MLContext.Data.ReadFromBinary to accept IMultiStreamSource rather than Stream (dotnet#2058)

* MLContext.Data.ReadFromBinary to accept IMultiStreamSource rather than Stream

* Hiding ctor and some methods in BinaryLoader that accept Stream

Author: najeeb-kazmi

Diff for: src/Microsoft.ML.Data/DataLoadSave/Binary/BinaryLoader.cs

@@ -823,7 +823,7 @@ private BinaryLoader(Arguments args, IHost host, Stream stream, bool leaveOpen)
         /// <param name="args">Arguments</param>
         /// <param name="env">Host environment</param>
         /// <param name="leaveOpen">Whether to leave the input stream open</param>
-        public BinaryLoader(IHostEnvironment env, Arguments args, Stream stream, bool leaveOpen = true)
+        internal BinaryLoader(IHostEnvironment env, Arguments args, Stream stream, bool leaveOpen = true)
             : this(args, env.Register(LoadName), stream, leaveOpen)
         {
         }
@@ -904,7 +904,7 @@ private BinaryLoader(IHost host, ModelLoadContext ctx, Stream stream)
             }
         }
 
-        public static BinaryLoader Create(IHostEnvironment env, ModelLoadContext ctx, IMultiStreamSource files)
+        private static BinaryLoader Create(IHostEnvironment env, ModelLoadContext ctx, IMultiStreamSource files)
         {
             Contracts.CheckValue(env, nameof(env));
             IHost h = env.Register(LoadName);
@@ -940,7 +940,7 @@ public static BinaryLoader Create(IHostEnvironment env, ModelLoadContext ctx, IM
         /// Creates a binary loader from a stream that is not owned by the loader.
         /// This creates its own independent copy of input stream for the binary loader.
         /// </summary>
-        public static BinaryLoader Create(IHostEnvironment env, ModelLoadContext ctx, Stream stream)
+        private static BinaryLoader Create(IHostEnvironment env, ModelLoadContext ctx, Stream stream)
         {
             Contracts.CheckValue(env, nameof(env));
             IHost h = env.Register(LoadName);

Diff for: src/Microsoft.ML.Data/DataLoadSave/Binary/BinaryLoaderSaverCatalog.cs

@@ -11,17 +11,17 @@ namespace Microsoft.ML
     public static class BinaryLoaderSaverCatalog
     {
         /// <summary>
-        /// Read a data view from a Stream on a binary file using <see cref="BinaryLoader"/>.
+        /// Read a data view from an <see cref="IMultiStreamSource"/> on a binary file using <see cref="BinaryLoader"/>.
         /// </summary>
         /// <param name="catalog">The catalog.</param>
-        /// <param name="stream">The stream to read from.</param>
-        public static IDataView ReadFromBinary(this DataOperations catalog, Stream stream)
+        /// <param name="fileSource">The file source to read from. This can be a <see cref="MultiFileSource"/>, for example.</param>
+        public static IDataView ReadFromBinary(this DataOperations catalog, IMultiStreamSource fileSource)
         {
-            Contracts.CheckValue(stream, nameof(stream));
+            Contracts.CheckValue(fileSource, nameof(fileSource));
 
             var env = catalog.GetEnvironment();
 
-            var reader = new BinaryLoader(env, new BinaryLoader.Arguments(), stream);
+            var reader = new BinaryLoader(env, new BinaryLoader.Arguments(), fileSource);
             return reader;
         }