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Add Generators For Hex Char And String Values #470

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Aug 29, 2019
Merged

Add Generators For Hex Char And String Values #470

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17 changes: 17 additions & 0 deletions jvm/src/test/scala/org/scalacheck/GenSpecification.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -270,6 +270,11 @@ object GenSpecification extends Properties("Gen") with GenSpecificationVersionSp
charType == Character.MODIFIER_SYMBOL || charType == Character.OTHER_SYMBOL
}

property("hexChar") = forAll(hexChar){ ch =>
val l: Long = java.lang.Long.parseLong(ch.toString, 16)
l < 16 && l >= 0
}

property("identifier") = forAll(identifier) { s =>
s.length > 0 && s(0).isLetter && s(0).isLower &&
s.forall(_.isLetterOrDigit)
Expand Down Expand Up @@ -312,6 +317,18 @@ object GenSpecification extends Properties("Gen") with GenSpecificationVersionSp
}
}

property("hexStr") = forAll(hexStr) { s =>
if (s.size > 0) {
Try(BigInt(new java.math.BigInteger(s, 16))) match {
case Success(bi) => bi >= BigInt(0L)
case _ => false
}
}
else {
true
}
}

// BigDecimal generation is tricky; just ensure that the generator gives
// its constructor valid values.
property("BigDecimal") = forAll { _: BigDecimal => true }
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18 changes: 16 additions & 2 deletions src/main/scala/org/scalacheck/Gen.scala
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Expand Up @@ -694,7 +694,7 @@ object Gen extends GenArities with GenVersionSpecific {
choose(1, gs.length+2).flatMap(pick(_, g1, g2, gs: _*))

/** A generator that randomly picks a given number of elements from a list
*
*
* The elements are not guaranteed to be permuted in random order.
*/
def pick[T](n: Int, l: Iterable[T]): Gen[collection.Seq[T]] = {
Expand Down Expand Up @@ -722,7 +722,7 @@ object Gen extends GenArities with GenVersionSpecific {
}

/** A generator that randomly picks a given number of elements from a list
*
*
* The elements are not guaranteed to be permuted in random order.
*/
def pick[T](n: Int, g1: Gen[T], g2: Gen[T], gn: Gen[T]*): Gen[Seq[T]] = {
Expand Down Expand Up @@ -766,6 +766,15 @@ object Gen extends GenArities with GenVersionSpecific {
/** Generates a ASCII printable character */
def asciiPrintableChar: Gen[Char] = choose(32.toChar, 126.toChar)

/** Generates a character that can represent a valid hexadecimal digit. This
* includes both upper and lower case values.
*/
def hexChar: Gen[Char] =
Gen.oneOf(
Gen.oneOf("0123456789abcdef".toSeq),
Gen.oneOf("0123456789ABCDEF".toSeq)
)

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This could be:

  def hexChar: Gen[Char] =  Gen.frequency(
    10 -> Gen.oneOf('0' to '9'),
     3 -> Gen.oneOf('a' to 'f'),
     3 -> Gen.oneOf('A' to 'F'))

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I agree. I was trying to be consistent with the rest of the file.

//// String Generators ////

/** Generates a string that starts with a lower-case alpha character,
Expand Down Expand Up @@ -803,6 +812,11 @@ object Gen extends GenArities with GenVersionSpecific {
def asciiPrintableStr: Gen[String] =
listOf(asciiPrintableChar).map(_.mkString)

/** Generates a string that can represent a valid hexadecimal digit. This
* includes both upper and lower case values.
*/
def hexStr: Gen[String] =
listOf(hexChar).map(_.mkString)

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This produces a lengthy string by default (up to 100?). That works for your test with BigInteger, but may not for when people want byte, int or long from hex?

I guess you've copied the definition of Gen.numStr. I guess it has these same sort of problems.

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Again, I agree. I did this for consistency. That being said, I'm not too worried about this. If people want to create a String which represents a bounded type, such as i32, then it would be consistent with current idioms to just map on this generator.

//// Number Generators ////

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