make TokenWriterProducer compatible with jsoniter

modules/core/src/main/scala/tethys/commons/RawJson.scala

@@ -20,12 +20,7 @@ object RawJson {
   ): JsonReader[RawJson] = new JsonReader[RawJson] {
     override def read(
         it: TokenIterator
-    )(implicit fieldName: FieldName): RawJson = {
-      val stringWriter = new StringWriter()
-      val tokenWriter: TokenWriter = tokenWriterProducer.forWriter(stringWriter)
-      JsonStreaming.streamValue(it, tokenWriter)
-      tokenWriter.flush()
-      RawJson(stringWriter.toString)
-    }
+    )(implicit fieldName: FieldName): RawJson =
+      RawJson(tokenWriterProducer.withTokenWriter(JsonStreaming.streamValue(it, _)))
   }
 }

modules/core/src/main/scala/tethys/package.scala

@@ -1,4 +1,4 @@
-import java.io.{Reader, StringReader, StringWriter, Writer}
+import java.io.{Reader, StringReader}
 
 import tethys.readers.{FieldName, ReaderError}
 import tethys.readers.tokens.{TokenIterator, TokenIteratorProducer}
@@ -18,11 +18,8 @@ package object tethys {
     def asJson(implicit
         jsonWriter: JsonWriter[A],
         tokenWriterProducer: TokenWriterProducer
-    ): String = {
-      val stringWriter = new StringWriter()
-      writeJson(tokenWriterProducer.forWriter(stringWriter))
-      stringWriter.toString
-    }
+    ): String =
+      tokenWriterProducer.withTokenWriter(jsonWriter.write(a, _))
 
     def asJsonWith(
         jsonWriter: JsonWriter[A]
@@ -31,7 +28,7 @@ package object tethys {
     }
 
     def writeJson(
-        tokenWriter: TokenWriter
+        tokenWriter: TokenWriter with TokenWriter.Flushing
     )(implicit jsonWriter: JsonWriter[A]): Unit = {
       try jsonWriter.write(a, tokenWriter)
       finally {
@@ -40,12 +37,6 @@ package object tethys {
     }
   }
 
-  implicit class WriterOps(val w: Writer) extends AnyVal {
-    def toTokenWriter(implicit
-        tokenWriterProducer: TokenWriterProducer
-    ): TokenWriter = tokenWriterProducer.forWriter(w)
-  }
-
   implicit class StringReaderOps(val json: String) extends AnyVal {
     def jsonAs[A](implicit
         jsonReader: JsonReader[A],

modules/core/src/main/scala/tethys/writers/tokens/SimpleTokenWriter.scala

@@ -7,7 +7,7 @@ import tethys.readers.tokens.TokenIteratorProducer
 
 import scala.collection.mutable
 
-class SimpleTokenWriter extends TokenWriter {
+class SimpleTokenWriter extends TokenWriter with TokenWriter.Flushing {
   val tokens: mutable.ArrayBuffer[TokenNode] = mutable.ArrayBuffer.empty
 
   override def writeArrayStart(): SimpleTokenWriter.this.type = append(

modules/core/src/main/scala/tethys/writers/tokens/TokenWriter.scala

@@ -49,8 +49,11 @@ trait TokenWriter {
 
   @throws[UnsupportedOperationException]
   def writeRawJson(json: String): this.type
+}
 
-  def close(): Unit
-
-  def flush(): Unit
+object TokenWriter {
+  trait Flushing {
+    def flush(): Unit
+    def close(): Unit
+  }
 }

modules/core/src/main/scala/tethys/writers/tokens/TokenWriterProducer.scala

@@ -1,7 +1,6 @@
 package tethys.writers.tokens
 
-import java.io.Writer
-
 trait TokenWriterProducer {
-  def forWriter(writer: Writer): TokenWriter
+  type ExactTokenWriter <: TokenWriter
+  def withTokenWriter(writer: ExactTokenWriter => Unit): String
 }

modules/jackson-backend/src/main/scala/tethys/jackson/JacksonTokenWriter.scala

@@ -3,7 +3,7 @@ package tethys.jackson
 import com.fasterxml.jackson.core.JsonGenerator
 import tethys.writers.tokens.TokenWriter
 
-class JacksonTokenWriter(jsonGenerator: JsonGenerator) extends TokenWriter {
+class JacksonTokenWriter(jsonGenerator: JsonGenerator) extends TokenWriter with TokenWriter.Flushing {
   override def writeArrayStart(): JacksonTokenWriter.this.type = {
     jsonGenerator.writeStartArray()
     this

modules/jackson-backend/src/main/scala/tethys/jackson/package.scala

@@ -2,7 +2,7 @@ package tethys
 
 import java.io.{Reader, Writer}
 
-import com.fasterxml.jackson.core.JsonFactory
+import com.fasterxml.jackson.core.{JsonFactory, JsonGenerator}
 import tethys.readers.{FieldName, ReaderError}
 import tethys.readers.tokens.{TokenIterator, TokenIteratorProducer}
 import tethys.writers.tokens.{TokenWriter, TokenWriterProducer}
@@ -14,14 +14,24 @@ package object jackson {
     f
   }
 
-  implicit def jacksonTokenWriterProducer(implicit
-      jsonFactory: JsonFactory = defaultJsonFactory
-  ): TokenWriterProducer = new TokenWriterProducer {
-    override def forWriter(writer: Writer): TokenWriter = {
-      new JacksonTokenWriter(jsonFactory.createGenerator(writer))
+  class JacksonTokenWriterProducer(
+    jsonFactory: JsonFactory,
+    configure: JsonGenerator => JsonGenerator
+  ) extends TokenWriterProducer {
+    type ExactTokenWriter = JacksonTokenWriter
+
+    override def withTokenWriter(write: JacksonTokenWriter => Unit): String = {
+      val stringWriter = new java.io.StringWriter()
+      val tw = new JacksonTokenWriter(configure(jsonFactory.createGenerator(stringWriter)))
+      try write(tw) finally tw.flush()
+      stringWriter.toString
     }
   }
 
+  implicit def jacksonTokenWriterProducer(implicit
+      jsonFactory: JsonFactory = defaultJsonFactory
+  ): JacksonTokenWriterProducer = new JacksonTokenWriterProducer(jsonFactory, identity)
+
   implicit def jacksonTokenIteratorProducer(implicit
       jsonFactory: JsonFactory = defaultJsonFactory
   ): TokenIteratorProducer = new TokenIteratorProducer {

modules/jackson-backend/src/main/scala/tethys/jackson/pretty/package.scala

@@ -9,13 +9,8 @@ import tethys.writers.tokens.{TokenWriter, TokenWriterProducer}
 package object pretty {
   implicit def prettyJacksonTokenWriterProducer(implicit
       jsonFactory: JsonFactory = defaultJsonFactory
-  ): TokenWriterProducer = new TokenWriterProducer {
-    override def forWriter(writer: Writer): TokenWriter = {
-      new JacksonTokenWriter(
-        jsonFactory.createGenerator(writer).useDefaultPrettyPrinter()
-      )
-    }
-  }
+  ): JacksonTokenWriterProducer =
+    new tethys.jackson.JacksonTokenWriterProducer(jsonFactory, _.useDefaultPrettyPrinter())
 
   implicit def jacksonTokenIteratorProducer(implicit
       jsonFactory: JsonFactory = defaultJsonFactory

modules/jackson-backend/src/test/scala/tethys/jackson/JacksonTokenWriterTest.scala

@@ -1,21 +1,18 @@
 package tethys.jackson
 
-import java.io.StringWriter
-
 import org.scalatest.matchers.should.Matchers
 import org.scalatest.flatspec.AnyFlatSpec
 import tethys._
 import tethys.writers.tokens.TokenWriter
 
 class JacksonTokenWriterTest extends AnyFlatSpec with Matchers {
 
-  def iterate(fun: (TokenWriter) => Unit): String = {
-    val sw = new StringWriter()
-    val tokenWriter = sw.toTokenWriter
-    fun(tokenWriter)
-    tokenWriter.close()
-    sw.toString
-  }
+  def iterate(fun: TokenWriter => Unit): String =
+    implicitly[JacksonTokenWriterProducer]
+      .withTokenWriter { tokenWriter =>
+        fun(tokenWriter)
+        tokenWriter.close()
+      }
 
   behavior of "JacksonTokenWriter"