Scala example source code file (AbstractFile.scala)

This example Scala source code file (AbstractFile.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 scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

abstractfile, boolean, collection, jfile, mutable, none, option, plainfile, reflection, string, tried, url, utilities, ziparchive

The AbstractFile.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2005-2013 LAMP/EPFL
 * @author  Martin Odersky
 */


package scala
package reflect
package io

import java.io.{ FileOutputStream, IOException, InputStream, OutputStream, BufferedOutputStream, ByteArrayOutputStream }
import java.io.{ File => JFile }
import java.net.URL
import scala.collection.mutable.ArrayBuffer
import scala.reflect.internal.util.Statistics

/**
 * An abstraction over files for use in the reflection/compiler libraries.
 *
 * ''Note:  This library is considered experimental and should not be used unless you know what you are doing.''
 *
 * @author Philippe Altherr
 * @version 1.0, 23/03/2004
 */
object AbstractFile {
  /** Returns "getFile(new File(path))". */
  def getFile(path: String): AbstractFile = getFile(File(path))
  def getFile(path: Path): AbstractFile = getFile(path.toFile)

  /**
   * If the specified File exists and is a regular file, returns an
   * abstract regular file backed by it. Otherwise, returns `null`.
   */
  def getFile(file: File): AbstractFile =
    if (file.isFile) new PlainFile(file) else null

  /** Returns "getDirectory(new File(path))". */
  def getDirectory(path: Path): AbstractFile = getDirectory(path.toFile)

  /**
   * If the specified File exists and is either a directory or a
   * readable zip or jar archive, returns an abstract directory
   * backed by it. Otherwise, returns `null`.
   */
  def getDirectory(file: File): AbstractFile =
    if (file.isDirectory) new PlainFile(file)
    else if (file.isFile && Path.isExtensionJarOrZip(file.jfile)) ZipArchive fromFile file
    else null

  /**
   * If the specified URL exists and is a readable zip or jar archive,
   * returns an abstract directory backed by it. Otherwise, returns
   * `null`.
   */
  def getURL(url: URL): AbstractFile = {
    if (url == null || !Path.isExtensionJarOrZip(url.getPath)) null
    else ZipArchive fromURL url
  }

  def getResources(url: URL): AbstractFile = ZipArchive fromManifestURL url
}

/**
 * <p>
 *   This class and its children serve to unify handling of files and
 *   directories. These files and directories may or may not have some
 *   real counter part within the file system. For example, some file
 *   handles reference files within a zip archive or virtual ones
 *   that exist only in memory.
 * </p>
 * <p>
 *   Every abstract file has a path (i.e. a full name) and a name
 *   (i.e. a short name) and may be backed by some real File. There are
 *   two different kinds of abstract files: regular files and
 *   directories. Regular files may be read and have a last modification
 *   time. Directories may list their content and look for subfiles with
 *   a specified name or path and of a specified kind.
 * </p>
 * <p>
 *   The interface does <b>not</b> allow to access the content.
 *   The class `symtab.classfile.AbstractFileReader` accesses
 *   bytes, knowing that the character set of classfiles is UTF-8. For
 *   all other cases, the class `SourceFile` is used, which honors
 *   `global.settings.encoding.value`.
 * </p>
 *
 * ''Note:  This library is considered experimental and should not be used unless you know what you are doing.''
 */
abstract class AbstractFile extends Iterable[AbstractFile] {

  /** Returns the name of this abstract file. */
  def name: String

  /** Returns the path of this abstract file. */
  def path: String

  /** Returns the path of this abstract file in a canonical form. */
  def canonicalPath: String = if (file == null) path else file.getCanonicalPath

  /** Checks extension case insensitively. */
  def hasExtension(other: String) = extension == other.toLowerCase
  private lazy val extension: String = Path.extension(name)

  /** The absolute file, if this is a relative file. */
  def absolute: AbstractFile

  /** Returns the containing directory of this abstract file */
  def container : AbstractFile

  /** Returns the underlying File if any and null otherwise. */
  def file: JFile

  /** An underlying source, if known.  Mostly, a zip/jar file. */
  def underlyingSource: Option[AbstractFile] = None

  /** Does this abstract file denote an existing file? */
  def exists: Boolean = {
    if (Statistics.canEnable) Statistics.incCounter(IOStats.fileExistsCount)
    (file eq null) || file.exists
  }

  /** Does this abstract file represent something which can contain classfiles? */
  def isClassContainer = isDirectory || (file != null && (extension == "jar" || extension == "zip"))

  /** Create a file on disk, if one does not exist already. */
  def create(): Unit

  /** Delete the underlying file or directory (recursively). */
  def delete(): Unit

  /** Is this abstract file a directory? */
  def isDirectory: Boolean

  /** Does this abstract file correspond to something on-disk? */
  def isVirtual: Boolean = false

  /** Returns the time that this abstract file was last modified. */
  def lastModified: Long

  /** returns an input stream so the file can be read */
  def input: InputStream

  /** Returns an output stream for writing the file */
  def output: OutputStream

  /** Returns a buffered output stream for writing the file - defaults to out */
  def bufferedOutput: BufferedOutputStream = new BufferedOutputStream(output)

  /** size of this file if it is a concrete file. */
  def sizeOption: Option[Int] = None

  def toURL: URL = if (file == null) null else file.toURI.toURL

  /** Returns contents of file (if applicable) in a Char array.
   *  warning: use `Global.getSourceFile()` to use the proper
   *  encoding when converting to the char array.
   */
  @throws(classOf[IOException])
  def toCharArray = new String(toByteArray).toCharArray

  /** Returns contents of file (if applicable) in a byte array.
   */
  @throws(classOf[IOException])
  def toByteArray: Array[Byte] = {
    val in = input
    sizeOption match {
      case Some(size) =>
        var rest = size
        val arr = new Array[Byte](rest)
        while (rest > 0) {
          val res = in.read(arr, arr.length - rest, rest)
          if (res == -1)
            throw new IOException("read error")
          rest -= res
        }
        in.close()
        arr
      case None =>
        val out = new ByteArrayOutputStream()
        var c = in.read()
        while(c != -1) {
          out.write(c)
          c = in.read()
        }
        in.close()
        out.toByteArray()
    }
  }

  /** Returns all abstract subfiles of this abstract directory. */
  def iterator: Iterator[AbstractFile]

  /** Returns the abstract file in this abstract directory with the specified
   *  name. If there is no such file, returns `null`. The argument
   *  `directory` tells whether to look for a directory or
   *  a regular file.
   */
  def lookupName(name: String, directory: Boolean): AbstractFile

  /** Returns an abstract file with the given name. It does not
   *  check that it exists.
   */
  def lookupNameUnchecked(name: String, directory: Boolean): AbstractFile

  /** Return an abstract file that does not check that `path` denotes
   *  an existing file.
   */
  def lookupPathUnchecked(path: String, directory: Boolean): AbstractFile = {
    lookup((f, p, dir) => f.lookupNameUnchecked(p, dir), path, directory)
  }

  private def lookup(getFile: (AbstractFile, String, Boolean) => AbstractFile,
                     path0: String,
                     directory: Boolean): AbstractFile = {
    val separator = java.io.File.separatorChar
    // trim trailing '/'s
    val path: String = if (path0.last == separator) path0 dropRight 1 else path0
    val length = path.length()
    assert(length > 0 && !(path.last == separator), path)
    var file = this
    var start = 0
    while (true) {
      val index = path.indexOf(separator, start)
      assert(index < 0 || start < index, ((path, directory, start, index)))
      val name = path.substring(start, if (index < 0) length else index)
      file = getFile(file, name, if (index < 0) directory else true)
      if ((file eq null) || index < 0) return file
      start = index + 1
    }
    file
  }

  private def fileOrSubdirectoryNamed(name: String, isDir: Boolean): AbstractFile = {
    val lookup = lookupName(name, isDir)
    if (lookup != null) lookup
    else {
      val jfile = new JFile(file, name)
      if (isDir) jfile.mkdirs() else jfile.createNewFile()
      new PlainFile(jfile)
    }
  }

  /**
   * Get the file in this directory with the given name,
   * creating an empty file if it does not already existing.
   */
  def fileNamed(name: String): AbstractFile = {
    assert(isDirectory, "Tried to find '%s' in '%s' but it is not a directory".format(name, path))
    fileOrSubdirectoryNamed(name, isDir = false)
  }

  /**
   * Get the subdirectory with a given name, creating it if it
   * does not already exist.
   */
  def subdirectoryNamed(name: String): AbstractFile = {
    assert (isDirectory, "Tried to find '%s' in '%s' but it is not a directory".format(name, path))
    fileOrSubdirectoryNamed(name, isDir = true)
  }

  protected def unsupported(): Nothing = unsupported(null)
  protected def unsupported(msg: String): Nothing = throw new UnsupportedOperationException(msg)

  /** Returns the path of this abstract file. */
  override def toString() = path

}