Scala example source code file (SourceFile.scala)

This example Scala source code file (SourceFile.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

abstractfile, array, array, batchsourcefile, boolean, int, int, io, offsetposition, position, position, regex, scriptsourcefile, sourcefile, string, string

The Scala SourceFile.scala source code

/* NSC -- new Scala compiler
 * Copyright 2005-2011 LAMP/EPFL
 * @author  Martin Odersky
 */


package scala.tools.nsc
package util

import io.{ AbstractFile, VirtualFile }
import scala.collection.mutable.ArrayBuffer
import annotation.tailrec
import java.util.regex.Pattern
import java.io.IOException
import Chars._

/** abstract base class of a source file used in the compiler */
abstract class SourceFile {
  def content : Array[Char]         // normalized, must end in SU
  def file    : AbstractFile
  def isLineBreak(idx : Int) : Boolean
  def isSelfContained: Boolean
  def length : Int
  def position(offset: Int) : Position = {
    assert(offset < length, file + ": " + offset + " >= " + length)
    new OffsetPosition(this, offset)
  }
  def position(line: Int, column: Int) : Position = new OffsetPosition(this, lineToOffset(line) + column)
  def offsetToLine(offset: Int): Int 
  def lineToOffset(index : Int): Int
  /** Map a position to a position in the underlying source file.
   *  For regular source files, simply return the argument.
   */
  def positionInUltimateSource(position: Position) = position
  override def toString(): String = file.name /* + ":" + content.length */
  def dbg(offset: Int) = (new OffsetPosition(this, offset)).dbgString
  def path = file.path

  def beginsWith(offset: Int, text: String): Boolean =
    (content drop offset) startsWith text

  def lineToString(index: Int): String =
    content drop lineToOffset(index) takeWhile (c => !isLineBreakChar(c.toChar)) mkString
    
  @tailrec
  final def skipWhitespace(offset: Int): Int =  
    if (content(offset).isWhitespace) skipWhitespace(offset + 1) else offset
  
  def identifier(pos: Position): Option[String] = None
}

object ScriptSourceFile {
  /** Length of the script header from the given content, if there is one.
   *  The header begins with "#!" or "::#!" and ends with a line starting
   *  with "!#" or "::!#".
   */
  def headerLength(cs: Array[Char]): Int = {
    val headerPattern = Pattern.compile("""^(::)?!#.*(\r|\n|\r\n)""", Pattern.MULTILINE)
    val headerStarts  = List("#!", "::#!")
    
    if (headerStarts exists (cs startsWith _)) {
      val matcher = headerPattern matcher cs.mkString
      if (matcher.find) matcher.end
      else throw new IOException("script file does not close its header with !# or ::!#")
    }
    else 0
  }
  def stripHeader(cs: Array[Char]): Array[Char] = cs drop headerLength(cs)
  
  def apply(file: AbstractFile, content: Array[Char]) = {
    val underlying = new BatchSourceFile(file, content)
    val headerLen = headerLength(content)
    val stripped = new ScriptSourceFile(underlying, content drop headerLen, headerLen)
    
    stripped
  }
}
import ScriptSourceFile._

class ScriptSourceFile(underlying: BatchSourceFile, content: Array[Char], override val start: Int) extends BatchSourceFile(underlying.file, content) {  
  override def isSelfContained = false

  override def positionInUltimateSource(pos: Position) =
    if (!pos.isDefined) super.positionInUltimateSource(pos)
    else new OffsetPosition(underlying, pos.point + start)
}

/** a file whose contents do not change over time */
class BatchSourceFile(val file : AbstractFile, val content: Array[Char]) extends SourceFile {
  
  def this(_file: AbstractFile)                 = this(_file, _file.toCharArray)
  def this(sourceName: String, cs: Seq[Char])   = this(new VirtualFile(sourceName), cs.toArray)
  def this(file: AbstractFile, cs: Seq[Char])   = this(file, cs.toArray)
    
  override def equals(that : Any) = that match {
    case that : BatchSourceFile => file.path == that.file.path && start == that.start
    case _ => false
  }
  override def hashCode = file.path.## + start.##
  val length = content.length
  def start = 0
  def isSelfContained = true

  override def identifier(pos: Position) = 
    if (pos.isDefined && pos.source == this && pos.point != -1) {
      def isOK(c: Char) = isIdentifierPart(c) || isOperatorPart(c)
      Some(new String(content drop pos.point takeWhile isOK))
    } else {
      super.identifier(pos)
    }
  
  def isLineBreak(idx: Int) =
    if (idx >= length) false else {
      val ch = content(idx)
      // don't identify the CR in CR LF as a line break, since LF will do.
      if (ch == CR) (idx + 1 == length) || (content(idx + 1) != LF)
      else isLineBreakChar(ch)
    }

  def calculateLineIndices(cs: Array[Char]) = {
    val buf = new ArrayBuffer[Int]
    buf += 0
    for (i <- 0 until cs.length) if (isLineBreak(i)) buf += i + 1
    buf += cs.length // sentinel, so that findLine below works smoother
    buf.toArray
  }  
  private lazy val lineIndices: Array[Int] = calculateLineIndices(content)  

  def lineToOffset(index : Int): Int = lineIndices(index)

  private var lastLine = 0

  /** Convert offset to line in this source file
   *  Lines are numbered from 0
   */
  def offsetToLine(offset: Int): Int = {
    val lines = lineIndices
    def findLine(lo: Int, hi: Int, mid: Int): Int =
      if (offset < lines(mid)) findLine(lo, mid - 1, (lo + mid - 1) / 2)
      else if (offset >= lines(mid + 1)) findLine(mid + 1, hi, (mid + 1 + hi) / 2)
      else mid
    lastLine = findLine(0, lines.length, lastLine)
    lastLine
  }
}