Clarify and make public RESPEncoder

Sources/NIORedis/ChannelHandlers/RESPEncoder.swift

@@ -1,20 +1,17 @@
 import Foundation
 import NIO
 
-/// Handles outgoing `RESPValue` on the wire by encoding it to the Redis RESP protocol.
+/// Translates `RedisValue` into raw bytes, formatted according to the Redis Serialization Protocol (RESP).
 ///
 /// See: https://redis.io/topics/protocol
-internal final class RESPEncoder: MessageToByteEncoder {
-    /// See `MessageToByteEncoder.OutboundIn`
-    typealias OutboundIn = RESPValue
-
-    /// See `RESPEncoder.encode(ctx:data:out:)`
-    func encode(ctx: ChannelHandlerContext, data: RESPValue, out: inout ByteBuffer) throws {
-        out.write(bytes: _encode(data: data))
-    }
-
-    func _encode(data: RESPValue) -> Data {
-        switch data {
+public final class RESPEncoder {
+    /// Encodes the `RedisValue` to bytes, following the RESP specification.
+    ///
+    /// See https://redis.io/topics/protocol
+    /// - Parameter value: The `RESPValue` to encode.
+    /// - Returns: The encoded value as a collection of bytes.
+    public func encode(_ value: RESPValue) -> Data {
+        switch value {
         case .simpleString(let string):
             return "+\(string)\r\n".convertedToData()
 
@@ -31,8 +28,20 @@ internal final class RESPEncoder: MessageToByteEncoder {
             return "-\(error.description)\r\n".convertedToData()
 
         case .array(let array):
-            let encodedArray = array.map { _encode(data: $0) }.joined()
+            let encodedArray = array.map(encode).joined()
             return "*\(array.count)\r\n".convertedToData() + encodedArray
         }
     }
 }
+
+// MARK: MessageToByteEncoder
+
+extension RESPEncoder: MessageToByteEncoder {
+    /// See `MessageToByteEncoder.OutboundIn`
+    public typealias OutboundIn = RESPValue
+
+    /// See `RESPEncoder.encode(ctx:data:out:)`
+    public func encode(ctx: ChannelHandlerContext, data: RESPValue, out: inout ByteBuffer) throws {
+        out.write(bytes: encode(data))
+    }
+}

Tests/NIORedisTests/ChannelHandlers/RESPEncoder+ParsingTests.swift

@@ -8,11 +8,11 @@ final class RESPEncoderParsingTests: XCTestCase {
 
     func testSimpleStrings() {
         XCTAssertEqual(
-            encoder._encode(data: .simpleString("Test1")),
+            encoder.encode(.simpleString("Test1")),
             "+Test1\r\n".convertedToData()
         )
         XCTAssertEqual(
-            encoder._encode(data: .simpleString("®in§³¾")),
+            encoder.encode(.simpleString("®in§³¾")),
             "+®in§³¾\r\n".convertedToData()
         )
     }
@@ -20,40 +20,40 @@ final class RESPEncoderParsingTests: XCTestCase {
     func testBulkStrings() {
         let t1 = Data(bytes: [0x01, 0x02, 0x0a, 0x1b, 0xaa])
         XCTAssertEqual(
-            encoder._encode(data: .bulkString(t1)),
+            encoder.encode(.bulkString(t1)),
             "$5\r\n".convertedToData() + t1 + "\r\n".convertedToData()
         )
         let t2 = "®in§³¾".convertedToData()
         XCTAssertEqual(
-            encoder._encode(data: .bulkString(t2)),
+            encoder.encode(.bulkString(t2)),
             "$10\r\n".convertedToData() + t2 + "\r\n".convertedToData()
         )
         let t3 = "".convertedToData()
         XCTAssertEqual(
-            encoder._encode(data: .bulkString(t3)),
+            encoder.encode(.bulkString(t3)),
             "$0\r\n\r\n".convertedToData()
         )
     }
 
     func testIntegers() {
         XCTAssertEqual(
-            encoder._encode(data: .integer(Int.min)),
+            encoder.encode(.integer(Int.min)),
             ":\(Int.min)\r\n".convertedToData()
         )
         XCTAssertEqual(
-            encoder._encode(data: .integer(0)),
+            encoder.encode(.integer(0)),
             ":0\r\n".convertedToData()
         )
     }
 
     func testArrays() {
         XCTAssertEqual(
-            encoder._encode(data: .array([])),
+            encoder.encode(.array([])),
             "*0\r\n".convertedToData()
         )
         let a1: RESPValue = .array([.integer(3), .simpleString("foo")])
         XCTAssertEqual(
-            encoder._encode(data: a1),
+            encoder.encode(a1),
             "*2\r\n:3\r\n+foo\r\n".convertedToData()
         )
         let bytes = Data(bytes: [ 0x0a, 0x1a, 0x1b, 0xff ])
@@ -62,19 +62,19 @@ final class RESPEncoderParsingTests: XCTestCase {
             .bulkString(bytes)
         ])])
         XCTAssertEqual(
-            encoder._encode(data: a2),
+            encoder.encode(a2),
             "*1\r\n*2\r\n:3\r\n$4\r\n".convertedToData() + bytes + "\r\n".convertedToData()
         )
     }
 
     func testError() {
         let error = RedisError(identifier: "testError", reason: "Manual error")
-        let result = encoder._encode(data: .error(error))
+        let result = encoder.encode(.error(error))
         XCTAssertEqual(result, "-\(error.description)\r\n".convertedToData())
     }
 
     func testNull() {
-        XCTAssertEqual(encoder._encode(data: .null), "$-1\r\n".convertedToData())
+        XCTAssertEqual(encoder.encode(.null), "$-1\r\n".convertedToData())
     }
 }