Do not use Either in parser API. It propably simpler just to throw an…

… exception.
jonifreeman · Aug 12, 2009 · 22147cf · 22147cf
1 parent 5405b91
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diff --git a/lift-json/README.md b/lift-json/README.md
@@ -97,8 +97,8 @@ Any valid json can be parsed into internal AST format.
 
     scala> import net.liftweb.json.JsonParser._
     scala> parse(""" { "numbers" : [1, 2, 3, 4] } """)
-    res0: Either[net.liftweb.json.JsonParser.ParseError,net.liftweb.json.JsonAST.JValue] = 
-          Right(JObject(List(JField(numbers,JArray(List(JInt(1), JInt(2), JInt(3), JInt(4)))))))
+    res0: net.liftweb.json.JsonAST.JValue = 
+          JObject(List(JField(numbers,JArray(List(JInt(1), JInt(2), JInt(3), JInt(4))))))
 
 Queries
 -------
@@ -183,7 +183,7 @@ Indexed path expressions work too.
                  }
                ]
              }
-           """).right.get
+           """)
 
     scala> (json \ "children")(0)
     res0: net.liftweb.json.JsonAST.JValue = JObject(List(JField(name,JString(Mary)), JField(age,JInt(5))))

diff --git a/lift-json/src/main/scala/net/liftweb/json/JsonParser.scala b/lift-json/src/main/scala/net/liftweb/json/JsonParser.scala
@@ -5,7 +5,7 @@ package net.liftweb.json
 object JsonParser {
   import JsonAST._
 
-  case class ParseError(message: String)
+  class ParseException(message: String) extends Exception
 
   sealed abstract class Token
   case object OpenObj extends Token
@@ -61,11 +61,11 @@ object JsonParser {
     def toJValue = JArray(elems.map(_.toJValue).reverse)
   }
 
-  def parse(s: String): Either[ParseError, JValue] = 
+  def parse(s: String): JValue = 
     try {
-      Right(parse0(s))
+      parse0(s)
     } catch {
-      case e: Exception => Left(ParseError(e.getMessage))
+      case e: Exception => throw new ParseException(e.getMessage)
     }
 
   private def parse0(s: String): JValue = {

diff --git a/lift-json/src/test/scala/net/liftweb/json/Examples.scala b/lift-json/src/test/scala/net/liftweb/json/Examples.scala
@@ -10,57 +10,40 @@ object Examples extends Specification {
   import JsonParser._
 
   "Lotto example" in {
-    parse(lotto) match {
-      case Right(json) =>
-        val renderedLotto = compact(render(json))
-        json mustEqual parse(renderedLotto).right.get
-      case Left(err) => fail(err.message)
-    }
+    val json = parse(lotto)
+    val renderedLotto = compact(render(json))
+    json mustEqual parse(renderedLotto)
   }
 
   "Person example" in {
-    parse(person) match {
-      case Right(json) =>
-        val renderedPerson = JsonDSL.pretty(render(json))
-        json mustEqual parse(renderedPerson).right.get
-        render(json) mustEqual render(personDSL)
-        compact(render(json \\ "name")) mustEqual """{"name":"Joe","name":"Marilyn"}"""
-        compact(render(json \ "person" \ "name")) mustEqual "\"name\":\"Joe\""
-      case Left(err) => fail(err.message)
-    }
+    val json = parse(person)
+    val renderedPerson = JsonDSL.pretty(render(json))
+    json mustEqual parse(renderedPerson)
+    render(json) mustEqual render(personDSL)
+    compact(render(json \\ "name")) mustEqual """{"name":"Joe","name":"Marilyn"}"""
+    compact(render(json \ "person" \ "name")) mustEqual "\"name\":\"Joe\""
   }
 
   "Object array example" in {
-    parse(objArray) match {
-      case Right(json) =>
-        compact(render(json \ "children" \ "name")) mustEqual """["name":"Mary","name":"Mazy"]"""
-        compact(render((json \ "children")(0) \ "name")) mustEqual "\"name\":\"Mary\""
-        compact(render((json \ "children")(1) \ "name")) mustEqual "\"name\":\"Mazy\""
-      case Left(err) => fail(err.message)
-    }
+    val json = parse(objArray)
+    compact(render(json \ "children" \ "name")) mustEqual """["name":"Mary","name":"Mazy"]"""
+    compact(render((json \ "children")(0) \ "name")) mustEqual "\"name\":\"Mary\""
+    compact(render((json \ "children")(1) \ "name")) mustEqual "\"name\":\"Mazy\""
   }
 
   "Quoted example" in {
-    parse(quoted) match {
-      case Right(json) => List("foo \" \n \t \r bar") mustEqual json.values
-      case Left(err) => fail(err.message)
-    }
+    val json = parse(quoted)
+    List("foo \" \n \t \r bar") mustEqual json.values
   }
 
   "Extraction example" in {
-    parse(objArray) match {
-      case Right(json) =>
-        json.extract[Person] mustEqual Person("joe", Address("Bulevard", "Helsinki"), List(Child("Mary", BigInt(5)), Child("Mazy", BigInt(3))))
-      case Left(err) => fail(err.message)
-    }
+    val json = parse(objArray)
+    json.extract[Person] mustEqual Person("joe", Address("Bulevard", "Helsinki"), List(Child("Mary", BigInt(5)), Child("Mazy", BigInt(3))))
   }
 
   "Partial extraction example" in {
-    parse(objArray) match {
-      case Right(json) =>
-        json.extract[SimplePerson] mustEqual SimplePerson("joe", Address("Bulevard", "Helsinki"))
-      case Left(err) => fail(err.message)
-    }
+    val json = parse(objArray)
+    json.extract[SimplePerson] mustEqual SimplePerson("joe", Address("Bulevard", "Helsinki"))
   }
 
   val lotto = """

diff --git a/lift-json/src/test/scala/net/liftweb/json/ParserTest.scala b/lift-json/src/test/scala/net/liftweb/json/ParserTest.scala
@@ -12,7 +12,7 @@ object ParserSpec extends Specification with JValueGen with ScalaCheck {
   import JsonParser._
 
   "Any valid json can be parsed" in {
-    val parsing = (json: JValue) => parse(JsonDSL.pretty(render(json))).isRight
+    val parsing = (json: JValue) => { parse(JsonDSL.pretty(render(json))); true }
     forAll(parsing) must pass
   }