Enumerable.Range() usages improved

- use ToArray(count)/ToList(capacity) if possible
- if used only for foreach replaced with regular for with index
- replaced some of usages with CollectionUtils.RangeToXxx()

Author: alex-kulakov

Orm/Xtensive.Orm.SqlServer/Sql.Drivers.SqlServer/ErrorMessageParser.cs

@@ -23,12 +23,12 @@ public sealed class ErrorMessageParser
     private sealed class PreparedTemplate
     {
       public readonly Regex ParserExpression;
-      public readonly ReadOnlyCollection<int> Indexes;
+      public readonly IReadOnlyList<int> Indexes;
 
-      public PreparedTemplate(string regex, IEnumerable<int> indexes)
+      public PreparedTemplate(string regex, IReadOnlyList<int> indexes)
       {
         ParserExpression = new Regex(regex, RegexOptions.Compiled | RegexOptions.CultureInvariant);
-        Indexes = indexes.ToList().AsReadOnly();
+        Indexes = indexes;
       }
     }
 
@@ -190,7 +190,7 @@ private static PreparedTemplate PrepareEnglishTemplate(string template)
       }
 
       CollectLastChunk(regexBuilder, template, offset);
-      return new PreparedTemplate(regexBuilder.ToString(), Enumerable.Range(1, count));
+      return new PreparedTemplate(regexBuilder.ToString(), Enumerable.Range(1, count).ToArray(count));
     }
 
     private static PreparedTemplate PrepareNonEnglishTemplate(string template)
@@ -219,7 +219,7 @@ private static PreparedTemplate PrepareNonEnglishTemplate(string template)
       }
 
       CollectLastChunk(regexBuilder, template, offset);
-      return new PreparedTemplate(regexBuilder.ToString(), indexes);
+      return new PreparedTemplate(regexBuilder.ToString(), indexes.ToArray());
     }
 
 

Orm/Xtensive.Orm/Orm/Building/Builders/IndexBuilder.cs

@@ -809,16 +809,17 @@ private IEnumerable<ColumnInfo> GatherValueColumns(IEnumerable<ColumnInfo> colum
     private ColumnGroup BuildColumnGroup(IndexInfo index)
     {
       var reflectedType = index.ReflectedType;
+      var indexKeyColumns = index.KeyColumns;
       var keyColumns = index.IsPrimary
-        ? Enumerable.Range(0, index.KeyColumns.Count).ToList()
-        : index.KeyColumns
+        ? (IReadOnlyList<int>) CollectionUtils.RangeToArray(0, indexKeyColumns.Count)
+        : indexKeyColumns
             .Select(pair => pair.Key)
             .Concat(index.ValueColumns)
             .Select((c, i) => new {c, i})
             .Where(arg => arg.c.IsPrimaryKey)
             .Select(arg => arg.i)
             .ToList();
-      var columns = Enumerable.Range(0, index.KeyColumns.Count + index.ValueColumns.Count).ToList();
+      var columns = CollectionUtils.RangeToArray(0, indexKeyColumns.Count + index.ValueColumns.Count);
       return new ColumnGroup(reflectedType, keyColumns, columns);
     }
 

Orm/Xtensive.Orm/Orm/EntitySetBase.cs

@@ -942,7 +942,7 @@ private static EntitySetTypeState BuildEntitySetTypeState(object key, EntitySetB
             .Where(ci => ci.IsPrimaryKey)
             .Select(ci => ci.Field.MappingInfo.Offset)
             .ToList()
-        : Enumerable.Range(0, targetDescriptor.Count).ToList();
+        : CollectionUtils.RangeToList(0, targetDescriptor.Count);
 
       var keyFieldCount = ownerDescriptor.Count + itemColumnOffsets.Count;
       var keyFieldTypes = ownerDescriptor

Orm/Xtensive.Orm/Orm/Internals/Prefetch/EntityGroupTask.cs

@@ -171,16 +171,18 @@ private QueryTask CreateQueryTask(List<Tuple> currentKeySet)
 
     private static CompilableProvider CreateRecordSet(object cachingKey)
     {
-      var pair = (Pair<object, CacheKey>) cachingKey;
-      var selectedColumnIndexes = pair.Second.ColumnIndexes;
-      var keyColumnsCount = pair.Second.Type.Indexes.PrimaryIndex.KeyColumns.Count;
+      var cachedKey = ((Pair<object, CacheKey>) cachingKey).Second;
+      var selectedColumnIndexes = cachedKey.ColumnIndexes;
+      var primaryIndex = cachedKey.Type.Indexes.PrimaryIndex;
+      var keyColumnsCount = primaryIndex.KeyColumns.Count;
+
       var keyColumnIndexes = new int[keyColumnsCount];
-      foreach (var index in Enumerable.Range(0, keyColumnsCount)) {
+      for(var index = 0; index < keyColumnsCount; index++) {
         keyColumnIndexes[index] = index;
       }
 
-      var columnCollectionLength = pair.Second.Type.Indexes.PrimaryIndex.Columns.Count;
-      return pair.Second.Type.Indexes.PrimaryIndex.GetQuery().Include(IncludeAlgorithm.ComplexCondition,
+      var columnCollectionLength = primaryIndex.Columns.Count;
+      return primaryIndex.GetQuery().Include(IncludeAlgorithm.ComplexCondition,
         true, context => context.GetValue(includeParameter), $"includeColumnName-{Guid.NewGuid()}",
         keyColumnIndexes).Filter(t => t.GetValue<bool>(columnCollectionLength)).Select(selectedColumnIndexes);
     }

Orm/Xtensive.Orm/Orm/Providers/TemporaryTables/TemporaryTableManager.cs

@@ -22,7 +22,6 @@ namespace Xtensive.Orm.Providers
   public class TemporaryTableManager : DomainBoundHandler
   {
     private const string TableNamePattern = "Tmp_{0}";
-    private const string ColumnNamePattern = "C{0}";
 
     private TemporaryTableBackEnd backEnd;
 
@@ -151,9 +150,13 @@ private void EnsureTemporaryTablesSupported()
 
     private string[] BuildFieldNames(TupleDescriptor source)
     {
-      return Enumerable.Range(0, source.Count)
-          .Select(i => string.Format(ColumnNamePattern, i))
-          .ToArray();
+      var names = new string[source.Count];
+      for(int i = 0, count = names.Length; i < count; i++) {
+#pragma warning disable IDE0071 // Simplify interpolation
+        names[i] = $"C{i.ToString("G")}";
+#pragma warning restore IDE0071 // Simplify interpolation
+      }
+      return names;
     }
 
     private Table CreateTemporaryTable(Schema schema, string name, TupleDescriptor source, TypeMapping[] typeMappings, string[]fieldNames, Collation collation)

Orm/Xtensive.Orm/Orm/Rse/Transformation/Internals/SkipTakeRewriter.cs

@@ -10,6 +10,7 @@
 using Xtensive.Core;
 using Xtensive.Orm.Rse.Providers;
 using Xtensive.Orm;
+using Xtensive.Collections;
 
 namespace Xtensive.Orm.Rse.Transformation
 {
@@ -52,10 +53,12 @@ protected override Provider Visit(CompilableProvider cp)
           visitedProvider = new SkipProvider(visitedProvider, State.Skip);
 
         // add select removing RowNumber column
-        if (requiresRowNumber)
+        if (requiresRowNumber) {
+          var headerCount = visitedProvider.Header.Length - 1;
           visitedProvider = new SelectProvider(
             visitedProvider,
-            Enumerable.Range(0, visitedProvider.Header.Length - 1).ToArray());
+            CollectionUtils.RangeToArray(0, headerCount));
+        }
 
         return visitedProvider;
       }