Add renderer for JSON

gnieh · Jan 29, 2024 · 360515f · 360515f
1 parent 9e4007b
commit 360515f
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Showing 2 changed files with 115 additions and 0 deletions.
diff --git a/json/src/main/scala/fs2/data/json/tokens.scala b/json/src/main/scala/fs2/data/json/tokens.scala
@@ -18,9 +18,15 @@ package fs2
 package data
 package json
 
+import fs2.Pure
+import fs2.data.text.render.{DocEvent, Renderable, Renderer}
+
+import scala.annotation.switch
+
 sealed abstract class Token(val kind: String) {
   def jsonRepr: String
 }
+
 object Token {
 
   case object StartObject extends Token("object") {
@@ -58,4 +64,104 @@ object Token {
     def jsonRepr: String = s""""$value""""
   }
 
+  implicit object renderable extends Renderable[Token] {
+
+    private val startObject =
+      Stream.emits(DocEvent.GroupBegin :: DocEvent.Text("{") :: DocEvent.IndentBegin :: DocEvent.LineBreak :: Nil)
+
+    private val endObject =
+      Stream.emits(DocEvent.IndentEnd :: DocEvent.LineBreak :: DocEvent.Text("}") :: DocEvent.GroupEnd :: Nil)
+
+    private val startArray =
+      Stream.emits(DocEvent.GroupBegin :: DocEvent.Text("[") :: DocEvent.IndentBegin :: DocEvent.LineBreak :: Nil)
+
+    private val endArray =
+      Stream.emits(DocEvent.IndentEnd :: DocEvent.LineBreak :: DocEvent.Text("]") :: DocEvent.GroupEnd :: Nil)
+
+    private val objectSep =
+      Stream.emits(
+        DocEvent.Text(",") :: DocEvent.IndentEnd :: DocEvent.GroupEnd :: DocEvent.GroupEnd :: DocEvent.Line :: Nil)
+
+    private val arraySep =
+      Stream.emits(DocEvent.Text(",") :: DocEvent.GroupEnd :: DocEvent.Line :: Nil)
+
+    private val nullValue =
+      Stream.emit(DocEvent.Text("null"))
+
+    private val trueValue =
+      Stream.emit(DocEvent.Text("true"))
+
+    private val falseValue =
+      Stream.emit(DocEvent.Text("false"))
+
+    private final val FirstObjectKey = 0
+    private final val ObjectKey = 1
+    private final val ObjectValue = 2
+    private final val FirstArrayValue = 3
+    private final val ArrayValue = 4
+
+    override def newRenderer(): Renderer[Token] = new Renderer[Token] {
+
+      // the current stack of states, helping to deal with comma and indentation
+      // states are described right above
+      private[this] var states = List.empty[Int]
+
+      private def separator(): Stream[Pure, DocEvent] =
+        states match {
+          case Nil =>
+            Stream.empty
+          case state :: rest =>
+            (state: @switch) match {
+              case FirstObjectKey =>
+                states = ObjectValue :: rest
+                Stream.empty
+              case ObjectKey =>
+                states = ObjectValue :: rest
+                objectSep
+              case ObjectValue =>
+                states = ObjectKey :: rest
+                Stream.emit(DocEvent.GroupBegin)
+              case FirstArrayValue =>
+                states = ArrayValue :: rest
+                Stream.empty
+              case ArrayValue =>
+                states = ArrayValue :: rest
+                arraySep
+            }
+        }
+
+      override def doc(token: Token): Stream[Pure, DocEvent] =
+        token match {
+          case StartObject =>
+            val res = separator() ++ startObject
+            states = FirstObjectKey :: states
+            res
+          case EndObject =>
+            states = if (states.isEmpty) Nil else states.tail
+            endObject
+          case StartArray =>
+            val res = separator() ++ startArray
+            states = FirstArrayValue :: states
+            res
+          case EndArray =>
+            states = if (states.isEmpty) Nil else states.tail
+            endArray
+          case Key(value) =>
+            separator() ++ Stream.emits(
+              DocEvent.GroupBegin :: DocEvent.IndentBegin :: DocEvent.Text(s""""$value":""") :: DocEvent.Line :: Nil)
+          case NullValue =>
+            separator() ++ nullValue
+          case TrueValue =>
+            separator() ++ trueValue
+          case FalseValue =>
+            separator() ++ falseValue
+          case NumberValue(value) =>
+            separator() ++ Stream.emit(DocEvent.Text(value))
+          case StringValue(value) =>
+            separator() ++ Stream.emit(DocEvent.Text(s""""$value""""))
+        }
+    }
+
+  }
+
 }
diff --git a/json/src/test/scala/fs2/data/json/RenderSpec.scala b/json/src/test/scala/fs2/data/json/RenderSpec.scala
@@ -59,4 +59,13 @@ object RenderSpec extends SimpleIOSuite {
 
   }
 
+  pureTest("An object should be properly pretty renderer with line width of 10") {
+    val input = Stream.emits("""{"field1": "test", "field2": [23, [true, null]]}""")
+
+    println(
+      input.through(tokens[Fallible, Char]).through(fs2.data.text.render.pretty(width = 20, indent = 2)).compile.string)
+    expect(true)
+
+  }
+
 }