Allow CSVWriter escapingScalar to be disabled

Author: josh

Sources/Active/Writer/Writer.swift

@@ -181,28 +181,36 @@ extension CSVWriter {
         var result: [Unicode.Scalar]
 
         if field.isEmpty {
-            result = .init(repeating: escapingScalar, count: 2)
+            if let escapingScalar = escapingScalar {
+                result = .init(repeating: escapingScalar, count: 2)
+            } else {
+                result = []
+            }
         } else {
             let input: [Unicode.Scalar] = .init(field.unicodeScalars)
             result = .init()
             result.reserveCapacity(input.count + 2)
-            var (index, needsEscaping) = (0, false)
+            var index = 0
+            var needsEscaping: Unicode.Scalar?
 
             while index < input.endIndex {
                 let scalar = input[index]
 
                 if scalar == escapingScalar {
-                    needsEscaping = true
+                    needsEscaping = scalar
                 } else if self.isFieldDelimiter(input, &index, &result) || self.isRowDelimiter(input, &index, &result) {
-                    needsEscaping = true
+                    needsEscaping = scalar
                     continue
                 }
 
                 index += 1
                 result.append(scalar)
             }
 
-            if needsEscaping {
+            if let needsEscaping = needsEscaping {
+                guard let escapingScalar = escapingScalar else {
+                    throw Error.unescapedDelimiter(needsEscaping)
+                }
                 result.insert(escapingScalar, at: result.startIndex)
                 result.append(escapingScalar)
             }
@@ -220,6 +228,13 @@ extension CSVWriter {
 }
 
 fileprivate extension CSVWriter.Error {
+    static func unescapedDelimiter(_ delimiter: Unicode.Scalar) -> CSVError<CSVWriter> {
+        .init(.invalidInput,
+              reason: "A field cannot include a delimiter if escaping strategy is disabled.",
+              help: "Remove delimiter from field or set an escaping strategy.",
+              userInfo: ["Invalid character": delimiter])
+
+    }
     /// Error raised when the a field is trying to be writen and it overflows the expected number of fields per row.
     static func fieldOverflow(expectedFields: Int) -> CSVError<CSVWriter> {
         .init(.invalidOperation,

Sources/Active/Writer/WriterConfiguration.swift

@@ -53,7 +53,7 @@ extension CSVWriter {
         /// Boolean indicating whether the received CSV contains a header row or not.
         let headers: [String]
         /// The unicode scalar used as encapsulator and escaping character (when printed two times).
-        let escapingScalar: Unicode.Scalar = "\""
+        let escapingScalar: Unicode.Scalar? = "\""
         /// The encoding used to identify the underlying data.
         let encoding: String.Encoding