Eliminate .ToList() in IFilterable<>.Find()

Author: SergeiPavlov

Orm/Xtensive.Orm/Orm/Model/ColumnInfoCollection.cs

@@ -21,27 +21,16 @@ public sealed class ColumnInfoCollection : NodeCollection<ColumnInfo>,
   {
     #region IFilterable<ColumnAttributes,ColumnInfo> Members
 
-    public IEnumerable<ColumnInfo> Find(ColumnAttributes criteria)
-    {
-      return Find(criteria, MatchType.Partial);
-    }
+    public IEnumerable<ColumnInfo> Find(ColumnAttributes criteria) => Find(criteria, MatchType.Partial);
 
-    public IEnumerable<ColumnInfo> Find(ColumnAttributes criteria, MatchType matchType)
-    {
-      // We don't have any instance that has attributes == FieldAttributes.None
-      if (criteria == ColumnAttributes.None)
-        return Array.Empty<ColumnInfo>();
-
-      switch (matchType) {
-        case MatchType.Partial:
-          return this.Where(f => (f.Attributes & criteria) > 0).ToList();
-        case MatchType.Full:
-          return this.Where(f => (f.Attributes & criteria) == criteria).ToList();
-        case MatchType.None:
-        default:
-          return this.Where(f => (f.Attributes & criteria) == 0).ToList();
-      }
-    }
+    public IEnumerable<ColumnInfo> Find(ColumnAttributes criteria, MatchType matchType) =>
+      criteria == ColumnAttributes.None
+        ? Array.Empty<ColumnInfo>()   // We don't have any instance that has attributes == FieldAttributes.None
+        : matchType switch {
+          MatchType.Partial => this.Where(f => (f.Attributes & criteria) > 0),
+          MatchType.Full => this.Where(f => (f.Attributes & criteria) == criteria),
+          _ => this.Where(f => (f.Attributes & criteria) == 0)
+        };
 
     #endregion
 

Orm/Xtensive.Orm/Orm/Model/FieldInfoCollection.cs

@@ -27,22 +27,14 @@ public sealed class FieldInfoCollection
     public IEnumerable<FieldInfo> Find(FieldAttributes criteria) => Find(criteria, MatchType.Partial);
 
     /// <inheritdoc/>
-    public IEnumerable<FieldInfo> Find(FieldAttributes criteria, MatchType matchType)
-    {
-      // We don't have any instance that has attributes == FieldAttributes.None
-      if (criteria == FieldAttributes.None)
-        return Array.Empty<FieldInfo>();
-
-      switch (matchType) {
-        case MatchType.Partial:
-          return this.Where(f => (f.Attributes & criteria) > 0).ToList();
-        case MatchType.Full:
-          return this.Where(f => (f.Attributes & criteria) == criteria).ToList();
-        case MatchType.None:
-        default:
-          return this.Where(f => (f.Attributes & criteria) == 0).ToList();
-      }
-    }
+    public IEnumerable<FieldInfo> Find(FieldAttributes criteria, MatchType matchType) =>
+      criteria == FieldAttributes.None
+        ? Array.Empty<FieldInfo>()    // We don't have any instance that has attributes == FieldAttributes.None
+        : matchType switch {
+          MatchType.Partial => this.Where(f => (f.Attributes & criteria) > 0),
+          MatchType.Full => this.Where(f => (f.Attributes & criteria) == criteria),
+          _ => this.Where(f => (f.Attributes & criteria) == 0)
+        };
 
     /// <inheritdoc/>
     public override void UpdateState()

Orm/Xtensive.Orm/Orm/Model/IndexInfoCollection.cs

@@ -24,32 +24,22 @@ public class IndexInfoCollection: NodeCollection<IndexInfo>,
     /// </summary>
     /// <param name="criteria">The criteria.</param>
     /// <returns>A sequence of found objects.</returns>
-    public IEnumerable<IndexInfo> Find(IndexAttributes criteria)
-    {
-      return Find(criteria, MatchType.Full);
-    }
+    public IEnumerable<IndexInfo> Find(IndexAttributes criteria) => Find(criteria, MatchType.Full);
 
     /// <summary>
     /// Finds <see cref="IndexInfo"/> objects by the specified criteria and match type.
     /// </summary>
     /// <param name="criteria">The criteria.</param>
     /// <param name="matchType">Type of the match.</param>
     /// <returns>A sequence of found objects.</returns>
-    public IEnumerable<IndexInfo> Find(IndexAttributes criteria, MatchType matchType)
-    {
-      if (criteria == IndexAttributes.None)
-        return Array.Empty<IndexInfo>();
-
-      switch (matchType) {
-        case MatchType.Partial:
-          return this.Where(f => (f.Attributes & criteria) > 0).ToList();
-        case MatchType.Full:
-          return this.Where(f => (f.Attributes & criteria) == criteria).ToList();
-        case MatchType.None:
-        default:
-          return this.Where(f => (f.Attributes & criteria) == 0).ToList();
-      }
-    }
+    public IEnumerable<IndexInfo> Find(IndexAttributes criteria, MatchType matchType) =>
+      criteria == IndexAttributes.None
+        ? Array.Empty<IndexInfo>()
+        : matchType switch {
+          MatchType.Partial => this.Where(f => (f.Attributes & criteria) > 0),
+          MatchType.Full => this.Where(f => (f.Attributes & criteria) == criteria),
+          _ => this.Where(f => (f.Attributes & criteria) == 0)
+        };
 
 
     // Constructors

Orm/Xtensive.Orm/Orm/Model/TypeInfoCollection.cs

@@ -280,19 +280,14 @@ private TypeInfo FindAncestor(Type type)
     /// <returns><see cref="IEnumerable{TItem}"/> that contains all found instances.</returns>
     public IEnumerable<TypeInfo> Find(TypeAttributes criteria) => Find(criteria, MatchType.Partial);
 
-    public IEnumerable<TypeInfo> Find(TypeAttributes criteria, MatchType matchType)
-    {
-      if (criteria == TypeAttributes.None)
-        return Array.Empty<TypeInfo>();
-      switch (matchType) {
-        case MatchType.Partial:
-          return this.Where(f => (f.Attributes & criteria) > 0);
-        case MatchType.Full:
-          return this.Where(f => (f.Attributes & criteria) == criteria);
-        default:
-          return this.Where(f => (f.Attributes & criteria) == 0);
-      }
-    }
+    public IEnumerable<TypeInfo> Find(TypeAttributes criteria, MatchType matchType) =>
+      criteria == TypeAttributes.None
+        ? Array.Empty<TypeInfo>()
+        : matchType switch {
+          MatchType.Partial => this.Where(f => (f.Attributes & criteria) > 0),
+          MatchType.Full => this.Where(f => (f.Attributes & criteria) == criteria),
+          _ => this.Where(f => (f.Attributes & criteria) == 0)
+        };
 
     #endregion