From 93481d2463d355a36ffcd0f6f7ef86013dd22cf7 Mon Sep 17 00:00:00 2001
From: Rikiya Yamamoto <r.yamamoto.ve@future.co.jp>
Date: Wed, 18 Nov 2020 00:02:02 +0900
Subject: [PATCH] add Shift-JIS encoding support.

---
 .../writer/internal/WriterEncoder.swift       | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/sources/imperative/writer/internal/WriterEncoder.swift b/sources/imperative/writer/internal/WriterEncoder.swift
index ca0e3ce..e6e9fe5 100644
--- a/sources/imperative/writer/internal/WriterEncoder.swift
+++ b/sources/imperative/writer/internal/WriterEncoder.swift
@@ -68,11 +68,28 @@ internal extension CSVWriter {
                 }
                 try CSVWriter._streamWrite(on: stream, bytes: bytes, count: bytes.count)
             }
+        case .shiftJIS:
+            return { [unowned stream] (scalar) in
+                guard let tmp = String(scalar).data(using: .shiftJIS) else { throw Error._invalidShiftJIS(scalar: scalar) }
+                guard let bytes = tmp.encodedHexadecimals else { throw Error._invalidShiftJIS(scalar: scalar) }
+                try CSVWriter._streamWrite(on: stream, bytes: bytes, count: bytes.count)
+            }
         default: throw Error._unsupported(encoding: encoding)
         }
     }
 }
 
+extension Data {
+    var encodedHexadecimals: [UInt8]? {
+        let responseValues = self.withUnsafeBytes({ (pointer: UnsafeRawBufferPointer) -> [UInt8] in
+            let unsafeBufferPointer = pointer.bindMemory(to: UInt8.self)
+            let unsafePointer = unsafeBufferPointer.baseAddress!
+            return [UInt8](UnsafeBufferPointer(start: unsafePointer, count: self.count))
+        })
+        return responseValues
+    }
+}
+
 fileprivate extension CSVWriter {
     /// Writes on the stream the given bytes.
     /// - precondition: `count` is always greater than zero.
@@ -142,6 +159,13 @@ fileprivate extension CSVWriter.Error {
               help: "Make sure the CSV only contains UTF32 characters.",
               userInfo: ["Unicode scalar": scalar])
     }
+    /// Error raised when a Shift-JIS character cannot be constructed from a Unicode scalar value.
+    static func _invalidShiftJIS(scalar: Unicode.Scalar) -> CSVError<CSVWriter> {
+        .init(.invalidInput,
+              reason: "The Unicode Scalar couldn't be encoded to multibyte Shift-JIS",
+              help: "Make sure the CSV only contains Shift-JIS characters.",
+              userInfo: ["Unicode scalar": scalar])
+    }
     /// Error raised when the output stream failed to write some bytes.
     static func _streamFailed(error: Swift.Error?, status: Stream.Status) -> CSVError<CSVWriter> {
         .init(.streamFailure, underlying: error,