Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data.Linq/SqlClient/Common/InheritanceRules.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Linq.Expressions;
+using System.Reflection;
+using System.Text;
+using System.Linq;
+using System.Data.Linq.Mapping;
+using System.Data.Linq.Provider;
+
+namespace System.Data.Linq.SqlClient {
+    /// <summary>
+    /// This class defines the rules for inheritance behaviors. The rules:
+    /// 
+    ///  (1) The same field may not be mapped to different database columns.    
+    ///      The DistinguishedMemberName and AreSameMember methods describe what 'same' means between two MemberInfos.
+    ///  (2) Discriminators held in fixed-length fields in the database don't need
+    ///      to be manually padded in inheritance mapping [InheritanceMapping(Code='x')]. 
+    ///  
+    /// </summary>
+    static class InheritanceRules {
+        /// <summary>
+        /// Creates a name that is the same when the member should be considered 'same'
+        /// for the purposes of the inheritance feature.
+        /// </summary>
+        internal static object DistinguishedMemberName(MemberInfo mi) {
+            PropertyInfo pi = mi as PropertyInfo;
+            FieldInfo fi = mi as FieldInfo;
+            if (fi != null) {
+                // Human readable variant:
+                // return "fi:" + mi.Name + ":" + mi.DeclaringType;
+                return new MetaPosition(mi);
+            }
+            else if (pi != null) {
+                MethodInfo meth = null;
+
+                if (pi.CanRead) {
+                    meth = pi.GetGetMethod();
+                }
+                if (meth == null && pi.CanWrite) {
+                    meth = pi.GetSetMethod();
+                }
+                bool isVirtual = meth != null && meth.IsVirtual;
+                
+                // Human readable variant:
+                // return "pi:" + mi.Name + ":" + (isVirtual ? "virtual" : mi.DeclaringType.ToString());
+
+                if (isVirtual) {
+                    return mi.Name;
+                } else {
+                    return new MetaPosition(mi);
+                }
+            }
+            else {
+                throw Error.ArgumentOutOfRange("mi");
+            }
+        }
+
+        /// <summary>
+        /// Compares two MemberInfos for 'same-ness'.
+        /// </summary>
+        internal static bool AreSameMember(MemberInfo mi1, MemberInfo mi2) {
+            return DistinguishedMemberName(mi1).Equals(DistinguishedMemberName(mi2));
+        }
+        
+        /// <summary>
+        /// The representation of a inheritance code when mapped to a specific provider type.
+        /// </summary>
+        internal static object InheritanceCodeForClientCompare(object rawCode, System.Data.Linq.SqlClient.ProviderType providerType) {
+            // If its a fixed-size string type in the store then pad it with spaces so that 
+            // comparing the string on the client agrees with the value returnd on the store.
+            if (providerType.IsFixedSize && rawCode.GetType()==typeof(string)) {
+                string s = (string) rawCode;
+                if (providerType.Size.HasValue && s.Length!=providerType.Size) {
+                    s = s.PadRight(providerType.Size.Value).Substring(0,providerType.Size.Value);
+                }
+                return s;
+            }
+            return rawCode;
+        }
+
+
+    }
+}