.Scripting.Utils;
+#else
+using System.Linq.Expressions;
+#endif
+using System.Runtime.CompilerServices;
+
+namespace Dlrsoft.VBScript.Runtime
+{
+    //#####################################################
+    //# Dynamic Helpers for HasMember, GetMember, SetMember
+    //#####################################################
+
+    // DynamicObjectHelpers provides access to IDynObj members given names as
+    // data at runtime.  When the names are known at compile time (o.foo), then
+    // they get baked into specific sites with specific binders that encapsulate
+    // the name.  We need this in python because hasattr et al are case-sensitive.
+    //
+    class DynamicObjectHelpers
+    {
+
+        static private object _sentinel = new object();
+        static internal object Sentinel { get { return _sentinel; } }
+
+        internal static bool HasMember(IDynamicMetaObjectProvider o,
+                                       string name)
+        {
+            return (DynamicObjectHelpers.GetMember(o, name) !=
+                    DynamicObjectHelpers.Sentinel);
+            //Alternative impl used when EOs had bug and didn't call fallback ...
+            //var mo = o.GetMetaObject(Expression.Parameter(typeof(object), null));
+            //foreach (string member in mo.GetDynamicMemberNames()) {
+            //    if (string.Equals(member, name, StringComparison.OrdinalIgnoreCase)) {
+            //        return true;
+            //    }
+            //}
+            //return false;
+        }
+
+        static private Dictionary<string,
+                                  CallSite<AspClassic.Scripting.Utils.Func<CallSite, object, object>>>
+            _getSites = new Dictionary<string,
+                                       CallSite<AspClassic.Scripting.Utils.Func<CallSite, object, object>>>();
+
+        internal static object GetMember(IDynamicMetaObjectProvider o,
+                                         string name)
+        {
+            CallSite<AspClassic.Scripting.Utils.Func<CallSite, object, object>> site;
+            if (!DynamicObjectHelpers._getSites.TryGetValue(name, out site))
+            {
+                site = CallSite<AspClassic.Scripting.Utils.Func<CallSite, object, object>>
+                               .Create(new DoHelpersGetMemberBinder(name));
+                DynamicObjectHelpers._getSites[name] = site;
+            }
+            return site.Target(site, o);
+        }
+
+        static private Dictionary<string,
+                                  CallSite<AspClassic.Scripting.Utils.Action<CallSite, object, object>>>
+            _setSites = new Dictionary<string,
+                                       CallSite<AspClassic.Scripting.Utils.Action<CallSite, object, object>>>();
+
+        internal static void SetMember(IDynamicMetaObjectProvider o, string name,
+                                       object value)
+        {
+            CallSite<AspClassic.Scripting.Utils.Action<CallSite, object, object>> site;
+            if (!DynamicObjectHelpers._setSites.TryGetValue(name, out site))
+            {
+                site = CallSite<AspClassic.Scripting.Utils.Action<CallSite, object, object>>
+                          .Create(new DoHelpersSetMemberBinder(name));
+                DynamicObjectHelpers._setSites[name] = site;
+            }
+            site.Target(site, o, value);
+        }
+
+    }
+
+    class DoHelpersGetMemberBinder : GetMemberBinder
+    {
+
+        internal DoHelpersGetMemberBinder(string name) : base(name, true) { }
+
+        public override DynamicMetaObject FallbackGetMember(
+                DynamicMetaObject target, DynamicMetaObject errorSuggestion)
+        {
+            return errorSuggestion ??
+                   new DynamicMetaObject(
+                           Expression.Constant(DynamicObjectHelpers.Sentinel),
+                           target.Restrictions.Merge(
+                               BindingRestrictions.GetTypeRestriction(
+                                   target.Expression, target.LimitType)));
+
+        }
+    }
+
+    class DoHelpersSetMemberBinder : SetMemberBinder
+    {
+        internal DoHelpersSetMemberBinder(string name) : base(name, true) { }
+
+        public override DynamicMetaObject FallbackSetMember(
+                DynamicMetaObject target, DynamicMetaObject value,
+                DynamicMetaObject errorSuggestion)
+        {
+            return errorSuggestion ??
+                   RuntimeHelpers.CreateThrow(
+                       target, null, BindingRestrictions.Empty,
+                       typeof(MissingMemberException),
+                              "If IDynObj doesn't support setting members, " +
+                              "DOHelpers can't do it for the IDO.");
+        }
+    }
+}