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Scala example source code file (Streamable.scala)

This example Scala source code file (Streamable.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

bufferedreader, bytes, chars, codec, collection, inputstream, inputstreamreader, io, iterator, mutable, string, t, u

The Streamable.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2005-2013 LAMP/EPFL
 * @author Paul Phillips

package scala
package reflect
package io

import{ URI, URL }
import{ BufferedInputStream, InputStream, PrintStream }
import{ BufferedReader, InputStreamReader, Closeable => JCloseable }
import{ Codec, BufferedSource, Source }
import scala.collection.mutable.ArrayBuffer

/** Traits for objects which can be represented as Streams.
 *  @author Paul Phillips
 *  @since  2.8
 *  ''Note:  This library is considered experimental and should not be used unless you know what you are doing.''
object Streamable {
  /** Traits which can be viewed as a sequence of bytes.  Source types
   *  which know their length should override def length: Long for more
   *  efficient method implementations.
   *  ''Note:  This library is considered experimental and should not be used unless you know what you are doing.''
  trait Bytes {
    def inputStream(): InputStream
    def length: Long = -1

    def bufferedInput() = new BufferedInputStream(inputStream())
    def bytes(): Iterator[Byte] = bytesAsInts() map (_.toByte)
    def bytesAsInts(): Iterator[Int] = {
      val in = bufferedInput()
      Iterator continually takeWhile (_ != -1)

    /** This method aspires to be the fastest way to read
     *  a stream of known length into memory.
    def toByteArray(): Array[Byte] = {
      // if we don't know the length, fall back on relative inefficiency
      if (length == -1L)
        return (new ArrayBuffer[Byte]() ++= bytes()).toArray

      val arr = new Array[Byte](length.toInt)
      val len = arr.length
      lazy val in = bufferedInput()
      var offset = 0

      def loop() {
        if (offset < len) {
          val read =, offset, len - offset)
          if (read >= 0) {
            offset += read
      try loop()
      finally in.close()

      if (offset == arr.length) arr
      else fail("Could not read entire source (%d of %d bytes)".format(offset, len))

  /** For objects which can be viewed as Chars.
   * ''Note:  This library is considered experimental and should not be used unless you know what you are doing.''
  trait Chars extends Bytes {
    /** Calls to methods requiring byte<->char transformations should be offered
     *  in a form which allows specifying the codec.  When it is not specified,
     *  the one discovered at creation time will be used, which will always find the
     *  one in if no other is available.  This can be overridden
     *  to use a different default.
    def creationCodec: Codec = implicitly[Codec]

    def chars(codec: Codec): BufferedSource = Source.fromInputStream(inputStream())(codec)

    def lines(): Iterator[String] = lines(creationCodec)
    def lines(codec: Codec): Iterator[String] = chars(codec).getLines()

    /** Obtains an InputStreamReader wrapped around a FileInputStream.
    def reader(codec: Codec): InputStreamReader = new InputStreamReader(inputStream(), codec.charSet)

    /** Wraps a BufferedReader around the result of reader().
    def bufferedReader(): BufferedReader = bufferedReader(creationCodec)
    def bufferedReader(codec: Codec) = new BufferedReader(reader(codec))

    /** Creates a BufferedReader and applies the closure, automatically closing it on completion.
    def applyReader[T](f: BufferedReader => T): T = {
      val in = bufferedReader()
      try f(in)
      finally in.close()

    /** Convenience function to import entire file into a String.
    def slurp(): String = slurp(creationCodec)
    def slurp(codec: Codec) = {
      val src = chars(codec)
      try src.mkString finally src.close()  // Always Be Closing

  /** Call a function on something Closeable, finally closing it. */
  def closing[T <: JCloseable, U](stream: T)(f: T => U): U =
    try f(stream)
    finally stream.close()

  def bytes(is: => InputStream): Array[Byte] =
    (new Bytes {
      def inputStream() = is

  def slurp(is: => InputStream)(implicit codec: Codec): String =
    new Chars { def inputStream() = is } slurp codec

  def slurp(url: URL)(implicit codec: Codec): String =

Other Scala source code examples

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