ICsvReader returns IEnumerable instead of List

NCsvPerf/CsvReadable/Benchmarks/PackageAssetsSuite.cs

@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using BenchmarkDotNet.Attributes;
 
 namespace Knapcode.NCsvPerf.CsvReadable.TestCases
@@ -43,14 +44,16 @@ private void Execute(ICsvReader reader)
             {
                 var result = reader.GetRecords<PackageAsset>(memoryStream);
 
-                if (result.Count != LineCount)
+                if (_saveResult)
                 {
-                    throw new InvalidDataException($"ICsvReader '{reader.GetType().FullName}' failed to produce correct number of rows. Expected: {LineCount}, actual: {result.Count}.");
+                    result = LatestResult = result.ToList();
                 }
 
-                if (_saveResult)
+                var count = result.Count();
+
+                if (count != LineCount)
                 {
-                    LatestResult = result;
+                    throw new InvalidDataException($"ICsvReader '{reader.GetType().FullName}' failed to produce correct number of rows. Expected: {LineCount}, actual: {count}.");
                 }
             }
         }

NCsvPerf/CsvReadable/ICsvReader.cs

@@ -5,6 +5,6 @@ namespace Knapcode.NCsvPerf.CsvReadable
 {
     public interface ICsvReader
     {
-        List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new();
+        IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new();
     }
 }

NCsvPerf/CsvReadable/Implementations/Angara_Table.cs

@@ -30,22 +30,20 @@ public override FSharpOption<Type> Invoke(Tuple<int, string> func)
             }
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
 
             using (var reader = new StreamReader(stream))
             {
                 var cols = new FSharpOption<FSharpFunc<Tuple<int, string>, FSharpOption<Type>>>(new Types());
                 var table = Table.Load(reader, new ReadSettings(Delimiter.Comma, false, false, FSharpOption<int>.None, cols));
-                var allRecords = new List<T>(table.RowsCount);
                 for (int r = 0; r < table.RowsCount; r++)
                 {
                     var item = activate();
                     item.Read(i => table[i].Rows.Item(r).AsString);
-                    allRecords.Add(item);
+                    yield return item;
                 }
-                return allRecords;
             }
         }
     }

NCsvPerf/CsvReadable/Implementations/CSVFile.cs

@@ -16,10 +16,9 @@ public CSVFile(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
-            var allRecords = new List<T>();
 
             var config = new global::CSVFile.CSVSettings
             {
@@ -32,11 +31,9 @@ public CSVFile(ActivationMethod activationMethod)
                 {
                     var record = activate();
                     record.Read(i => row[i]);
-                    allRecords.Add(record);
+                    yield return record;
                 }
             }
-
-            return allRecords;
         }
     }
 }

NCsvPerf/CsvReadable/Implementations/Cesil.cs

@@ -19,29 +19,27 @@ public Cesil(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             // specialize for T == PackageAsset
-            return GetAssets(stream) as List<T>;
+            return GetAssets(stream) as IEnumerable<T>;
         }
 
-        public List<PackageAsset> GetAssets(MemoryStream stream) {
-            var allRecords = new List<PackageAsset>();
+        public IEnumerable<PackageAsset> GetAssets(MemoryStream stream) {
             using (var reader = new StreamReader(stream))
             {
                 var config = Configuration.For<PackageAsset>();
                 var csv = config.CreateReader(reader);
                 foreach (var row in csv.EnumerateAll())
                 {
-                    allRecords.Add(row);
                     // for some reason this final field is null for certain records
                     // which was causing tests to fail
                     if (row.PlatformVersion == null)
                         row.PlatformVersion = "";
+
+                    yield return row;
                 }
             }
-
-            return allRecords;
         }
     }
 }

NCsvPerf/CsvReadable/Implementations/ChoEtl.cs

@@ -15,15 +15,13 @@ public ChoETL(ActivationMethod _)
         {
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
-            return GetAssets(stream) as List<T>;
+            return GetAssets(stream) as IEnumerable<T>;
         }
 
-        List<PackageAsset> GetAssets(MemoryStream stream)
+        IEnumerable<PackageAsset> GetAssets(MemoryStream stream)
         {
-            var allRecords = new List<PackageAsset>();
-
             var config = new global::ChoETL.ChoCSVRecordConfiguration
             {
                 FileHeaderConfiguration = new global::ChoETL.ChoCSVFileHeaderConfiguration
@@ -37,10 +35,8 @@ List<PackageAsset> GetAssets(MemoryStream stream)
                 {
                     var asset = new PackageAsset();
                     asset.Read(i => record.GetString(i));
-                    allRecords.Add(asset);
+                    yield return asset;
                 }
-
-            return allRecords;
         }
     }
 }

NCsvPerf/CsvReadable/Implementations/CommonLibrary_Net.cs

@@ -19,10 +19,9 @@ public CommonLibrary_NET(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
-            var allRecords = new List<T>();
 
             string text;
             using (var reader = new StreamReader(stream))
@@ -37,11 +36,9 @@ public CommonLibrary_NET(ActivationMethod activationMethod)
                 {
                     var record = activate();
                     record.Read(i => row[i]);
-                    allRecords.Add(record);
+                    yield return record;
                 }
             }
-
-            return allRecords;
         }
     }
 }

NCsvPerf/CsvReadable/Implementations/Csv.cs

@@ -16,10 +16,9 @@ public Csv(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
-            var allRecords = new List<T>();
 
             using (var reader = new StreamReader(stream))
             {
@@ -33,11 +32,9 @@ public Csv(ActivationMethod activationMethod)
                 {
                     var record = activate();
                     record.Read(i => row[i]);
-                    allRecords.Add(record);
+                    yield return record;
                 }
             }
-
-            return allRecords;
         }
     }
 }

NCsvPerf/CsvReadable/Implementations/CsvHelper.cs

@@ -17,10 +17,9 @@ public CsvHelper(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
-            var allRecords = new List<T>();
 
             using (var reader = new StreamReader(stream))
             {
@@ -33,11 +32,9 @@ public CsvHelper(ActivationMethod activationMethod)
                 {
                     var record = activate();
                     record.Read(i => csvParser[i]);
-                    allRecords.Add(record);
+                    yield return record;
                 }
             }
-
-            return allRecords;
         }
     }
 }

NCsvPerf/CsvReadable/Implementations/CsvTextFieldParser.cs

@@ -16,10 +16,9 @@ public CsvTextFieldParser(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
-            var allRecords = new List<T>();
 
             using (var reader = new StreamReader(stream))
             {
@@ -29,11 +28,9 @@ public CsvTextFieldParser(ActivationMethod activationMethod)
                     var fields = parser.ReadFields();
                     var record = activate();
                     record.Read(i => fields[i]);
-                    allRecords.Add(record);
+                    yield return record;
                 }
             }
-
-            return allRecords;
         }
     }
 }

NCsvPerf/CsvReadable/Implementations/CsvTools.cs

@@ -18,10 +18,9 @@ public CsvTools(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
-            var allRecords = new List<T>();
 
             if (stream.Length > 0)
             {
@@ -30,17 +29,15 @@ public CsvTools(ActivationMethod activationMethod)
                 // Read header as a row.
                 var r = activate();
                 r.Read(i => table.ColumnNames.ElementAt(i));
-                allRecords.Add(r);
+                yield return r;
 
                 foreach (var row in table.Rows)
                 {
                     var record = activate();
                     record.Read(i => row.Values[i]);
-                    allRecords.Add(record);
+                    yield return record;
                 }
             }
-
-            return allRecords;
         }
     }
 }

NCsvPerf/CsvReadable/Implementations/Ctl_Data.cs

@@ -17,10 +17,9 @@ public Ctl_Data(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
-            var allRecords = new List<T>();
 
             using (var streamReader = new StreamReader(stream))
             {
@@ -32,11 +31,9 @@ public Ctl_Data(ActivationMethod activationMethod)
                     // Empty fields are returned as null by this library. Convert that to empty string to be more
                     // consistent with other libraries.
                     record.Read(i => csvReader.CurrentRow[i].Value ?? string.Empty);
-                    allRecords.Add(record);
+                    yield return record;
                 }
             }
-
-            return allRecords;
         }
     }
 }

NCsvPerf/CsvReadable/Implementations/Cursively.cs

@@ -27,7 +27,7 @@ public Cursively(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             using var vis = new Vis<T>(_activationMethod);
             if (stream.TryGetBuffer(out var buf))

NCsvPerf/CsvReadable/Implementations/DSV.cs

@@ -18,10 +18,9 @@ public Dsv(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
-            var allRecords = new List<T>();
 
             using (var reader = new StreamReader(stream))
             {
@@ -30,11 +29,9 @@ public Dsv(ActivationMethod activationMethod)
                 {
                     var record = activate();
                     record.Read(i => row[i]);
-                    allRecords.Add(record);
+                    yield return record;
                 }
             }
-
-            return allRecords;
         }
 
         static IEnumerable<string> EnumerateLines(TextReader r)

NCsvPerf/CsvReadable/Implementations/FastCsvParser.cs

@@ -21,22 +21,19 @@ public FastCsvParser(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
-            var allRecords = new List<T>();
 
             using (var parser = new global::FastCsvParser.CsvReader(stream, Encoding.UTF8))
             {
                 while (parser.MoveNext())
                 {
                     var record = activate();
                     record.Read(i => parser.Current[i]);
-                    allRecords.Add(record);
+                    yield return record;
                 }
             }
-
-            return allRecords;
         }
     }
 }

NCsvPerf/CsvReadable/Implementations/FileHelpers.cs

@@ -17,10 +17,9 @@ public FileHelpers(ActivationMethod activationMethod)
             _activationMethod = activationMethod;
         }
 
-        public List<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
+        public IEnumerable<T> GetRecords<T>(MemoryStream stream) where T : ICsvReadable, new()
         {
             var activate = ActivatorFactory.Create<T>(_activationMethod);
-            var allRecords = new List<T>();
 
             using (var reader = new StreamReader(stream))
             {
@@ -36,12 +35,10 @@ public FileHelpers(ActivationMethod activationMethod)
                         // bind directly to the PackageAsset.
                         var record = activate();
                         record.Read(i => item.GetString(i));
-                        allRecords.Add(record);
+                        yield return record;
                     }
                 }
             }
-
-            return allRecords;
         }
         [global::FileHelpers.DelimitedRecord(",")]
         public class PackageAssetData