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SI-10148 Follow Java for float literals #5648

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Feb 16, 2017
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SI-10148 Follow Java for float literals #5648

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4 changes: 2 additions & 2 deletions src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1263,8 +1263,8 @@ self =>
case CHARLIT => in.charVal
case INTLIT => in.intVal(isNegated).toInt
case LONGLIT => in.intVal(isNegated)
case FLOATLIT => in.floatVal(isNegated).toFloat
case DOUBLELIT => in.floatVal(isNegated)
case FLOATLIT => in.floatVal(isNegated)
case DOUBLELIT => in.doubleVal(isNegated)
case STRINGLIT | STRINGPART => in.strVal.intern()
case TRUE => true
case FALSE => false
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34 changes: 28 additions & 6 deletions src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
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Expand Up @@ -972,23 +972,45 @@ trait Scanners extends ScannersCommon {

def intVal: Long = intVal(negated = false)

/** Convert current strVal, base to double value
/** Convert current strVal, base to float value.
*/
def floatVal(negated: Boolean): Double = {
val limit: Double = if (token == DOUBLELIT) Double.MaxValue else Float.MaxValue
def floatVal(negated: Boolean): Float = {
try {
val value: Double = java.lang.Double.valueOf(strVal).doubleValue()
if (value > limit)
val value: Float = java.lang.Float.parseFloat(strVal)
if (value > Float.MaxValue)
syntaxError("floating point number too large")
val zeroly = "0.fF"
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if (value == 0.0f && strVal.exists(c => !zeroly.contains(c)))
syntaxError("floating point number too small")
if (negated) -value else value
} catch {
case _: NumberFormatException =>
syntaxError("malformed floating point number")
0.0f
}
}

def floatVal: Float = floatVal(negated = false)

/** Convert current strVal, base to double value.
*/
def doubleVal(negated: Boolean): Double = {
try {
val value: Double = java.lang.Double.parseDouble(strVal)
if (value > Double.MaxValue)
syntaxError("double precision floating point number too large")
val zeroly = "0.dD"
if (value == 0.0d && strVal.exists(c => !zeroly.contains(c)))
syntaxError("double precision floating point number too small")
if (negated) -value else value
} catch {
case _: NumberFormatException =>
syntaxError("malformed double precision floating point number")
0.0
}
}

def floatVal: Double = floatVal(negated = false)
def doubleVal: Double = doubleVal(negated = false)

def checkNoLetter(): Unit = {
if (isIdentifierPart(ch) && ch >= ' ')
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14 changes: 13 additions & 1 deletion test/files/neg/literals.check
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Expand Up @@ -19,6 +19,18 @@ literals.scala:23: error: missing integer number
literals.scala:27: error: Decimal integer literals may not have a leading zero. (Octal syntax is obsolete.)
def tooManyZeros: Int = 00 // line 26: no leading zero
^
literals.scala:40: error: floating point number too small
def tooTiny: Float = { 0.7e-45f } // floating point number too small
^
literals.scala:42: error: double precision floating point number too small
def twoTiny: Double = { 2.0e-324 } // double precision floating point number too small
^
literals.scala:44: error: floating point number too large
def tooHuge: Float = { 3.4028236E38f } // floating point number too large
^
literals.scala:46: error: double precision floating point number too large
def twoHuge: Double = { 1.7976931348623159e308 } // double precision floating point number too large
^
literals.scala:14: error: identifier expected but '}' found.
def orphanDot: Int = { 9. } // line 12: ident expected
^
Expand All @@ -37,4 +49,4 @@ literals.scala:29: error: ';' expected but 'def' found.
literals.scala:33: error: identifier expected but 'def' found.
def zeroOfNineDot: Int = 09. // line 32: malformed integer, ident expected
^
13 errors found
17 errors found
13 changes: 12 additions & 1 deletion test/files/neg/literals.scala
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@

/* This took me literally all day.
*/
*/
trait RejectedLiterals {

def missingHex: Int = { 0x } // line 4: was: not reported, taken as zero
Expand Down Expand Up @@ -34,3 +34,14 @@ trait Braceless {

def noHexFloat: Double = 0x1.2 // line 34: ';' expected but double literal found.
}

trait MoreSadness {

def tooTiny: Float = { 0.7e-45f } // floating point number too small

def twoTiny: Double = { 2.0e-324 } // double precision floating point number too small

def tooHuge: Float = { 3.4028236E38f } // floating point number too large

def twoHuge: Double = { 1.7976931348623159e308 } // double precision floating point number too large
}
5 changes: 5 additions & 0 deletions test/files/run/literals.scala
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Expand Up @@ -84,6 +84,10 @@ object Test {
check_success("3.14f == 3.14f", 3.14f, 3.14f)
check_success("6.022e23f == 6.022e23f", 6.022e23f, 6.022e23f)
check_success("09f == 9.0f", 09f, 9.0f)
check_success("1.00000017881393421514957253748434595763683319091796875001f == 1.0000001f",
1.00000017881393421514957253748434595763683319091796875001f,
1.0000001f)
check_success("3.4028235E38f == Float.MaxValue", 3.4028235E38f, Float.MaxValue)
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Why no check using Float.MinValue? Probably demonstrating my ignorance of something here!

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My name isn't ScalaCheck. Also, the difference is just a sign bit which is turned on by a leading midlevel horizontal bar symbol. Of course, the test wouldn't hurt.

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@janekdb janekdb Jan 18, 2017 •
edited

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Ignorance of IEEE 754 fully demoed (by me)! Java MIN_VALUE is not the negative float with the greatest magnitude but the smallest positive nonzero value.

https://docs.oracle.com/javase/7/docs/api/java/lang/Float.html#MIN_VALUE

Having said that why not add a check for the effect of a leading hyphen-minus?

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OK, if I have time to switch my repo back to this branch on my old home machine.

There's a puzzler (BTW) that turns on the fact that -1.0f is a literal. See here.

check_success("1.asInstanceOf[Float] == 1.0", 1.asInstanceOf[Float], 1.0f)
check_success("1l.asInstanceOf[Float] == 1.0", 1l.asInstanceOf[Float], 1.0f)

Expand All @@ -97,6 +101,7 @@ object Test {
check_success("3.14 == 3.14", 3.14, 3.14)
check_success("1e-9d == 1.0e-9", 1e-9d, 1.0e-9)
check_success("1e137 == 1.0e137", 1e137, 1.0e137)
check_success("1.7976931348623157e308d == Double.MaxValue", 1.7976931348623157e308d, Double.MaxValue)
check_success("1.asInstanceOf[Double] == 1.0", 1.asInstanceOf[Double], 1.0)
check_success("1l.asInstanceOf[Double] == 1.0", 1l.asInstanceOf[Double], 1.0)

Expand Down