Re: [Pharo-dev] Fraction and ScaledDecimal should be not be serialized as Float in STON format

Oct. 10, 2018

      Sorry, I forgot to answer. This change is indeed really nice.

Thank you for it!

Cheers,

Julien

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Julien Delplanque
Doctorant Ã  lâUniversitÃ© de Lille
http://juliendelplanque.be/phd.html
Equipe Rmod, Inria
BÃ¢timent B 40, Avenue Halley 59650 Villeneuve d'Ascq
NumÃ©ro de tÃ©lÃ©phone: +333 59 35 86 40
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Le 9 oct. 2018 Ã  21:22, Sven Van Caekenberghe <sven@stfx.eu> a Ã©crit :
I decided to add it for real:
https://github.com/svenvc/ston/commit/9c83e3cc2f00cab83e57f2e10a139d6ecef3cb...
add support for Fraction and ScaledDecimal as direct numeric literals (in STON mode, not in JSON mode) with units tests
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On 25 Sep 2018, at 14:13, Sven Van Caekenberghe <sven@stfx.eu> wrote:
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On 18 Sep 2018, at 16:45, Sven Van Caekenberghe <sven@stfx.eu> wrote:
Of course, we could also extend the basic number parser and allow the native (stored) notation
1/3
3/2s2
Note how that last one should use the more exact #storeOn: notation, not the #printOn:
I'll have to think about this a bit more, as I can really not choose right now.
I am still not sure if we should do this or not, but here is a POC implementation of the above.
It implements the following syntax extension (see the class comment of STON for the rest).
number
int
int denominator
int denominator scale
int frac
int exp
int frac exp
denominator
/ digits
scale
s digits
STONWriter>>#writeFraction: fraction
  jsonMode
      ifTrue: [ self writeFloat: fraction asFloat ] 
      ifFalse: [
      	writeStream
      		print: fraction numerator;
      		nextPut: $/;
      		print: fraction denominator ]
STONWriter>>#writeScaledDecimal: scaledDecimal
  jsonMode
      ifTrue: [ self writeFloat: scaledDecimal asFloat ]
      ifFalse: [ 
      	writeStream
      		print: scaledDecimal numerator;
      		nextPut: $/;
      		print: scaledDecimal denominator;
      		nextPut: $s;
      		print: scaledDecimal scale ]
Fraction>>#stonOn: stonWriter
  stonWriter writeFraction: self
ScaledDecimal>>#stonOn: stonWriter
  stonWriter writeScaledDecimal: self
STONReader>>parseNumber
  | negated number |
  negated := readStream peekFor: $-.
  number := self parseNumberInteger.
  (readStream peekFor: $/)
      ifTrue: [ 
      	number := Fraction numerator: number denominator: self parseNumberInteger.
      	(readStream peekFor: $s)
      		ifTrue: [ number := ScaledDecimal newFromNumber: number scale: self parseNumberInteger ] ]
      ifFalse: [ 
      	(readStream peekFor: $.)
      		ifTrue: [ number := number + self parseNumberFraction ].
      	((readStream peekFor: $e) or: [ readStream peekFor: $E ])
      		ifTrue: [ number := number * self parseNumberExponent ] ].
  negated
      ifTrue: [ number := number negated ].
  self consumeWhitespace.
  ^ number
Sven