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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2006-2011, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.util.parsing.input
import scala.collection.immutable.PagedSeq
/** An object encapsulating basic character constants.
*
* @author Martin Odersky
* @author Adriaan Moors
*/
object PagedSeqReader {
final val EofCh = '\032'
}
/** A character array reader reads a stream of characters (keeping track of their positions)
* from an array.
*
* @param seq the source sequence
* @param offset starting offset.
*
* @author Martin Odersky
*/
class PagedSeqReader(seq: PagedSeq[Char],
override val offset: Int) extends Reader[Char] {
import PagedSeqReader._
override lazy val source: java.lang.CharSequence = seq
/** Construct a `PagedSeqReader` with its first element at
* `source(0)` and position `(1,1)`.
*/
def this(seq: PagedSeq[Char]) = this(seq, 0)
/** Returns the first element of the reader, or EofCh if reader is at its end
*/
def first =
if (seq.isDefinedAt(offset)) seq(offset) else EofCh
/** Returns a PagedSeqReader consisting of all elements except the first
*
* @return If `atEnd` is `true`, the result will be `this`;
* otherwise, it's a `PagedSeqReader` containing the rest of input.
*/
def rest: PagedSeqReader =
if (seq.isDefinedAt(offset)) new PagedSeqReader(seq, offset + 1)
else this
/** The position of the first element in the reader.
*/
def pos: Position = new OffsetPosition(source, offset)
/** true iff there are no more elements in this reader (except for trailing
* EofCh's).
*/
def atEnd = !seq.isDefinedAt(offset)
/** Returns an abstract reader consisting of all elements except the first
* `n` elements.
*/
override def drop(n: Int): PagedSeqReader =
new PagedSeqReader(seq, offset + n)
}
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