replpp.shaded.pprint.Util.scala Maven / Gradle / Ivy
package replpp.shaded.pprint
import replpp.shaded.fansi
import scala.annotation.{switch, tailrec}
object Util{
def concat[T](is: (() => Iterator[T])*) = new ConcatIterator(is.iterator.map(_()), () => Iterator.empty)
/**
* Basically a fast, efficient `.flatten` or `mkString` for nested iterators
*
* For some reason, the default way of concatenation e.g.
*
* val middle = first ++ lastChildIter ++ sep ++ remaining
*
* Was throwing weird NullPointerExceptions I couldn't figure out =(
*
* Also, ++ didn't seem to be sufficiently lazy, so it was forcing
* things earlier than it really needed to. It isn't documented anywhere
* how lazy it's meant to be, whereas `ConcatIterator` here is obviously
* lazy and won't even evaluate each iterator until you ask it to
*/
class ConcatIterator[T](it0: Iterator[Iterator[T]], joiner: () => Iterator[T]) extends Iterator[T]{
var head: Iterator[T] = null
var count = 0
@tailrec private[this] def check(): Boolean = {
if (head != null && head.hasNext) true
else if (!it0.hasNext) false
else {
if (count % 2 == 0) head = it0.next()
else head = joiner()
count += 1
check()
}
}
def hasNext = check()
def next() = {
check()
head.next()
}
}
def isOperator(ident: String) = {
(ident.size > 0) && (ident(0) match{
case '<' | '~' | '!' | '@' | '#' | '%' |
'^' | '*' | '+' | '-' | /*'<' | */
'>' | '?' | ':' | '=' | '&' |
'|' | '/' | '\\' => true
case _ => false
})
}
def escapeChar(c: Char,
sb: StringBuilder,
unicode: Boolean = true) = (c: @switch) match {
case '"' => sb.append("\\\"")
case '\\' => sb.append("\\\\")
case '\b' => sb.append("\\b")
case '\f' => sb.append("\\f")
case '\n' => sb.append("\\n")
case '\r' => sb.append("\\r")
case '\t' => sb.append("\\t")
case c =>
if (c < ' ' || (c > '~' && unicode)) sb.append("\\u%04x" format c.toInt)
else sb.append(c)
}
/**
* Convert a string to a C&P-able literal. Basically
* copied verbatim from the uPickle source code.
*/
def literalize(s: IndexedSeq[Char], unicode: Boolean = true) = {
val sb = new StringBuilder
sb.append('"')
var i = 0
val len = s.length
while (i < len) {
Util.escapeChar(s(i), sb, unicode)
i += 1
}
sb.append('"')
sb.result()
}
}