Brace expansion: Difference between revisions
Content added Content deleted
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{}} some }{,{\\ edge \,}{ cases, {here} \\\\\}
{}} some }{,{\\ edge \,}{ cases, {here} \\\\\}
</pre>
=={{header|Scala}}==
{{works with|Scala|2.11}}
<lang scala>
import collection.mutable.ListBuffer
case class State(isChild: Boolean, alts: ListBuffer[String], rem: List[Char])
def expand(s: String): Seq[String] = {
def parseGroup(s: State): State = s.rem match {
case Nil => s.copy(alts = ListBuffer("{" + s.alts.mkString(",")))
case ('{' | ',')::sp =>
val newS = State(true, ListBuffer(""), rem = sp)
val elem = parseElem(newS)
elem.rem match {
case Nil => elem.copy(alts = elem.alts.map(a => "{" + s.alts.map(_ + ",").mkString("") + a))
case elemrem => parseGroup(s.copy(alts = (s.alts ++= elem.alts), rem = elem.rem))
}
case '}'::sp =>
if (s.alts.isEmpty) s.copy(alts = ListBuffer("{}"), rem = sp)
else if(s.alts.length == 1) s.copy(alts = ListBuffer("{"+s.alts.head + "}"), rem = sp)
else s.copy(rem = sp)
case _ => throw new Exception("parseGroup should be called only with delimitors")
}
def parseElem(s: State): State = s.rem match {
case Nil => s
case '{'::sp =>
val ys = parseGroup(State(true, ListBuffer(), s.rem))
val newAlts = for { x <- s.alts; y <- ys.alts} yield x + y
parseElem(s.copy(alts = newAlts, rem = ys.rem))
case (',' | '}')::_ if s.isChild => s
case '\\'::c::sp => parseElem(s.copy(alts = s.alts.map(_ + '\\' + c), rem = sp))
case c::sp => parseElem(s.copy(alts = s.alts.map(_ + c), rem = sp))
}
parseElem(State(false, ListBuffer(""), s.toList)).alts
}
</lang>
Demonstrating:
<lang scala>
println(expand("""~/{Downloads,Pictures}/*.{jpg,gif,png}""") mkString "\n")
println(expand("It{{em,alic}iz,erat}e{d,}, please.") mkString "\n")
println(expand("""{,{,gotta have{ ,\, again\, }}more }cowbell!""") mkString "\n")
println(expand("""{}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\}""") mkString "\n")
</lang>
{{out}}
<pre>
~/Downloads/*.jpg
~/Downloads/*.gif
~/Downloads/*.png
~/Pictures/*.jpg
~/Pictures/*.gif
~/Pictures/*.png
Itemized, please.
Itemize, please.
Italicized, please.
Italicize, please.
Iterated, please.
Iterate, please.
cowbell!
more cowbell!
gotta have more cowbell!
gotta have\, again\, more cowbell!
{}} some }{,\\ edge \,{ cases, {here} \\\\\}
{}} some }{,\\ edge \,{ cases, {here} \\\\\}
</pre>
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