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/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Paul Phillips
*/
package scala.tools.nsc
package interpreter
package session
import scala.tools.nsc.io._
import FileBackedHistory._
/** TODO: file locking.
*/
trait FileBackedHistory extends JLineHistory with JPersistentHistory {
def maxSize: Int
protected lazy val historyFile: File = defaultFile
private var isPersistent = true
locally {
load()
}
def withoutSaving[T](op: => T): T = {
val saved = isPersistent
isPersistent = false
try op
finally isPersistent = saved
}
def addLineToFile(item: CharSequence): Unit = {
if (isPersistent)
append(item + "\n")
}
/** Overwrites the history file with the current memory. */
protected def sync(): Unit = {
val lines = asStrings map (_ + "\n")
historyFile.writeAll(lines: _*)
}
/** Append one or more lines to the history file. */
protected def append(lines: String*): Unit = {
historyFile.appendAll(lines: _*)
}
def load(): Unit = {
if (!historyFile.canRead)
historyFile.createFile()
val lines: IndexedSeq[String] = {
try historyFile.lines().toIndexedSeq
catch {
// It seems that control characters in the history file combined
// with the default codec can lead to nio spewing exceptions. Rather
// than abandon hope we'll try to read it as ISO-8859-1
case _: Exception =>
try historyFile.lines("ISO-8859-1").toIndexedSeq
catch { case _: Exception => Vector() }
}
}
repldbg("Loading " + lines.size + " into history.")
// avoid writing to the history file
withoutSaving(lines takeRight maxSize foreach add)
// truncate the history file if it's too big.
if (lines.size > maxSize) {
repldbg("File exceeds maximum size: truncating to " + maxSize + " entries.")
sync()
}
moveToEnd()
}
def flush(): Unit = ()
def purge(): Unit = historyFile.truncate()
}
object FileBackedHistory {
// val ContinuationChar = '\003'
// val ContinuationNL: String = Array('\003', '\n').mkString
import Properties.userHome
def defaultFileName = ".scala_history"
def defaultFile: File = File(Path(userHome) / defaultFileName)
}
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