Scala regex find/replace with additional formatting -

i'm trying replace parts of string contains should dates, possibly in impermissible format. specifically, of dates in form "mm/dd/yyyy" , need in form "yyyy-mm-dd". 1 caveat original dates may not exactly in mm/dd/yyyy format; "5/6/2015". example, if

val x = "where date >= '05/06/2017'" 

then

x.replaceall("'([0-9]{1,2})/([0-9]{1,2})/([0-9]{4})'", "'$3-$1-$2'") 

performs desired replacement (returns "2017-05-06"), for

val y = "where date >= '5/6/2017'" 

this not return desired replacement (returns "2017-5-6" -- me, invalid representation). joda time wrapper nscala-time, i've tried capturing dates , reformatting them:

import com.github.nscala_time.time.imports._ import org.joda.time.datetime  val f = datetimeformat.forpattern("yyyy-mm-dd") y.replaceall("'([0-9]{1,2}/[0-9]{1,2}/[0-9]{4})'",    "'"+f.print(datetimeformat.forpattern("mm/dd/yyyy").parsedatetime("$1"))+"'") 

but fails java.lang.illegalargumentexception: invalid format: "$1". i've tried using f interpolator , padding 0s, doesn't seem either.

are not able additional processing on captured groups ($1, etc.) inside replaceall? if not, how else can achieve desired result?

the $1 backreferences can used inside string replacement patterns. in code, "$1" not backreference longer.

you may use "callback" replaceallin match object , access groups further manipulate them:

val pattern = "'([0-9]{1,2}/[0-9]{1,2}/[0-9]{4})'".r y = pattern replaceallin (y, m => "'"+f.print(datetimeformat.forpattern("mm/dd/yyyy").parsedatetime(m.group(1)))+"'")