argonaut.JsonNumber.scala Maven / Gradle / Ivy
package argonaut
import java.math.MathContext
import scala.annotation.tailrec
import scala.util.matching.Regex
/**
* JSON numbers with optimization by cases.
* Note: Javascript numbers are 64-bit decimals.
*/
sealed abstract class JsonNumber {
/**
* Returns this number as a `BigDecimal`.
*/
def toBigDecimal: BigDecimal
/**
* Returns this number as a `Double`, only if this number can be represented as a `Double`.
*/
lazy val toDouble: Option[Double] = {
val asDouble = toBigDecimal.toDouble
if (BigDecimal(asDouble) == toBigDecimal) {
Some(asDouble)
} else {
None
}
}
/**
* Returns this number as a `Float`, only if this number can be represented as a `Float`.
*/
lazy val toFloat: Option[Float] = {
val asFloat = toBigDecimal.toFloat
if (BigDecimal(asFloat.toDouble) == toBigDecimal) {
Some(asFloat)
} else {
None
}
}
/**
* Returns this number as a `BigInt`, only if this number is an integer.
*/
def toBigInt: Option[BigInt] = {
val n = toBigDecimal
if (n.isWhole) Some(n.toBigInt)
else None
}
/**
* Returns this number as a `Long`, only if this number is a valid `Long`.
*/
def toLong: Option[Long]
/**
* Returns this number as a `Int`, only if this number is a valid `Int`.
*/
def toInt: Option[Int] = toLong.flatMap { n =>
val m = n.toInt
if (n == m) Some(m) else None
}
/**
* Returns this number as a `Short`, only if this number is a valid `Short`.
*/
def toShort: Option[Short] = toLong.flatMap { n =>
val m = n.toShort
if (n == m) Some(m) else None
}
/**
* Returns this number as a `Byte`, only if this number is a valid `Byte`.
*/
def toByte: Option[Byte] = toLong.flatMap { n =>
val m = n.toByte
if (n == m) Some(m) else None
}
/**
* Truncates this number to the best `Double` approximation to this number.
* Anything over `Double.MaxValue` gets rounded to `Double.PositiveInfinity`
* and anything below `Double.MinValue` gets rounded to
* `Double.NegativeInfinity`.
*/
def truncateToDouble: Double = toBigDecimal.toDouble
/**
* Truncates this number to the best `Float` approximation to this number.
* Anything over `Float.MaxValue` gets rounded to `Float.PositiveInfinity`
* and anything below `Float.MinValue` gets rounded to
* `Float.NegativeInfinity`.
*/
def truncateToFloat: Float = toBigDecimal.toFloat
/**
* Truncates the number to a BigInt. Truncation means that we round the real
* number towards 0 to the closest BigInt.
*
* Truncation fails for numbers whose decimal representation contains more
* than 2 ^ 18 digits, since creating `BigInt` values for these numbers is
* computationally expensive.
*/
def truncateToBigInt: Option[BigInt] = {
val asBigDecimal = toBigDecimal
val digits = asBigDecimal.underlying.unscaledValue.abs.toString.length.toLong - asBigDecimal.scale.toLong
if (digits <= (1 << 18)) Some(asBigDecimal.toBigInt) else None
}
/**
* Truncates the number to a Long. Truncation means that we round the real
* number towards 0 to the closest, valid Long. So, if the number is 1e99,
* then this will return `Long.MaxValue`.
*/
def truncateToLong: Long = toBigDecimal.toLong
/**
* Truncates the number to a Int. Truncation means that we round the real
* number towards 0 to the closest, valid Int. So, if the number is 1e99,
* then this will return `Int.MaxValue`.
*/
def truncateToInt: Int = toBigDecimal.toInt
/**
* Truncates the number to a Short. Truncation means that we round the real
* number towards 0 to the closest, valid Short. So, if the number is 1e99,
* then this will return `Short.MaxValue`.
*/
def truncateToShort: Short = {
val n = truncateToInt
if (n > Short.MaxValue) Short.MaxValue
else if (n < Short.MinValue) Short.MinValue
else n.toShort
}
/**
* Truncates the number to a Byte. Truncation means that we round the real
* number towards 0 to the closest, valid Byte. So, if the number is 1e99,
* then this will return `Byte.MaxValue`.
*/
def truncateToByte: Byte = {
val n = truncateToInt
if (n > Byte.MaxValue) Byte.MaxValue
else if (n < Byte.MinValue) Byte.MinValue
else n.toByte
}
// Force this `JsonNumber` into a `JsonDecimal` by using the underlying
// numbers toString. Isn't safe is `isReal` is `false.
private def toJsonDecimal: JsonDecimal = this match {
case n @ JsonDecimal(_) => n
case JsonBigDecimal(n) => JsonDecimal(n.toString)
case JsonLong(n) => JsonDecimal(n.toString)
}
override def hashCode: Int = toJsonDecimal.normalized.hashCode
override def equals(that: Any): Boolean = that match {
case that: JsonNumber => {
(this, that) match {
case (a @ JsonDecimal(_), b) => a.normalized == b.toJsonDecimal.normalized
case (a, b @ JsonDecimal(_)) => a.toJsonDecimal.normalized == b.normalized
case (JsonLong(x), JsonLong(y)) => x == y
case (a, b) => a.toBigDecimal == b.toBigDecimal
}
}
case _ => false
}
def asJson: Json = JNumber(this)
}
/**
* A JsonDecimal represents and valid JSON number as a String. Unfortunately,
* there is no type in the Scala standard library which can represent all valid
* JSON decimal numbers, since the exponent may be larger than an `Int`. Such
* a number can still be round tripped (parser to printer). We lazily parse the
* string to a `BigDecimal` or a `Double` on demand.
*/
case class JsonDecimal private[argonaut] (value: String) extends JsonNumber {
lazy val toBigDecimal: BigDecimal = BigDecimal(value, MathContext.UNLIMITED)
def toLong: Option[Long] = {
val n = toBigDecimal
if (n.isValidLong) Some(n.toLong)
else None
}
/**
* Returns a *normalized* version of this Decimal number. Since BigDecimal
* cannot represent all valid JSON value exactly, due to the exponent being
* limited to an `Int`, this method let's us get a normalized number that
* can be used to compare for equality.
*
* The 1st value (BigInt) is the exponent used to scale the 2nd value
* (BigDecimal) back to the original value represented by this number. The
* 2nd BigDecimal will always either be 0 or a number with exactly 1 decimal
* digit to the right of the decimal point. If the 2nd value is 0, then the
* exponent will always be 0 as well.
*/
def normalized: (BigInt, BigDecimal) = {
val JsonNumber.JsonNumberRegex(negative, intStr, decStr, expStr) = value
@tailrec
def decScale(i: Int): Option[Int] = {
if (i >= decStr.length) None
else if (decStr(i) == '0') decScale(i + 1)
else Some(- i - 1)
}
val rescale = {
if (intStr != "0") Some(intStr.length - 1)
else if (decStr != null) decScale(0)
else None
}
val unscaledExponent = Option(expStr) match {
case Some(exp) if exp.startsWith("+") => BigInt(exp.substring(1))
case Some(exp) => BigInt(exp)
case None => BigInt(0)
}
rescale match {
case Some(shift) => {
val unscaledValue =
if (decStr == null) BigDecimal(intStr, MathContext.UNLIMITED)
else BigDecimal(s"$intStr.$decStr", MathContext.UNLIMITED)
val scaledValue = BigDecimal(unscaledValue.bigDecimal.movePointLeft(shift))
(unscaledExponent + shift, if (negative != null) -scaledValue else scaledValue)
}
case None => (BigInt(0), BigDecimal(0))
}
}
}
case class JsonBigDecimal(value: BigDecimal) extends JsonNumber {
def toBigDecimal = value
def toLong: Option[Long] = {
if (value.isValidLong) Some(value.toLong)
else None
}
}
case class JsonLong(value: Long) extends JsonNumber {
def toBigDecimal: BigDecimal = BigDecimal(value)
def toLong: Option[Long] = Some(value)
override def truncateToLong: Long = value
}
object JsonNumber {
/**
* Returns a `JsonNumber` whose value is the valid JSON number in `value`.
* This value is **not** verified to be a valid JSON string. It is assumed
* that `value` is a valid JSON number, according to the JSON specification.
* If the value is invalid then the results are undefined. This is provided
* for use in places like a Jawn parser facade, which provides its own
* verification of JSON numbers.
*/
def unsafeDecimal(value: String): JsonNumber = JsonDecimal(value)
/**
* Parses a JSON number from a string. A String is valid if it conforms to
* the grammar in the JSON specification (RFC 4627 -
* http://www.ietf.org/rfc/rfc4627.txt), section 2.4. If it is valid, then
* the number is returned in a `Some`. Otherwise the number is invalid and
* `None` is returned.
*
* @param value a JSON number encoded as a string
* @return a JSON number if the string is valid
*/
def fromString(value: String): Option[JsonNumber] = {
// Span over [0-9]*
@tailrec
def digits(index: Int): Int = {
if (index >= value.length) value.length
else {
val char = value(index)
if (char >= '0' && char <= '9') digits(index + 1)
else index
}
}
// Verify [0-9]+
def digits1(index: Int): Int = {
val end = digits(index)
if (end == index) -1
else end
}
// Verify 0 | [1-9][0-9]*
def natural(index: Int): Int = {
if (index >= value.length) -1
else {
val char = value(index)
if (char == '0') index + 1
else if (char >= '1' && char <= '9') digits(index + 1)
else index
}
}
// Verify -?(0 | [1-9][0-9]*)
def integer(index: Int): Int = {
if (index >= value.length) -1
else if (value(index) == '-') natural(index + 1)
else natural(index)
}
// Span .[0-9]+
def decimal(index: Int): Int = {
if (index < 0 || index >= value.length) index
else if (value(index) == '.') digits1(index + 1)
else index
}
// Span e[-+]?[0-9]+
def exponent(index: Int): Int = {
if (index < 0 || index >= value.length) index
else {
val e = value(index)
if (e == 'e' || e == 'E') {
val index0 = index + 1
if (index0 < value.length) {
val sign = value(index0)
if (sign == '+' || sign == '-') digits1(index0 + 1)
else digits1(index0)
} else {
-1
}
} else {
-1
}
}
}
val intIndex = integer(0)
val decIndex = decimal(intIndex)
val expIndex = exponent(decIndex)
val invalid = {
(expIndex != value.length) ||
(intIndex == 0) ||
(intIndex == -1) ||
(decIndex == -1)
}
// Assuming the number is an integer, does it fit in a Long?
def isLong: Boolean = {
val upperBound = if (value(0) == '-') MinLongString else MaxLongString
(value.length < upperBound.length) ||
((value.length == upperBound.length) &&
value.compareTo(upperBound) <= 0)
}
if (invalid) {
None
} else if (intIndex == expIndex && isLong) {
Some(JsonLong(value.toLong))
} else {
Some(JsonDecimal(value))
}
}
private val MaxLongString = Long.MaxValue.toString
private val MinLongString = Long.MinValue.toString
/**
* A regular expression that can match a valid JSON number. This has 4 match
* groups:
*
* 1. The optional negative sign.
* 2. The integer part.
* 3. The fractional part without the leading period.
* 4. The exponent part without the leading 'e', but with an optional leading '+' or '-'.
*
* The negative sign, fractional part and exponent part are optional matches
* and may be `null`.
*/
val JsonNumberRegex: Regex =
"""(-)?((?:[1-9][0-9]*|0))(?:\.([0-9]+))?(?:[eE]([-+]?[0-9]+))?""".r
}
trait EncodeJsonNumber[T] { self =>
def encodeJsonNumber(value: T): JsonNumber
def contramap[A](f: A => T): EncodeJsonNumber[A] =
(value: A) => self.encodeJsonNumber(f(value))
}
trait EncodePossibleJsonNumber[T] { self =>
def possiblyEncodeJsonNumber(value: T): Option[JsonNumber]
def contramap[A](f: A => T): EncodePossibleJsonNumber[A] =
(value: A) => self.possiblyEncodeJsonNumber(f(value))
}
object EncodeJsonNumber {
implicit val encodeJsonNumberJavaByte: EncodeJsonNumber[java.lang.Byte] =
(value: java.lang.Byte) => new JsonLong(value.byteValue.toLong)
implicit val encodeJsonNumberJavaShort: EncodeJsonNumber[java.lang.Short] =
(value: java.lang.Short) => new JsonLong(value.shortValue.toLong)
implicit val encodeJsonNumberJavaInteger: EncodeJsonNumber[java.lang.Integer] =
(value: java.lang.Integer) => new JsonLong(value.intValue.toLong)
implicit val encodeJsonNumberJavaLong: EncodeJsonNumber[java.lang.Long] =
(value: java.lang.Long) => new JsonLong(value.longValue)
implicit val encodeJsonNumberJavaFloat: EncodePossibleJsonNumber[java.lang.Float] =
(value: java.lang.Float) => encodeJsonNumberFloat.possiblyEncodeJsonNumber(value.floatValue)
implicit val encodeJsonNumberJavaDouble: EncodePossibleJsonNumber[java.lang.Double] =
(value: java.lang.Double) => encodeJsonNumberDouble.possiblyEncodeJsonNumber(value.doubleValue)
implicit val encodeJsonNumberByte: EncodeJsonNumber[Byte] =
(value: Byte) => new JsonLong(value.toLong)
implicit val encodeJsonNumberShort: EncodeJsonNumber[Short] =
(value: Short) => new JsonLong(value.toLong)
implicit val encodeJsonNumberInt: EncodeJsonNumber[Int] =
(value: Int) => new JsonLong(value.toLong)
implicit val encodeJsonNumberLong: EncodeJsonNumber[Long] =
(value: Long) => new JsonLong(value)
implicit val encodeJsonNumberFloat: EncodePossibleJsonNumber[Float] = (value: Float) => {
if (value.isInfinity || java.lang.Float.isNaN(value)) {
None
} else {
Some(new JsonDecimal(value.toString))
}
}
implicit val encodeJsonNumberDouble: EncodePossibleJsonNumber[Double] = (value: Double) => {
if (value.isInfinity || java.lang.Double.isNaN(value)) {
None
} else {
Some(new JsonDecimal(value.toString))
}
}
implicit val encodeJsonNumberBigInt: EncodeJsonNumber[BigInt] =
(value: BigInt) => new JsonBigDecimal(BigDecimal(value, java.math.MathContext.UNLIMITED))
implicit val encodeJsonNumberBigDecimal: EncodeJsonNumber[BigDecimal] =
(value: BigDecimal) => new JsonBigDecimal(value)
}
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