add generate content type

Author: tanner0101

Sources/FormData/Serializer.swift

@@ -39,4 +39,10 @@ public final class Serializer {
         part.headers["Content-Disposition"] = contentDisposition
         try multipart.serialize(part)
     }
+    
+    /// Generates a Content-Type header value from a boundary
+    public static func generateContentType(boundary: BytesConvertible) throws -> Bytes {
+        let b = try boundary.makeBytes()
+        return  "multipart/form-data; boundary=".bytes + b
+    }
 }

Sources/Multipart/Parser.swift

@@ -1,5 +1,6 @@
 import Core
 import HTTP
+import Foundation
 
 /**
     Parses preamble, Parts, and epilogue from a Multipart 
@@ -72,6 +73,15 @@ public final class Parser {
         buffer = []
 	}
 
+    /// Extracts the boundary from a multipart Content-Type header
+    public static func extractBoundary(contentType: BytesConvertible) throws -> Bytes {
+        let boundaryPieces = try contentType.makeBytes().string.components(separatedBy: "boundary=")
+        guard boundaryPieces.count == 2 else {
+            throw Error.invalidBoundary
+        }
+        return boundaryPieces[1].bytes
+    }
+    
     /// Create a new multipart parser from a 
     /// Content-Type header value.
     public convenience init(contentType: BytesConvertible) throws {
@@ -227,15 +237,6 @@ public final class Parser {
         }
     }
 
-    /// Extracts the boundary from a multipart Content-Type header
-    public static func extractBoundary(contentType: BytesConvertible) throws -> Bytes {
-        let boundaryPieces = try contentType.makeBytes().string.components(separatedBy: "boundary=")
-        guard boundaryPieces.count == 2 else {
-            throw Error.invalidBoundary
-        }
-        return boundaryPieces[1].bytes
-    }
-    
     // Private flag for tracking whether `finish()`
     // has been called.
     private var hasFinished = false