#37 Changed the JNumber conversion methods to follow semantics of types

mdedetrich · Dec 4, 2017 · f7539ad · f7539ad
1 parent 302f1dc
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diff --git a/README.md b/README.md
@@ -91,6 +91,28 @@ in an undefined manner.
 Do note that according to the JSON spec, whether to order keys for a `JObject` is not specified. Also note that `Map` 
 disregards ordering for equality, however `Array`/`js.Array` equality takes ordering into account.
 
+## Number conversions
+ScalaJSON `JNumber` provides conversions to various number types with the following conventions
+
+* `toInt`: Safe conversion to `Int` which accounts for values such as `1.0` and `100.00e-2` (which both evaluate to `1`).
+Also safely detects over/underflow.
+* `toLong`: Safe conversion to `Long` which accounts for values such as `1.0` and `100.00e-2` (which both evaluate to `1`).
+Also  safely detects over/underflow.
+* `toDouble`: Converts to a `Double` assuming the same semantics of `Double` (i.e. precision loss is expected).
+* `toFloat`: Converts to a `Float` assuming the same semantics of `Float` (i.e. precision loss is expected).
+* `toBigInt`: Converts to a `BigInt` which accounts for values such as `1.0` and `100.00e-2` (which evaluates to `1`).
+Can construct a `BigInt`for as much as memory as the system has (if your system runs out of memory this is considered
+undefined behaviour).
+* `toBigDecimal`: Converts to a `BigDecimal` with all of the caveats of `BigDecimal` construction. The `BigDecimal` is
+constructed with `MathContext.UNLIMITED` precision.
+
+With the `.toFloat` and `.toDouble` methods, if you don't want any loss in precision, its advisable to convert to
+`BigDecimal` first and then work from there, i.e. when working with `Decimal`/`Float`, its implied that you will
+have loss of precision.
+
+Remember that in all cases if these methods are not applicable, you can always use the `.value` field to get the
+original string representation of the number.
+
 ## Scala.js
 ScalaJSON also provides support for [Scala.js](https://github.com/scala-js/scala-js).
 The usage of Scala.js mirrors the usage of Scala on the JVM however Scala.js also implements
@@ -103,6 +125,10 @@ underlying number (numbers in Javascript are represented as double precision flo
 You can use the `.value` method on a `scalajson.ast.JNumber`/`scalajson.ast.unsafe.JNumber` to
 get the raw string value as a solution to this problem.
 
+Further, `toFloat` on `JNumber` (see [Number Conversions](#number-conversions) ) can have different semantics on Scala.js, depending on whether you have
+strict-floats enabled in your application. Please see the [Scala.js semantics page](https://www.scala-js.org/doc/semantics.html)
+for more information.
+
 ## jNumberRegex
 `scalajson.JNumber` uses `jNumberRegex` to validate whether a number is a valid
 JSON number. One can use `jNumberRegex` explicitly if you want to use the validation that

diff --git a/js/src/main/scala-2.10/scalajson.ast/JValue.scala b/js/src/main/scala-2.10/scalajson.ast/JValue.scala
@@ -145,7 +145,9 @@ final class JNumber private[ast] (val value: String) extends JValue {
 
   def toLong: Option[Long] = scalajson.ast.toLong(value)
 
-  def toDouble: Option[Double] = scalajson.ast.toDouble(value)
+  def toDouble: Double = scalajson.ast.toDouble(value)
+
+  def toFloat: Float = scalajson.ast.toFloat(value)
 
   def toBigDecimal: Option[BigDecimal] = scalajson.ast.toBigDecimal(value)
 }

diff --git a/js/src/main/scala-2.10/scalajson.ast/unsafe/JValue.scala b/js/src/main/scala-2.10/scalajson.ast/unsafe/JValue.scala
@@ -87,14 +87,14 @@ object JNumber {
 final case class JNumber(value: String) extends JValue {
   override def toStandard: ast.JValue =
     value match {
-      case jNumberRegex(_ *) => new ast.JNumber(value)
-      case _ => throw new NumberFormatException(value)
+      case jNumberRegex(_*) => new ast.JNumber(value)
+      case _                => throw new NumberFormatException(value)
     }
 
   override def toJsAny: js.Any = value.toDouble match {
-    case n if n.isNaN => null
+    case n if n.isNaN      => null
     case n if n.isInfinity => null
-    case n => n
+    case n                 => n
   }
 
   def toInt: Option[Int] = scalajson.ast.toInt(value)
@@ -103,7 +103,9 @@ final case class JNumber(value: String) extends JValue {
 
   def toLong: Option[Long] = scalajson.ast.toLong(value)
 
-  def toDouble: Option[Double] = scalajson.ast.toDouble(value)
+  def toDouble: Double = scalajson.ast.toDouble(value)
+
+  def toFloat: Float = scalajson.ast.toFloat(value)
 
   def toBigDecimal: Option[BigDecimal] = scalajson.ast.toBigDecimal(value)
 }
@@ -235,11 +237,11 @@ final case class JObject(value: js.Array[JField] = js.Array()) extends JValue {
                               else {
                                 result = 31 * result + elem.field.##
                                 elem.value match {
-                                  case unsafe.JNull => unsafe.JNull.##
-                                  case unsafe.JString(s) => s.##
-                                  case unsafe.JBoolean(b) => b.##
-                                  case unsafe.JNumber(i) => i.##
-                                  case unsafe.JArray(a) => a.##
+                                  case unsafe.JNull        => unsafe.JNull.##
+                                  case unsafe.JString(s)   => s.##
+                                  case unsafe.JBoolean(b)  => b.##
+                                  case unsafe.JNumber(i)   => i.##
+                                  case unsafe.JArray(a)    => a.##
                                   case unsafe.JObject(obj) => obj.##
                                 }
                               })
@@ -307,11 +309,11 @@ final case class JArray(value: js.Array[JValue] = js.Array()) extends JValue {
       result = 31 * result + (if (elem == null) 0
                               else {
                                 elem match {
-                                  case unsafe.JNull => unsafe.JNull.##
-                                  case unsafe.JString(s) => s.##
-                                  case unsafe.JBoolean(b) => b.##
-                                  case unsafe.JNumber(i) => i.##
-                                  case unsafe.JArray(a) => a.##
+                                  case unsafe.JNull        => unsafe.JNull.##
+                                  case unsafe.JString(s)   => s.##
+                                  case unsafe.JBoolean(b)  => b.##
+                                  case unsafe.JNumber(i)   => i.##
+                                  case unsafe.JArray(a)    => a.##
                                   case unsafe.JObject(obj) => obj.##
                                 }
                               })

diff --git a/js/src/main/scala/scalajson/ast/JValue.scala b/js/src/main/scala/scalajson/ast/JValue.scala
@@ -128,7 +128,9 @@ final case class JNumber private[ast] (value: String) extends JValue {
 
   def toLong: Option[Long] = scalajson.ast.toLong(value)
 
-  def toDouble: Option[Double] = scalajson.ast.toDouble(value)
+  def toDouble: Double = scalajson.ast.toDouble(value)
+
+  def toFloat: Float = scalajson.ast.toFloat(value)
 
   def toBigDecimal: Option[BigDecimal] = scalajson.ast.toBigDecimal(value)
 }

diff --git a/js/src/main/scala/scalajson/ast/unsafe/JValue.scala b/js/src/main/scala/scalajson/ast/unsafe/JValue.scala
@@ -101,7 +101,9 @@ final case class JNumber(value: String) extends JValue {
 
   def toLong: Option[Long] = scalajson.ast.toLong(value)
 
-  def toDouble: Option[Double] = scalajson.ast.toDouble(value)
+  def toDouble: Double = scalajson.ast.toDouble(value)
+
+  def toFloat: Float = scalajson.ast.toFloat(value)
 
   def toBigDecimal: Option[BigDecimal] = scalajson.ast.toBigDecimal(value)
 }

diff --git a/jvm/src/main/scala-2.10/scalajson.ast/JValue.scala b/jvm/src/main/scala-2.10/scalajson.ast/JValue.scala
@@ -132,7 +132,9 @@ final class JNumber private[ast] (val value: String) extends JValue {
 
   def toLong: Option[Long] = scalajson.ast.toLong(value)
 
-  def toDouble: Option[Double] = scalajson.ast.toDouble(value)
+  def toDouble: Double = scalajson.ast.toDouble(value)
+
+  def toFloat: Float = scalajson.ast.toFloat(value)
 
   def toBigDecimal: Option[BigDecimal] = scalajson.ast.toBigDecimal(value)
 }

diff --git a/jvm/src/main/scala-2.10/scalajson.ast/unsafe/JValue.scala b/jvm/src/main/scala-2.10/scalajson.ast/unsafe/JValue.scala
@@ -83,7 +83,9 @@ final case class JNumber(value: String) extends JValue {
 
   def toLong: Option[Long] = scalajson.ast.toLong(value)
 
-  def toDouble: Option[Double] = scalajson.ast.toDouble(value)
+  def toDouble: Double = scalajson.ast.toDouble(value)
+
+  def toFloat: Double = scalajson.ast.toFloat(value)
 
   def toBigDecimal: Option[BigDecimal] = scalajson.ast.toBigDecimal(value)
 }

diff --git a/jvm/src/main/scala/scalajson/ast/JValue.scala b/jvm/src/main/scala/scalajson/ast/JValue.scala
@@ -113,7 +113,9 @@ final case class JNumber private[ast] (value: String) extends JValue {
 
   def toLong: Option[Long] = scalajson.ast.toLong(value)
 
-  def toDouble: Option[Double] = scalajson.ast.toDouble(value)
+  def toDouble: Double = scalajson.ast.toDouble(value)
+
+  def toFloat: Float = scalajson.ast.toFloat(value)
 
   def toBigDecimal: Option[BigDecimal] = scalajson.ast.toBigDecimal(value)
 }

diff --git a/jvm/src/main/scala/scalajson/ast/unsafe/JValue.scala b/jvm/src/main/scala/scalajson/ast/unsafe/JValue.scala
@@ -83,7 +83,9 @@ final case class JNumber(value: String) extends JValue {
 
   def toLong: Option[Long] = scalajson.ast.toLong(value)
 
-  def toDouble: Option[Double] = scalajson.ast.toDouble(value)
+  def toDouble: Double = scalajson.ast.toDouble(value)
+
+  def toFloat: Float = scalajson.ast.toFloat(value)
 
   def toBigDecimal: Option[BigDecimal] = scalajson.ast.toBigDecimal(value)
 }

diff --git a/shared/src/main/scala-2.10/scalajson.ast/package.scala b/shared/src/main/scala-2.10/scalajson.ast/package.scala
@@ -698,25 +698,18 @@ package object ast {
     }
   }
 
-  private[ast] def toDouble(value: String): Option[Double] = {
-    try {
-      val asDouble = value.toDouble
-      if (BigDecimal(value, MathContext.UNLIMITED) == BigDecimal(
-            asDouble,
-            MathContext.UNLIMITED))
-        Some(asDouble)
-      else
-        None
-    } catch {
-      case _: java.lang.NumberFormatException => None
-    }
-  }
+  @inline private[ast] def toDouble(value: String): Double =
+    value.toDouble
+
+  @inline private[ast] def toFloat(value: String): Float =
+    value.toFloat
 
   private[ast] def toBigDecimal(value: String): Option[BigDecimal] = {
     try {
       Some(BigDecimal(value, MathContext.UNLIMITED))
     } catch {
-      case _: java.lang.NumberFormatException => None
+      case _: NumberFormatException | _: ArithmeticException =>
+        None
     }
   }
 }
diff --git a/shared/src/main/scala/scalajson/ast/package.scala b/shared/src/main/scala/scalajson/ast/package.scala
@@ -698,25 +698,17 @@ package object ast {
     }
   }
 
-  private[ast] def toDouble(value: String): Option[Double] = {
-    try {
-      val asDouble = value.toDouble
-      if (BigDecimal(value, MathContext.UNLIMITED) == BigDecimal(
-            asDouble,
-            MathContext.UNLIMITED))
-        Some(asDouble)
-      else
-        None
-    } catch {
-      case _: java.lang.NumberFormatException => None
-    }
-  }
+  @inline private[ast] def toDouble(value: String): Double =
+    value.toDouble
+
+  @inline private[ast] def toFloat(value: String): Float =
+    value.toFloat
 
   private[ast] def toBigDecimal(value: String): Option[BigDecimal] = {
     try {
       Some(BigDecimal(value, MathContext.UNLIMITED))
     } catch {
-      case _: java.lang.NumberFormatException => None
+      case _: NumberFormatException | _: ArithmeticException => None
     }
   }
 }