From a18842b9d8b70958afadc1a9d48771a8ce52c4fb Mon Sep 17 00:00:00 2001
From: Sedat Kapanoglu <ssg@sourtimes.org>
Date: Sat, 17 Nov 2018 00:12:52 -0800
Subject: [PATCH] add stream encoding/decoding support to Base85

---
 src/Base85.cs              | 44 +++++++++++++++++++++++++++++++++++++-
 test/Base85/Ascii85Test.cs | 27 ++++++++++++++++++++++-
 test/Base85/Z85Test.cs     |  2 +-
 3 files changed, 70 insertions(+), 3 deletions(-)

diff --git a/src/Base85.cs b/src/Base85.cs
index 69626b9..93edeb8 100644
--- a/src/Base85.cs
+++ b/src/Base85.cs
@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 using System;
+using System.IO;
 using System.Runtime.CompilerServices;
 
 namespace SimpleBase
@@ -122,9 +123,50 @@ private unsafe void writeOutput(ref char* pOutput, string table, long input, int
             pOutput += stringLength;
         }
 
-        public unsafe Span<byte> Decode(string text)
+        public void Encode(Stream input, TextWriter output)
+        {
+            Require.NotNull(input, nameof(input));
+            Require.NotNull(output, nameof(output));
+            const int bufferSize = 4096;
+            var buffer = new byte[bufferSize];
+            while (true)
+            {
+                int bytesRead = input.Read(buffer, 0, bufferSize);
+                if (bytesRead < 1)
+                {
+                    break;
+                }
+                var result = Encode(buffer.AsSpan(0, bytesRead));
+                output.Write(result);
+            }
+        }
+
+        public void Decode(TextReader input, Stream output)
+        {
+            Require.NotNull(input, nameof(input));
+            Require.NotNull(output, nameof(output));
+            const int bufferSize = 5120;
+            var buffer = new char[bufferSize];
+            while (true)
+            {
+                int charsRead = input.Read(buffer, 0, bufferSize);
+                if (charsRead < 1)
+                {
+                    break;
+                }
+                var result = Decode(buffer.AsSpan(0, charsRead));
+                output.Write(result.ToArray(), 0, result.Length);
+            }
+        }
+
+        public Span<byte> Decode(string text)
         {
             Require.NotNull(text, nameof(text));
+            return Decode(text.AsSpan());
+        }
+        
+        public unsafe Span<byte> Decode(ReadOnlySpan<char> text)
+        {            
             int textLen = text.Length;
             if (textLen == 0)
             {
diff --git a/test/Base85/Ascii85Test.cs b/test/Base85/Ascii85Test.cs
index 274293d..e05fd2f 100644
--- a/test/Base85/Ascii85Test.cs
+++ b/test/Base85/Ascii85Test.cs
@@ -1,6 +1,7 @@
 using NUnit.Framework;
 using SimpleBase;
 using System;
+using System.IO;
 
 namespace SimpleBaseTest.Base85Test
 {
@@ -30,6 +31,18 @@ public void Decode_Whitespace_IsIgnored(byte[] expectedOutput, string input)
             CollectionAssert.AreEqual(expectedOutput, result.ToArray());
         }
 
+        [Test]
+        [TestCaseSource(nameof(testVectors))]
+        public void Encode_TestVectorsOnStream_ShouldEncodeCorrectly(byte[] input, string expectedOutput)
+        {
+            using (var inputStream = new MemoryStream(input))
+            using (var writer = new StringWriter())
+            {
+                Base85.Ascii85.Encode(inputStream, writer);
+                Assert.AreEqual(expectedOutput, writer.ToString());
+            }
+        }
+
         [Test]
         [TestCaseSource(nameof(testVectors))]
         public void Encode_TestVectors_ShouldEncodeCorrectly(byte[] input, string expectedOutput)
@@ -59,7 +72,19 @@ public void Decode_UnevenText_DoesNotThrowArgumentException()
         [Test]
         public void Decode_NullText_ThrowsArgumentNullException()
         {
-            Assert.Throws<ArgumentNullException>(() => Base85.Ascii85.Decode(null));
+            Assert.Throws<ArgumentNullException>(() => Base85.Ascii85.Decode((string)null));
+        }
+
+        [Test]
+        [TestCaseSource(nameof(testVectors))]
+        public void Decode_TestVectorsWithStream_ShouldDecodeCorrectly(byte[] expectedOutput, string input)
+        {
+            using (var inputStream = new StringReader(input))
+            using (var writer = new MemoryStream())
+            {
+                Base85.Ascii85.Decode(inputStream, writer);
+                CollectionAssert.AreEqual(expectedOutput, writer.ToArray());
+            }
         }
 
         [Test]
diff --git a/test/Base85/Z85Test.cs b/test/Base85/Z85Test.cs
index e22021d..6c3e7b7 100644
--- a/test/Base85/Z85Test.cs
+++ b/test/Base85/Z85Test.cs
@@ -36,7 +36,7 @@ public void Encode_NullBuffer_ReturnsEmptyString()
         [Test]
         public void Decode_NullText_ThrowsArgumentNullException()
         {
-            Assert.Throws<ArgumentNullException>(() => Base85.Z85.Decode(null));
+            Assert.Throws<ArgumentNullException>(() => Base85.Z85.Decode((string)null));
         }
 
         [Test]